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Ion exchange is one of the methods used to remove heavy metal such as copper and cobalt from wastewaters. Parameters affecting the ion-exchange of copper and cobalt aqueous solutions using clinoptilolite are the objectives of this study. Synthetic solutions were prepared with the concentration of 0.02M, 0.06M and 0.1M. The cobalt solution was maintained to 0.02M while varying the copper solution to the above stated concentrations. The clinoptilolite was activated with HCl and H2SO4 for removal efficiency. The pHs of the solutions were found to be acidic hence enhancing the copper and cobalt removal. The natural clinoptilolite performance was also found to be lower compared to the HCl and H2SO4 activated one for the copper removal ranging from 68% to 78% of Cu2+ uptake with the natural clinoptilolite to 66% to 51% with HCl and H2SO4 respectively. It was found that the activated clinoptilolite removed more copper and cobalt than the natural one and found that the electronegativity of the metal plays a role in the metal removal and the clinoptilolite selectivity., {"references":["R.E. Clement,G.A. Eiceman, C.J. Koester, \"Environmental analysis\". J. Anal. Chem. 1995, vol.67,pp.221-255.","E. Muzenda, J. Kabuba,F. Ntuli, M. Mollagee and A.F. Mulaba-Bafubiandi, \"Cu (II) Removal from Synthetic Waste Water by Ion Exchange Process\", Proceedings of the WCECS, vol. II, 2011, Oct. 19-21, San Francisco, USA.","S.A. Abdulkareen, E. Muzenda, A.S. Afolabi , J. Kabuba, \" Treatment of clinoptilolite as an Adsorbent for the Removal of copper Ion from Synthetic Wastewater solution\", Arab. J. Sci. Eng., 2013, vol. 38, pp. 2263-2272.","A. Thanasiadis, B. Helmreich , \"Influence of chemical conditioning of the ion-exchange capacity and onnatural silicate minerals\",J. Clay Miner., 2005, vol. 38, pp. 501-509.","M. Kormaz, C. Ozmetin, B. Ali Fil, Y. Yasar,\"Determination of Parameters Affecting Copper Removal from Solution by Clinoptilolite: Adsorption Isotherm and Thermodynamic\",Igdir Univ. J. Inst. Sci& Tech. 2012, vol. 3, pp. 47-54","V.J. Inglezakis, A.A. Zorpas, M.D. Loizidou and H.P. Grigolopoulou, \"The effects of competitive cations and anions on ion exchange of heavy metals\", Separation Purification Technology, 2005, vol. 46, pp. 202-207.","J. Kabuba , A.F. Mulaba-Bafubiandi, K. Battle,\"A critical study of Neural networks Applied to ion-exchange Process\",World Academy of Science, Engineering and Technology, 2012, vol. 68, pp. 1226-1229.","M.A. Kuronem, A. Weller, \"Ion exchange selectivity and structural changes in highly aluminous zeolite\", React. Funct., 2006, vol. 66, pp. 1350-1361.","K.S. Hui, C.Y.H. Chao, S.C. Koi, \" Removal of heavy metal ions in wastewater by zeolite 4A and residual product from recycled coal fly ash\",J. Hazard. Mat., 2005, vol. B127, pp. 89-101.\n[10]\tB.B. Mamba, D.W. Nyembe and A.F. Mulala-Bafubiandi, \"The effects of conditioning withNaCl, KCl and HCl on the performance of natural clinoptilolite's removal efficiency of Cu2+ and Co2+ from Co/Cu synthetic solutions\", Water SA,2009, vol. 36, pp. 437-444\n[11]\tA. Yorukoglu, \"Influence of acid activation on the ion-exchange properties of the Manisa-gordesclinoptilolite\", Physicochemical problems of mineral processing, 2012, vol. 48, pp. 591-598."]}

Sulphur dioxide is a harmful gaseous product that needs to be minimized in the atmosphere. This research work investigates the use of zeolite as a possible additive that can improve the sulphur dioxide capture in wet flue gas desulphurisation dissolution process. This work determines the effect of temperature, solid to liquid ratio, acid concentration and stirring speed on the leaching of zeolite using a pH stat apparatus. The atomic absorption spectrometer was used to measure the calcium ions from the solution. It was found that the dissolution rate of zeolite decreased with increase in solid to liquid ratio and increases with increase in temperature, stirring speed and acid concentration. The activation energy for the dissolution rate of zeolite in hydrochloric acid was found to be 9.29kJ/mol. and therefore the product layer diffusion was the rate limiting step., {"references":["Z. Klimont, S. J. Smith and J. Cofala, \"The last decade of global\nanthropogenic sulfur dioxide: 2000–2011 emissions\", Environmental\nResearch Letters, 2013, vol. 14, pp. 1-3.","D. Kunkel, H. Tost and M. Lawrence, \"Impact of anthropogenic\nemissions from major population centers on global and regional aerosol\nbudgets\", .EGU General Assembly Conference Abstracts, 2013, vol.