Eco-friendly and Easily Prepared GrapheneNanosheets for Safe Drinking Water: Removal of Chlorophenoxyacetic Acid Herbicides

The environmental friendly and cost-effective few-layered graphene nanosheets (GNs) are identified as superior adsorbent for chlorophenoxyacetic acid herbicides, such as 2,4-dichlorophenoxyacetic acid (2,4-D), 2-(2,4-dichlorophenoxy) propanoic acid (2,4-DP), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2-(2-methyl-4-chlorophenoxy) propionic acid (MCPP) from an aqueous solution. The effects of pH, ionic strength and temperature on the adsorption of herbicides were explored. The prepared GNs showed the maximum removal efficiencies of 82, 80, 86, 82 and 70% for 2,4-D, 2,4-DP, 2,4,5-T, MCPA and MCPP respectively. The results revealed that the adsorption follows a pseudo-secondorder kinetics model and confirms the Langmuir adsorption isotherm. From the thermodynamic parameters, it is suggested that the adsorption of herbicides on GNs follows the endothermic and spontaneous processes. The results show that the electrochemically prepared GNs will be considered the suitable material for water purification in the near future.