Ultrasound-assisted removal of chlorpyrifos using magnetic activated carbon– carboxymethyl cellulose hydrogel beads derived from orange peel waste

Chlorpyrifos, an organophosphate insecticide, has been frequently detected in water resources, raising concerns about environmental and health risks. In this study, hydrogel beads based on carboxymethyl cellulose (CMC) were synthesized by incorporating magnetic activated carbon derived from orange peel waste (0–30 wt%). The prepared composites were characterized using FT-IR, XRD, FESEM, BET, VSM, and other techniques. Adsorption parameters were optimized through the Taguchi method, identifying the optimal conditions at an initial chlorpyrifos concentration of 90 mg/L, adsorbent dosage of 2 g/L, contact time of 60 min, and solution pH of 9. The hydrogel containing 30 wt% magnetic activated carbon (CMC/MAC30) exhibited nearly 100 % removal efficiency. Nonlinear fitting revealed that the adsorption process followed the Toth model under ultrasonic irradiation and the Sips model in its absence. According to the Langmuir model, the maximum adsorption capacity increased from 162.96 to 211.86 mg/g upon ultrasonic treatment, attributed to enhanced mass transfer via cavitation. Comparative analysis with previously reported adsorbents confirmed the superior adsorption capacity of CMC/MAC30. Moreover, the adsorbent maintained 92 % removal efficiency after eight regeneration cycles. Importantly, CMC/MAC30 was also evaluated in simulated agricultural wastewater containing competing ions, where the removal efficiency decreased from ∼100 % to ∼70 %, yet still demonstrated the strong potential of the adsorbent in realistic complex matrices. These findings highlight CMC/MAC30, especially when assisted by ultrasound, as a promising green adsorbent for the efficient removal of chlorpyrifos from aqueous environment.