Properties of Zeolites as Cataystics

Properties of Zeolites as Cataystics 1.0 INTRODUCTION TO ZEOLITES Zeolites are crystalline aluminosilicates, composed of TO4 tetrahedra (T = Si, Al) with O atoms connecting neighbouring tetrahedral, that contain pores and cavities of molecular dimensions (Breck, 1974). Many occur as natural minerals, but it is the synthetic varieties which are among the most widely used sorbents, catalysts and ion-exchange materials in the world (Barrer, 1982). The channels are large enough to allow the passage of guest species. In the hydrated phases, dehydration occurs at temperatures mostly below about 400 °C and is largely reversible. The framework may be interrupted by (OH, F) groups: these occupy a tetrahedron apex that is not shared with adjacent tetrahedra. Zeolites are different from other porous hydrates, as they retain their structural integrity upon loss of water. The Structure Commission of the International Zeolite Association identifies each framework with a three-letter mnemonic code (Baerlocher et al., 2001) e.g. Amicite- GSI; Faujasite- FAU etc. 1.1 IMPORTANCE OF GREEN PROCESSES In the chemical industry, the acceptability of a process is not only governed by cost and yield but in terms of eco-friendliness and pollution abatement. Choosing a more efficient catalytic route has greatly improved the efficiency of chemical processes. Green chemistry has been defined as the design of chemical products and processes in order to reduce or eliminate the generation of hazardous substances (Armor, 1999). The principles of green chemistry listed by Armor (1999) employs future approaches to new chemical processes. It includes: efficient use of raw materials, energy efficiency, use of biodegradable products and other subtle features. 2.0 HISTORICAL DEVELOPMENT OF ZEOLITES 2.1 NATURAL ZEOLITES Research in the field of zeolite science and technology made its first steps with natural zeolites and was mostly focused on natural zeolites until the beginning of the 1950s. The history of zeolites began in 1756 when Swedish mineralogist A.F. Cronstedt discovered the first zeolite mineral, stilbite when studying its apparent properties discovered its strange behaviour upon heating although there is no certain proof of its identity. The term ‘zeolite was coined from two Greek words, ‘zeo (to boil) and ‘lithos (stone). On the contrary, the first zeolite, chabazite, described by Bosch DAntic in 1792 has clear evidence in literature. Several other zeolites were discovered in the following years and around 1850, only about 20 zeolite types were reported in mineralogy books, including analcime, brewsterite, chabazite, edingtonite, epistilbite, faujasite, gismondine, gmelinite, harmotome, heulandite, laumontite, levyne, mesolite, natrolite, phillipsite, scolecite, stilbi te, and thomsonite. Starting from the middle of the 19th century until about 1975, there was a moderate increment in the number of zeolites discovered (about one new type every 6-7 years) and a clear acceleration in the last twenty five-thirty years. About 40 natural zeolites are known (Tschernich, 1992). Most zeolites known to occur in nature are of lower Si/Al ratios, since organic structure-directing agents necessary for formation of siliceous zeolites are absent. Sometimes natural zeolites are found as large single crystals, though are very difficult to make in the laboratory. The catalytic activity of natural zeolites is limited by their impurities and low surface areas. However, interests in natural zeolites shifted towards zeolite synthesis and synthetic materials, as they offered a series of advantages such as wider versatility, more open frameworks( for adsorption and catalysis),and quality in constitution and chemistry. As a result, research on natural zeolites, was mainly devoted to ion exchange process which was discovered around 1850 (Thompson, 1850; Way, 1850). Few years later, Eichhorn observed that chabazite and natrolite behaved as reversible ion exchangers. In the early decades of the 20th century, ion exchange selectivity of a variety of zeolites for peculiar cations, e.g., ammonium was performed (Barrer, 1950) and starting from the end of the 1950s, found uses in various sectors of environmental relevance, e.g., treatment of wastewaters and soil rebuilding and remediation. The most recent frontier in the application of natural zeolites is in the field of life sciences. One of the drawbacks of natural zeolite research for application purposes is due to the limited availability of zeolite as it is a precious mineral, compared to the synthetic counterparts which could be mass produced at a lower cost (Colella, 2005). 2.1.1 Formation The pathway of natural zeolite formation is similar to the laboratory synthesis of zeolite. Zeolite nucleation, crystallisation and crystal growth take place as a result of slow to fast cooling of warm to hot magmas(of volcanic origin), which are basic, oversaturated in silicate and aluminate species and contain alkaline and/or alkali-earth cations. hot fluid + volcanic ash oversaturated basic magma zeolite crystals {solution + gel) The magma is obtained via hydrolysis of the original glassy material and is responsible for the tetrahedral coordination of aluminium and together with silicon. The main factors responsible for the structural formation are temperature, chemistry of the ash and the chemical composition of the resulting solution. Gel is formed along the process but is however not directly connected to nucleation and growth, as there is evidence that zeolite nuclei form from the oversaturated solution at the glass shards / solution interface (Aiello et al., 1980). Temperature and time are two factors which differentiate natural zeolitisation from laboratory synthesis. 