Removal of 2,4-dichlorophenoxyacetic acid through nitrogen doped modified palm kernel shell from aqueous solutions

Abstract

The 2,4-Dichlorophenoxyacetic acid (2,4-D) is extensively used herbicide to boost crop productivity by reducing weed and pest infestation in agricultural fields. Due to the high solubility, mobility and low biodegradability, the ubiquitous presence of 2,4-D in the soil, surface and underground water has become serious threat for environment and human health.The present study addresses removal of hazardous 2,4-D by melamine-modified palm kernel shell biochar. A thorough examination was carried out, encompassing proximate analysis, elemental analysis, X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) analysis, particle size distribution assessment, SEM (Scanning Electron Microscopy), and TEM (Transmission Electron Microscopy). Additionally, a comparative analysis was conducted, comparing palm kernel shell powder with biochar activated by KOH. The melamine-modified biochar (PKS-BM) exhibited notable characteristics, including nitrogen composition of 4.2 %, enhanced surface groups, a BET surface area 794.70 m2/g, total pore volume 0.449 cm3/g, particle size of 1400 nm, and 85 % removal of 2,4-D. Adsorption kinetics were accurately described by both pseudo-second-order model. According to the Langmuir model, the adsorption process was favorable, demonstrating a maximum adsorption capacity 990.10 mg/g. Enthalpy, entropy, and Gibbs free energy were computed from adsorption data, revealing exothermic and thermodynamically spontaneous 2,4-D adsorption on PKS-BM. These findings confirm the suitability of the synthesized melamine-impregnated palm kernel shell biochar to be used as adsorbent for removal of toxic herbicide from contaminated water.