\n7083.","National Environmental Management, South Africa, Air and Quality\nAct, Act No. 30 of 2004, 2005.","C. You and Y. Li, \"Desulfurization Characteristics of Rapidly Hydrated\nSorbents with Various Adhesive Carrier Particles for a Semidry CFBFGD\nSystem\", Environ. Sci. Technol., 2013, vol. 47, pp. 2754-2759.","H. Song and J. Park, \"Improvement of SO2 removal by the solubility\nchange of Ca (OH)2 in the spray dryer system\" ,Environ. Technol., 2001,\nvol. 22, pp. 1001-1006.","H. Rutto and C. Enweremadu, \"A study on dissolution of a South\nAfrican calcium based material in acetic acid solution for flue gas\ndesulphurization\", Electrical and Control Engineering (ICECE)\nInternational Conference. 2011, pp. 5701-5705.","S. Shih, J. Lin and G. Shiau, \"Dissolution rates of limestones of\ndifferent sources\", J. Hazard. Mater., 2000, vol.79, pp.159-171.","Z. Siagi and M. Mbarawa., \"Dissolution rate of South African calciumbased\nmaterials at constant pH\", J. Hazard. Mater., 2009, vol.163,\npp.678-682.","H. Rutto and C. Enweremadu., \"The dissolution study of a South\nAfrican magnesium-based material from different sources using a pHstat',\nChemical Industry and Chemical Engineering Quarterly, 2011, vol.\n17, pp.459-468.\n[10] N. Karatepe, A. Mericboyu and S. Küçükbayrak, \"Effect of Hydration\nConditions on the Physical Properties of Fly Ash-Ca (OH)2 Sorbents\"\n,Energy Source. 1998, vol.20, pp. 505-511.\n[11] A. Garea, I. Fernandez, J. Viguri, M. Ortiz, J. Fernandez, M. Renedo and\nJ. Irabien, \"Fly-ash/calcium hydroxide mixtures for SO2 removal:\nstructural properties and maximum yield\", Chem. Eng. J., 1997, vol.66,\npp. 171-179.\n[12] C. Jorgensen, J.C.S. Chang and T.G. Brna, \"Evaluation of sorbents and\nadditives for dry SO2 removal\", Environmental Progress. 198, vol.6, pp.\n26–32.\n[13] N. Karatepe, N. Erdog˘an, A.E. Meriçboyu, S. Küçükbayrak,\n\"Preparation of diatomite/Ca(OH)2 sorbents and modelling their\nsulphation reaction\", Chemical Engineering Science. 2004, vol. 59, pp.\n3883-3889.\n[14] S.A. Abdulkareen, E. Muzenda, A.S. Afolabi , J. Kabuba, \" Treatment of\nclinoptilolite as an Adsorbent for the Removal of copper Ion from\nSynthetic Wastewater solution\", Arab. J. Sci. Eng., 2013, vol. 38, pp.\n2263-2272.\n[15] J.D. Gilchrist, Extraction Metallurgy, Pergamon Press.1989\n[16] B.B. Mamba, D.W. Nyembe and A.F. Mulaba-Bafubiandi, \"The effect\nof conditioning with NaCl, KCl and HCl on the performance of natural\nclinoptilolite's removal efficiency of Cu2+ and Co2+ Synthetic solution\",\nWater SA., 2009, vol. 36, pp. 437-444.\n[17] K.T. Lee, M.A. Mothar, N.F. Zainudin, S. Bhatia and A.R. Mohamed,\n\"Optimum conditions for the preparation of flue gas desulphurization\nsorbent from rice husk ash\", 2004, vol.84, pp. 143-151.\n[18] E.M. Van der Merwe and C. Strydom, \"Hydration of medium reactive\nmagnesium oxide using hydration agents\", Journal of Thermal Analysis\nand Calorimetry. 2006, vol. 84, pp. 467-471.\n[19] Z. I. Zafar. \"Determination of semi empirical kinetic model for \ndissolution of bauxite ore with sulfuric acid: Parametric cumulative \neffect on the Arrhenius parameters\", Chem. Eng. J., 2008, vol.141, \npp.233-241."]}

