SYNTHESIS AND OPTIMIZATION OF GREEN ADSORBENTS FOR THE REMOVAL OF 2,4-DICHLOROPHENOL FROM THE WASTEWATER

Abstract

2, 4-Dichlorophenol (2, 4-DCP) is a water-soluble contaminant that is frequently discovered in wastewater from a variety of industries, including triclosan's aerobic breakdown and pharmaceutical and fungicide production facilities. It is necessary to create an efficient treatment method for the removal of DCP from contaminated water because it has a particularly detrimental impact on both human health and aquatic life. Comparing wastewater treatment methods, adsorption is believed to be one of the most practical methods for removing contaminants from water. The objective of this study is to produce a green adsorbent (biochar) that is efficient and affordable to use in the adsorption process to remove 2, 4-DCP from wastewater. Biochar is synthesized by hydrothermal method using tamarind seed powder (food waste) and chemically activated by phosphoric acid at low temperatures. The most effected factors with their ranges were selected as temperatures (160 to 200 °C) , time of reaction (4 to 8 hr) and concentration of phosphoric acid (0 to 2 mol/L). The hydrothermal synthesis conditions for the optimum removal of 2, 4-DCP were optimized using response surface methodology (RSM) based on Box Behnken design. The regression model predicted that 187°C,, 8 hours, and 1.2 mol/L of phosphoric acid were the optimum hydrothermal temperature, reaction time, and concentration. The regression model predicted a removal of 47%, however, batch adsorption experiments using biochar synthesized under the optimal conditions provided a reduction of 45%. The prepared biochar under optimum conditions was characterized using TGA, XRD, BET, FTIR, SEM-EDX, and particle size analysis and compared with raw samples. Additionally, using Box-Behnken design to analyze the impact of various factors on the adsorption capabilities, the synthesized biochar was used to remove 2, 4-DCP. The regression model predicted that the ideal adsorbent dosage, starting concentration, contact duration, and pH values were 0.2g, 117mg/L, 4.3hr, and 4.3, respectively. The regression model predicted 75.2% optimal 2,4-DCP removal, while the batch experiments attained 70% removal under the predicted optimal conditions. Many models, including the Langmuir, Freundlich, and Temkin, have been used in studies on isotherms and kinetics. The adsorption process follows Temkin isotherm, and the pseudo-second-order kinetics model and the outcomes demonstrated the multi-layer adsorption of 2, 4-DCP. Overall, this work supports the viability of using proposed green adsorbents like biochar to remove chlorophenols from contaminated water.