Research Journal of Environmental Sciences1819-34122151-8238Academic Journals Inc.10.3923/rjes.2017.116.129VelempiniTarisai PillayKriveshini MbiandaXavier Y. 32017113Background and Objective: Multiwalled carbon nanotubes functionalized with 2-aminoethylphosphonic acid denoted phosphorylated multiwalled carbon nanotubes, (P-MWCNTs) were synthesized by first oxidizing pristine MWCNTs to obtain a number of functional groups which included carboxylic acids. The carboxylic acids were reacted with oxalyl chloride to obtain acyl chloride (-COCl). The 2-aminoethylphosphonic acid (AMP) was subsequently grafted onto acyl chloride (-COCl). This study aimed to report, the recovery of lowly concentrated Cr(VI) ions from aqueous solutions by using phosphorylated multiwalled carbon nanotubes (P-MWCNTs). Materials and Methods: The material was characterised by various techniques, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and thermo gravimetric analysis (TGA). The effectiveness of P-MWCNTs as an adsorbent for the removal of Cr(VI) from aqueous solutions were studied in a batch mode. To ensure that the data was reliable all batch adsorption experiments were carried out in triplicate. The standard deviation of the triple analytical data was determined and probability level used was <5%. Results: The results indicated a maximum adsorption of 93% at a pH of 2. Other parameters such as adsorbent dosage, contact time, initial ion concentration, temperature and the presence of competing ions were also investigated. The adsorption equilibrium was reached after 60 min and uptake decreased with initial anion concentration increments. Both Langmuir and Freundlich isotherms were applied to describe Cr(VI) adsorption process and Freundlich isotherm correlated well with the adsorption data. The adsorption reaction followed pseudo-second-order kinetics under different initial ion concentration, while removal percentage increased with increase in temperature. Conclusion: The enthalpy Gibbs free energy revealed that the adsorption process is endothermic (G<0) and spontaneous, as confirmed by standard enthalpy (S>0). Furthermore, regeneration of the adsorbent was successfully demonstrated with 1.0 M NaOH.]]>O'Leary, M.,20112011pp: 175-186pp: 175-186Nordstrom, D.K.,200910097104Jacobs, J.A. and S.M. Testa,20042004Beukes, J.P., P.G. van Zyl and M. Ras,2012112347352Shechan, P.J., D.M. Meyer, M.M. Sauer and D.J. Paustenbach,199132161201Ballav, N., A. Maity and S.B. Mishra,2012198-199536546Hawley, E.L., R.A. Deeb, M.C. Kavanaugh and R.G. James Jacobs,20042004Mohan, D., S. Rajput, V.K. Singh, P.H. Steele and C.U. Pittman, Jr.,2011188319333Gupta, V.K., R. Jain, A. Mittal, T.A. Saleh, A. Nayak, S. Agarwal and S. Sikarwar,20122/UV in aqueous suspensions.]]>321217Al-Othman, Z.A., R. Ali and M. Naushad,2012184238247Jung, C., J. Heo, J. Han, N. Her and S.J. Lee et al.,20131066371ALOthman, Z.A., M. Naushad and R. Ali,20132033513365Mohan, D. and C.U. Pittman, Jr.,2006137762811Peigney, A., C. Laurent, E. Flahaut, R.R. Bacsa and A. Rousset,200139507514Ji, L., Y. Shao, Z. Xu, S. Zheng and D. Zhu,20104464296436Amar, H., J. Benzakour, A. Derja, D. Villemin and B. Moreau,2003558131139Lacour, S., V. Deluchat, J.C. Bollinger and B. Serpaud,1998469991009Jin, X., B. He, J. Miao, Q. Zhang and L. Niu,20125030833091Zhang, Y., S. Qi and F. Zhang,20124737433746Gashti, M.P. and A. Almasian,201345282289Oki, A., L. Adams, V. Khabashesku, Y. Edigin, P. Biney and Z. Luo,200862918922Muleja, A.A., X.Y. Mbianda, R.W. Krause and K. Pillay,20125027412751Adolph, M.A., Y.M. Xavier, P. Kriveshini and K. Rui,20122411331141Mamba, G., X.Y. Mbianda and P.P. Govender,201398470476Lv, X., J. Xu, G. Jiang and X. Xu,20118512041209Deb, A.K.S., V. Dwivedi, K. Dasgupta, S.M. Ali and K.T. Shenoy,2017313899911Kera, N.H., M. Bhaumik, N. Ballav, K. Pillay, S.S. Ray and A. Maity,2016476144157Xu, J., P. Yao, X. Li and F. He,2008para-phenylenediamine-functionalized multi-walled carbon nanotubes nano-composite.]]>151210219Zenobi, M.C., C.V. Luengo, M.J. Avena and E.H. Rueda,200870270276Vukovic, G.D., A.D. Marinkovic, M. Colic, M.D. Ristic, R. Aleksic, A.A. Peric-Grujic and P.S. Uskokovic,2010157238248Saleh, T.A. and V.K. Gupta,2012371101106Gupta, V.K., R. Kumar, A. Nayak, T.A. Saleh and M.A. Barakat,2013193-1942434Jiang, D.D., Q. Yao, M.A. McKinney and C.A. Wilkie,199963423434Fierro, V., V. Torne-Fernandez and A. Celzard,200692243250Hayashi, J., A. Kazehaya, K. Muroyama and A.P. Watkinson,20003818731878Gupta, V.K., S. Agarwal and T.A. Saleh,20111851723Li, K., P. Li, J. Cai, S. Xiao, H. Yang and A. Li,2016154310318Petersen, E.J., J. Akkanen, J.V.K. Kukkonen and W.J. Weber, Jr.,2009Daphnia magna.]]>4329692975Hu, J., C. Chen, X. Zhu and X. Wang,200916215421550Albadarin, A.B., A.H. Al-Muhtase, G.M. Walker, S.J. Allen and M.N.M. Ahmad,20113PO4-activated lignin: Effect of salts and desorption studies.]]>2746473Giraldo-Gutierrez, L. and J.C. Moreno-Pirajan,200881278284Park, S.J., B.J. Park and S.K. Ryu,19993712231226Kotas, J. and Z. Stasicka,2000107263283Lu, C. and H. Chiu,20066111381145Pillay, K., E.M. Cukrowska and N.J. Coville,200916610671075Gupta, A. and C. Balomajumder,20153785796Chen, J., N. Xia, T. Zhou, S. Tan, F. Jiang and D. Yuan,2009410631073Sharma, D.C. and C.F. Forster,199622153160Wu, F.C., R.L. Tseng and R.S. Juang200915318Kapur, M. and M.K. Mondal,2013Mangifera indica sawdust.]]>218138146Hu, X.J., J.S. Wang, Y.G. Liu, X. Li and G.M. Zeng et al.,2011185306314Unnithan, M.R. and T.S. Anirudhan,20014026932701Yadav, S., V. Srivastava, S. Banerjee, C.H. Weng and Y.C. Sharma,2013100120127Duranoglu, D., A.W. Trochimczuk and U. Beker,2012187193202Saleh, T.A. and V.K. Gupta,201421193101Jagtoyen, M., J. Pardue, T. Rantell, E. Grulke and F. Derbyshire,2000Vol. 45,pp: 908-911pp: 908-911