COD removal from landfill leachate using a high-performance and low-cost activated carbon synthesized from walnut shell

• Published in: Chemical engineering communications Vol. 205; no. 9; pp. 1193 - 1206
• Main Authors: Mahdavi, A. R., Ghoresyhi, A. A., Rahimpour, A., Younesi, H., Pirzadeh, K.
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 02-09-2018; Taylor & Francis Ltd
• Subjects: Activated carbon; Adsorption; Chemical oxygen demand; Chemical synthesis; COD; Endothermic reactions; Hazardous materials; Heavy metals; isotherm; Landfill; landfill leachate; Leachates; Lead; Municipal landfills; Organic chemistry; Reagents; walnut shell; Walnuts
• ISSN: 0098-6445; 1563-5201
• DOI: 10.1080/00986445.2018.1441831

An activated carbon with high adsorption capacity was synthesized from walnut shell as a solid waste using different chemical reagents. It was used to mitigate chemical oxygen demand from municipal landfill leachate. The activated carbon synthesized with impregnation ratio of 4:1 (H
3
PO
4
to char) at a temperature of 500°C (ACH4-500) demonstrated the best textural properties based on Brunauer-Emmett-Teller analysis, i.e., specific surface area of 1,851.1 m
2
/g, total pore volume of 1.03 cm
3
/g, and mean pore diameter of 2.24 nm and was selected for adsorption experiments. The maximum adsorption capacity and removal were 123.1 mg/g and 84.7% under optimum condition, respectively. The equilibrium data were fitted with different model isotherms and Redlich-Peterson model showed the best match with experimental data. Kinetic data were well described by pseudo-second-order equation. Study of adsorption thermodynamics revealed spontaneous and endothermic nature of adsorption. In addition, the adsorbent showed satisfactory results, e.g., 100% removal of Pb
2+
, Cd
2+
, and Mn
2+
, in diminishing heavy metals as hazardous materials from landfill leachate.