Extraction of Fluoride from Polluted Waters Using Low-cost Active Carbon Derived from Stems of Acalypha indica Plant
Batch mode adsorption experiments have been conducted successfully for the removal of fluoride from polluted waters with nitric acid active carbon derived from stems of Acalypha indica plant (NAcIC). The effect of various parameters such as pH, sorbent dosage, agitation time, initial concentration of fluoride, temperature, particle size and presence of foreign ions have been studied in detail and optimized for the maximum extraction of fluoride. Adsorption data have been modelled using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms and it has been observed that Langmuir isotherm well describes the experimental data because of RL and highest R2 values. Further, the Dubinin-Radushkevich mean free energy (E = 3.16 kJ/mol) and Temkin heat of sorption (B = 0.210 J/mol) for the NAcIC indicates the physisorption. Further, the adsorption kinetics is found to be pseudo-second order rate mechanism followed by pseudo-first order, intra particle diffusion, pore diffusion and Elovich model. FTIR, SEM and EDX studies confirm the fluoride binding ability of adsorbent. Field studies have been carried out with the fluoride-contaminated groundwater samples in order to test the suitability of the NAcIC using the same methodology at field conditions and it is found to be remarkably successful.
Adhikary, S.K., Tipnis, U.K., Harkare, W.P. and K.P. Govindan (1989). Defluoridation during desalination of brackish water by electrodialysis. Desalination, 71: 301-312.
Aharoni, C. and M. Ungarish (1977). Kinetics of activated chemisorption. Part 2, Theoretical Models. Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases, 7(3): 456-464.
Alagumuthu, G. and M. Rajan (2010) . Kinetic and equilibrium studies on fluoride removal by zirconium (IV) – impregnated ground nutshell carbon. Hemijska Industrija, 64(4): 295-304.
Alagumuthu, G., Veeraputhiran, V. and R. Venkataraman (2011). Fluoride sorption using Cynodon dactylon based activated carbon. Hemijska Industrija, 65(1): 23-35.
Altundogan, H., Altundogan, S., Tumen, F. and B. Memnune (2000) . Arsenic removal from aqueous solutions by adsorption on red mud. Waste Management, 20: 761-767.
Amer, Z., Bariou, B., Mameri, N., Taky, M., Nicolas, S. and A. Elimidaoui (2001). Fluoride removal from brackish water by electro dialysis. Desalination, 133: 215-223.
APHA (1998). Standard Methods for the Examination of Water and Waste Water. 20th edition, American Public Health Association. Water Environment Federation Publication, Washington, DC.
ASTM D4607-94 (2006) . Standard test method for Determination of Iodine number of Activated Carbon.
Atkins, P. (1999). Physical chemistry. 6th edn. Oxford University Press, London.
Attia, A.A., Rashwan, W.E. and S.A. Khedr (2006). Capacity of activated carbon in the removal of acid dyes subsequent to its thermal treatment. Dyes and Pigments, 69: 128-136.
Ayoob, S. and A.K. Gupta (2006). Fluoride in drinking water: A review on the status and stress effects. Environmental Science and Technology, 36: 433-487.
Bandosz, T.J., Jagiello, J. and J.A. Schwarz (1992). A comparison of methods to assess surface acidic groups on activated carbons. Analytical Chemistry, 64: 892.
Barbier, O., Arreola-Mendoza, L. and L.M. Del Razo (2010). Molecular mechanisms of fluoride Toxicity. Chemico- Biological Interactions, 188: 319-333.
Biniak, S., Szymanski, G., Siedlewski, J. and A. Swiatkowski (1997). The characterization of activated carbons with oxygen and nitrogen surface groups. Carbon, 35(12): 1799-1810.
BIS (1991). Indian Standards for Drinking Water-Specification, Bureau of Indian Standards, New Delhi.
Boehm, H.P. (1994). Some aspects of the surface chemistry of carbon blacks and other carbons. Carbon, 32: 759-769.
Boehm, H.P. (2002). Surface oxides on carbons and their analysis: A critical assessment. Carbon, 40: 145.
Bouberka, Z., Kaoha, S., Kamecha, M., Elmaleh, S. and Z. Derriche (2005). Sorption study of an acid dye from an aqueous solutions using modified clays. Journal of Hazardous Materials, 119: 117-124.
Brunauer, S., Emmett, P.H. and E. Teller (1938). Adsorption of gases in multi molecular Layers. Journal of the American Chemical Society, 60: 309-319.
