The New Buckwheat Hull Composite Material Absorbs Cr(Ⅵ) And Dyes In Water Attached Performance Research

Cr(VI)and dye molecules are widely used in the printing and dyeing industry,but the residual concentration in the wastewater generated during the production process is relatively large.If it is improperly treated,it is easy to pollute the water body and affect the ecological environment.At present,the use of biomass adsorption materials to remove heavy metals Cr(Ⅵ)and dye molecules in water has become a research hotspot in order to realize the resource treatment of agricultural waste.In this study,the agricultural by-product buckwheat husk(BN)in northern Shaanxi was used as the raw material,combined with the adsorption characteristics of polyaniline(PANI),and the BN/PANI buckwheat husk composite adsorption material was prepared by chemical polymerization.And the adsorption performance of dye molecules,and through the means of scanning electron microscopy(SEM),infrared analysis(FT-IR),X-ray diffraction analysis(XRD)and other means to conduct structural and morphological characterization analysis before and after adsorption,and finally combine the dynamics and Thermodynamics explore its adsorption mechanism.The main research conclusions are as follows:(1)The optimal process conditions for preparing the adsorbent obtained by orthogonal test were:the molar ratio of ammonium persulfate(APS)to aniline(AN)was 1:1,the concentration of HNO3 was 0.5 mol/L,and the reaction time was 4 h.SEM,FT-IR,XRD and other microstructure characterization analysis of the prepared adsorption material-showed that polyaniline was successfully loaded onto buckwheat hulls.(2)The adsorption performance of BN/PANI adsorbent for Cr(Ⅵ)in simulated wastewater was studied.The results showed that:when the pH was 2,the initial concentration of Cr(Ⅵ)was 200 mg/L,the amount of adsorbent was 0.1 g,and the adsorption When the equilibrium time was 8 h,the maximum adsorption capacity of Cr(Ⅵ)reached 151.35 mg/g.Through X-ray electron spectroscopy(XPS)characterization and analysis,the adsorption process was mainly that the imino and amino groups on the surface of polyaniline form complexes with Cr(Ⅵ),and there was electrostatic adsorption;BET characterization analysis showed that the BN/PANI composite material is The specific surface area was 26.3%larger than that of the raw material before loading.The adsorption thermodynamic model showed that the adsorption process of Cr(Ⅵ)on the BN/PANI composite was in accordance with the Freundlich equation,and its l/n was 0.45,so the adsorption was easier;the adsorption kinetics shows that the adsorption of Cr(Ⅵ)by the composite was in line with the quasi-two Rate equation.Compared with unloaded buckwheat hulls,the BN/PANI composite material had a significantly higher adsorption capacity of Cr(Ⅵ)after repeated desorption,and the adsorption efficiency of the first three times reached more than 80%,indicating that it had good desorption and regeneration adsorption performance.(3)The BN/PANI adsorbent was used to study the adsorption of anionic dye methyl orange(MO)and cationic dye methylene blue(MB)respectively.The results showed that the BN/PANI adsorbent had a better adsorption effect on methyl orange.Under the conditions of pH 8,MO and MB initial concentration of 100 mg/L,adsorbent dosage MO of 0.1 g,MB of 0.3 g,and equilibrium adsorption time of 300 min,the anion Cl-,SO42-,NO3-pair The effect of BN/PANI adsorbent,the results showed that the three anions had a greater impact on MB and MO in the solution,and the MO is different,the order was Cl->NO3->SO42-,but it had an impact on the MB adsorption process There was no difference in degree.The analysis showed that the adsorption of MO and MB on the BN/PANI composite conforms to the Langmuir adsorption isotherm model,and R2>0.98.The fitted maximum adsorption capacities of MO and MB were 137.55 mg/g and 39.09 mg/g,respectively.The adsorption capacities of MO and MB obtained by the quasi-second-order rate equation were 34.05 mg/g and 11.18 mg/g,respectively,while the actual adsorption capacities were 33.23 mg/g and 10.08 mg/g,respectively.The results were similar.The BN/PANI adsorbent pair The adsorption process of methylene blue and methyl orange conforms to the quasi-second order rate equation.The first three adsorption efficiency of BN/PANI on MO can also reach more than 80%.(4)In the mixed system of Cr(Ⅵ)and MO,the pH of the BN/PANI adsorbent has a greater influence on the simultaneous adsorption effect of the two.When the pH was 3.87,the co-adsorption capacity of the two reaches the maximum,but the adsorption capacity Cr(Ⅵ)>MO in the early stage of adsorption,and MO>Cr(Ⅵ)in the later stage.When the initial concentrations of Cr(Ⅵ)and MO were 100 mg/L,respectively,after the adsorption process,the adsorption capacity of the former was 14.51 mg/g and the adsorption capacity of the latter was 12.31 mg/g.The characterization analysis results show that the surface functional groups mainly involved in the adsorption of the BN/PANI composite to the mixed system were-OH,-C=N-,and amino and imino groups.The actual production wastewater adsorption experiment results showed that the adsorption effect of Cr(Ⅵ)and chroma in water was significant,but the removal ability of other pollutants was average.