苯乙烯系双腈胺螯合树脂对水相中As(Ⅴ)的吸附性能研究

Adsorption of As(Ⅴ) from aqueous solution onto a novel chelating resin containing cyanoguanidine moiety based on polystyrene

将PS-DCDA树脂用于水相中As(Ⅴ)的吸附净化处理,探讨了溶液的pH值、初始As(Ⅴ)质量浓度、接触时间、温度、NaCl、竞争性阴离子等因素对吸附性能的影响,并研究了其对As(Ⅴ)的吸附等温线、动力学和热力学。结果表明,NaCl和竞争性阴离子(Cl-、SO24-、CO23-、NO3-、HPO24-等)明显地抑制了PS-DCDA树脂对As(Ⅴ)的吸附。PS-DCDA树脂对As(Ⅴ)的吸附符合Langmuir等温式,准二级吸附动力学方程能够很好地描述As(Ⅴ)在树脂上的吸附动力学行为。粒子内扩散方程表明,表面吸附和内部扩散参与到As(Ⅴ)的吸附过程当中。PS-DCDA树脂对As(Ⅴ)的热力学参数表明,PS-DCDA树脂对As(Ⅴ)的吸附是自发的、吸热的过程。已吸附As(Ⅴ)的PS-DCDA树脂可以用0.1 mol/L NaOH有效解吸,解吸后的树脂对As(Ⅴ)仍具有较高的吸附量。

The paper is to introduce its research on the adsorption of As（Ⅴ） from aqueous solution onto a novel chelating resin containing cyanoguanidine moiety based on polystyrene a novel chelating resin（PS-DCDA） containing cyanoguanidine moiety.For this purpose,first of all,it has prepared As（Ⅴ） from the aqueous solutions.And then we have investigated and analyzed various factors affecting the adsorption behavior,such as solution pH,initial As（Ⅴ） concentration,contact time,solution temperature,the NaCl and competitive anions.Through our experiments,we have found the adsorption of As（Ⅴ） was highly dependent on the solution pH while the maximum As（Ⅴ） adsorption rate could reach around pH=3.0.At the same time,the equilibrium data of As（Ⅴ） were analyzed by using Langmuir and Freundlich isotherm models.Through experiments,it has been found that the adsorption data of As（Ⅴ） can best be described by the Langmuir isotherm model with the maximum monolayer adsorption capacities of 42.01 mg/g,45.06 mg/g and 52.17 mg/g at 20 ℃,30 ℃ and 40 ℃,respectively.We have also found that the thermodynamic parameters such as enthalpy（ΔH）,Gibbs free energy（ΔG） and entropy （ΔS） changes were detected and the results of the experiment show that the adsorption of As（Ⅴ） onto PS-DCDA resin proves to be feasible and endothermic in nature.The kinetic data have also been evaluated based on the pseudo-second order and intraparticle diffusion models,indicating that the adsorption kinetics of As（Ⅴ） was found to follow the pseudo-second order kinetic model.At the same time,the intraparticle diffusion model reveals that the adsorption of As（Ⅴ） on PS-DCDA resin is mainly governed by the surface adsorption and particle diffusion. Moreover,the increase of the concentration（0.01-1.0 mol/L） of NaCl in As（Ⅴ） solution can significantly reduce As（Ⅴ） adsorption on PS-DCDA resins.The competitive adsorption studies also confirm that the presence of Cl-,SO2-4,CO2-3,NO-3,HPO2-4 tends to highly inhibit the adsorption of As（Ⅴ） due to the competitive effect.And,finally,the As（Ⅴ） adsorbed in the experimental process could be efficiently desorbed with 0.1 mol/L NaOH solution.After five cycles of adsorption-desorption operations,it would be possible to increase the re-adsorption capacities to be as high as 75.69% of initial adsorption value.All the above results indicate that PS-DCDA resin was an eco-friendly,efficient and reusable adsorbent for removing As（Ⅴ） from the aqueous solution due to its simple preparation,high adsorption,quick and high adsorption rate,besides the effective regeneration and perfect reusability.