Budinova, T., Ekinci, E., Yardim, F., Grimm, A., Bjornbom, E., Minkova,V. and M. Goranova (2006). Characterization and application of activated carbon produced by H3PO4 and water vapour activation. Fuel Processing Techonology, 87: 899-905.
Castel, C., Schweizer, M., Simonnot, M.O. and M. Sardin (2000). Selective removal of fluoride ions by a two-way ion-exchange cyclic processes. Chemical Engineering Science, 55: 3341-3352.
Cengeloglu,Y., Esengul, K. and M. Ersoz (2002). Removal of Fluoride from aqueous Solution by Using Bauxite Wastes. Separation and Purification Technology, 28: 81-86.
Chang, Yu., Jie Shan, Qiu, Yu Feng Sun, Xian Hui Li, Gang Chen and Zong Bin Zhao (2008). Adsorption removal of thiophene and dibenzothiophene from oils with activated carbon as adsorbent: Effect of surface chemistry. Porous Materials, 15: 151-157.
Chaturvedi, A.K., Pathak, K.C. and V.N. Singh (1988). Fluoride removal from water by adsorption on China clay. Applied Clay Science, 3: 337-346.
Chaturvedi, A.K., Yadva, K.P., Yadava, K.C., Pathak, K.C. and V.N. Singh (1990) . Deflouridation of Water by Adsorption on Fly Ash. Water, Air, Soil Pollution, 49(1- 2): 51-61.
Chien, S.H. and W.R. Clayton (1980). Application of Elovich equation to the kinetics of phosphate release and sorption in soils. Soil Science Society of America Journal, 44: 265-268.
Chinoy, N . J . (1991) . Effects of fluoride on physiology of animals and human beings. Indian Journal of Environment and Toxicology, 1: 17-32.
Coates, J. (2000). Interpretation of Infrared Spectra, A practical approach. In: Encyclopedia of Analytical Chemistry, Meyer, R.A. (Ed.), John Wiley and Sons, Chicester.
Contescu, A., Vass, M., Contescu, C., Putyera, K. and J.A. Schwarz (1998). Acid Buffering Capacity of Basic Carbons Revealed by Their Continuous pK Distribution. Carbon, 36: 247-258.
Daifullah, A.A.M., Yakout, S.M. and S.A. Elreefy (2007). Adsorption of fluoride in aqueous solutions using KMnO4 modified activated carbon derived from steam pyrolysis of rice straw. Journal of Hazardous Materials, 147: 633-643.
Dogan, M., Alkan, M., Turkyilmaz, A. andY. Ozdemir (2004). Kinetics and mechanism of removal of methylene blue by adsorption onto perlite. Journal of Hazardous Materials, 109: 141-148.
Dubinin, M.M. and L.V. RadushKevich (1947). The equation of the characteristic curve of the activated charcoal. Proceedings of the USSR Academy of Sciences, Physical Chemistry Section, 55: 331-333.
El-Hendawy, A.N.A. (2003). Influence of HNO3 oxidation on the structure and adsorptive properties of corncob-based activated carbon. Carbon, 41: 713-722.
El-Hendawy, A.N.A., Samra, S.E. and B.S. Girgis (2001). Adsorption characteristics of activated carbons obtained from corncobs. Colloids and Surfaces A: Physicochem. Eng. Aspects, 180: 209-221.
Fanning, P.E. and M.A. Vannice (1993). A DRIFTS study of the formation of surface groups on carbon by oxidation. Carbon, 31(5): 721-730.
Figueiredo, J.L., Perria, M.F.R., Freitas, M.M.A. and J.J.M. Orfao (1999). Modification of the surface chemistry of activated carbons. Carbon, 37(9): 1379-1389.
Freundlich, H.M.F. (1906). Over the adsorption in solution. Journal of Physical Chemistry, 57: 385-471.
Ganvir, V. and K. Das (2011). Removal of Fluoride from Drinking Water Using Aluminum Hydroxide Coated Rice Husk Ash. Journal of Hazardous Materials, 185(2-3): 1287-1294.
Garmes, H., Persin, F. and J. Sandeaux (2002). Defluoridation of groundwater by a hybrid process combining adsorption and Donnan dialysis. Desalination, 145: 287-291.
Gazzano, E., Bergandi, L., Riganti, C., Aldieri, E., Doublier, S., Costamagna, C., Bosia, A. and D. Ghigo (2010). Fluoride effects: The two faces of Janus. Current Medicinal Chemistry, 17: 2431-2441.
