Study On The Adsorption Of Pollutants In Water And The Effect Of Soil Microenvironmental By Co-pyrolysis Biochars Derived From Cantaloupe Vines And Plastic

As Hainan cantaloupes are mainly grown off the ground with supporting devices,plastic products are widely used to fix vines in the growth.After the harvest,vines mixed with plastics will cause great harm to the environment if they are inappropriately treated.Increasing cantaloupe yield also makes the research on the harmless treatment of above-mentioned waste more urgent.In such a condition,the biomass pyrolysis technology emerged in recent years is expected to solve this problem.In this study,waste vines and plastic ropes were used as raw materials to produce co-pyrolysis biochar with different mixing ratios.We analyzes the effects of different raw material make-ups and heating temperatures on the physicochemical properties and structural composition of biochar through the means including element analysis,BET,XRD,FTIR and SEM-EDS.The adsorption capacity and mechanism of 1 g·L^-1 co-pyrolysis biochar added for simulated pollutants cadmium(Cd²⁺)and methylene blue（MB）were studied in batch adsorption experiments.Also,with the help of indoor culturing experiments,the environmental effects of 2%co-pyrolysis biochar on the physicochemical properties,soil enzyme activities,and microbial communities of red soil were investigated;and the factors affecting the impact of this co-pyrolysis biochar on the soil ecosystem were determined.The study’s major findings are as follows.When the pyrolysis temperature rose,co-pyrolysis biochar with the different mixing ratio of raw materials showed a gradual decrease in yield and an increase in p H.Besides,an increase was also seen in the content of ash,while the reduction was found in the content of dissolved organic carbon and the total amount of acidic functional group.And the specific surface area and total pore volume mounted.At the same temperature,biochar with different mixing ratios also showed some differences in physicochemical properties.Under 300°C pyrolysis conditions,the yield of co-pyrolysis biochar increased as the proportion of plastic hanging rope in the raw material increased,while ash content,specific surface area,and total pore volume changed in the opposite direction.Under 500°C pyrolysis conditions,as the plastic content grew,the yield and ash content declined,whereas the specific surface area and total pore volume initially increased and then decreased;When 20%plastic was added,the specific surface area and pore volume of the biochar increased by 82.32%and 59.15%,respectively.The addition of plastic decreased biochar yield,increased ash content,and increased specific surface area and total pore volume at a pyrolysis temperature of 700°C.In general,the 500°C co-pyrolysis biochar has a larger specific surface area,a more developed pore structure,and a higher concentration of surface functional groups.The pyrolyzed biochar obtained at 500℃is able to absorb a considerable amount of Cd and MB,whose adsorption capacity can be affected by reaction time,solution’s initial p H and concentration.Additionally,this biochar’s isothermal adsorption on Cd and MB complies with Langmuir model,and its dynamics data of adsorption show a best fitting effect with the quasi second-order model.Specifically,the biochar prepared with 20%plastics manifests the best adsorption effect on Cd and MB with the maximum absorbing amount of108.91 mg·g^-1 and 40.31 mg·g^-1 respectively.Co-pyrolyzed biochar shares some commonalities in absorbing Cd and MB at the mechanism level,including physical adsorption,ion exchange,complexation of oxygen-containing functional groups,andπ-πinteraction.Soil p H can be significantly enhanced by co-pyrolyzed biochar,particularly an increase of p H value by 2.5 is easy to achieve by the biochar prepared at 700°C.Co-pyrolysis of biochar can dramatically enhance the amount of available phosphorus and available potassium in the soil.And the biochar made at 300°C can increase the contents of soil total carbon and dissolved organic carbon by 739.06%and 580.18%respectively.Co-pyrolysis at 500°C has been shown to significantly boost the amount of available nitrogen in soil by131.40%.Co-pyrolyzed biochar takes a little impact on sucrase’s activity in the soil,but is able to facilitate catalase’s activity remarkably.For instance,catalase’s activity can be risen by59.8%with the addition of biochar prepared at 700℃.The 300°C co-pyrolysis biochar had the greatest effect in promoting urease activity.The richness and diversity of the bacterial population reduced after co-pyrolysis of biochar in soil,the structure of the soil bacterial community changed,and the relative abundance of Firmicutes,Proteobacteria,Actinomyces,and Acidobacteria changed dramatically.The primary determinants affecting changes in soil bacterial community structure were soil p H,total carbon,total nitrogen,and available potassium.Co-pyrolysis biochar made from cantaloupe vines and plastic ropes can not only reduce the risk of environmental pollution,but also be likely to provide cheap environmental remediation materials for water and soil.Therefore,this study can serve as a reference for the safe treatment and recycling of agricultural waste.