Chromium (VI) and zinc (II) waste water co-treatment by forming layered double hydroxides: mechanism discussion via two different processes and application in real plating water.
Two processes, adsorption after synthesis (AAS) and adsorption during synthesis (ADS) were compared in CrO4(2-) and Zn2+/CrO4(2-) removal. Kinetic results showed that ADS was a better method than AAS, since Cr content was 0.65/0.81 mmol/g in Cr-ADS/ZnCr-ADS, but it was only 0.37/0.56 mmol/g in Cr-AAS/ZnCr-AAS. Then, a low-cost mixture was proposed to function as ADS raw materials in treating real plating waters. This mixture first got an isothermal saturation of 1.1 mmol/g in simulated CrO4(2-) water. When Zn2+ was co-treated, it was increased to 1.3 mmol/g. At the same time, a Zn2+ removal of 1.5 mmol/g was attained. Furthermore, real plating water co-treatment reached equilibrium in 6h and obtained 1.4/0.9 mmol/g for Zn2+/CrO4(2-), respectively. According to XRD analysis, this co-treatment enhancement resulted from the formation of Zn and Cr contained layered double hydroxide.
School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200072, PR China.
Jia
J
Zhang
Yang
Y
Li
Jizhi
J
Zhou
Dan
D
Chen
Guangren
G
Qian
D000327:Adsorption; D000535:Aluminum / Q000032:analysis; D002118:Calcium / Q000032:analysis; D002857:Chromium / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry*; D007220:Industrial Waste; D007700:Kinetics; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods; D014961:X-Ray Diffraction; D015032:Zinc / Q000737:chemistry*
D006878:Hydroxides; D007220:Industrial Waste; D014874:Water Pollutants, Chemical; D002857:Chromium; D000535:Aluminum; D015032:Zinc; D002118:Calcium