Sequential shape-selective adsorption and photocatalytic transformation of acrylonitrile production wastewater. (15th November 2015)

• Record Type: Journal Article
• Authors: Dai, Yunrong; Song, Yonghui; Tu, Xiang; Jiang, Yanpeng; Yuan, Yu
• Is Part Of: Water research. Volume 85(2015)
• Page Start: 216
• Page End: 225
• Publication Date: 2015-11-15
• Subjects: Acrylonitrile production wastewater -- Zeolite -- Shape-selective adsorption -- Photocatalysis -- Sequential treatment; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2015.08.034
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: Acrylonitrile production wastewater has been widely recognized as one type of refractory organic wastewater because of its complicated composition and low bioavailability. It usually contains plenty of micromolecular nitrile and pyridine, resulting in high chemical oxygen demand (CODCr ), total organic carbon (TOC) and total nitrogen (TN) concentrations. In this study, a novel microporous zeolite, CS-Z1, was developed as an adsorbent for rapidly shape-selective adsorption of the micromolecular pollutants from the acrylonitrile production wastewater, and a visible light-driven Ti- β -Bi2 O3 photocatalysis was introduced to sequentially treat the residual macromolecular pollutants for complete purification. The adsorption processes by CS-Z1 were mostly achieved within the first 5 min, and the equilibrium was reached quickly after 30 min, where the CODCr, TOC and TN removal efficiencies of the wastewater were as high as 93.5%, 92.2% and 96.8%, respectively, much higher than those by other adsorbents. Furthermore, the adsorption efficiencies of CS-Z1 were barely affected by the variation of pH value and temperature, which was mainly attributed to the shape-selective adsorption mechanism of the CS-Z1 zeolite. The Ti- β -Bi2 O3 photocatalysis could remove more than 95% of the residual macromolecular pollutants in the wastewater, where a synergistic mechanism of reduction–oxidation/polymerization was proposed. In a 108 h of CS-Z1 adsorption and Ti- β -Bi2 O3 photocatalysis sequential process, the CODCr, TOC and TN concentrations was reduced to below 20, 7 and 5 mg L −1, respectively, demonstrating the excellent practical potential of the sequential treatment system for acrylonitrile production wastewater. Graphical abstract: Highlights: CS-Z1 zeolite was synthesized and used to adsorb acrylonitrile production wastewater. Adsorption efficiency of CS-Z1 was above 90% under a wide pH and temperature range. CS-Z1 removed micromolecular pollutants in wastewater by shape-selective adsorption. Ti- β -Bi2 O3 photocatalysis was combined to remove remaining macromolecular pollutants. Adsorption-photocatalysis sequential treatment showed excellent practical potential.