2.1.2 Physico-chemical properties i.Cation exchange: The ion exchange properties of natural zeolites depend on their chemistry which ismainly in terms of selectivity. Selectivity depends on the framework topology, ion size and shape, charge density on the anionic framework, ion valence and electrolyte concentration in the aqueous phase (Barrer et al., 1978). ii.Reactions with alkalis: Oncein alkaline environments, zeolites become unstable as they tend to transform, similarlyto glassy systems, into more stable phases, usually into other framework silicates (Goto and Sand, 1988). The interaction of zeolite-rich materials with Ca(OH)2 give rise to calcium silicates and aluminates, which upon hydration are able to harden in both aerial and aqueous environments. This behaviour makes them to be known as pozzolanic materials Thermal properties: Heating of zeolite powder induces physical and chemical changes, which have been shown to include water loss (which causes expansion on heating), decomposition and gas evolution, phase transition, structure breakdown, re-crystallisation, melting etc (Colella, 1998). This property enables zeolite tuff stones to display good sound-proofing and heat insulation and serve as good building materials. Depending on zeolite nature, chemical composition and rock constitution, the tuff expands as a result of quick heating at temperatures of 1250 °C or above, inadvertently followed by a rapid quenching to room temperature. 2.2 SYNTHETIC ZEOLITES Early work could be traced back to the claimed synthesis of levynite by St Claire Deville in 1862 as there were no reliable methods for fully identifying and characterising the products. The origin of zeolite synthesis however, evolved from the work of Richard Barrer and Robert Milton which commenced in the late 1940s. The first synthetic zeolite unknown as a natural mineral later found to have the KFI structure (Baerlocher et al., 2001 ) was discovered by Barrer when investigating the conversion of known mineral phases under the action of strong salt solutions at fairly high temperatures (ca. 170-270  °C). Robert Milton was the first person to use freshly precipitated aluminosilicate gels to carry out reactions under milder conditions. This led to the discovery of zeolites A and X (Milton et al., 1989). Initially, the synthesis of zeolites required the use of only inorganic reactants but was however expanded in 1961 to include quaternary ammonium cations leading to the discovery o f silica-rich phases (high-silica zeolites). Subsequently, more synthetic zeolites have been discovered (Baerlocher et al., 2001), as well as zeolite-like or zeolite-related materials (Szostak, 1989) known as zeotypes- represented by microporous alumino- and gallo phosphates (AlPO4s and GaPO4s) and titanosilicates. Studies on understanding zeolite synthesis have continued to be carried out upto the present day (Table 1). This has been due to discoveries of new materials, advances in synthetic procedures, innovations in theoretical modelling methods and, especially, by the development of new techniques for the investigation of reaction mechanisms and the characterisation of products. Table 1: Evolution of materials development in the zeolite field ‘‘Low Si/Al zeolites (1-1.5) A, X ‘‘Intermediate Si/Al zeolites (f2-5) A) Natural zeolites: erionite, chabazite, clinoptilolite, Mordenite Synthetic zeolites: Y, L, large-pore mordenite, omega ‘‘High Si/Al zeolites (ËÅ"10-100) By thermochemical framework modification: highly silicious variants of Y, mordenite, erionite By direct synthesis: ZSM-5, Silicate Silica molecular sieves silicalite Source: Flanigen (1980) 2.2.1 Mechanism of Hydrothermal Synthesis Experimental observations of a typical hydrothermal zeolite synthesis Due to its chemical reactivity and low cost, amorphous and oxide-like Si and Al which make up the microporous framework are mixed with a cation source usually, in a basic water-based medium. The resulting aqueous mixture is then heated in a sealed autoclave at above 100ËšC allowing the reactants to remain amorphous for sometime (induction period) after which crystalline zeolites are detected (Figure 2). Gradually, an approximately equal mass of zeolite crystals which is recovered by filtration, washing and drying replaces all the amorphous materials (Cundy and Cox, 2005).The bond type created in the crystalline zeolite product (e.g. zeolite A or ZSM-5) which contains Si-O-Al linkages is similar to that present in its precursor oxides, therefore the enthalpy change is not great. This process reduces nucleation rates, thereby forming larger crystals. Reactivity of the gel, temperature and pH affect the rate of zeolite formation as an increase in pH and temperature leads to increase in the rate of formation of zeolite crystals. In their mother liquors, the zeolitic phases are metastable, thereby transforming the initial zeolite into an undesired thermodynamically more stable phase (Ullmann, 2002). 