Adsorption Of Contaminants In Water By Modified Carbon Nanotubes And Sodium Alginate

In this study,chitosan modified multi-wall carbon nanotubes（CS-MWCNT）,sodium alginate modified multi-wall carbon nanotubes（SA-MWCNT）and ferric modified sodium alginate（Fe-SA）were prepared and the adsorption quantity was improved.The three composites were characterized by isoelectric point,FTIR,TEM,Raman,BET,XPS and the results showed the successful modification.In addition,the adsorption properties of congo red（CR）onto CS-MWCNT,methylene blue（MB）onto SA-MWCNT,and phosphate onto Fe-SA were presented in batch mode and column mode.The batch adsorption results showed that the optimum pH of CR adsorption was4,the optimum pH range of MB adsorption was 5-11,and the optimum pH for the phosphate adsorption was 3.The presence of coexisting ions had a positive effect on the adsorption of CR and phosphate,but had a negative effect on the removal of methylene blue.The adsorption capacity of CR,MB and phosphate reached to 623mg·g^-1,184 mg·g^-11 and 17.7 mg·g^-1,respectively.The adsorption ability was enhanced after modification.The results of isothermal analysis showed that the adsorption behavior of CR was in accordance with the Koble-Corrigan equation,and the value of n was more biased toward 1,suggesting that the adsorption process was heterogeneous multi-molecular layer adsorption;the adsorption behavior of MB and phosphate were in accordance with the Temkin equation,suggesting that there may be multiple adsorptions in the adsorption process.The kinetic data indicated that all three adsorption processes were suitable described by pseudo-second-order equation,suggesting that the adsorption process contain chemisorption.The thermodynamic parameters showed that the three adsorption behaviors were the processes of spontaneous,entropy-increasing and endothermic.In the study of column adsorption,effects of bed depth,flow rate,initial concentration of solution were also investigated.It was found that the faster the flow rate,the greater the concentration,the smaller the column height were not favor of adsorption.Yan model was good to describe column adsorption process of phosphate onto Fe-SA while Mass transfer model based on batch isotherm was suitable to predict the process of MB adsorption onto SA-MWCNT and phosphate adsorption onto Fe-SA.Desorption regeneration study showed that 0.01 mol·L^-11 NaOH solution had a good desorption regeneration ability toward CR-loaded CS-MWCNT,0.1 mol·L^-1CaCl₂ solution had the good desorption regeneration ability toward MB-loaded SA-MWCNT,and 0.1 mol?L^-11 HCl solution had the good desorption regeneration ability toward spent Fe-SA.There were coordination,electrostatic attraction or molecular actions between adsorbents and adsorbates.The results showed that the composites may be promising as adsorbents to remove some pollutants from solution.