Evaluation of the rubber seed shell (hevea brasiliensis) as an adsorbent: kinetic study/Avaliação da casca da semente de borracha (hevea brasiliensis) como adsorvente: estudo cinético

Abstract

This study consisted in a technical evaluation of the adsorption process as a treatment for effluents contaminated by dyes. Due to that, a methyl orange solution was used in order to simulate a textile effluent, and the rubber seed shell was used as an adsorbent. It was evaluated an untreated seed shell (CS), the calcinated seed shell (CCS) and the calcinated shell that was also submitted to a chemical treatment using a solution of HNO3 15% (CCS-T). The experiments were performed in a batch mode to evaluate the individual efficiency of each treatment. The adsorbent’s mass and the initial concentration of the solutions used were remained constant at 0.15 g and 100 mg/L, respectively. The absorbance analysis was done for all the samples obtained during 6 h of operational time. The results indicated that the CCS-T provided the best efficiency in the removal of methyl orange dye, reducing its concentration to 55.98 mg/L, whereas the use of the CCS achieved a value of only 75.53 mg/L. It was not observed adsorption using CS. The maximum adsorption capacity of methyl orange was 7.59 mg/g, through the CCS-T adsorbent. Two kinetic models were used to model the experimental data obtained with the CCS-T adsorbent, with the pseudo-first order model providing the best correlation with the experimental data.