Study On Preparation, Characterization And Adsorption Properties Of Chitosan Resin With Metal As Imprinted Ions

Harmful heavy metals are more common pollutants, causing cancer, teratogenicand mutation of adverse effects to the human body. With the development ofindustrialization, the harmful heavy metals content in the enviroment is increasing,which influencing the human being seriously. Therefore, seeking a kind of materialsfor adsorbing heavy metals from aqueous solution becomes a urgently problem to besolved.Chitosan is the only alkaline polysaccharide in nature, which is the secondlargest renewable resources. Chitosan has been widely applied in waste watertreatment, food and medicine, paper and textile, water purification. Chitosan has a lotof free amino and hydroxyl groups, it is easily to be modified to enhance theadsorption properties, adsorption selectivity and adapting ability to the environment.In this topic, chitosan was used as functional monomer, inorganic material,amination and sulfur based modification were investigated to the adsorptionproperties for harmful heavy metals, their structures were preliminary characterized,the adsorption properties of modified chitosan resin for heavy metals was discussedfrom aspects of adsorption capacity, adsorption selectivity and adsorption at low pH,which provide powerful scientific support and theoretical basis for researching andapplying of chitosan resin in the heavy metals adsorption areas.1) The detection methods of total arsenic was established with HVG-FAAS forthe first time. Digestion temperature, the selection of pre-reduction agents andreduction agents NaBH4concentration were investigated to determine the the optimalconditions: digestion temperature was180℃, acid medium was nitric acid, the pre-reduction agent Vc concentration was1%, reduction agent NaBH4concentrationwas1.8%, detection limit was0.95μg/L, RSD was1.3%～7.6%, recovery rate was83.1%～105.3%, total arsenic detection was stable.2) Chitosan resin was prepared with As(III) as imprinted ion As-ICR wasprepared to investgated the adsorption property. As-ICR was prepared throughmolecular imprinted technology with As(III) as imprinted ion to adsorb As(III) fromaqueous solution and Laminaria japonica juice. The adsorption of As-ICR for As(III)was investagted at different pH and temperature. The adsorption process was that theamino groups of As-ICR adsorb As(III), and the thermal stability and crystalline bothreduce after formed into chitosan resin. As-ICR selectively adsorbed As(III) fromaqueous solution. It also could adsorbed As(III) from Laminaria japonica juice.3) As-ICR was modified to enhance the adsorption capacity. α-Fe2O3modifiedchitosan resin with As(III) as imprinted ions As-IFICR was prepared to improve theadsorption capacity of chitosan resin for As(III). The adsorption capacity of As-IFICRfor As(III) was6.20mg/g at pH5,30℃, As(III) concentration50mg/L, theadsorption process fit Langmuir isothermal adsorption model and pseudo secondkinetic equation. The adsorption capacity of As-IFICR for As(III) was improvedsignificantly. The adsorption capacity of As-IFICR for As(III) from Laminariajaponica juice was more than that of As-ICR, the adsorption for beneficial metalelements was less.4) Chitosan resin was prepared with Pb2+as imprinted ion was prepared toinvestgated the adsorption property. Amino and hydroxyl groups were mainlyfunctional groups of Pb-ICR for Pb2+. The adsorption capacity of Pb-ICR for Pb2+wassaturated at40℃, pH6.0, contact time4h, and it could selectively adsorb Pb2+fromaqueous solution.5) The Pb-ICR was modified to enhance the adsorption selectivity. The tetraethylene pentamine (TEPA) modified chitosan resin with Pb2+as imprinted ionsPb-ITMCR was prepared to enhance the adsorption selectivity of chitosan resin formetal ions. The amino groups of Pb-ITMCR participate in the adsorption. Theadsorption capacity of Pb-ITMCR for Pb2+was saturated at pH6.0,40℃, contacttime8h, the adsorption could fit the pseudo second kinetic equation and Langmuirisothermal adsorption model. The adsorption selectivity of Pb-ITMCR for Pb2+washigher than that of Pb-ICR.6) The Pb-ICR was modified to enhance the pH adaptability. The sodiumdithiocarbamate modified chitosan resin with Pb2+as imprinted ions Pb-IDMCR wasprepared to widen the application scope of chitosan resin to pH. Amino, sulfydryl andthiocarbonyl groups of Pb-IDMCR involved in the adsorption process, and the thermalstability of chitosan decrease. The adsorption capacity of Pb-IDMCR for Pb2+washigher than that of chitosan resin at low pH (pH1.0), and the adaptability ofPb-IDMCR to pH improved greatly.Nowdays, our country is one of the serious countries in heavy metal pollution,but no mature methods were applied to solve heavy metal pollution up to now. In thisresearch, chitosan was used as functional monomer to prepare crosslinked chitosanresin, chitosan resin was modified to selectively adsorb heavy metals from liquid foodand aqueous solution, which providing theory support for heavy metals removal.