Gercel, O., Ozcan, A., Ozcan, A.S. and H.F. Gercel (2007). Preparation of activated carbon from a renewable bio-plant of Euphorbia rigida by H2SO4 activation and its adsorption behaviour in aqueous solutions. Applied Surface Science, 253: 4843-4852.
Gerente, C., Lee, V.K.C., Le Cloirec, P. and G. McKay (2007). Application of Chitosan for the Removal of Metals from Wastewaters by Adsorption-Mechanisms and Models Review. Critical Reviews in Environmental Science and Technology, 37: 41-127.
Girgis, B.S. and A.N.A. El-Hendawy (2002) . Porosity development in activated carbons obtained from date pits under chemical activation with phosphoric acid. Microporous and Mesoporous Materials, 52: 105-117.
Goldberg, S. and G. Sposito (1984a). A chemical model of phosphate adsorption by soils: 1. Reference oxide minerals. Soil Science Society of America Journal, 48: 772-778.
Goldberg, S. and G. Sposito (1984b). A chemical model of phosphate adsorption by soils: II. Noncalcareous soils. Soil Science Society of America Journal, 48: 779-783.
Gomez-Serrano, V., Acedo-Ramos, M., Lopez-Peinado, A.J. and C. Venezuela-Calahorro (1994). Study of Surface Functional Groups by FT-IR. Fuel, 73(3): 387-395.
Hall, K.R., Eagleton, L.C., Acrivos, A. and T. Vermevlem (1966). Pore and solid diffusion kinetics in fixed bed adsorption under constant pattern conditions. Industrial and Engineering Chemistry Fundamentals, 5: 212-219.
Hameed, B.H. (2009). Evaluation of papaya seed as a non- conventional low cost adsorbent for removal of MB. Journal of Hazardous Materials, 162: 939-944.
Hashim, M.A. (ed.) (1994). Symposium on Bioproducts Processing-Technologies for the Tropics. INST Chemical Engineers, Kualalumpur, Malaysia.
Hichour, M., Persin, F., Sandeaux, J. and C. Gavach (2000). Water defluoridation by Donann Dialysis and electro dialysis. Separation and Purification Technology, 18: 1-11.
Hill, A. and H. Marsh (1968). A study of the adsorption of iodine and acetic acid from aqueous solutions on characterized porous carbons. Carbon, 6(l): 31-39.
Ho, Y.S. and G. McKay (1999). Pseudo-second order model for sorption processes. Process Biochemistry, 34: 451-465.
Ho, Y.S., Ng, J.C.Y. and G. McKay (2000). Kinetics of pollutant sorption by biosorbents: Review. Separation and Purification Methods, 29: 189-232.
Ho, Y.S. and G. Mackay (2000). The kinetics of sorption of divalent metal ions onto sphagnum moss peat. Water Research, 34: 735-742.
Hu, C.Y., Lo, S.L. and W.H. Kuan (2003). Effect of co- existing anions on fluoride removal in electrocoagulation process using aluminium electrodes. Water Research, 37: 4513-4523.
Ibrahim, D.M., El-Hemaly, S.A. and F.M. Abdel-Kerim (1980) . Study of rice-husk ash silica by infrared spectroscopy. Thermo Chimica Acta, 37: 307- 314.
Ishizaki, C. and I. Marti (1981). Surface oxide structures on a commercial activated carbon. Carbon, 19: 409.
ISI (1989). Activated Carbon, Powdered and Granular – Methods of sampling and its tests, Bureau of Indian Standards, New Delhi, IS 877.
Jamode, A.V. , Sapkal, V.S. and V.S. Jamode (2004) . Defluoridation of water using inexpensive adsorbents. Journal of the Indian Institute of Science, 84: 163-171.
Joshi, S., Adhikari, M. and R.R. Pradhananga (2012) . Adsorption of Fluoride Ion onto Zirconyl–Impregnated Activated Carbon Prepared from Lapsi Seed Stone. Journal of Nepal Chemical Society, 30: 13-23.
Kadirvelu, K., Faur-Brasquet, C. and P. Le Cloirec (2000). Removal of Cu(II), Pb(II),and Ni(II) by Adsorption onto Activated Carbon Cloths. Langmuir, 16(22): 8404-8409.
Kagne, S., Jagtap, S., Dhawade, P., Kamble, S.P., Devotta, S. and S.S. Rayalu (2008). Hydrated cement: A promising adsorbent for the removal of fluoride from aqueous solution. Journal of Hazardous Materials, 154: 88-95.
