Study On Passivation Of Wood Vinegar For Heavy Metal Passivation

In recent years,Chinese animal husbandry has begun to develop vigorously,and animal husbandry has become a new economic model and an important pillar in the countryside,but with it is the rapid growth of livestock and poultry manure emissions.The ability of heavy metals in livestock and poultry manure to migrate and transform is poor.The long-term use of such manure in large quantities will enrich the heavy metals in the soil,causing the soil to harden,reducing the quality and yield of crops,and even endangering human health.Compost can stabilize organic matter,eliminate odors,passivate heavy metals,and kill harmful bacteria.It has become an important way to utilize livestock and poultry manure resources.In this study,wood vinegar solution prepared by pyrolysis of cotton stalks was used as a passivating agent to study the physical and chemical properties of solid products during the composting process,the total heavy metals Cu,Zn and their morphological evolution,using Fourier infrared spectroscopy?FTIR?technology analyzes the humification changes of organic matter in the composting process,and establishes a quantitative analysis and prediction model for the heavy metals Cu and Zn of the wood vinegar liquid manure compost solid product,and explores the use of wood vinegar liquid for the passivation of heavy metals The mechanism of action and the feasibility of near-infrared technology in the detection of the content of heavy metals Cu and Zn in the compost of livestock and poultry manure.Obtain the following main research results:?1?Adding cotton stalk wood vinegar treatment,the pile enters the high temperature period 3 days in advance,and the high temperature duration increases by more than 7 days.The passivation effect of Cu in the exchangeable state of heavy metals increases with the increase of the addition ratio of cotton vinegar.When the addition ratio is 0.65%,the passivation effect on Cu is best to reach 32.28%.The passivation effect of Zn is that the low addition ratio has a certain inhibitory effect.When the addition ratio reaches0.5%,it plays a promoting role,and the 0.65%addition ratio reaches the best,which is 26.29%.The addition of cotton vinegar liquid improves the temperature rise rate,high temperature duration and heavy metal passivation effect of cow dung composting process,and is an effective heavy metal passivator.?2?The addition of cotton vinegar liquid is beneficial to the conversion of organic carbon in the solid product of cow dung compost from water-soluble state to solid state,and promotes the degree of humification of organic matter.In the early stage of composting,most of the Cu and Zn in the humus are mainly combined with FA.As the composting progresses,HA/FA,HA-Cu and HA-Zn all show a clear increase trend.The process of humification and the formation of HA-Cu and HA-Zn during the process can enhance the stability of Cu and Zn in humus.?3?The results of FTIR spectroscopy of the solid products of cow manure compost showed that there were five similar absorption peaks near 1650cm-¹,3414cm-¹,2922cm-¹,1410cm-¹,1376cm-¹ and 1106cm-¹.Its main functional groups are C=O,O-H,C-H,-C-O,O-H,C-O,etc.,which can be divided into carboxylic acids,carbohydrates and aromatic compounds.According to the semi-quantitative analysis of the ratio of the characteristic peaks at 1650cm^-1 to the peak intensities at 3414cm^-1,2922cm^-1,1410cm^-1and 1106cm^-1,it can be seen that as the composting progresses,the content of complex compounds containing aromatic ring structures increases,and The possibility of complexing heavy metals is increased,which is beneficial to improve the passivation effect of heavy metals.The intensity ratio of each characteristic peak in the wood vinegar treatment group did not change significantly except at 1410 cm-¹,and the intensity ratio of the remaining characteristic peaks was greater than that of the CK treatment,with a larger increase and an earlier change time.?4?The continuous projection algorithm?SPA?and the competitive adaptive reweighting algorithm?CARS?are used to screen the feature bands and establish the two feature wave screening methods and full band PLS model with some differences in model accuracy for the three groups.The heavy metal Cu model was significantly reduced in modeling volume and improved in model accuracy after the SPA and CARS methods of screening variables,and the The CARS method screened the characteristic variables to construct the model with the highest accuracy,with r and R² of 0.9664 and 0.9248,respectively.The Zn model was reduced from 1801 to 21 and 30 modeled by the SPA and CARS method of screening variables,but the modeling accuracy was reduced,with r being 0.9271 and 0.954 and R² being 0.8466 and 0.8941,respectively.