2.2.3 Synthesis from Clay minerals Kaolin and metakaolin (calcining kaolin at 500-700 °C) are two important clays used for the production of the zeolites NaA, NaX, and NaY (Breck, 1974; Barrer, 1978) because binder-free extrudates and granules which offer advantages in adsorption technology are produced. 2Al2Si2O5(OH)4 2Al2Si2O7+4H2O Kaolin Metakaolin Depending on the zeolite, the clay is shaped and, SiO2and seed crystals are added and while in the preformed shape, the zeolite crystallises. Alternatively, zeolite is formed when the binder component of metakaolin undergoes hydrothermal treatment with sodium hydroxide solution (Goytisolo et al., 1973; Chi and Hoffman, 1977). Using ultrasonic radiation, reaction rate is enhanced and there is energy saving and lower production cost due to lower temperatures. This process is less often used as it could cause odor of the product due to impurities present in clay e.g. iron 2.2.2 Industrial Zeolite Synthesis Zeolite synthesis is an extremely broad area of research and due to differences in the preparation of each zeolite type, two representative zeolite types, TPA-ZSM-5 and zeolite Na-A, are chosen for a more detailed presentation of the synthesis {Table 2} (Jansen, 2001). Table 2: Synthesis mixtures, physical chemical properties of the representative zeolites Molar oxide ratio Na-A TPA-ZSM-5 SiO2 1 1 Al2O3 0.5 Na2O 1 0.16 H2O 17 49 TPA2O 0.3 T (ËšC) > 150 Physical Chemical properties Pore arrangements 3D, cages connected via windows 2D, intersecting channels Bronsted activity low High Affinity hydrophilic Hydrophobic Pore volume (cm3/g) 0.37 0.18 Source: Jansen (2001) The composition of zeolite product can be expressed by the cation type and its overall Si/Al ratio. In the preparation of zeolite, nucleation is the rate determining step which is influenced by a range of factors dependent on the temperature of the reaction mixture. Low Temperature Reaction Mixture: Here, the reaction mixture is prepared at low temperature, At high pH, condensation occurs when the nucleophilic deprotonated silanol group on monomeric neutral species is attacked (Figure 5). The acidity of the silanol group depends on the number and type of substituents on the silicon-atom (Jansen, 2001). Temperature raise of the reaction mixture from High Temperature Reaction Mixture: At this temperature, zeolites are formed from amorphous material which involves, reorganisation of the low temperature synthesis mixture, nucleation and precipitation (crystallisation). During the induction period, gel and species in solution rearrange from a continuous changing phase of monomers and clusters which disappears through hydrolysis and condensation, in which nucleation occurs (Jansen, 2001). The process particles become stable and nuclei forms, followed by crystallisation which could occur in metastable solid, highly dispersed or dense gel forms. Product quality, reaction time and yield influence efficient production of zeolites by optimising their composition. 2.2.2 Secondary Synthesis Methods Catalytic or adsorbent properties that cannot be achieved by direct synthesis utilise post-synthesis (secondary) treatments to increase catalytic activity, shape selectivity or porosity and thermal/hydrothermal stability. Dealumination and ion exchange are used to carry out these modifications. Dealumination The zeolite structure is selectively dealuminated by acid solutions, washing out aluminium out of the crystal, as was observed for zeolite A. However, for higher silica containing materials (clinoptilolite), a fully decationated structure is produced after continuous acid treatment. The metal ion is replaced with H3O+ followed by (Al+3 + H3O+) removal, generating a hydroxyl nest. Aluminium is removed from the framework but not the crystal by hydrothermal dealumination. The heterogeneity in the concentration of the framework and non-framework of aluminium depends on the type of modification used. Hydrothermal treatment causes the amorphous aluminium to collect on the crystal surface which through fluorosilicate treatment can reduce aluminium centred acid sites. Often, a secondary pore system is generated and hydroxyl nests can be annealed. In order to enhance the catalytic properties as well as stability, silicon, aluminium and other metal ions are introduced into the framework (Szostak, 2001). Other methods of producing thermally and hydrothermally stable cracking catalysts include: use of EDTA, SiCl4 vapor, and (NH4)2SiF6. Acid mediated dealumination process via aluminium extraction and generation of hydroxyl nest (Szostak, 2001) Ion Exchange This is an important technique in pore-size engineering for the production of zeolitic adsorbents (Breck, 1974). Ion exchange used in the production of Brà ¸nsted acid sites has major importance in the synthesis of solid acid catalysts (Ullmann, 2002). Ion exchange can be achieved also, for certain intermediate-silica and high-silica zeolites (e.g., mordenite) by treatment with mineral acids although involves the risk of dealuminating the zeolite framework (McDaniel and Maher, 1976). An indirect route via an ion exchange with ammonium salt solutions must be followed, producing the â€Å"ammonium form† calcined at ca. 400 °C to liberate ammonia and give the hydrogen form (Ullmann, 2002). When