Design Of Environmentally Friendly PCNs Derivatives And Its Risk Regulation Based On The Concept Of Cleaner Production

Polychlorinated naphthalenes(PCNs)are a group of industrial chemicals consisting of naphthalene substituted with 1-8 chlorine atoms,yielding 75 possible congeners.PCNs has been widely used in the history as insulating oil,lubricating oil additive,cable insulator and preservative in the container or transformer due to its thermal stability in medium fluid and insulator.Although PCNs have been banned since 1977,they can still be detected in the atmosphere,water,soil,sediments and organisms.PCNs have significant biological toxicity,bioaccumulation,environmental persistence and long-distance migration in the environment,so they were classified as persistent organic pollutants(POPs)in 2015.Among them,the biological toxicity is the most concerned.However,previous studies were limited to the representative homologues,and lack of analysis,regulation and internal law summary of environmental behavior of 75 PCNs.Moreover,they mostly focused on one POPs' characteristics.In addition,due to the specific practical properties of many banned pollutants,experts have begun to research and develop their substitutes.However,these substitutes caused new environmental problems in the process of production and use.Therefore,it is very important to design environment-friendly insulating oil and flame retardant(PCNs substitutes).This study took the POP characteristics of PCNs as the breakthrough point,first evaluated the POP characteristics of 75 PCNs,and analyzed the internal mechanism of influencing the POP characteristics of PCNs.Then we regulated the existing PCNs from three aspects:source control,pollution process control and end treatment.Meanwhile,new environmentally friendly PCN insulating oil and flame retardant were designed(the control of 4 POPs characteristics at the same time).In the aspect of source control of PCNs,the traditional single effect 3D-QSAR models of POP characteristics were established based on the indexes of biological toxicity(logEC50),bioaccumulation(logBCF),long-range migration(logPL)and environmental persistence(total-score)of PCNs.As a result,five,six,four and three new PCNs with low toxicity,low enrichment,low migration and high degradation were designed,respectively.At the same time,they had the similar insulation and flame retardant properties as the homologues before modification.In addition,a modified multi-effect 3D-QSAR model was established on the basis of single effect models and vector analysis method.The model took into account the multiple environmental characteristics of POPs,broke the limitation of traditional 3D-QSAR model which can only carry out single effect modeling.And an environmentally friendly high-performance material screening system integrating environmental characteristics evaluation,practical performance evaluation and risk evaluation was constructed.Based on the established model and screening system,two kinds of high-performance insulating oil and flame retardant materials(PCN derivatives)which are environment-friendly and risk-free to human body were designed,one of which has been separated from the biological enrichment characteristics of POPs(logKow<5).In terms of the regulation of PCN pollution process,this study took the compound toxicity of PCNs to the food chain(green algae-Daphnia magna-fish)in the artificial aquaculture area and the human exposure health risk in industrial pollution areas as examples.The method of combining multi-effect 2D-QSAR model with molecular dynamics simulation reveals the composite of PCNs to the key link organisms of aquatic ecosystem food chain.The mechanism of its combined interference mechanism on various endocrine interference receptors in human body were established.What's more,the macro-control scheme of the transmission resistance of PCNs aquatic toxicity in food chain and the recommended food supplement scheme for preventing human health risk in industrial pollution areas were formulated.The results showed that the toxic effects of PCNs on aquatic food chain belonged to high toxicity and extremely high toxicity,and they belonged to non-polar anesthetic and reactive chemicals;the binding ability of PCN molecules to aquatic receptors was the main factor affecting the toxicity of PCNs to the food chain;improving the external stimulation conditions of solvation effect,dechlorination hydrogenation and molecular adsorption can reduce the aquatic toxicity effect of PCNs in aquatic food chain,and the decrease rates were by-66.26%--263.16%,-198.93%--323.98%and-189.24%--549.48%,respectively.Moreover,The electronic parameters of PCNs are the main factors that affect the joint toxicity of PCNs to human endocrine disruptor receptors,and the lowest occupied orbital energy(ELUMO)>the difference of orbital energy(?E)>the most positive vertical charge(q+).Vitamin and carotene can be used as the best recommended nutritional composition to prevent the health risk of workers in PCN-contaminated areas,and it is not recommended to eat foods rich in lactoglobulin,vitamins,carotene and ginseng together.In the aspect of terminal treatment of PCNs,the organic combined remediation system of PCNs was constructed by combining genetic engineering and environmental remediation technology.The regulation scheme was determined to promote the plant-microorganism system to simultaneously and efficiently repair different types of PCN-contaminated soil through a variety of remediation methods,and the regional regulation of PCN-contaminated soil was realized.In this study,a modified 2D-QSAR model was used to construct a joint repair mechanism model which considered multiple repair methods of plant-microorganism system,and broken the limitation of traditional 2D-QSAR model.At the same time,the traditional homologous modeling method was improved,and 4 kinds of multifunctional repair proteins with absorption,degradation and mineralization functions were designed.The repair effect was improved by 12.07%-41.87%.And the organic remediation scheme of PCN-contaminated soil was proposed to improve the remediation effect(increased by 4.40%-7.26%on the basis of the above).This study aimed to provide an important theoretical method for the prediction of POPs characteristic values of PCNs and its homologues and derivatives,moreover,this study also provided a new insight and method for the realization of source control,process control,terminal treatment and environment-friendly material design of PCNs,so as to realize cleaner production.