This paper presents a critical study about the application of Neural Networks to ion-exchange process. Ionexchange is a complex non-linear process involving many factors influencing the ions uptake mechanisms from the pregnant solution. The following step includes the elution. Published data presents empirical isotherm equations with definite shortcomings resulting in unreliable predictions. Although Neural Network simulation technique encounters a number of disadvantages including its "black box", and a limited ability to explicitly identify possible causal relationships, it has the advantage to implicitly handle complex nonlinear relationships between dependent and independent variables. In the present paper, the Neural Network model based on the back-propagation algorithm Levenberg-Marquardt was developed using a three layer approach with a tangent sigmoid transfer function (tansig) at hidden layer with 11 neurons and linear transfer function (purelin) at out layer. The above mentioned approach has been used to test the effectiveness in simulating ion exchange processes. The modeling results showed that there is an excellent agreement between the experimental data and the predicted values of copper ions removed from aqueous solutions., {"references":["J. Warchol, R. Petrus, \"modeling of heavy metal removal dynamics in\nclinoptilolite packed beds,\" Microporous and Mesoporous Materials.\nvol. 93, 2006, pp. 29-39.","B. B. Mamba, D.W. Nyembe and A.F. Mulaba-Bafubiandi. \"Removal\nof copper and cobalt from aqueous solutions using natural clinoptilolite\"\nWater SA, vol. 3-35, 2009, pp. 307-314.","S. Kesraoui-Ouki, C.R. Cheeseman, R. Perry, \"Natural Zeolite\nutilization in pollution control: A review of applications to metals\neffluents,\" J. Chem.Tech. Biotechnol. vol. 59, 1994, pp.121-126.","P. Kittisupakom, P. Tangteerasunun and P. Thitiyasook, \"Dynamic\nNeural Network Modeling for Hydrochloric Acid Recovery Process\",\nKorean J. Chem. Eng. vol. 22(6), 2005, pp. 813-821.","M. M. Van den Bosch. \"Simulation of ion exchange processes using\nneuro-fuzzy reasoning\". Cape Peninsula University of Technology,\nSouth Africa, Theses & Dissertation. 2009","S. Haykin. \"A Comprehensive Foundation, Prentice Hall\". 1999.","X. Du, J. Yuan, Y. Zhao, Y. Li. \"Comparison of general rate model with\na new model-artificial neural network model in describing\nchromatographic kinetics of solanesol adsorption in packed column by\nmacro porous resins.\" J. Chromatogr. vol. A 23, 2007, pp.165-174.","W. Gao and S. Engell. \"Estimation of general nonlinear adsorption\nisotherms from chromatograms\". Comput. Chem.Eng. vol. 29, pp. 2242-\n2255.","J. S. J. Deventer van, S. P. Liebenbert, L. Lorenzen. \"Dynamic modeling\nof competitive elution of activated carbo in columns using neural\nnetworks.\" Miner. Eng., vol. 8, 1995, pp. 1489-1501."]}

In this study a neural network (NN) was proposed to predict the sorption of binary mixture of copper-cobalt ions into clinoptilolite as ion-exchanger. The configuration of the backpropagation neural network giving the smallest mean square error was three-layer NN with tangent sigmoid transfer function at hidden layer with 10 neurons, linear transfer function at output layer and Levenberg-Marquardt backpropagation training algorithm. Experiments have been carried out in the batch reactor to obtain equilibrium data of the individual sorption and the mixture of coppercobalt ions. The obtained modeling results have shown that the used of neural network has better adjusted the equilibrium data of the binary system when compared with the conventional sorption isotherm models.

The aim of this study was to investigate ammonium exchange capacity of natural and activated clinoptilolite from Kwazulu-Natal Province, South Africa. X – ray fluorescence (XRF) analysis showed that the clinoptilolite contained exchangeable ions of sodium, potassium, calcium and magnesium. This analysis also confirmed that the zeolite sample had a high silicon composition compared to aluminium. Batch equilibrium studies were performed in an orbital shaker and the data fitted the Langmuir isotherm very well. The ammonium exchange capacity was found to increase with pH and temperature. Clinoptilolite functionalization with hydrochloric acid increased its ammonia uptake ability.