cations to be exchanged are positioned inaccessible cages, a sieve effect is produced. pH is an important factor in ion exchanging of highly charged transition metal ions in order to prevent metal hydroxide precipitation especially at low pH. 2.3 CHARACTERISATION OF ZEOLITES In order to determine the relationships between the physical and physicochemical as well as sorptive and catalytic properties of zeolites, it is important to know the structural, chemical and catalytic characteristics of zeolites. Several standard techniques are employed in zeolite characterisation. The most common of which is X-ray diffraction used in determining the structure and purity of zeolites. Others include: x-ray fluorescence spectroscopy (XRF) or atomic absorption spectrometry, used to analyze elemental composition, sorption analysis to study the pore system, IR-spectroscopy, typically using adsorbed probe molecules to characterize the acid sites, scanning electron microscopy (SEM), for determining the size and morphology of zeolite crystallites, high-resolution transmission electron microscopy (HRTEM), nuclear magnetic resonance (NMR) spectroscopy, temperature programme desorption (TPD) and many others (Schà ¼th, 2005). 3.0 GENERAL APPLICATIONS OF ZEOLITES Zeolites are used primarily in 3 major applications: ion-exchange, adsorbents, and catalysts. Natural zeolites play an important role in bulk mineral applications. Adsorbent applications: Common adsorbent applications focus on removal of small polar molecules and bulk separations, by more aluminous zeolites and based on molecular sieving processes respectively (Table 3). Table 3: Zeolite commercial applications as adsorbents Purification Bulk separations Drying: natural gas (including LNG), cracking gas (ethylene plants), refrigerant Normal/iso-paraffin separation, Xylene separation CO2 removal: natural gas, flue gas (CO2 + N2) cryogenic air separation plants Olefin separation, Separation of organic solvents Pollution abatement: removal of Hg, NOx, SO Separation of amino acids, n-nitrosoamines Sweetening of natural gas and liquefied petroleum gas Separation of CO2, SO2, NH3 Source: Flanigen (1980). Catalyst applications: Zeolites have the greatest use in catalytic cracking. They also play a role in hydroisomerisation, hydrocracking and aromatics processing. The strong acidity of zeolites plays a role in hydrocarbon processing. Asides this, they are finding increasing use in synthesis of fine chemicals and organic intermediates in isomerisation reactions, nucleophilic substitution and addition etc. Table 4: Zeolite applications in Catalysis Inorganic reactions: H2S oxidation, NO reduction of NH3, CO oxidation, reduction Hydrocarbon conversion: Alkylation, Cracking Organic reactions: Aromatization (C4 hydrocarbons), Aromatics (disproportionation, hydroalkylation, hydrogenation, hydroxylation, nitration, etc.) Dehydration Epoxidation Beckman rearrangement (cyclohexanone to caprolactam) Methanol to gasoline Chlorofluorocarbon decomposition Shape-selective reforming Source: Flanigen (1980); Galarneau et al (2001). Ion-exchange applications: Zeolite properties are directly exploited in several applications such as in the detergent industry, where zeolites are used for water softening or ‘building, animal food supplementation and in the treatment of wastewater (Townsend and Coker, 2001). Zeolite A has selectivity for Ca2+, thereby providing a unique advantage. Also, natural zeolites can be used to remove of Cs+ and Sr 2+radioisotopes through ion-exchange (Payra and Dutta, 2003). Table 5: Applications and advantages of Ion-exchange Applications Advantage Metals removal and recovery High selectivities for various metals Removal of Cs+ and Sr2+ Stable to ionizing radiation Detergent builder zeolite A, zeolite X (ZB-100, ZB-300) Remove Ca2+ and Mg2+ by selective exchange, no environmental problem Ion exchange fertilizers Exchange with plant nutrients such as NH4+ and K+ with slow release in soil Source: Flanigen (1980) Other Applications: Zeolites also play important roles in health-related applications (such as antibacterial agents, vaccine adjuvants, drug delivery, bone formation, biosensors and enzyme mimetics), oil refining, and petrochemical processes. Zeolite powders are used for odor removal and as plastic additives. Zeolitic membranes offer the possibility of organic transformations and separations coupled into one unit (Payra and Dutta, 2003). 3.1 ZEOLITES AND THE ENVIRONMENT Nearly all applications of zeolites are driven by environmental concerns, from cleaning toxic (nuclear) wastes, to treatment of wastewater, thereby reducing pollution. Zeolites have now been used to replace harmful phosphate builders in powder detergents due to water pollution risks. Zeolite catalysts help to save energy as they make chemical processes more efficient, minimising un-necessary waste and by-products. When used as solid catalysts and redox catalysts/sorbents, they reduce the need for corrosive liquid acids and remove atmospheric pollutants, (such as engine exhaust gases and ozone-depleting CFCs) respectively (Bell, 2001). In wastewater, zeolites (clinoptilolite, mordenite) are used to remove ammonia and ammonium ions (Townsend and Coker, 2001), as well as heavy metal cations and transition metals. 