Microfluidic Preparation Of Chitosan Microspheres For Adsorption Treatment Of Heavy Metal Wastewater

Heavy metal wastewater pollution is one of the most urgent environmental problems.Adsorption is mainly treatment process due to its easy handing and efficient capacity.Common adsorbents have some disadvantages,such as low capacity,poor stability,irregular shape,hard recovery and further pollution.Microfluidic technology can fully exert its advantages for preparing monodispersed functional materials with controllable size,morphology,structure and component in materials synthesis field.In this work,we used microfluidic technology as preparation approach of droplets and natural chitosan as raw material to prepare chitosan microspheres（CSMS）with uniform size（CV=1.52%）,controllable morphology and component,high mechanical strength and excellent renewability.On this basis,we combined microfluidic technology with functional group grafting technology to prepare thiourea modified chitosan microspheres（TMCM）with high specific surface.Lots of amino functional group were grafted on the microspheres surface for improving adsorption capacity(qe=60.6mg g^-1)and quickening adsorption rate.The adsorption kinetic was described well by the pseudo-second order kinetic model.A novel ion-imprinted approach combined with microfluidic technology was explored.We took Cu2+ as ionic template and chitosan as carrier material,and applied chemical crosslinking in the formation of the imprinted sign.A selective biosorbent of ion-imprinted microspheres（IIMS）was synthesized through a practicable process with high adsorption capacity(qm=81.97mg g^-1)and excellent selectivity.The adsorption isotherm fitted the Langmuir equation while thermodynamic adsorption results were considered as strong proof of an adsorption exothermal process.The results analysis of technique methods suggested that chemical adsorption was dominant and amino played an important role in adsorption process.Combining microfluidic technology with functional group grafting and ion-imprinted technology to prepare adsorbent for heavy metal wastewater treatment has outstanding practical application prospect.Prepared functional material can achieve efficient,fast and selective adsorption for target metal ions.