A sustainable approach for the removal of chlorpyrifos pesticide from aqueous phase using novel nano magnetized biochar

In last two decades, organophosphate pesticides have become a prominent class of toxic water pollutants. Besides, these are not only poisonous for living beings, but their decomposition is also a time-taking process. For the first time, our study reports the application of nano-magnetized and carbonaceous adsorbents, obtained from orange peels (bio-waste), for the removal of chlorpyrifos from water resources. The -nano magnetized orange peels (NMOPs) were synthesized by the co-precipitation method with the use of iron salts. The competency of orange peels for chlorpyrifos adsorption was further enhanced by converting untreated orange peels (UOPs) into carbonaceous orange peels (COPs). The adsorbents were analyzed with FT-IR, SEM, EDX, XRD and VSM. The peak at 540 cm⁻¹ in FTIR spectra corresponded to the Fe-O bond and confirmed the successful doping of iron salts on orange peels. Biosorption studies carried out by varying different parameters showed that these adsorbents are efficient for the uptake of chlorpyrifos. The effects of adsorbent dose, contact time, chlorpyrifos initial concentration, and pH were investigated to assess the adsorbents’ efficiency via biosorption studies. It was noted that the adsorbents showed maximum adsorption with adsorbent dose = 0.4 g, contact time = 50 mins, chlorpyrifos concentration = 150 ppm, pH = 4 and temperature = 30 °C. The adsorption maximum values (q_max) were found to be 68, 108 & 100 mg g⁻¹ for the UOPs, COPs and NMOPs, respectively. Kinetic studies indicate that the removal of chlorpyrifos followed the pseudo-second-order model of adsorption. The adsorption results were effectively described by the Langmuir isotherm and Freundlich isotherm models.