Karthikeyan, G. and S. Siva Elango (2007). Fluoride sorption using Morringa Indica-based activated carbon. Iranian Journal of Environmental Health Science & Engineering, 4(1): 21-28.
Karthikeyan, M., Satheesh Kumar, K.K. and K.P. Elango (2011). Batch sorption studies on the removal of fluoride ions from water using eco-friendly conducting polymer/ bio-polymer composites. Desalination, 267: 49-56.
Kumar, E., Bhatnagar, A., Kumar, U. and M. Sillanpaa (2011). Journal of Hazardous Materials, 186: 1042-1049.
Lagergren, S. (1898) . About the theory of so-called adsorption of soluble substances. Kungliga Svenska, Vetenskapsakademiens, Handlingar, 24(4): 1-39.
Langmur, I. (1918). The adsorption of gases on plane surfaces of glass, mica, and platinum. Journal of the American Chemical Society, 40: 1361-1368.
Lapuente, R., Cases, F., Garces, P., Morallon, E. and J.L. Vazquez (1998). A voltammetric and FTIR–ATR study of the electropolymerization of phenol on platinum electrodes in carbonate medium: Influence of sulfide. Journal of Electroanalytical Chemistry, 451: 163-171.
Leon y Leon, C.A. and L.R. Radovic (1994). Interfacial chemistry and electrochemistry of carbon surfaces. In: Thrower, P.A. (ed.) Chemistry and Physics of Carbon, Marcel Dekker, New York, 24: 213-310.
Lhassani, A., Rumeau, M., Benjelloun, D. and M. Pontie (2001). Selective demineralization of water by nanofiltration application to the defluoridation of brackish water. Water Research, 35: 3260-3264.
Liu, J., Xu, Z., Li, X., Zhang, Y., Zhou, Y., Wang, Z. and X. Wang (2007). An Improved process to prepare high separation performance PA/PVDF hollow fiber composite nano filtration membranes. Separation and Purification Technology, 58: 53-60.
Lounici, H., Addour, L., Belhocine, D., Grib, H., Nicolas, S. and B. Bariou (1997). Study of a new technique for fluoride removal from water. Desalination, 114: 241-251.
Lounici, H., Belhocine, D., Grib, H., Drouiche, M., Pauss, A. and N. Mameri (2004). Fluoride removal with electro- activated alumina. Desalination, 161: 287-293.
Mahramanlioglu, M., Kizilcikli, I. and I.O. Bicer (2002). Adsorption of fluoride from aqueous solution by acid treated spent bleaching earth. Journal of Fluorine Chemistry, 115: 41-47.
Mameri, N., Lounici, H., Belhocine, D., Grib, H., Prion, D.L. andY. Yahiat (2001). Defluoridation of Sahara Water by small electro coagulation using bipolar Aluminium Electrodes. Separation and Purification Technology, 24: 113-119.
Marsh, H. and F. Rodriguez-Reinoso (2006). Activated Carbon. Elsevier Science & Technology Books.
Meenakshi, S. and N. Viswanathan (2007). Identification of selective ion-exchange resin for fluoride sorption. Journal of Colloid and Interface Science, 308: 438-450.
Meldrum, B.J. and C.H. Rochester (1990a). In situ infrared study of the surface oxidation of activated carbon dispersed in potassium bromide. Journal of the Chemical Society, Faraday Transactions, 86: 2997-3002.
Meldrum, B.J. and C.H. Rochester (1990b). In situ infrared study of the surface oxidation of activated carbon in oxygen and carbon dioxide. Journal of the Chemical Society, Faraday Transactions, 86(5): 861-865.
Menendez, J.A., Suarez, D., Fuente, E. and M.A. Montes- Moran (1999). Contribution of pyrone-type structures to carbon basicity: Theoretical evaluation of the pK(a) of model compounds. Carbon, 37: 1002.
Mjengera, H . and G. Mkongo (2003) . Appropriate defluoridation technology for use in fluorotic areas in Tanzania. Physics and Chemistry of the Earth, 28: 1097- 1104.
Monika, J., Garg, V. and K. Kadirvelu (2009). Chromium (VI) removal from aqueous solution, using sunflower stem waste. Journal of Hazardous Materials, 162: 365-372.
Moreno-Castilla, C., Carrasco-Marın, F., Maldonado-Hodar, F.J. and J. Rivera-Utrilla (1998). Effects of non-oxidant and oxidant acid treatments on the surface properties of an activated carbon with very low ash content. Carbon, 36(1-2): 145-151.
