Activated carbon synthesis and methylene blue adsorption from pepper stem using microwave assisted impregnation method: Isotherm and kinetics

Background: Adsorption is a potent technique used to separate hazardous compounds due to its practical, affordable, and ecologically benign uses. Activated carbons are often employed for better results in adsorption processes. Agricultural by-products and wastes have recently been used in the development of large-pored adsorbents. These adsorbents are gaining popularity as an alternative to commercial activated carbons. Methods: This study integrated the known carbonization method with a microwave device, and waste pepper stalks (locally known as isot) activated with phosphoric acid were carbonized at 650 degrees C for 30 min. The activated carbon (BSAC) obtained was utilized in the adsorption of dyestuff (methylene blue MtB). The adsorption was investigated according to pH, concentration, and kinetic model. Results: The monolayer adsorption capacity (qmax) was 178.4121 mg g(-1) based on Langmuir isotherm, which was the most appropriate match. Response surface methodology (RSM) was used to examine the removal of MtB. The central composite method was used in RSM. In experimental design, solution initial concentration (75-150 ppm), adsorption time (120-240 min) and activated carbon amount (50-100 mg) were selected and adsorption capacity (qe) was chosen as response parameter. The adsorption capacity was 75.0072 mg g(-1) under optimum conditions (88 ppm solution initial concentration, 191 min, adsorption time and 95 mg activated carbon). Conclusion: The activated carbon obtained from pepper (isot) stems with microwave impregnation process integrated into the traditional method are a cheap and environmentally friendly adsorbent for MtB removal. (c) 2023 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This study developed activated carbon from waste pepper stalks using a combination of carbonization and microwave impregnation methods. The obtained activated carbon exhibited high adsorption capacity for methylene blue, with a maximum capacity of 75.0072 mg/g under optimal conditions.