Stabilization/solidification of chromium-bearing electroplating sludge with alkali-activated slag binders
| Autor: | Honghong Yuan, Huxing Chen, Xianjin Tang, Linqing Mao, Muhammad Zaffar Hashmi, Fangnan Xu |
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| Rok vydání: | 2020 |
| Předmět: |
Chromium
Hazardous Waste Environmental Engineering Materials science Scanning electron microscope Health Toxicology and Mutagenesis 0208 environmental biotechnology chemistry.chemical_element 02 engineering and technology Alkalies 010501 environmental sciences 01 natural sciences chemistry.chemical_compound Humans Environmental Chemistry Fourier transform infrared spectroscopy Calcium silicate hydrate Electroplating Environmental Restoration and Remediation 0105 earth and related environmental sciences Sewage Public Health Environmental and Occupational Health General Medicine General Chemistry Pollution 020801 environmental engineering Compressive strength chemistry Chemical engineering Ground granulated blast-furnace slag Leaching (metallurgy) |
| Zdroj: | Chemosphere. 240:124885 |
| ISSN: | 0045-6535 |
| DOI: | 10.1016/j.chemosphere.2019.124885 |
| Popis: | Chromium (Cr)-bearing electroplating sludge is a hazardous solid waste and has a detrimental effect on human health and the environment. In this study, an alkali-activated slag binders, namely, formed by the reaction of blast furnace slag (BFS) with alkali, was applied to the stabilization/solidification (S/S) of electroplating sludge. The effects of liquid–solid ratio, water glass modulus ratio (molar ratio of SiO2 to Na2O), water glass dosage, and electroplating sludge amount on the compressive strength and Cr leachability of binders were analyzed. The related mechanism of the S/S of electroplating sludge was discussed on the basis of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy coupled with energy-dispersive spectrometry (SEM–EDS). Results showed that the compressive strength of the alkali-activated slag binder first increased and then remained stable with the increase in liquid–solid ratio, water glass modulus ratio, and water glass dosage. By contrast, the leaching concentrations of Cr(VI) and total Cr decreased with the increase in liquid-solid ratio, water glass modulus ratio, water glass dosage, and curing time. In addition, XRD, FTIR, and SEM–EDS revealed that the hydration products of the binders were mainly low-crystallinity and dense calcium silicate hydrate gels, and Cr(VI) had been effectively immobilized in the structure. The reduction in Cr(VI) by the reductive components in the BFS boosted the stabilization of Cr-bearing electroplating sludge. Overall, the BFS binders containing electroplating sludge had relatively high compressive strengths and low Cr(VI) leaching concentrations. The physical encapsulation, chemical bonding, and absorption contributed the Cr immobilization during the S/S process of electroplating sludge. |
| Databáze: | OpenAIRE |
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