Nageswara Rao, M . , Chakrapani, Ch . , Raje swara Reddy, B.V., Suresh Babu, Ch., Hanumantha Rao, Y., Somasekhara Rao, K. and K. Rajesh (2011). Preparation of activated Kaza’s Carbons from Bio-Materials and their Characterization. International Journal of Applied Biology and Pharmaceutical Technology, 2(3): 610-618.
Namasivayam, C. and K. Kadirvelu (1997). Agricultural solid wastes for the removal of heavy metals: Adsorption of Cu (II) by coir pith carbon. Chemosphere, 34(2): 377-399.
Namasivayam, C. and K. Kadirvelu (1994). Coir pith, an agricultural waste by-product, for the treatment of dyeing waste water. Bioresource Technology, 48: 79-81.
Nawlakhe, W.G., Kulkarni, D.N., Pathak, B.N. and K.R. Bulusu (1975). Defluoridation of Water by Nalgonda Technique. Indian Journal of Environmental Health, 17: 26-65.
Newcombe, G., Hayes, R. and M. Drikas (1993). Granular activated carbon: Importance of surface properties in the adsorption of naturally occurring organics. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 78: 65-71.
Nunes,A., Franca, S.A. and L.S. Olievera (2009). Activated carbon from waste biomass: An alternative use for biodiesel production solid residues. Bioresource Technology, 100: 1786-1792.
Onyango, M.S., Kojima, Y., Aoyi, O., Bernardo, E.C. and H. Matsuda (2004). Adsorption equilibrium modeling and solution chemistry dependence of fluoride removal from water by trivalent-cation-exchanged zeolite F-9. Journal of Colloid and Interface Science, 279(2): 341-350.
Ozacar, M. and I.A. Sengil (2005). A kinetic study of metal dye sorption on to pine saw dust. Process Biochemistry, 40: 565-572.
Ozcan,A. and A.S. Ozcan (2005). Adsorption of Acid Red 57 from aqueous solutions onto surfactant-modified sepiolite. Journal of Hazardous Materials, 125: 252-259.
Painter, P. , Starsinic, M . and M . Coleman (1985) . Determination of functional groups in coal by Fourier transform interferometry, Fourier transform infrared spectroscopy. Academic Press, New York. 4: 169-189.
Papirer, E., Li, S. and J.B. Donnet (1987). Contribution to the study of basic surface groups on carbons. Carbon, 25(2): 243-247.
Park, S.H., McClain, S., Tian, Z.R., Suib, S.L. and C. Karwacki (1997). Surface and bulk measurements of metals deposited on activated carbon. Chemistry of Materials, 9: 176-183.
Puziy, I., Poddubnaya, O., Martinez-Alonso, A., Suarez- Garcia, F. and J. Tascon (2003) . Synthetic carbons activated with phosphoric acid III: Carbons prepared in air. Carbon, 41: 1181-1191.
Raichur, A.M. and M.J. Basu (2001) . Adsorption of fluoride onto mixed rare earth oxides. Separation and Purification Technology, 24: 121-127.
Rajeshwari, S., Sivakumar, S., Senthilkumar, P. and V. Subburam (2001). Carbon from cassava peel, an agricultural waste, as an adsorbent in the removal of dyes and metal ions from aqueous solutions. Bioresource Technology, 81: 1-3.
Ramachandramurthy, T. (2003). Fluoride estimation in potable water in Tiruchurapalli rock fort area: Dental fluorosis survey and defluoridation with Emblica phyllanthus. Indian Journal of Environmental Protection, 23(3): 317- 320.
Reardon, E.J. and Y. Wang (2000). A limestone reactor for fluoride removal from waste waters. Environmental Science & Technology, 34: 3247-3253.
Rozada, F., Otero, M. and I. Garcia (2005). Activated carbons from sewage sludge and discarded tyres: Production and optimization. Journal of Hazardous Materials, 124(1-3): 181-191.
Sai Sathish, R., Sairam, S., Guru Raja, V., Nageswara Rao, G. and C. Janardhana (2008). Defluoridation of Water Using Zirconium Impregnated Coconut Fiber Carbon. Separation Science and Technology, 43(14): 3676-3694.
Sairam Sundaram, C., Viswanathan, N. and S. Meenakshi (2009). Defluoridation of water using magnesia/chitosan composite. Journal of Hazardous Materials, 163(2-3): 618-624.
