Optimization of silver recovery from used radiograph films (URF) via sodium hydroxide stripping

Date

6-2016

Degree

Bachelor of Science in Chemical Engineering

College

College of Engineering and Agro-Industrial Technology (CEAT)

Adviser/Committee Chair

Michael Vincent O. Laurio

Restrictions

Restricted: Not available to the general public. Access is available only after consultation with author/thesis adviser and only to those bound by the confidentiality agreement.

Abstract

This study focused on the recovery of the residual silver from used radiograph films (URFs) via sodium hydroxide stripping by conducting factorial and response surface experiments. Initially, 100g of 4 x 4 cm^2 URF samples were found to have 0.5845 grams of silver at 30.91 % purity based on the AAS and XRF analyses, respectively. At 95% confidence level, results from the 2^k full factorial experiment showed that sodium hydroxide concentration, reaction temperature, and contact time were significant in the recovery process. Further, a quadratic model was found to conform the central composite experimental design with significant effects of NaOH concentration, temperature, time and quadratic effects of concentration and time. The response surface model was used for numerical optimization, From 46 possible solutions, the selected condition was 90°C, 1.75 M and 194 seconds based on highest percent recovery and lowest NaOH concentration. Experimental verification showed 69.69 % silver recovery with a reasonable difference of 12.62 % from the predicted value. At these conditions, preliminary cost analysis showed that the recovery process costs P 54.72, with profit of P 39.26 per kilogram of film processed.

Language

English

Location

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

Call Number

LG 993.5 2016 E62 R63

Document Type

Thesis

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