Study Of Biochar Preparation Based On Wetland Plants And Its Ibuprofen Removal Performance In Aqueous Solution

In this study,three plants widely distributed in wetland ecosystems in temperate regions Alternanthera philoxeroides?Mart.?Griseb,Potamogeton crispus L and Paspalum paspaloides?Michx.?Scribn were selected as raw materials to prepare biomass carbon.Studies on the removal and mechanism of typical PPCPs pollutant Ibuprofen?IBU?were carried out on APBC,PCBC and PPBC.Scanning electron microscope?SEM?,Brunauer emmett teller?BET?and Fourier Transform infrared spectroscopy?FTIR?were used to characterize the surface structure,aperture,specific surface area and surface functional groups of three kinds of biomass charcoal prepared by phosphoric acid activation method.The adsorption mechanism was determined by combining adsorption kinetics,adsorption isotherm and adsorption thermodynamics.The optimal adsorption conditions were determined and the influence of various factors on the adsorption effect was explored through five sets of single-factor control experiments including initial concentration of ibuprofen,dosage of adsorbent,temperature,time and pH value.In addition,this study studied the biocompatibility of APBC and PCBC with high adsorption performance of ibuxen through systematic toxicity evaluation experiments based on Chlorella Pyrenoidosa and human bronchial epithelial cells?BEAS-2B?,in order to explore the safety issues in their environmental remediation applications.The main conclusions of this study are as follows:?1?SEM analysis showed that APBC,PCBC and PPCB all had developed pore structure,and the comparison of electron microscope images before and after adsorption showed that there was obvious ibuprofen adsorption accumulation in the pore structure of biochar.The BET method was used to measure the specific surface area of APBC 831.70 m²/g,PCBC 946.35 m²/g and PPCB 715.92 m²/g,and the pore sizes of the three biochar were all mesopore micropore composite pore structures with mesopore as the main pore size.Capillary condensation was observed in both adsorption and desorption curves of N₂,which were in accordance with isotherm type I and type IV.In the infrared spectroscopy test,new functional groups appeared,APBC appeared-NO₂ and C=C,C=N and other new functional groups,PCBC appeared-C=C-H,-CH₃,-C?CH₃?₂ and multi-molecular association or dimolecular association,PPCB appeared saturated fatty aldehyde,?,?-unsaturated fatty aldehyde,aromatic aldehyde,may appear multi-molecular association or dimolecular association.?2?In the APBC adsorption experiment,the maximum adsorption rate was93.3%when ibuprofen concentration reached 100 mg/L.The maximum adsorption capacity was 105 mg/g after 4 hours of adsorption.The optimal biochar dosage was0.06 g/L.The optimal adsorption time was 240 min.The optimum adsorption temperature is 25?;When pH value is 4,it has the highest removal rate?Re?and adsorption amount?Qe?.The kinetic data simulation conforms to the pseudo-two-order kinetic model,which indicates that the adsorption process is dominated by the chemisorption mechanism.Isotherm study proved that the chemical reaction process of Freundlich model had the highest degree of fit?R²>0.998?.The fitting data of the thermodynamic model show that the reaction gibbs free energy??G?and enthalpy change??H?are negative values,and the entropy change??S?is 9.74 J/mol,indicating that the chemisorption reaction is a spontaneous exothermic reaction process,which is consistent with the phenomenon that Re and Qe decrease with temperature increase in the single-factor temperature experiment.?3?In the PCBC adsorption experiment,the dosage of 0.06 g/L biochar reached the maximum Qe of 78 mg/g.Ibuprofen solution concentration reached the maximum Re of 79.47%at 100 mg/L.The adsorption equilibrium time was 240 min,Re was79.5%,and Qe was 101 mg/g.The optimal adsorption temperature was 25?,the maximum Re was 68%,and the Qe was 85 mg/g.The optimal pH was 4?pKa=4.5?,Re was 90%,and Qe reached 115 mg/g.The kinetic data simulation conforms to the pseudo-two-order kinetic model,which indicates that the adsorption process is dominated by the chemisorption mechanism.The isotherm data simulation conforms to the Freundlich model?R²>0.998?.Thermodynamic data simulated?G<0,?H=15.3kJ/mol,?S=-34.4 J/mol,and determined that the chemisorption reaction was a spontaneous exothermic reaction process,which was consistent with the phenomenon that Re and Qe decreased with temperature increase in the single-factor temperature experiment.?4?In the PPCB adsorption experiment,the optimal dosage was 0.06 g;The maximum Re was reached at ibuprofen concentration of 100 mg/L.The adsorption equilibrium time was 240 min.When the temperature is 20?,Re and Qe reach the maximum.When pH=4,the maximum Re is close to 90%,and the maximum Qe is120 mg/g.The kinetic data simulation conforms to the pseudo-two-order kinetic model,which indicates that the adsorption process is dominated by the chemisorption mechanism.The isotherm study was consistent with the Freundlich model?R²>0.995?.Thermodynamic data simulated that?G and?H were both less than 0,indicating that the chemisorption reaction was a spontaneous exothermic reaction process,which was consistent with the phenomenon that Re and Qe decreased with temperature increase in the single-factor temperature experiment.?5?The results of APBC and PCBC inhibition experiments on the growth of chlorella proteinucleus showed that the two activated carbons exhibited similar time patterns in the inhibition of chlorella at four concentrations,and the inhibition rate reached a peak at about 72-96 h,and then significantly decreased and maintained a low inhibition rate.In general,neither APBC nor PCBC had significant inhibitory activity against chlorella,and chlorella grew in an environment containing both extracts after a certain period of adaptation.In comparison,chlorella was more sensitive to APBC than PCBC.?6?APBC and PCBC on human bronchial epithelial cells is adopted in BEAS-2B cell toxicity evaluation determined by MTT test,cell morphological observation,intracellular reactive oxygen species?ROS?and apoptosis flow analysis method,the experimental results show that APBC and PCBC to BEAS-2B were no obvious inhibition of cell proliferation,inhibition concentrations are related,both in the highest concentration of 600 ug/mL APBC inhibition rate was 33.1%,the PCBC inhibition rate was 24.9%;The ROS quantitative analysis results showed that the intracellular reactive oxygen species?ROS?level after the treatment of the two extracts was lower than that of the control group?CNC?.The results of apoptosis analysis showed that there was no significant increase in the number of apoptosis and necrotic cells after treatment with the two biochar extracts,which was consistent with the results of reactive oxygen species.BEAS-2B is more sensitive to APBC extract.This study for wetland plants and efficient utilization of main invasion plants provides a way based on biomass carbon preparation,wetland plant biomass carbon is verified by experimental research and has a good ibuprofen removal performance,and through the nuclear chlorella protein and human bronchial epithelial cells?BEAS-2B?toxicity evaluation experiment,shows that the preparation of biomass charcoal has a good application security,as the real scale of the water environment restoration international application provide the scientific basis.