Applications Of Functionalized Biochar In Alleviation Of Nanoparticle Toxicity And Membrane Fouling As Well As Energy Storage

Biochar is a by-product of biomass pyrolysis.In recent years,biochar has been widely used in mitigating climate change,improving soil properties,and remediating contaminated water and soil.In this thesis,the application of biochar in reducing the toxicity of CuO NPs to crops and alleviating membrane fouling in a membrane bioreactor(MBR)were investigated,and the mechanisms of detoxification and antifouling were explored.In addition,we explored the potential application of Ni-contained biochar as high-efficiency supercapacitor material by fast pyrolysis of water hyacinth biomass containing Ni.The main contents and results of this thesis are as follows:1.The detoxification mechanism of CuO NPs to wheat by biochar was investigated.The seed germination and hydroponic culture of wheat were conducted in CuO NPs suspension up to 500 mg L-1 with or without biochar.We determined the germination rate,growth,fresh and dry weight of wheat,and the Cu contents of the wheat during the hydroponic culture process.The results indicated that the addition of 3%wt of biochar in hydroponic culture system completely eliminated the plant growth inhibition of CuO NPs even the concentration was up to 500 mg L-1,Simultaneously,the Cu content of shoot and root were decreased in the presence of biochar.Further exploration indicated both the adsorption of Cu2+ and space shield by biochar significantly decreased the entrance of Cu2+ and CuO NPs into plant cells,and consequently reduced the wheat growth inhibition of CuO NPs.2.Alleviation of membrane fouling in a MBR by biochar has been demonstrated and the modification methods of biochar and its anti fouling effect was correlated.Trans-membrane pressure(TMP)tests showed that alkali treated(AW-BC),hydrophilized(HL-BC),and activated biochars(AC-BC)exhibited robust antifouling capability.The TMP was decreased by as much as 36.8%and 31.4%at 24 h and 10 d respectively for AW-BC(most easily prepared)compared with the control group,which was comparable to the results obtained in the use of expensive activated carbon(AC).Instead of dealing with the large surface area and scouring effects of AC,it was found that the indirect effects of biochar on sludge may be the basis for the antifouling mechanism,where the hydrophilicity of the biochar improved the settling of the sludge.In addition,it was speculated that the abundant functional groups of the biochar increased the adsorption of EPS.3.Ni-contained biochar obtained by fast pyrolysis of Ni enriched water hyacinth biomass was used as energy storage material and the effect of Ni species was investigated.The Ni-N doped porous carbon materials were prepared via fast pyrolysis and KOH activation of WH biomass that containing absorbed Ni or adsorbed Ni.The electrochemical properties of electrode materials were characterized and the role of the endogenous Ni in electrochemical behavior of Ni-N doped materials was investigated.The results indicated that the assimilated Ni playd a more important role than post-adsorbed Ni in the enhancement of capacitance performance.Multiple characterizations demonstrated that the assimilated Ni was more effective than post-adsorbed Ni in the catalytic formation of a porous structure during drastic pyrolysis and activation.In addition,the assimilated Ni tended to generate NiO nanoparticles with smaller size than post-adsorbed Ni in the materials preparation process,which was more advantageous to improve the capacitance performance.