Title: Mechanochemical treatment of hexachlorobenzene: effect of additives

Authors: Qiongjing Mao; Shengyong Lu; Zhiliang Chen; Alfons Buekens; Jianhua Yan

Addresses: College of Civil Engineering and Architecture, Zhejiang University of Water Resources; Electric Power, Hangzhou 310018, China ' State Key Laboratory of Clean Energy Utilisation, Zhejiang University, Hangzhou 310027, China ' State Key Laboratory of Clean Energy Utilisation, Zhejiang University, Hangzhou 310027, China ' State Key Laboratory of Clean Energy Utilisation, Zhejiang University, Hangzhou 310027, China ' State Key Laboratory of Clean Energy Utilisation, Zhejiang University, Hangzhou 310027, China

Abstract: Mechanochemical (MC) methods have shown an excellent performance while decomposing a number of halogenated persistent organic pollutants (POPs). In this study, a number of MC degradation tests were performed on hexachlorobenzene (HCBz), using an all-dimensional planetary ball mill and applying selected additives, including CaO, CaO-SiO2, CaO-Al2O3, CaO-Al and Fe-SiO2. After 8 h of milling, up to 99.7% of the original HCBz was removed by processing with a combined CaO-Al additive. Different ratios of Al to CaO were compared and the highest (99.70%) destruction efficiency of HCBz was achieved after 3 h by the additive CaO-Al (11.1% added), considered to be the most practical pair. Sequential dechlorination of HCBz and polymerisation of the resulting residual benzene should be the main degradation pathway; this conclusion is reached by observing lower chlorinated intermediates and graphite and amorphous carbon as final products. Strong radical signals and micro-spheres as well as tribo-microplasma phenomena were induced by severe mechanical ball milling.

Keywords: mechanochemical treatment; hexachlorobenzene; HCBz; CaO-Al; additives; ball mill; degradation; mechanism; environmental pollution.

DOI: 10.1504/IJEP.2017.087772

International Journal of Environment and Pollution, 2017 Vol.61 No.3/4, pp.293 - 313

Accepted: 17 Jul 2017
Published online: 27 Oct 2017 *

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