Abstract
A novel amino-functionalized silica-coated nanoscale zerovalent iron (NZVI@SiO2-NH2) was successfully synthesized by using one-step liquid-phase method with the surface functionalization of nanoscale zerovalent iron (NZVI) to enhance degradation of chlorinated organic contaminants from anaerobic microbial system. NZVI@SiO2-NH2 nanoparticles were synthesized under optimal conditions with the uniform core-shell structure (80–100 nm), high loading of amino functionality (~0.9 wt%), and relatively large specific surface area (126.3 m2/g). The result demonstrated that well-dispersed NZVI@SiO2-NH2 nanoparticle with nFe0-core and amino-functional silicon shell can effectively remove 2,4,6-trichlorophenol (2,4,6-TCP) in the neutral condition, much higher than that of NZVI. Besides, the surface-modified nanoparticles (NZVI@SiO2-NH2) in anaerobic granule sludge system also showed a positive effect to promote anaerobic biodechlorination system. More than 94.6% of 2,4,6-TCP was removed from the combined NZVI@SiO2-NH2-anaerobic granular sludge system during the anaerobic dechlorination processes. Moreover, adding the appropriate concentration of NZVI@SiO2-NH2 in anaerobic granular sludge treatment system can decrease the toxicity of 2,4,6-TCP to anaerobic microorganisms and improved the cumulative amount of methane production and electron transport system activity. The results from this study clearly demonstrated that the NZVI@SiO2-NH2/anaerobic granular sludge system could become an effective and promising technology for the removal of chlorophenols in industrial wastewater.
Highlights
Chlorophenols (CPs), a group of toxic and suspected carcinogenic pollutants, have been widely identified in chemical industrial wastewater
Chemicals ferrous sulfate heptahydrate (FeSO4⋅7H2O), ferric chloride hexahydrate (FeCl3⋅6H2O), ferrous chloride tetrahydrate (FeCl2⋅4H2O), isopropanol, tetraethyl orthosilicate (TEOS, ≥98.0%), and methyl alcohol (99.93%, highperformance liquid chromatography (HPLC) grade) and other chemical reagents were purchased from the Jinke Chemical Reagent Co., Ltd. (Guangzhou, China). 3-Aminopropyl trimethoxysilane (APTMS, ≥97.0%), poly(ethylene glycol) (PEG20000, ≥96.0%), and 2,4,6-trichlorophenol (2,4,6-TCP, 98%) were purchased from Aladdin Chemistry Co., Ltd. (China)
The sampled 2,4,6TCP reaction solution was firstly centrifuged for 10 min at 10000 g, and the supernatant was filtered through a 0.45 μm hydrophilic polyethersulfone (PES) syringe filter for highperformance liquid chromatography (HPLC) analysis. 2,4,6TCP was analyzed on a Shimadzu LC-2010A HPLC equipped with a UV detector
Summary
Chlorophenols (CPs), a group of toxic and suspected carcinogenic pollutants, have been widely identified in chemical industrial wastewater. The development of technologies for the remediation of CPs from industrial wastewater has attracted a great deal of attention in recent years, such as activated carbon absorption, photocatalytic degradation, electrochemical oxidation, and biodegradation [4,5,6,7]. Among these methods, anaerobic biological treatment technology is widely applied in toxic industrial wastewater treatment process due to convenient usage and economy [8, 9]. It is necessary to develop the advanced anaerobic technologies with high biodegradation rates and suitable microbial system for removal and mineralization of CPs into harmless end products from industrial wastewater
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