Preparation of mesoporous activated carbon from novel African walnut shells (AWS) for deltamethrin removal: kinetics and equilibrium studies

Abstract

Novel African walnut shell (AWS) was treated and improved as an agricultural waste by-product to produce high surface area activated carbon via chemical activation with potassium hydroxide (KOH) to achieve extremely effective adsorptive characteristics for deltamethrin removal. The adsorbent (KOHAWS) was characterized by scanning electron microscopy, Fourier transform infrared (FT-IR) spectroscopy, the Brunauer–Emmett–Teller surface area, and pH point of zero charge (PHPZC). Batch sorption experiments were investigated to study the effect of pH, initial concentration and contact time, sorbent dosage, and agitation speed. The results reveal that the experimental data fitted well with Langmuir isotherm model (R2 = 0.997) with maximum adsorption capacity at 57.64 mg g−1 and the kinetics of the sorption follows the pseudo-first-order model (R2 = 0.995). The sorption of deltamethrin onto KOHAWS reveals a high removal efficiency of 98.2%. The findings show that the novel AWS has excellent regeneration and reusability properties and may be used to remove pesticides from aqueous solutions instead of conventional activated carbon.