Stabilization/solidification on chromium (III) wastes by C(3)A and C(3)A hydrated matrix.
Hazardous wastes are usually used in the Portland cement production in order to save energy, costs and/or stabilize toxic substances and heavy metals inside the clinker. This work focus on the stabilization/solidification on chromium (III) wastes by C(3)A and C(3)A hydrated matrix. The immobilization rate of chromium in C(3)A and the leaching characteristics of the C(3)A hydrated matrixes containing chromium were investigated by ICP-AES. The results indicated that C(3)A had a good solidifying effect on chromium using the clinkering process, however, the Cr leaching content of Cr-doped C(3)A was higher than that of hydrated C(3)A matrix in Cr(NO(3))3 solution and was lower than that of the hydrated C(3)A matrix in K(2)CrO(4) solution, no matter the leachant was sulphuric acid & nitric acid or water. To explain this, C(3)A formation, chemical valence states of chromium in C(3)A, hydration products and Cr distribution in the C(3)A-gypsum hydrated matrixes were studied by XRD, XPS and FESEM-EDS. The investigation showed that part of Cr(3+) was oxidized to Cr(6+) in the clinkering process and identified as the chromium compounds Ca(4)Al(6)O(12)CrO(4) (3CaO·Al(20O(3)·CaCrO(4)), which resulted in the higher leaching of hydrated matrix of Cr-doped C(3)A.
State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China. Electronic address: lxggroup@163.com.
Xiangguo
X
Li
State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China.
Chao
C
He
Advanced & Innovative Materials (AIM) Group, Department of Civil, Environmental & Geomatic Engineering, University College London, London WC1E 6BT, UK.
Yun
Y
Bai
State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China.
Baoguo
B
Ma
State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China.
Guandong
G
Wang
State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China.
Hongbo
H
Tan
D017607:Aluminum Compounds / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D017608:Chromium Compounds / Q000737:chemistry*; D003252:Construction Materials; D006256:Hazardous Waste; D008855:Microscopy, Electron, Scanning; D044367:Phase Transition; D012037:Refuse Disposal / Q000379:methods*; D013499:Surface Properties; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
D017607:Aluminum Compounds; D017610:Calcium Compounds; D017608:Chromium Compounds; D006256:Hazardous Waste; D014867:Water; C035219:calcium aluminate
C(3)A; Chemical state; Chromium; Hydration; Stabilization/solidification