Electrolytic recovery of silver from dichromate-based COD ( Chemical Oxygen Demand) analysis wastewater

Date

2011

Degree

Bachelor of Science in Chemical Engineering

College

College of Engineering and Agro-Industrial Technology (CEAT)

Adviser/Committee Chair

Catalino G. Alfafara

Co-adviser

Veronica P. Migo

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Abstract

The study investigated the technical feasibility of applying electrochemical treatment for the recovery of silver metal from laboratory (dichromate-based) COD-analysis wastewater, prior to submission of the effluent to an environmental service provider. The effects of the operating current and time on silver recovery were investigated from silver residual concentration time profiles. Also, effects on pH, temperature and the other three heavy metals (chromium, iron and mercury) were observed. Results showed that the silver removal increased with time, and the rate of silver removal was observed to increase with the operating current. The maximum percent silver removal of about 91% was achieved at all operating currents, but silver removal rate was fastest at the highest operating current of 7 amperes. Temperature and acidity increased with time and operating current. Mercury was found to simultaneously electrodeposit with silver, at slightly higher removal efficiencies. Chromium and iron removals were also observed (in reactions not involving metal deposition), but with lower removal efficiencies. XRF results showed that mercury deposits had the highest amount, followed by silver and then iron, and the least was chromium. Charge dose for the electrolytic recovery of silver was found to be approximately 57 Coulombs/mg silver removed. The computed average values for energy requirement and energy cost were 47.50 KWh/kg-Ag and Php 413.25 per kg-Ag removed (Php 266.03 per cu.meter wastewater), respectively.

Language

English

LC Subject

Sewage, Factory and trade waste

Location

UPLB College of Engineering and Agro-Industrial Technology (CEAT)

Call Number

LG 993.5 2011 E62 G88

Document Type

Thesis

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