3.2 ZEOLITE CATALYSTS IN GREEN CHEMISTRY Zeolite catalysts have contributed to the design and synthesis of novel materials and development of new methodologies in organic synthesis, displacing the conventional and waste generating reagents thereby maximising atom utilization and reducing waste generated (E-factor). Zeolites play an important role in acid-catalyzed reactions such as acylation, alkylation, isomerisation and condensation, cyclisation and electrophilic aromatic substitution. Acylation of aromatic substrates: used in fine chemicals manufacture although has proven unsuccessful in less reactive aromatic compounds due to adsorption imbalance, unless performed in vapor phase using H-ZSM-5 (Singh and Pandey, 1997). 4.0 CONCLUSION Due to the role zeolites play mainly as catalysts in the environment as well as in chemical industry, the efficiency of the zeolite catalysts has been greatly improved. The yield and selectivity of the zeolite process is quantitative and in addition, reduces energy requirements, capital costs and complexity of equipments. Over the years, the synthesis process of zeolites have encompassed the principles of green chemistry as described in the report which has included waste prevention, energy efficiency, fewer environmental impacts, safer solvents, renewable materials, process intensification, catalysis and reduction in capital cost. Though present techniques seem to apply some of the principles of green chemistry, further research is still being employed to improve the overall process. 3.0 REFERENCES Aiello, R., Colella, C., Casey, D. G. and Sand, L.B. 1980. In L.V.C. Rees, ed. Proc. 5th Int. Conf. on Zeolites. Heyden Son, London, U.K. pp. 49. Armor, J. N. Applied Catalysis A: 189 (1999) 153-162. Baerlocher, C., Meier, W.M., Holson, D. 2001. Atlas of Zeolite Framework Types. 5th ed. Amsterdam: Elsevier. Barrer, R. M. 1978.Zeolite and Clay Minerals as Sorbents and Molecular Sieves. Academic Press, London. Barrer, R.M. 1978. In L.B. Sand and F.A. Mumpton, eds. Natural Zeolites. Occurrence, Properties, Use. Pergamon Press, Elmsford, NY. pp. 385. Barrer, R.M. 1982. Hydrothermal Chemistry of Zeolites; Academic Press: London. Barrer, R.M. J. Chem. Soc. (1950) 2342. Bell, R.G. 2001. Zeolites. [Online]Available at http://www.bza.org/zeolites.html. [Accessed 1 May 2010]. Breck, D.W. 1974. Zeolite Molecular Sieves. New York: Wiley. Colella, C. 1998. In J. Ma. Rincon and M. Romero, eds. Characterization Techniques of Glasses and Ceramics. Springer-Verlag, Berlin Heidelberg, Germany. pp. 112. Colella, C. 2005. Natural zeolites. In J. Cejka and H. van Bekkum, eds.Stud Surf Sci Catal 157. Cundy, C. S., Cox, P. A. 2003 .The Hydrothermal Synthesis of Zeolites: History and Development from the Earliest Days to the Present Time. Chem. Rev.103, pp.663-701. Cundy, C.S. and Cox, P.A. 2005. The hydrothermal synthesis of zeolites: Precursors, intermediates and reaction mechanism. Microporous and Mesoporous Materials. 82, 1-78. Damour, A., Hebd, C. R. Seances Acad. Sci. 44 (1857), pp. 975; also Ann. Chim. Phys., 3rd series, 53 (1858), pp. 438 (in French). De Gennaro, M., Colella, C., Franco, E. and Stanzione, D. Neues Jahrb. Mineral.-Mon.hefte. H.4(1988)149. Flanigen, E.M. 1980. Pure Appl Chem 52:2191-2211. Galarneau, A., Di Renzo, F., Fajula, F., Vedrine, J. eds., 2001. Zeolites and Mesoporous Materials at the Dawn of the 21st Century. Stud Surf Sci Catal 135. Goto and L.B. Sand. 1988. In D. Kallo and H.S. Sherry, eds. Occurrence, Properties and Utilisations of Natural Zeolites. Akademiai Kiado, Budapest, Hungary. pp. 161. Jansen, J.C. 2001. The preparation of oxide molecular sieves: synthesis of zeolites. In H. Van Bekkum, E.M. Flanigen, P.A. Jacobs, J.C. Jansen, eds. Introduction to zeolite science and practice.2nd ed. Stud Surf Sci Catal 137. Lancaster, M. 2002. Green Chemistry: an introductory text. Cambridge: Royal society of chemistry. Ch.4. McDaniel, C.V., Maher, P.K. In J. A. Rabo, ed. Zeolite Chemistry and Catalysis. ACS Monogr.171(1976) pp.285 Milton, R.M. In M.L. Occelli, H.E. Robson, eds. Zeolite Synthesis. ACS Symp. Ser. 398 (1989) pp.1 Payra, P., Dutta, P.K. 2003. Zeolites: A Primer. In S.M. Auerbach, K. Carrado, P.K. Dutta, eds. Handbook of zeolite science and technology.New York: Marcel Dekker Inc. Ch.1. Schà ¼th, F. 2005. In J. Cejka and H. van Bekkum, eds. High-throughput experiments for synthesis and applications of zeolites. Stud Surf Sci Catal 157. Sheldon, R.A. 2000. A special topic issue on green chemistry: Atom efficiency and catalysis in organic synthesis. Pure Appl. Chem., 72(7), pp. 1233-1246. Singh, A. P., Pandey, A. K. J. Mol. Catal. A: Chemical 123(1997), 141 Szostak, R. 1989. Molecular Sieves Principles of Synthesis and Identification. 2nd Edition: Van Nostrand Reinhold, New York, Blackie, London. Thompson, H.S. J. Royal Agric. Soc. Engl. 11 (1850), pp. 68. Townsend, R.P., Coker, E.N. 2001. Ion exchange in zeolites. In H. Van Bekkum, E.M. Flanigen, P.A. Jacobs, J.C. Jansen, eds. Introduction to zeolite science and practice. 2nd ed. Stud Surf Sci Catal 137. Tschernich, R.W. 1992. Zeolites of the World. Phoenix: Geoscience Press. Ullmann: Encyclopaedia of Industrial Chemistry. 2002. Zeolites. Wiley Interscience. W.R. Grace Co., DE2707313, 1977 (C. W. Chi, G. H. Hoffman). W.R. Grace Co., US3906076, 1973 (J. A. Goytisolo, D. D. Chi, H. Lee). Way, J.T. J. Royal Agric. Soc. Engl. 11 (1850), pp. 313.

