Modification And Adsorption Behavior Of Bacterial Cellulose For Wastewater

Bacterial cellulose(BC)is a potential bioadsorbent for wastewater treatment due to its unique three-dimensional(3D)cross-linked network structure characterized by high specific surface area,porosity,no secondary pollution and other advantages.However,the potential applications of BC are hindered by its low adsorption capacity since its single surface functional group.Moreover,the fine nanopores of BC is easily degraded by traditional recycling process.In order to improve the adsorption capacity of BC for heavy metal ions,and achieve the purpose of efficient recovery through simple technology,a blocky magnetic BC film was prepared by magneticization and stabilization(denoted as MSBC)in this paper.Besides,to make BC has good adsorption both on heavy metal ions and organic dyes,this paper also prepared amino-functionalized magnetic BC/activated carbon(AC))powdery composites(denoted as AMBCAC).The composition and microstructure of MSBC and AMBCAC were characterized by X-ray diffraction(XRD),Scanning electron microscope(SEM)and Fourier transform infrared spectra(FT-IR).Dynamic adsorption experiments were carried to evaluate the adsorption properties of MSBC to Pb2+ and Cu2+ and AMBCAC to Pb2+ and Methyl orange(MO),and investigated the effects of pH,modification and initial pollutants concentration(C0)to adsorption.Adsorption mechanisms of MSBC and AMBCAC on pollutants were analyzed by Langmuir and Freundlich adsorption isotherm models,as well as adsorption kinetic and thermodynamics.The results of XRD and SEM indicated that Fe3O4 and SiO2 can be uniformly loaded onto MSBC,AC can also be evenly loaded on AMBCAC.MSBC and AMBCAC can still maintain the BC three-dimensional network structure after modifications,and FT-IR results showed that the amino group was grafted onto AMBCAC successfully.The results of dynamic adsorption experiments show that the pH of the solution has an important effect on the adsorption properties of MSBC and AMBCAC because pH can change the charge distribution of the adsorbent surface.Owing to magnetic modification provides more active adsorption sites for BC,the equilibrium adsorption capacity(qe)of Pb2+ increased by 1.66 times,and the qe of Cu2+ was increased by 1.75 times than BC,respectively;AMBCAC increased the qe of Pb2+ by 2.14 times and 2.55 times of MO after amino modification;C0 has a great relationship with the adsorption capacity of MSBC and AMBCAC,the adsorption capacity significantly increased with the increase of C0,and then increased slowly,finally reached a saturated adsorption state,which is because C0 affect the driving force between the adsorbent and pollutants;The pseudo-second order kinetic and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data,respectively,which indicating that the adsorption sites on the surface of MSBC and AMBCAC are uniformly distributed,and the adsorption process is a monolayer chemical adsorption;The thermodynamic results(△G<0,△H>0,△S>0)implied that the adsorption process was feasible,endothermic and spontaneous in nature.In addition,the AMBCAC showed good reproducibility and regeneration stability.These results demonstrated that the modified-BC has promising value in wastewater treatment.