Preparation Of Functional Biomacromolecules Adsorbents For Lead Ion Adsorption

The residual presence of heavy metal ions Pb???in food is a great threat to human health.Hence,it has a practical significance to investigate Pb???removing from aqueous solutions.Sodium alginate?Alg?and chitosan?CS?are marine natural polymers which are widely used in biomedicine and adsorption fields.Two adsorbents were fabricatedbased on Alg and CS,and their adsorption properties of Pb???were studied.The specific studies results are as follows:?1?In the present study,we synthesized an effective Pb???adsorbent from magnetic carboxyl-functionalized attapulgite?McAPT?and sodium alginate by simple mechanical agitation at room temperature.The novel McAPT@Alg composite was systematically characterized using a number of instrumental techniques,and the effects of adsorbent dosage,initial concentration of Pb???,adsorption time,pH,and temperature on the adsorption capacity were investigated by performing batch experiments.The obtained results demonstrated that adsorption equilibrium could be reached within 1.5 h,with the maximum adsorption capacity of 471.20 mg g^–1at 297.2K.The experimental datas were suitable for application to the Langmuir isotherm model,and the adsorption kinetics agreed with the pseudo-second-order model.More importantly,a Pb???removal efficiency graterthan70%could be achieved after six adsorbent recycling.?2?In this work,a MCS-PAA adsorbent was synthesized bygrafting polyacrylic acid?PAA?with magnetized chitosan.The poor acid tolerance and solid-liquid separation performance of the chitosan could be improved by the chemical modification.The physical and chemical characteristics of the composite adsorbent,MCS–PAA,were determined by scanning electron microscopy,transmission electron microscopy,Fourier transform infrared spectroscopy,energy-dispersive X-ray spectroscopy,X-ray diffraction,and X-ray photoelectron spectroscopy.Thisadsorbentwas applied to adsorb Pb???from water.The adsorption conditions including pH,adsorption time and initial concentration of Pb???solution were optimized.The maximum adsorption capacity was 204.89 mg/g according to the Langmuir isotherm model.The main adsorption mechanism was the formation of a complex between the carboxyl and hydroxyl groups in MCS–PAA and Pb???.