Preparation Of Natural Manganese Ore Modified Biochar Composites And Study On The Degradation Of Bisphenol A In Water By Activated Peroxymonosulfate

As agriculture and industry developed rapidly,numerous new artificial organic compounds have been developed and used.Its direct or indirect entry into the natural water body will cause pollution of the water environment and water scarcity and constrain the sustainable development of society.Edocrine disrupting chemicals have been frequently detected in all types of water bodies as one of the emerging contaminants and if left unchecked will pose a serious threat to ecological safety and human health.Advanced oxidation process is considered to be an efficient method to degrade environmental pollutants because of its excellent performance.The advanced oxidation process based on persulfate activation has been widely studied because of its unique advantages.The development of efficient,low-cost and environmentally friendly heterogeneous persulfate activator is the key to the further development of advanced oxidation process.Biochar is a potential environment-friendly material,but the ability of original biochar to activate persulfate is limited.In order to improve the catalytic capacity of biochar,the paper would use natural manganese ore containing transition metal oxides to modify cornstalk biochar,with a view to synthesizing green and environmentally friendly biochar composites with efficient activation of persulfate,providing a theoretical theoretical basis for the removal of typical endocrine disruptors in the aqueous environment and exploring possible ways for the resource utilization of agricultural waste.Main research contents and results were as follows:(1)Natural manganese ore-cornstalk biochar composites(MCC)with peroxymonosulfate(PMS)activated capability were successfully synthesized using impregnation method.The MCC/PMS system was highly effective in the removal of bisphenol A(BPA),a typical endocrine disruptor in water bodies.It was found that MCC could activate PMS through non-radical mechanism and excited PMS to metastable state.Then BPA molecule transfered electrons to the metastable PMS via MCC and underwent a redox reaction in the presence of MCC,thus effectively degrading BPA.In addition,the MCC/PMS system(BPA concentration:20 mg/L;MCC dosage:1.0 g/L;PMS concentration:1 m M;reaction temperature:25°C)had a high stability over a wide p H range(3?10)and its degradability was less affected by co-existing ions(Cl^-,SO₄^2-and HCO₃^-)and humic acids.MCC/PMS system also exhibited excellent activation performance when the tap water and the Yellow River water were used as background solutions.The cycling experiments showed that the catalytic activity of MCC decreased with the number of repeated uses,but the activation performance could be effectively restored by thermal treatment methods.(2)By adding chitosan to the synthesis of natural manganese ore-cornstalk biochar composites,the structural characteristics of the composites were modified to obtain biochar composites with enhanced activation properties(CMCC_X).A linear fit of the structural properties and activation performance of the composites revealed that C-C/C-H on the CMCC_X surface was the active site for the production of metastable PMS,C-OH reduced the degradation capacity of the system by occupying the generation site of the active complex on the surface.In addition,Mn-O,carboxyl and hydroxyl groups affected the electron transfer process from BPA to metastable PMS,thus affecting the degradation of pollutants by the PMS activation system.The heat treatment restored the active functional groups in CMCC_X and therefore effectively recovered the activation properties of CMCC_X,90.97%of BPA could be removed after thermal regeneration.The chitosan-modified natural manganese ore-cornstalk biochar composites had enhanced environmental adaptability and maintained excellent degradation of BPA even in the presence of high concentrations of metal ions.(3)The most active CMCC_10%was successfully loaded onto the PVDF membrane by the facile phase invasion technique to make CMCC_10%@PVDF membrane.The performance of the activated PMS for BPA degradation was evaluated in static(The sequential batch mode)and dynamic(The continuous flow mode)water experiments.The best BPA degradation was obtained with PVDF membranes loaded with 0.07 g CMCC_10%in 1 m M PMS whether in static or dynamic water experiments.High BPA degradation efficiency(96.82%)were obtained in the sequential batch mode(speed:250 rpm;temperature:25°C;PMS concentration:1.0 m M),better BPA throughput(1.16 mg/sheet)was obtained in the continuous flow mode(influent flow rate:10m L/min;residence time:10 min;PMS concentration:1.0 m M).The continuous flow reactor showed good degradation of BPA in experiments with actual water such as the tap water and the Yellow River water as background solution.To simulate the engineering use,the device could still maintain high BPA degradation levels after increasing the treated water volume proportionally and expanding the column reactor.The results of the study showed that the experimental setup had excellent potential for practical applications.