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The removal of pesticide (ethoprophos) from aqueous solution using a natural biosorbent such as chitosan (CH) prepared from a biopolymer waste obtained from marine industry was studied. The Fourier Transform Infrared Spectroscopy (FTIR), Scanning electron microscopy (SEM), and X-ray diffraction spectroscopy (XRD) were used to study the structure of the adsorbent. The biosorption studies were carried out under various parameters, such as biosorbent dose, initial pesticide concentration and contact time. The experimental results show that the removal percentage of ethoprophos increased from 85.693% to 89.234%, as adsorbent dose (CH) increased from 0.02 to 0.1 g/100ml. The equilibrium uptake was increased with an increase in the initial pesticide concentration in solution. Biosorption kinetic data were fitted well with the pseudo-second order kinetic model. The experimental isotherms data were analyzed using Freundlich, Langmuir, Temkin and Dubinin-Radushkevich (D-R) isotherm equations. The best fit was obtained by Freundlich isotherm with high correlation coefficients. That the value of energy calculated from the D-R isotherm was 5.56 KJ/mol suggests the adsorption of ethoprophos on Chitosan is physical. All the results indicating CH was chosen as low-cost biosorbent could be applied for the removal of organophosphorous pesticide from aqueous solutions.

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A facile eco-friendly approach for acetampirid pesticide removal is presented. The method is based on the use of micro- and mesoporous activated carbon (TPAC) as a natural adsorbent. TPAC was synthesized via chemical treatment of tangerine peels with phosphoric acid. The prepared activated carbon was characterized before and after the adsorption process using Fourier- transform infrared (FTIR), X-ray diffraction (XRD), particle size and surface area. The effects of various parameters on the adsorption of acetampirid including adsorbent dose (0.02–0.2 g), pH 2–8, initial adsorbate concentration (10–100 mg/L), contact time (10–300 min) and temperature (25–50 °C) were studied. Batch adsorption features were evaluated using Langmuir and Freundlich isotherms. The adsorption process followed the Langmuir isotherm model with a maximum adsorption capacity of 35.7 mg/g and an equilibration time within 240 min. The adsorption kinetics of acetamiprid was fitted to the pseudo-second-order kinetics model. From the thermodynamics perspective, the adsorption was found to be exothermic and spontaneous in nature. TPAC was successfully regenerated and reused for three consecutive cycles. The results of the presented study show that TPAC may be used as an effective eco-friendly, low cost and highly efficient adsorbent for the removal of acetamiprid pesticides from aqueous solutions.

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The preparation of eco-friendly low-cost silkworm feces activated carbon (SFAC) for the removal of oxamyl pesticide from aqueous solution has been investigated in batch experiments. Structure and morphology of SFAC were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (SEM). The specific surface area and mean pore diameter were obtained as 75.219 and 0.2035 cm 3 g -1 , respectively. The effect of different physicochemical parameters such as initial oxamyl concentrations, activated carbon dose and contact time has been studied. The results showed that the oxamyl removal on SFAC was unaffected in the pH range of 2-10. The percent removal of oxamyl onto SFAC was 99.48% from aqueous solutions. The adsorption process attained equilibrium within 120 min of contact time. Equilibrium data were analyzed by the Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherm models. Freundlich isotherm provided the best fit to the equilibrium data. Adsorption kinetic was fitted well by the pseudo-secondorder kinetic model. The results revealed that SFAC could be used a low-cost and eco-friendly alternative to other adsorbents for the oxamyl removal from aqueous solution.

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