Waste-to-resources: Exploratory surface modification of sludge-based activated carbon by nitric acid for heavy metal adsorption. (15th March 2019)

• Record Type: Journal Article
• Authors: Li, Loretta Y.; Gong, XuDong; Abida, Otman
• Is Part Of: Waste management. Volume 87(2019)
• Page Start: 375
• Page End: 386
• Publication Date: 2019-03-15
• Subjects: Sewage sludge -- Activated carbon -- Sorbents -- Heavy metals -- Acid rock drainage; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2019.02.019
• Languages: English
• ISSNs: 0956-053X

Abstract

Graphical abstract: Highlights: Sludge-based activated carbon HNO3 -impregnated for 4 h at 90 °C removed 98% of Pb 2+ . This sorbent removed 99% Cu, 43% Zn and 35% Al from complexed acid rock drainage. Removal was likely due to carboxyl groups (R-COO − ) on activated carbon surface. After 24-h desorption of pH 3 solution, 0.90% (mass) of sorbed Pb 2+ had leached. This sorbent had greater and faster Pb 2+ removal than other sorbents tested. Abstract: Sewage sludge has the potential to be utilised as a sorbent for dissolved pollutant removal. This study investigated metal removal efficiency of carbonised sewage sludges obtained via pyrolysis at 500 °C: biochar/carbonised sludge (CS), ZnCl2 -activated sludge-based active carbon (SBAC), and three SBACs modified by nitric acid at different concentration and temperature (MSBACs). Batch adsorption kinetic tests indicated that the Pb 2+ adsorption equilibrated in <5 min. Efficiencies of these sludge-based sorbents for Pb 2+ adsorption followed the order MSBAC > SBAC > CS. Metal leachabilities were low or negligible for the SBAC and MSBACs. A comparison of 5-min adsorption of the best-performing MSBAC with different sorbents indicates that performance followed the trend MSBAC > grundite (illite) > zeolite (clinoptilolite) > commercial activated carbon (CAC) > kaolinite > perlite. Furthermore, MSBAC achieved 98.9%, 42.6%, and 34.6% removal of Cu, Zn, and Al, respectively, from spiked natural acid rock drainage in <5 min. The modified sludge-based activated carbon is an effective and sustainable sorbent for removing metals from aqueous environments.