Carvão ativado a partir de resíduos agrícolas e suas aplicações na adsorção de íons metálicos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The present research project tried to develop new activated carbons from agricultural side products in an attempt to use them as ion adsorbents for industrial waste water effluents containing pollutant metal ions. Those industrial effluents represent important environmental threats and are considered as important contaminants. We generated activated carbons from macadamia nut shells (EM) and guava seeds (SG) by using chemical (ZnCl2) and/or physical (CO2) activation procedures. These technical manipulations increased the specific surface area, as well as the volume and micropore area, of both materials conferring them adsorbent characteristics. Further evaluation of the adsorptive capacity of copper ions (Cu2+) was performed in solution, in a side by side comparison between these materials and a commercial activated carbon made out of coconut shells. Moreover, we performed the analysis of the adsorption kinetics, the isotherms that could be applied to each material, as well as the analysis of the adsorbent power versus pH variation. The capacity to adsorb copper ions by the different carbons generated was higher when the latter were subjected to just a carbonization process, 3,3093 mg/g and 0,9312 mg/g respectively for carbonized nut shells (EMC) and carbonized guava seeds (SGC), compared to the same materials being impregnated and carbonized, 2,0984 mg/g (EMIC) and 0,8688 mg/g (SGIC) respectively. However, all those materials displayed a lower capacity of ion binding when compared to an activated carbon from a commercial source (CAI), e.g. 4,7806 mg/g adsorption. All three materials displayed similar optimal results in kinetics and in pH variation studies, being the highest adsorbencies displayed at 24 hours and at a pH range between 5,0 and 5,7. Although the SBET of EMC and SGC were 418,3 m2/g and 323,4 m2/g respectively, values that could be considered medium to low, these materials were able to adsorb copper ions significantly in solution. Thus, we can conclude that, due to their favorable characteristics, it is feasible to generate activated carbons with a satisfactory adsorbent power from macadamia nut shells and guava seeds.

ASSUNTO(S)

efluente, endocarpo de macadâmia semente de goiaba adsorção cobre tratamento de minerios carvão ativado

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