Groundnut shell was used as an adsorbent by chemical activation with ZnCl2 under optimized conditions and its comparative characterization was conducted with commercially available powdered activated carbon (CPAC) for its physical, chemical and adsorption properties [157]. The groundnut shell based powdered activated carbon (GSPAC) had higher surface area, iodine and methylene blue numbers compared to CPAC. Both the carbons were used for the removal of malachite green dye from aqueous solution and the effect of various operating variables, viz. adsorbent dose (0.1–1 g/L), contact time (5–120 min) and adsorbate concentrations (100–200 mg/L) were examined for the removal of dye. The experimental results indicate that at a dose of 0.5 g/L and initial concentration of 100 mg/L, GSPAC showed 94.5% removal of the dye in 30 min equilibrium time, while CPAC removed 96% of the dye in 15 min.
Adsorption of Neutral Red (NR) onto peanut husk in aqueous solutions was investigated at 295 K [158]. Experiments were carried out as a function of pH, adsorbent dosage, contact time, and initial dye concentration. The adsorption capacity of peanut husk for the removal of NR was found to be 37.5 mg/g at 295 K. The adsorption kinetic data followed pseudo-first-order and pseudo-second-order kinetic models. The intraparticle diffusion model was also used to explain the adsorption process at the two-step stage.
Besides these, several other researchers also investigated the potential of peanut or groundnut waste for the removal of different pollutants from water [159], [160], [161], [162] and [163].