Removal of Congo red dye from aqueous solutions by a low-cost adsorbent: activated carbon prepared from Aloe vera leaves shell

Background: Synthetic dyes have several harmful effects on human health as well as aquatic life. In this study, activated carbon (AV-AC), based on Aloe vera leaf shells, was used as a novel agricultural adsorbent, one that is low-cost and available for the removal of Congo red (CR) as a carcinogenic dye from aqueous solutions. Methods: In the batch system, the influence of different parameters like contact time, pH, adsorbent dosage, and initial CR concentration were examined on the dye removal from liquid medium. The experimental data were fitted by pseudo-first-order and pseudo-second-order kinetics, and also Langmuir and Freundlich isotherms models. Results: The optimum contact time and pH for the uptake of CR were obtained at 20 minutes and acidic pH of 2. The maximum uptake capacity of CR dye by AV-AC was 1850 mg/g. The results showed that the experimental data were well-fitted by the pseudo-second-order kinetic model (R2 > 0.99) and Freundlich isotherm model (R2 > 0.99). Conclusion: According to the results of our study, the AV-AC is a low-cost, non-toxic, and effective adsorbent for the uptake of CR dye from aqueous media.