The removal of Cr(VI) with Dimocarpus longan as a low cost biosorbent

Florenly, Refi Ikhtiari, Herma

Abstract

Dimocarpus longan has been proposed to be a low cost biosorbent. The adsorption ability of its seed and skin to remove the Cr (VI) in aqueous solution has been investigated in a batch method. Longan`s seed showed better ability compared to longan`s skin at any experimental condition. Adsorption capacity showed the optimum values at pH 3, initial concentration 300 mg/L, biosorbent dose 0.25 g and contact time 15 min. Langmuir and Freundlich models have the value of R2 = 0.5408 and 0.8976. Results showed that Freundlich model was better than Langmuir, proposed a multilayer biosorption ofCr (VI). FTIR showed strecthing vibration of hydroxil groups, sp3 alkanes, carbonyl groups, alkanes, and bending of primary amines. Both of the biosorbent also showed the stretching vibration of symmetric nitro compounds which supported by other peaks in the fingerprint area. SEM observation showed the surface of Dimocarpus longan has pores, granules and fibers. Typical morphological damages found after biosorption. Based on Isotherm models, FTIR and SEM images, we suggested a physico-chemical pathway could describe the metal sorption mechanism.