Extraction of humicsubstances from tannery effluent to study their complexation with chromium and manganese

Abstract

Tannery effluent contains large amount of toxic chemical compounds. Effluentswere collected from tanneries nearSavar, Dhaka, Bangladesh. The concentration of Cr and Mn was traced from the point source towards the mixing zone in the nearby river. Flame-AAS and ICP-OES analysis showed concentrations of Cr ranged from 4213.908 mg/L to 0.015mg/L and Mn: 1.723 mg/L to 0.010 mg/Lin four different points towards the river direction. The attenuation of the discharged manganese and chromium was studied through complexation with the humic substances present in the effluent.The extracted Humic substances from the effluent were characterized with Fourier Transform Infrared spectroscopy (FTIR), Energy dispersive (EDX), proton magnetic nuclear resonance (1H-NMR), GC-MS and CHN analyzer. A comparison of Humic-metal complexation was donebetween Humic substance extractedfrom uncontaminated swampsoil and tannery effluent.These complexes were characterized by FTIR and SEM-EDX. FTIR spectra indicated that Cr and Mninteracted withHumicsubstances primarily through oxygen containing functional groups.Metal percentage calculated from EDX data showed humic acids obtained from both the sources has higher affinity for Mn than Cr. Humic acid from tannery showed higher metal content compared to swamp humic acid. Present study suggests that the unique composition of humic substances from different natural set-ups can affect their complexation capacity for different metals.