Date

10-2009

Degree

Bachelor of Science in Chemical Engineering

College

College of Engineering and Agro-Industrial Technology (CEAT)

Adviser/Committee Chair

Amelia E. Parao

Committee Member

Jerico R. Aguila, Jovita L. Movillon

Abstract

Reduction of hexavalent chromium from actual plating wastewater by hydrazine treatment was studied. The effects of initial pH (2,3.8, 6, and 9) of wastewater, hydrazine dosage (0.75:1, 1:1, 2:1, 3:1, and 4:1) and catalyst (0.1%, 0.5%, and 0.9%) on reducing Cr⁶⁺ in chrome electroplating wastewater were determined. Cost analysis of hydrazine per liter of hexavalent chromium treated was also done. Results showed that the best combination for optimum pH hydrazine dosage was at pH 3.8 and molar ratio of 3:1 hydrazine to Cr(VI). No significant increase in reaction rate was observed when cobalt chloride was used as a catalyst. The effectiveness of hydrazine could be attributed to the strong property of hydrazine as reducing agent and increase in reaction rate decreasing pH could probably be attributed to the presence of HCrO₄ present at low pH which is reduced more easily than CrO₄.At pH 3.8 and molar ratio #:1 hydrazine to Cr(VI), the final percent Cr(VI) reduction was about 99.98% Or 0.11ppm which is below the maximum limit set by DAO 35. Based on the amounts of chemicals used (hydrazine and sulfuric acid), the cost for treating chrome electroplating wastewater with initial concentration of about 708ppm at 99.98% Vr(VI) reduction would be P0.44 per liter of wastewater.

Language

English

Document Type

Thesis

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