Investigation of the performance of activated carbon cloth to remove glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos from aqueous solutions by adsorption/electrosorption.

Abstract

The present study investigates the removal of glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos herbicides from their 5 × 10-5M aqueous solutions onto activated carbon cloth by adsorption and electrosorption. Analysis of these highly polar herbicides was achieved by UV-visible absorbance measurements, after derivatization with 9-fluorenylmethyloxycarbonyl chloride. The limit of quantification values of glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos were 1.06 × 10-6mol L-1, 1.38 × 10-6mol L-1, 1.32 × 10-6mol L-1 and 1.08 × 10-6mol L-1, respectively. Glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos were removed from their aqueous solutions with higher efficiencies by means of electrosorption (78.2%, 94.9%, 82.3% and 97%, respectively) than of open-circuit adsorption (42.5%, 22%, 6.9% and 81.8%, respectively). Experimental kinetic data were fitted to pseudo-first order and pseudo-second order kinetic models. It was determined that pseudo-second order kinetic model represents experimental data better with satisfactory coefficient of determination, r2 (> 0.985) and normalized percent deviation, P (< 5.15) values. Adsorption isotherm data were treated according to Freundlich and Langmuir isotherm models. Based on the r2 (> 0.98) and P (< 5.9) values, it was found that experimental data well fitted to Freundlich isotherm model. Adsorption capacities of activated carbon cloth for glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos, expressed in terms of Freundlich constant, were calculated as 20.31, 118.73, 239.33 and 30.68mmolg-1, respectively. The results show that the studied ACC can be used in home/business water treatment systems as an adsorbent due to its high adsorption capacity.