Cadmium and lead adsorption and desorption by coffee waste-derived biochars

Author(s)

Ruan Carnier ^[1] ; Aline Renée Coscione ^[2] ; Cleide Aparecida de Abreu ^[3] ; Leônidas Carrijo Azevedo Melo ^[4] ; Andressa Ferreira da Silva ^[5]

Affiliation

^[1] Instituto Agronômico. Centro de Solos e Recursos Ambientais - Brasil

^[2] Instituto Agronômico. Centro de Solos e Recursos Ambientais - Brasil

^[3] Instituto Agronômico. Centro de Solos e Recursos Ambientais - Brasil

^[4] Universidade Federal de Lavras. Departamento de Ciência do Solo - Brasil

^[5] Instituto Agronômico. Centro de Solos e Recursos Ambientais - Brasil

• Document type: Journal article
• Source: Bragantia; v. 81, 2022-02-16.

Abstract

ABSTRACT Biochar derived from coffee waste has been reported as a promising material for heavy metal sorption. However, if the intended use is environmental remediation, knowing the extent to which desorption may occur is critical. Thus, the objective of this work was to evaluate the efficiency of spent coffee ground (SCG) and coffee parchment (CP) biochars pyrolyzed at 700 °C under laboratory conditions, in the sorption of Cd and Pb from aqueous solutions, in a pH range from 2 to 10, and their retention after an induced desorption process with a 2.9 pH acetic acid solution. Both biochars were alkaline, and the initial pH of the solution had a large effect on the sorption capacity of SCG but a small effect on the sorption capacity of CP. The Pb sorption capacity was higher for CP (18.6 mg·g–1) than for SCG (11.4 mg·g–1), while both biochars had low Cd retention capacities (1.18 mg·g–1). Coffee parchment also showed the highest Pb retention (30% to 87%), while for Cd there was no difference between CP and SCG biochars. Our results showed that metal precipitation was the main mechanism for metal immobilization and CP biochar proved to be more reliable than SCG, mainly for Pb, due to its higher sorption capacity and lower metal release by desorption than SCG. These characteristics are particularly important for the use of biochar in environmental remediation. Besides that, the biochar production represents an eco-friendly destination for these feedstocks, contributing to the circular economy. (AU)

• FAPESP's process: 16/19368-6 - Biochars to improve the quality of soils contaminated with heavy metals
• Grantee: Cleide Aparecida de Abreu
• Support Opportunities: Regular Research Grants