Study On The Removal Of Tebuconazole And Linuron From Aqueous Environment By Sludge Based Biochar

Pesticides have played a crucial role in producing high crop yields,preventing diseases and controlling pests.However,due to their physical and chemical properties,high toxicity and occasionally high endurance in the environment,these pesticides may cause environmental and health problems.Pesticides are widely detected atμg·L^-1levels in rivers,soils,as well as other environmental compartments,while some compounds are considered reprotoxic.Therefore,researchers are working to develop effective remediation methods or new materials to remove pesticide residues from aqueous environments.Recent studies have shown that the use of low-cost adsorbents for rapid water purification is not only a research hotspot,but also a main development trend.The purpose of this study was to investigate the adsorption effect and mechanism of sludge based biochar on two typical common pesticides:tebuconazole and linuron.The environmental friendliness and the cost analysis of the material itself were also taken into account.The full research is mainly divided into the following three parts:The first part was the optimization of the preparation conditions for the sludge based biochar:the adsorbent with Fe Cl₃and waste activated sludge molar ratio of 0.25:1,the pyrolysis time,temperature and ultrasonic time were 60 min,600°C and 30 min were selected for further systematic research.The activation time had a greater effect on the specific surface area of the modified sludge biochar,the results showed that the material was nano irregular particles,containing a large number of microporous mesoporous structures with a specific surface area of 73.00 m~2/g and an average pore diameter of 4.83nm.The second part is the batch adsorption experiment and characterization/mechanism analysis of biochar:the batch experiment shows that under the optimal conditions,the maximum adsorption capacity of sludge based biochar for tebuconazole is 12.37 mg/g;acidic conditions facilitate the reaction.Freundlich model and the pseudo second order model are more suitable to fit the adsorption process,indicating that the process is mainly heterogeneous multi-layer chemisorption.Cr⁶⁺and humic acid can inhibit the process of tebuconazole,Pb²⁺can promote the adsorption process.After five cycles regeneration,the adsorption capacity of sludge based biochar for tebuconazole remained above 37.79%of the initial adsorption capacity,indicating that the adsorbent can be effectively recycled to some extent.The aging experiment shows that within 60days,the removal rate decreases to 76.31%of the raw material,and then tends to be stable.Sludge based biochar can efficiently linuron from water,reaching more than 98%of the equilibrium adsorption capacity in 120 min with the maximum adsorption capacity of 11.41mg/g;solution p H have little effect on the adsorption process.The higher fit of pseudo second order model and Langmuir equation to the adsorption process indicated that the adsorption is dominated by chemisorption from monolayers.Cr⁶⁺,humic acid and soluble starch inhibited the adsorption,Ca²⁺promoted.Regeneration test and aging experiment showed that the material had some reusability and stability.At the same time,the section conducted general applicability,which can simultaneously achieve the efficient removal of five pesticides;the unit adsorption amounts of the two pesticides in real water bodies decreased by about 17%～20%,respectively,compared with those in deionized water.Characterization and mechanistic analysis revealed that the specific area of modified biochar（BCF600）was larger,more stable,more aromatic and less polar than the common biochar（BC600）.SEM,EDS,XRD as well as VSM etc.indicated that the iron element was successfully loaded on BCF600.The large presence of Si O₂ helps to prevent the aging reaction from proceeding.BCF600 adsorbed tebuconazole and linuron mainly byπ-πinteraction and pore filling effect,meanwhile Si-O-Si groups,hydroxyl groups as well as ferric compounds were also involved in the adsorption reaction.The dominant mixed silicate compounds such as potassium sodium aluminum similarly contribute to the adsorption reaction of linuron.The third part is about the toxicity and cost analysis of the adsorbent material:EPFRs data show that the structure of sludge based biochar is mainly a carbon center structure with adjacent oxygen atoms.The metal leaching concentration of BCF600biochar will not cause secondary pollution to the natural water environment,and meets the requirements of the national secondary product of activated carbon for water quality and water purification.The experiment of seed germination showed that the low-dose biochar extract had a promoting effect,and the high-dose biochar extract had an inhibitory effect,which caused the changes of ROS content,POD,SOD and CAT enzyme activities.The evaluation of the production cost of sludge based biochar BCF600 shows that it has a certain potential for practical production and application.