Chromium Leachability from Leather Waste and Eco-toxicity under Environmental Conditions

Abstract

Chromium (III) is currently used in leather manufacture worldwide and the attention has been centered on the alleged environmental impact of chromium in leather waste. The effects of liquid-solid ratio, pH, contact time, rotational speed and temperature on the leachability of chromium from leather waste and the eco-toxicity were evaluated to investigate the ecological impact under environmental conditions. The characterization of leachate included the determination of total Cr and total organics (TOC), analysis of UV-visible absorption spectra, as well as the toxicity test with Photobacterium phosphoreum. The liquid-solid ratio, extractant pH, contact time and temperature significantly affected the leachability of chromium and toxicity of the leachate, whereas rotational speed slightly affected the leaching behavior when beyond 100 RPM. The toxicity of the leachate was related to both the amount of released substance which was mainly affected by contact time and liquid-solid ratio, and the species which was mainly affected by temperature and extractant pH. Finally, three samples from different tannery corresponding to leather waste were leached and characterized by total Cr, TOC and toxicity test under the environmental conditions of liquid-solid ratio 20:1(mL/g), pH 7.0, contact time 8 hours, rotational speed 100 RPM and temperature 25°C. These results contributed to the risk assessment of stacking field and waste management of chrome-containing leather.