CWPO Research CuO-based Catalyst And Phenol Wastewater

The fast developing of industrialization and urbanization causes various seriousenvironmental issues to human being, and these environmental problems significantlyaffect the human themselves sustainable development. Water pollution, one of mostimportant environmental issues, attracts additional concerns due to its closerelationship with the biosphere. The phenolic compounds are one representive kindsof hazardous organic pollutants group and have been listed as priority pollutants byUS EPA in the Clean Water Act and the European Decision2055/2011/EC (2001).Due to the characters of high toxicity and chemical oxidation demand (COD) and lowbiodegradability, such compounds are refractory to the traditional wastewatertreatment. Therefore, the others techniques should be developed to handle thephenolic compounds to tolerable level or even up to mineralization. Catalytic WetPeroxide Oxidation (CWPO) process receives preferential interest due to thesimplicity of design and setup, safe operation, high efficiency and the use of readilyavailability oxidants. As reported in literature, various heterogeneous catalysts havebeen investigated as potential one applied in the CWPO process. However, theresearch concerned on Cu-based catalyst is initial stage and need to be further studied.In present dissertation, we prepared two different types of Cu-based catalyst,CuCe composite oxides and CuO/SBA-15, over complexing metheod andimpregnation. X-ray powder diffraction (XRD), the scanning electron microscope(SEM), H2temperature-programmed reduction (H2-TPR), N2adsorption-desorptionisotherms, transmission electron microscope (TEM), atom absorptionspectrophotometer (AAS), techniques were used to study systematically the effects ofprepared conditions on CuCe and CuO/SBA-15catalyst structural property, surfacemorphology and redox property. The performance of CWPO of phenol,4-CP and2,4-DCP were evaluated by ion chromatography (IC), ultraviolet and visiblespectrophotometer and total organic compounds analyzer (TOC). Additionally, therelationship between catalytic performance and reaction conditions, including H2O2dosage, catalyst concentration, react temperature, target compounds concentration,initial pH values and reusability of catalyst, have also been scientific investigated.Some main conclusion in present work has been concluded as follow:1. The CuCe composite catalyst with Ce/Cu=6, M(Cu+Ce)/CA=1.8and calcined at450°C for3h possesses the best CWPO of4-CP and2,4-DCP activity and good pHadaptability. When the initial pH at6.2, TOC removal in4-CP and2,4-DCP were87% and81%after120min at50°C, respectively. The formation of CuCe solid solutionwith high specific surface, coarse porous cotton-like structure on CuCe compositecatalyst can responsible for the superior CWPO activity of4-CP and2,4-DCP.2. Increasing the initial H2O2and catalyst concentration accelerated generation ofhydroxyl radicals (·OH). But the over the critical amount of H2O2and catalyst arousedside reaction and did less contribution to the TOC removal. Enhancing of temperaturecould provide more energy and then significantly increase the react rate. The greatertarget comounds concentration lead more amount absorbed organic molecular tocatalytic sites, which could hinder the catalytic sites available for the H2O2molecularabsorption and activation into·OH species, thus resulting in lower TOC removal.3. The reusability of CuCe composite catalyst results showed that crystalline phaseand surface morphology have not changed afer CWPO process. However, TOCremoval and dechlorination in4-CP and2,4-DCP solution decreased with times ofreusability, which can be attributed to the Cu and active species leaching on catalystsurface during CWPO process.4. The CWPO of4-CP and2,4-DCP over CuCe composite catalyst fit the pseudo-firstorder reaction kinetics, and the kinetic equation can be expressed as: y=6959.3x－17.2and y=9725x－25.4, respectively, the apparent activation energy were calculatedwith Ea=57.8and80.8kJ/mol f, respectively. The2,4-DCP were more difficult bedegraded than4-CP, which can be ascribed to the effect of molecular polar andsubstituent steric hindrance of2,4-DCP.5. The study results of CuO/SBA-15catalyst indicated that the CuO/SBA-15catalystwith20wt%Cu loading calcined at450°C for3h possessed high orderedmesoporous structure,6nm of pore size and716m2/g of specific surface area. Thehigh oredered sturcure of SBA-15facilitated CuO species well distributed on innerchannel of supporter and then maintained small crystal size. The preparedCuO/SBA-15catalyst exhibited good pH adaptability, and pH range from4.2to7.9,the TOC removals in phenol more than90%. The Cu leaching from CuO/SBA-15catalyst surface was the main cause to the decrease of the CWPO activity.