Influence of salts and humic acid on 2,4-dichlorophenoxyacetic acid removing from aqueous solution by peanut shell activated carbon

The activated carbon (AC) was prepared from peanut shell and then used as adsorbent for 2,4-dichlo- rophenoxyacetic acid (2,4-D) removal from aqueous solution. The prepared AC was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The effects of sodium chloride, calcium chloride, and humic acid (HA) were investigated on adsorption process. The kinetics results yield well the pseudo-second-order model than pseudo-first-order kinetic. The L-shape type isotherm obtained with influence of salts were became S-shape type with simultaneous influence of salts and HA. The experimental data were best fitted with the Langmuir model with influence of salts, and best suitable with the competitive Langmuir with combined influence of HA and salts. The adsorption capacities were 281.22, 86.12, 160.32, and 154.96 mg g–1 with adsorption of 2,4-D only, and with influence of 0.01 M NaCl, 0.01 M CaCl2 and HA solutions respectively. The reusability property of AC slightly decreased during the first three cycles performed while the regeneration efficiency was remained higher after the five cycles attempted.