Removal of Arsenic from Aqueous Solution Using Single-Walled Carbon Nanotubes Modified with Poly Allylamine Hydrochloride

Arsenic in water is one of the highly toxic elements which has harmful influences on the human health and ecosystems. To address this problem, single-walled carbon nanotubes modified with poly (allylamine hydrochloride) (PAH/Ox-SWCNT) composite were synthesized and applied as an adsorbent for arsenic removal from aqueous solution in this study. The properties of PAH/Ox-SWCNT nanocomposite were characterized using scanning electron microscopy, Thermogravimetric, Fourier-transform infrared spectroscopy, and X-ray powder diffraction analysis. Batch experiments were executed to determine the ability of PAH/Ox-SWCNT to adsorb As from solution under various operational conditions. The experimental data were fitted by pseudo-first-order kinetic and pseudo-second-order kinetic models by nonlinear regression analysis using Mathematica software. Langmuir and Freundlich models were employed to describe the adsorption equilibrium isotherms. The removal percentage of As increased with initial solution pH from 3 to 7 while it decreased with the initial concentration of As. Moreover, the enhancement of contact time caused better adsorption efficiencies. The percentage removal of As using 10 mg of synthesized nanocomposite was more than 90% at pH=7 and contact time of 30 min. The adsorption experimental data had better agreement with pseudo-second-order kinetic and the Freundlich isotherm models. The maximum adsorption capacity of PAH/Ox-SWCNT was 275.07 mg/g at 298 K. The As removal percentage after eight adsorption-desorption cycles was higher than 65%. All results implied that the synthesized PAH/Ox-SWCNT could potentially be a promising adsorbent in arsenic water remediation.