混价MIL-53(Fe)催化过氧乙酸处理丝绸印染废水的影响因素及规律

Influencing factors of silk printing&dyeing wastewater treatment by mixed-valence MIL-53(Fe)activated peracetic acid process

芬顿氧化技术是丝绸印染废水深度处理中以保障水质达标排放或中水高效回用的新兴工艺,但常规芬顿工艺因H_(2)O_(2)难活化而效率偏低。为此,本文在开发混价MIL-53(Fe)催化过氧乙酸新型芬顿技术的基础上,通过考察其对模型污染物对硝基苯酚的降解性能,系统研究了过氧乙酸摩尔浓度、催化剂质量浓度、初始pH值、碳酸根摩尔浓度、氯离子摩尔浓度、腐殖酸质量浓度等关键因素的影响规律。结果表明:除了氯离子摩尔浓度,其他因素对降解性能均有重要影响,其中过氧乙酸摩尔浓度和催化剂的质量浓度与降解性能呈正相关,其余的都与降解性能呈负相关。该新型芬顿技术对丝绸印染二级出水具有良好的处理效果。

Silk is a typical type of natural protein fiber with a reputation of"queen of the fiber".Silk products have attracted much attention among consumers due to its bright color,soft hand feeling,as well as comfortable wearability.Mature printing and dyeing(P&D)technology with great ability is widely used to process raw silk fabrics into exquisite satins.However,the wastewater generated during the P&D processes containing a large number of organic pollutants such as dyes and surfactants has the characteristics of high complexity,large chemical oxygen demand and deep chromaticity.After common treatments,these organic pollutants are usually converted into nonbiodegradable and refractory phenolic compounds(e.g.,p-nitrophenol(4-NP))which require further purifications by advanced treatments.Due to its high efficiency,low cost,cleanness and environmental protection,Fenton oxidation has been applied as an emerging technique for the advanced treatment of silk P&D wastewater to control the quality of discharged effluent and/or to enable the efficient reuse of wastewater.Unfortunately,conventional Fenton processes initiated by hydrogen peroxide(H_(2)O_(2))are inefficient due to the difficult activation of H_(2)O_(2)and limitation of available pH range.Compared with H_(2)O_(2),peracetic acid(PAA)molecules have an asymmetrical structure with a relatively low bond energy of O—O(159 kJ/mol),suggesting the easier activation of PAA for potential usage.However,researches focusing on the potential of using PAA as oxygen source for Fenton process are scarce.Thereby,it is of great significance to develop an efficient and stable heterogeneous catalyst with PAA and investigate the relationship of treatment efficiency with catalytic process conditions and wastewater matrices for the advanced treatment of silk P&D wastewater.Recently,the Fenton catalytic activity of Fe-MOFs has been evidenced significantly greater compared with traditional oxide catalyst(e.g.,Fe;O;,Fe;O;).Furthermore,the pre-design and post-modification of the structure of Fe-MOFs show potential to further improve their catalytic performances.Herein,based on the development of new mixed-valence MIL-53(Fe)Fenton technology for PAA activation process,this work focuses on the investigation of effect of catalytic process conditions and wastewater matrice on the silk P&D wastewater treatment efficiency of mixed-valence MIL-53(Fe)/PAA system using 4-NP as a model substrate.In particular,various influencing factors,such as PAA and catalyst dosage,initial pH value,as well as the concentration of carbonate,chloride and humic acid are systematically evaluated.In addition,the aim of this study is also to identify the key modulation capacity of influencing factors and research the law of modulation while the treatment effect of mixed-valence MIL-53(Fe)/PAA system on the secondary effluent discharged from real silk P&D processes is tentatively demonstrated.The related findings are expected to provide essential data for efficiency enhancement of silk P&D wastewater treatment.We find that the developed mixed-valence MIL-53(Fe)/PAA process exhibits an excellent treatment capacity for real silk P&D effluent.The effects of the catalytic process conditions and the wastewater matrice on the efficiency are quite different.As for the process conditions,both the PAA and catalyst dosage present a positive correlation with the 4-NP degradation efficiency while the pH value is negatively correlated with the 4-NP degradation efficiency.In the case of the wastewater matrice,all the related influencing factors except chloride concentration show negative correlations with the 4-NP degradation efficiency.The results of the effect of catalytic process conditions and wastewater matrice on the treatment capacity of mixed-valence MIL-53(Fe)/PAA system can provide comprehensive research basis for the development and application of advanced treatment technique for silk P&D wastewater,which is conducive to evaluating the practicality of this technique.Our findings can also provide significant insights for the design and practice of high-efficient Fe-MOFs Fenton catalysts.