Assesment of Maerua Subcordata Root As Biosorbent for The Removal of Cr (Vi) Ions From Tannery Waste Water
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Date
2015-05
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Addis Ababa University
Abstract
Chromium containing wastes are generated by industries such as leather tannery, electroplating, paint and pigment manufacturing. The form of Cr (VI) is responsible for human carcinogen as well as water and soil pollution. The main objective of the present study was to evaluate the possibility of using Maerua Subcordata as a Biosorbent for the removal of Cr (VI) from tannery waste water and aqueous solution. The study was conducted in Addis Ababa university Environmental science laboratory center and Ethiopian leather industry development institute laboratory center, from January to May, 2015. Maerua Subcordata was collected from South Omo Zone DasenechWoreda and cut in to small pieces, dried in the sunlight and grind to produce the powder, treated with H3PO4 (45%w/w). Physical characterization such as moisture content and bulk density of activated Maerua Subcordata was done and it was found low moisture content which indicates high quality of the biosorbent.The Biosorption of Cr (VI) from aqueous solution and real tannery waste water by activated Maerua Subcordata was studied.
The biosorbent was characterized by FTIR spectroscopy and characterization of the Maerua Subcordata suggested the possible contribution of carboxyl and hydroxyl groups in Cr (VI) Biosorption. The Biosorption efficiency of the Maerua Subcordata was dependent on the pH of the Cr (VI) solution, with pH 3 being optimal. The removal rate of Cr (VI) ions increased with increase in contact time and remained constant after an equilibrium time of 60 min. The removal of Cr (VI) ions increased with increase in biosorbent concentration with the optimal biosorbent dosage at 125 mg/L. Both Langmuir and Freundlich model were followed by adsorption of Cr(VI) on activated MaeruaSubcordata. But Langmuir model best describes the adsorption data with coefficient of determination (r2) value 0.993.The maximum adsorption capacity obtained from Langmuir model is 4.54mg/g.The RL value obtained from Langmuir model shows the adsorption is favorable. When applying the biosorbent to real waste water 86.5% removal efficiency was obtained. The reduction in efficiency might be due to the presence of interfering ions which compete with Cr (VI) ion for Biosorption.
Therefore, the study revealed that the activated Maerua Subcordata could be used as an excellent biosorbent for the removal of Cr (VI) chromium from Tannery wastewater and aqueous solution.
Key words: Hexavalent chromium, Activated Maerua Subcordata, Biosorption
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Keywords
Hexavalent chromium, Activated Maerua Subcordata, Biosorption