Adsorption of 2,4-dichlorophenoxyacetic acid using rice husk biochar, granular activated carbon, and multi-walled carbon nanotubes in a fixed bed column system

Abstract

The 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide, as an aromatic hydrocarbon, is a dangerous and toxic organic pollutant among the agricultural pesticides. In this research, the performance of the biochar made from rice husk (BRH), granular activated carbon (GAC), and multi-walled carbon nanotubes (MWCNTs) was investigated for adsorption of 2,4-D in a fixed-bed column system. The influence of pH (2, 5, 7, 9), flow rate (0.5,1,1.5 mL min -1 ), bed depth (3, 6, 9 cm), and influent 2,4-D concentration (50,100,150, 300 mgL -1 ) on the adsorption process was evaluated. The resulting breakthrough curves indicated that the higher removal efficiency of 2,4-D took place at the lower flow rate, lower influent 2,4-D concentration, higher bed depth, and lower pH. While in most cases the removal ability of GAC was better than other adsorbents, generally, this study confirmed that the BRH, as a cheap and sustainable material, can be a viable alternative to GAC and MWCNTs for remediation and treatment scenarios, particularly in developing countries.