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URI permanente desta comunidadehttps://thoth.dti.ufv.br/handle/123456789/3352
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Item Cadmium and lead adsorption and desorption by coffee waste-derived biochars(Instituto Agronômico (IAC), 2022-02-16) Carnier, Ruan; Coscione, Aline Renée; Abreu, Cleide Aparecida de; Melo, Leônidas Carrijo Azevedo; Silva, Andressa Ferreira daBiochar 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.Item Coffee waste biochars: characterization and zinc adsorption from aqueous solution(Editora UFLA, 2019-10) Sertoli, Lindiamara; Carnier, Ruan; Abreu, Cleide Aparecida de; Coscione, Aline Renée; Melo, Leônidas Carrijo AzevedoThe final disposal of organic wastes has become a major challenge with increasing industrialization and population growth. Coffee wastes can be converted into biochar and provide economic and environmental benefits, such as heavy metal remediation in different media. We produced biochars at 700 °C from spent coffee grounds and coffee parchment, characterized them physically and chemically and evaluated their Zn adsorption capacity from aqueous solution. Batch adsorption experiments were performed with six Zn concentrations using four replicates. The desorption process was performed sequentially with a pH 4.9 buffer acetic acid solution. Langmuir and Freundlich isotherms were fitted to the adsorption data using non-linear models. Results show that both biochars are alkaline and have high values of point of zero charge (PZC) (9.2 and 7.7 for coffee parchment and spent coffee grounds biochar). These characteristics indicate precipitation as the main mechanism of Zn immobilization and may have contributed to the low adsorption capacity obtained (0.056 and 0.792 mg g-1 for spent coffee ground and coffee parchment biochar, respectively). Although the biochars have shown low adsorption capacity, they bound Zn strongly and the adsorption process is not easily reversed.