Data Protection Act 1998 and Broad Based Hr Essay

Assignment The main purpose of my current job role is the responsibility for processing all aspects of the Company’s payroll from start to finish and providing HR support to the other members of the team to ensure the effective day to day running of the HR function. This includes assisting with the recruitment of new staff and maintaining personnel records relating to employees in compliance with relevant legislation and regulation. To successfully undertake my role a wide range of skills, knowledge and behaviours are required.   The two professional areas Insight Strategy and Solutions and Leading HR are the heart of the profession and are the most important to all HR professionals. Very important is to understand the Company’s HR Strategy. The core of the Company’s HR strategy identifies two broad based HR objectives: Ensure that the talent and abilities of staff are recognised and developed to their full potential Ensure that the individual and collective skills and abilities of staff support the on-going delivery of Company objectives Develop understanding of the Company and use the insights to tailor strategy and solutions to meet organisational needs now and in the future Helping employees understand their role in change, the reason for it and the results that are expected In the design of the annual HR plans all members of the department work collaboratively to ensure the plans are challenging and deliver positive results for the company. As a leading HR it is important to support development plans and programmes. Provide advice confidently based on sound understanding of organisation’s policy and practice. Act as a role model leader, support, develop and measure others across the organisation. Work collaboratively with colleagues to deliver good policy, practice and advice. Employee engagement is important so that all employees have connection with their work, colleagues and to the organisation so that employees are more fulfilled by work and make a greater contribution towards organisational  objectives, therefore particular attention is needed to good leadership and management. To be effective in my role I need to refer to eight behaviours: 1. Curious- to be open to trying ideas reflect, analyse and test them and insight with others, take on board change, implement changes to payroll system and procedures try new ides 2. Decisive Thinker – analyse payroll data to ensure details and facts are correct, complete and consistent; use experience, standard procedure and common sense and knowledge to solve payroll problems while recognising limits of experience and authority within the organisation 3. Skilled influencer – understand how to influence within the culture, governance of performance framework and politics, identifying the key points to communicate on any interaction, selecting the right message and audience 4. Personally credible – improving own experience, knowledge, skills shearing it with colleagues, considering how to add value and ensure expertise is developed, accept and act on feedback on own performance to both criticism and praise 5. Collaborative – passing information promptly, keeping colleagues up to date, support them in their day-to-day work, handle disagreement as they occur, seeking a constructive solution, showing respect for diversity 6. Driven to deliver – identify the steps to achieve agreed tasks, goals and objectives in the immediate or short term, keep track of own progress, keeping deadlines or inform others when targets can’t be met, deliver to expectations and commitment, meeting or exceeding agreed standards 7. Courage to challenge – stand by own proposal in the face of difficult questions, providing supporting evidence, explore the full range of viewpoints, consult others when facing problems, undercover pertinent facts to move a debate forward 8. Role model – consistently act according to organisational and legal principles and agreed processes, deal with personal date and information in a highly professional manner and relevant legislation such as Data Pr otection Act, deliver expectations and promises Experience of processing all aspects of Payroll A good understanding of tax codes, tax and NI rates, thresholds, allowances  and deductions from pay Ability to calculate payroll manually A good understanding of SSP, SMP, SAP and Employment Law Experience of recruitment campaigns A good understanding of HR policies and procedures Ability to maintain confidentiality and ensure data protection principles are adhered to at all times Ability to work on own initiative and deal with difficult and sensitive situations Ability to organise and prioritise workload and to meet agreed deadlines and targets Excellent interpersonal skills

Was Convict Leasing a Form of Legalized Slavery

Convict leasing was a system of prison labor used mainly in the Southern United States from 1884 until 1928. In convict leasing, state-run prisons profited from contracting with private parties from plantations to corporations to provide them with convict labor. During the term of the contracts, the lessees—rather than the prisons—bore all cost and responsibility for overseeing, housing, feeding, and clothing the prisoners. Key Takeaways: Convict Leasing Convict leasing was an early system of prison labor that existed fromConvict leasing existed mainly in the Southern United States from 1884 until 1928.Convicts were typically leased to operators of plantations, railroads, and coal mines.The lessees assumed all costs of housing, feeding, and overseeing the convicts.The states profited greatly from convict leasing.Most leased convicts were recently-freed African American slaves.Many leased convicts suffered inhumane treatment.Public opinion, economic factors, and politics led to the abolishment of convict leasing.Convict leasing was justified by a loophole in the 13th Amendment.Most historians consider convict leasing to have been a form of state-sanctioned slavery. While it was first used by Louisiana as early as 1844, contract leasing spread quickly after the emancipation of slaves during the period of American Reconstruction following the end of the Civil War in 1865. As an example of how the states profited from the process, the percentage of Alabama’s total annual revenue generated from convict leasing increased from 10 percent  in 1846 to nearly 73 percent by 1889. As a result of aggressive and discriminatory enforcement of the numerous â€Å"Black Codes† laws passed in the South after the abolishment of slavery, the majority of prisoners leased out by the prisons were black. The practice of convict leasing extracted a substantial human cost, with death rates among leased convicts running about 10 times higher than death rates among prisoners in non-leasing states. During 