Adsorption characteristics in the removal of chlorpyrifos from groundwater using magnetic graphene oxide and carboxy methyl cellulose composite

Abstract

The widespread occurrence of chlorpyrifos (CPF) in water sources makes it critical to develop efficient and low-cost adsorbents. This work developed a simple approach to prepare a green, efficient, and recyclable composite of magnetic graphene oxide and carboxymethyl cellulose (MGOC) for CPF removal from groundwater. Various analytical techniques such as field emission scanning electron microscope (FE-SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Brunauer, Emmett and Teller (BET) analysis were used to characterize the MGOC composite. The experimental parameters used in the batch isotherm study were optimized using the response surface methodology (RSM) and central composite design (CCD). A maximum CPF removal efficiency of 98.3 % was predicted at an initial CPF concentration of 14.0 mg/L, MGOC dosage of 0.40 g/L, contact time of 40 min, and solution pH of 6.0. The RSM analysis provided a second-order polynomial model with a p-value ˃ 0.0001, F-value of 175.152, and R2 of 0.9786, to predict the CPF removal efficiency at various experimental conditions. The good adsorption ability was attributed to abundant active sites from MGOC composite. Of the eight isotherm models evaluated, the Langmuir isotherm model gave a best fit with a maximum monolayer adsorption capacity (qm) of 108.3 mg g−1.In the adsorption kinetic studies, the second-order kinetic model gave a best fit for the experimental data. Further, the MGOC composite proved to be effective in the removal of CPF from groundwater samples. The adsorption mechanism was discussed. The desorption and regeneration studies indicated that MGOC composite is viable upto five cycles with a 14 % drop in the adsorption capacity. Considering the high removal efficiency and adsorption capacity, easy separation, and proper regeneration, MGOC composite could be a promising adsorbent for removing CPF from groundwater and polluted water by pesticides.