Savinelli, E.A. and A.P. Black (1958). Defluoridation of Water with Activated Alumina. Journal of American Water Works Association, 50: 34-44.
Seethapathirao, D. (1964) . Defluoridation of water using sulphate d coconut shell carbon . Indian Journal of Environmental Health, 64: 11-12.
Sehn, P. (2008). Fluoride removal with extra low energy reverse osmosis membranes: Three years of large scale field experience in Finland. Desalination, 223: 73-84.
Shin, S., Jang, J., Yoon, S.H. and I. Mochida (1997). A study on the effect of heat treatment on functional groups of pitch based activated carbon fiber using FTIR. Carbon, 35(12): 1739-1743.
Simons, R. (1993) . Trace element removal from ash dam waters by nanofiltration and diffusion dialysis. Desalination, 89: 325-341.
Singh, G., Kumar, B., Sen, P.K. and J. Maunder (1999). Removal of fluoride from spent pot liner leachate using ion exchange. Water Environment Research, 71: 36-42.
Srimurali, M., Pragathi,A. and J. Karthikeyan (1998). A study on removal of fluorides from drinking water by adsorption onto low-cost materials. Environmental Pollution, 99: 285-289.
Starsinic, M., Taylor, R.L., Walker Jr., P.L. and P.C. Painter (1983). FTIR Studies of Saran Chars. Carbon, 1(1): 69-74.
Suarez, D., Menendez, J.A., Fuente, E. and M.A. Montes- Moran (1999). Contribution of Pyrone-Type Structures to Carbon Basicity: An abinitio Study. Langmuir, 15: 3897. Sunil Kumar, Asha Gupta and J.P. Yadav (2008). Removal of Fluoride by thermally activated carbon prepared from neem (Azadirachta indica) and kikar (Acacia arabica) leaves. Journal of Environmental Biology, 29(2): 227-232.
Temkin, M.J. and V. Pyzhev (1940). Recent modifications to Langmuir isotherms. Acta Physiochim, U.S.S.R., 12: 217-222.
Tor, A. (2007). Removal of fluoride from water using anion- exchange membrane under Donnan dialysis condition. Journal of Hazardous Materials, 141, 814-818.
Viswanathan,N. and S. Meenakshi (2010). Enriched fluoride sorption using alumina/chitosan Composite. Journal of Hazardous Materials, 178: 226-232.
Voll, M. and H.P. Boehm (1971). Basic surface oxides on carbons. IV. Chemical reactions for the identification of surface groups. Carbon, 9(4): 481-488.
Wang,Y. and E.J. Reardon (2001). Activation and regeneration of a soil sorbent for defluoridation of drinking water. Applied Geochemistry, 16: 531-539.
Weber Jr., W.J. and C. Morris (1963). Kinetics of adsorption on carbon from solution. Journal of the Sanitary Engineering Division, 89: 31-59.
WHO (2004). Guidelines for drinking water quality: Health criteria and other supporting information. Vol. 2, Geneva, Switzerland.
Xu Xiaotian, Li Qin, Cui Hao, Pang J., Sun Li, An Hao and Zhai Jianping (2011). Adsorption of fluoride from aqueous solution on magnesia-loaded fly ash cenospheres. Desalination, 272: 233-239.
Yadav, A.K., Kaushik, C.P., Haritash,A.K., Kansal,A. and R. Neetu (2006). Defluoridation of drinking water using brick powder as an adsorbent. Journal of Hazardous Materials, 128: 289-293.
Yang, T. and A. Lua (2003). Characteristics of activated carbons prepared from pistachio-nut shells by physical activation. Journal of Colloid and Interface Science, 267(2): 408-417.
Yongbin, Ji, Tiehu, Li, Zhu, Li, Xiaoxian, Wang and Liu Qilang (2007) . Preparation of activated carbons by microwave heating KOH activation. Applied Surface Science, 254(2): 506-512.
Zawadzki, J. (1989) . Infrared spectroscopy in surface chemistry of carbons. In: Thrower, P.A. (ed.) Chemistry and Physics of Carbon, Marcel Dekker, New York. 21: 147-380.
Zhang, P.C. and D.L. Spark (1990). Kinetics and mechanisms of sulfate adsorption/desorption on goethite using pressure- jump relaxation. Soil Science Society of America Journal, 54: 1266-1273.
Zhuang,Q.L., Kyotani, T. and A. Tomita (1994). DRIFT and TK/TPD analyses of surface oxygen complexes formed during carbon gasification. Energy & Fuels, 8: 714-718.