1873, for example, 25 percent  of all black leased convicts died while serving their sentences. Despite its profitability to the states, convict leasing was slowly phased out during the late 19th and early 20th centuries largely due to negative public opinion and opposition from the growing labor union movement. While Alabama became the last state to end the official practice of convict leasing in 1928, several of its aspects remain as part of today’s growing prison industrial complex. The Evolution of Convict Leasing On top of its human toll, the Civil War left the South’s economy, government, and society in a shambles. Getting little sympathy or aid from the U.S. Congress, the Southern states struggled to raise money to repair or replace damaged infrastructure—including prisons—most of which had been destroyed during the war. Before the Civil War, the punishment of slaves had been the responsibility of their owners. However, with a general increase in both black and white lawlessness during post-emancipation reconstruction, the lack of available prison space became a significant and costly problem. Having elevated many petty misdemeanors to felonies requiring jail time, enforcement of the former-slave-targeted Black Code laws greatly increased the number of prisoners needing housing. As they struggled to build new prisons, some states tried paying private contractors to confine and feed convicts. Soon, however, the states realized that by leasing them out to plantation owners and industrialists, they could turn their prison population from a costly liability into a ready source of revenue. Markets for imprisoned workers soon evolved as private entrepreneurs bought and sold convict labor leases. The Ills of Convict Leasing Revealed Having only a small capital investment in convict workers, employers had little reason to treat them well compared to their regular employees. While they were aware that convict laborers were often subjected to inhumane living and working conditions, the states found convict leasing so profitable that they were hesitant to abandon the practice. In his book, â€Å"Twice the Work of Free Labor: The Political Economy of Convict Labor in the New South,† historian Alex Lichtenstein noted that while some northern states used convict leasing, only in the South was complete control of prisoners turned over to  the contractors, and only in the South did the places where convict laborers worked become known as â€Å"penitentiaries.† State officials neither had nor wanted any authority to oversee the treatment of leased prisoners, choosing instead to give the employers complete control over their working and living conditions. Coal mines and plantations were widely reported to have hidden burial grounds for the bodies of leased prisoners, many of whom had been beaten to death or left to die from work-related injuries. Witnesses told of organized gladiator-style fights to the death between convicts staged for the amusement of their overseers. In many cases, the court records of convict workers were lost or destroyed, leaving them unable to prove that they had served their sentences or repaid their debts.   The Abolition of Convict Leasing While reports of the evils and abuses of convict leasing in newspapers and journals brought increasing public opposition to the system at the start of the 20th century, state politicians fought to maintain it. Unpopular or not, the practice proved extremely profitable for the state governments and the businesses that used convict labor. Slowly, however, employers began to recognize the business-related disadvantages of forced convict labor, such as minimal productivity and lower quality of work. While public exposure of the inhumane treatment and suffering of convicts surely played a part, opposition from organized labor, legislative reform, political pressure, and economic realities ultimately spelled the end of convict leasing. After reaching its peak around 1880, Alabama became the last state to formally abolish state-sponsored convict leasing in 1928. In reality, however, convict labor had been more transformed than abolished. Still faced with the costs of housing prisoners, the states turned to alternative forms of convict labor, such as the infamous â€Å"chain gangs,† groups of convicts forced to work on public sector tasks such as road construction, ditch digging, or farming while chained together. Practices like chain gangs persisted until December 1941, when President Franklin D. Roosevelt’s Attorney General Francis Biddle’s â€Å"Circular 3591† directive clarified federal regulations for handling cases relating to involuntary servitude, slavery and peonage. Was Convict Leasing Just Slavery? Many historians and civil rights advocates contended that state officials had exploited a loophole in the 13th Amendment to allow convict leasing as a method of continuing slavery in the post-Civil war South. The 13th Amendment, ratified on December 6, 1865, states: â€Å"Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, nor any place subject to their jurisdiction.† In establishing convict leasing, however, the southern states applied the Amendment’s qualifying phrase â€Å"except as punishment for crime† in the infamous Black Codes laws to allow lengthy prison terms as punishment for a wide variety of minor crimes from vagrancy to simple indebtedness. Left without the food and housing provided by their former owners, and largely unable to find jobs due to post-war racial discrimination, many newly-freed African-American slaves fell victim to selective enforcement of the Black Codes laws. In his book, â€Å"Slavery by Another Name: The Re-Enslavement of Black Americans from the Civil War to World War II,† writer Douglas A. Blackmon contends that while it differed in ways from pre-emancipation slavery, convict leasing â€Å"was nonetheless slavery† calling it â€Å"a system in which armies of free men, guilty of no crimes and entitled by law to freedom, were compelled to labor without compensation, were repeatedly bought and sold, and were forced to do the bidding of white masters through the regular application of extraordinary physical coercion.† During its heyday, defenders of convict leasing contended that its Black convict laborers were actually â€Å"better off† than they had been as slaves. They claimed that by being forced to conform to rigid discipline, observe regular working hours, and acquire new skills, the former slaves would lose their â€Å"old habits† and finish their prison term better equipped to assimilate into society as freemen. Sources Alex Lichtenstein, Twice the Work of Free Labor: The Political Economy of Convict Labor in the New South, Verso Press, 1996Mancini, Matthew J. (1996). One Dies, Get Another: Convict Leasing in the American South, 1866-1928. Columbia, SC: Universiry of South Carolina PressBlackmon, Douglas A., Slavery by Another Name: The Re-Enslavement of Black Americans from the Civil War to World War II, (2008) ISBN 978-0-385-50625-0Litwack, Leon F., Trouble in Mind: Black Southerners in the Age of Jim Crow, (1998) ISBN 0-394-52778-X

