Removing 2,4-D micropollutant herbicide using powdered activated carbons: the influence of different aqueous systems on adsorption process

Abstract

The presence of microcontaminants in the water supply system offers adverse impacts. This study analyzed the performance of two powdered activated carbons (PAC1 and PAC2) in the removal of 2,4-D herbicide in ultrapure water (UW) and natural water (NW) to verify the influence of natural organic matter (NOM) on the adsorptive process. The properties of PAC1 and PAC2 were analyzed by textural analysis, FTIR, TG, pH, XDR, NMR. The specific surface area of PAC2 was lower than PAC1 and PAC2 showed better adsorption capacity in UW (37.04 mg.g−1) and in NW (8.06 mg.g−1). The results of experiments performed in natural water showed that both activated carbons had reduced 2,4-D adsorption capacity in the presence of NOM, since it may compete for the same adsorption sites or block the access of the 2,4-D molecule to the pores of the activated carbon. PAC2 showed a higher mesopores percentage, decreasing the effects caused by NOM in 2,4-D adsorption. The use of activated carbons with varying pore sizes for the removal of microcontaminants is recommended, especially in NW. This result contributes to the choice of the adsorbent type to be applied in water treatment plants.