Modification of biochitin immobilized dithizone as adsorbent for Cr (VI) removal

Abstract

Biochitin is chitin obtained from a biological fermentation that could be used as adsorbent. Biochitin used in this study was produced by sequential fermentation method from white shrimp shell using Lactobacillus plantarum (L.plantarum) followed by using Bacillus thuringiensis (B.thuringiensis). Modification of biochitin was investigated by immobilization of dithizone onto the biochitin. Immobilization parameters were optimized including the mass of dithizone and reflux time. The optimum conditions were determined based on the optimum adsorption efficiency of Cr(VI) on the modified biochitin. Adsorption was conducted triplo using 50 mg/L Cr (VI) at pH 5.0 for 6 hours The modified biochitin produced by optimum parameters was then characterized including the functional groups, surface morphology, particle size, and adsorption efficiency for Cr(VI) from electroplating waste. Results of this study showed that the optimum modification conditions were achieved by immobilization of 0.015 g dithizone/ g of biochitin and the mixture was refluxed for 4 hours in toluene medium at 70o C. This modified biochitin had the FTIR spectra at wavelength numbers of 2376.13 cm-1 (S-H group), 1382.87 cm-1 (S=C group), and at 1558.38 cm-1 (N-H group) which shows that dithizone had been successfully immobilized onto biochitin. It was also showed from SEM images that the modified biochitin had more uniform pores than unmodified biochitin. In addition, the modified biochitin was micro particle with the size was in the range of 90-200 µm. In addition, the modified biochitin could be used to remove the diluted Cr(VI) from electroplating waste at pH 4.6 with the adsorption efficiency was 83.45% ± 0.40, higher than the one using the unmodified biochitin.