Piaget s Theory Of Cognitive Development Theory - 1174 Words

Piaget’s Cognitive Development Theory describes the way that people collect and categorise information to make sense of their surroundings (Woolfolk Margetts 2013, p. 81). Piaget’s theory is known as constructivist as it is based on the idea that people are active in their own learning (Institute for Inquiry 2017). The theory is based around the idea that a thinking process change and develop from birth to adulthood. According to Piaget, there were four influences involved in the changes that thinking undertakes. These influences included biological maturation, activity, social experiences and equilibration (Kamii 1985, p. 574). He also identified four stages in which people cognitively developed: sensorimotor, preoperational, concrete†¦show more content†¦To teach this, an educator may give a demonstration. This will create disequilibrium as the information known to the children and what they are observing will be different. It will then be the educators job to explain what has happened and give reasoning so students can then have a state of equilibrium once again. The theory given by the teacher after the demonstration will be sorted into schemas, through either assimilation or adaptation. Piaget also hypothesised four different stages – sensorimotor, preoperational, concrete operational, and formal operational- in which children develop (Woolfolk Margetts 2013, p.83). It was thought that every person passes through the stages in the exact same order, never skipping a stage. The stages are often categorised by age, from birth to adulthood. However, it was stated that people may experience long periods between stages, and others may show characteristics from different stages at different times. The sensorimotor stage is approximately from ages zero to two years old and involves the development of thinking and understanding through the five senses, and movement. Object permanence, which is the understanding that objects exist whether they are seen or not, and goal-oriented actions areShow MoreRelatedPiaget s Theory Of Cognitive Development Theory745 Words   |  3 PagesPiaget s Theory of Cognitive Development Numerous papers have been written on Piaget’s Theory of Cognitive Development Theory. Most fall short of helping others understand what exactly Jean Piaget means when it comes to the three basic components to Piaget’s Cognitive Theory. These two articles I have chosen to use in this paper, give the best explanation on his theory. This paper will go into detail on the key concepts of Piaget’s Cognitive Theory and hopefully help others understand in itsRead MorePiaget s Theory Of Cognitive Development1289 Words   |  6 Pagesare many great cognitive theorists, but the one that comes to mind is a development psychologist by the name of Jean Piaget. One of his prized declaration was in 1934, where he declared that education is capable of saving our society from collapsing whether its violent or gradual. Piaget had a key effect on education and psychology, and because of that effect he made many contributions to learning and to cognition. One of most important c ontribution was a model that was made by Piaget. This modelRead MorePiaget s Cognitive Development Theory1077 Words   |  5 PagesAccording to Piaget (1957), cognitive development was a continuous restructuring of mental processes due to varied situations and experiencing the world and maturing biologically. His view of cognitive development would have us look inside a child’s head and glimpse the inborn process of change that thinking goes through. â€Å"He was mainly interested in the biological influences on â€Å"how we come to know’† (Huitt and Hummel, 2003). 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Piaget was a Swiss psychologist who was interested on why children would give similar but wrong answers in an intelligence test (Vidal, 1994). Based on his observations, he concluded that children undergo sequential cognitive development patterns which occur in defined stagesRead MorePiaget s Theory Of Cognitive Development969 Words   |  4 Pa ges20th century, the development of psychology is constantly expanding. Erikson and Piaget are two of the ealier well known theorist, both being significant in the field. Their belief s are outlined in Piaget s Cognitive Development Theory and Erikson s Psychosocial Development Theory. These theories, both similar and different, have a certain significance as the stages are outlined.Erikson and Piaget were similar in their careers and made huge progressions in child development and education. WithRead MorePiaget s Theory Of Cognitive Development Essay1790 Words   |  8 PagesCognitive developmental theories provide a framework for understanding about how children act and perceive the world. However, every theory has both strengths and weaknesses. A certain theory may explain one aspect of cognitive development very well, but poorly address or completely ignore other aspects that are just as important. Two well known theories of cognitive development are Piaget’s stage theor y and Vygotsky’s sociocultural theory. As I plan to be a pediatric nurse, these two theories willRead MorePiaget s Theory Of Cognitive Development1111 Words   |  5 PagesPiaget’s theory of cognitive development Piaget’s theory of cognitive development was based around his belief that children will develop their intelligence through a series of stages: Sensorimotor (birth – 2yrs), Preoperational (2-7yrs), Concrete Operational (7-11yrs) and Formal Operational (11+). He believed these stages to be invariant, the same stages taking place in a fixed order, and universal, the same for every child regardless of their background or culture. (McLeod, 2015) Piaget believedRead MorePiaget s Theory Of Cognitive Development1519 Words   |  7 Pagesrelates to both Piaget and Vygotskian theories in the sense that they describe how the child s mind develops through different forms of stimuli that occur during early childhood. Piaget s theory focuses mainly on things such as; how children think; how the world around them is perceived and how the newly found information is explained through the language they use. Vygotsky s theory however differs as the effects of different forms of social interaction occur in cognitive development such as; internalisation;Read MorePiaget s Theory Of Cognitive Development1325 Words   |  6 PagesJean Piaget developed a systematic study of cognitive development. 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