Synthesis Of Magnetic Alginate Mesoporous Carbon Microspheres And Their Adsorption For Arsenic And Antimony In Water

In recent years,Arsenic and antimony have been studied two representative heavy metal elements for water hazards due to their diversity of valence,binding,and toxicity.Adsorption is a convenient and economical way to deal with heavy metal pollution in water which has been widely studied by scholars at home and abroad.Sodium Alginate is a polysaccharide extracted from natural algae.The sodium ion of gulonic acid can ionically crosslink with other divalent and trivalent cations under certain conditions(Ion-exchange).In this paper,magnetic mesoporous carbon microspheres(MAMC)were obtained by vacuum freezing and pyrolysis of sodium alginate microspheres which were pre-syntheszed by ion-crosslinking method using inexpensive sodium alginate as matrix precursor.A variety of methods were used to characterize MAMC.We investigated the sorption properties of MAMC towards As(?)?As(?)?Sb(?)?Sb(?)as a function of dosage,pH,contact time and initial metal concentration.The sorption process was characterized by kinetic and isothermal equation fitting.The desorption and regeneration of MAMC were also studied.Finally,this paper discusses the competitive adsorption performance of MAMC under the coexistence of two heavy metal ions.The results showed that MAMC exhibited good adsorption performance on As(?)and As(?),with a larger sorption capacity for As(?)than As(?).MAMC has the best effect on As adsorption at pH 5-7.The absorption capacity of MAMC increased with the time.The kinetic results indicated that the sorption process is best described by Pseudo-second-order kinetics model,while the isotherm adsorption curves are best fitted by Langmuir equation.Moreover,The regeneration results showed that the MAMC could be regenerated and reused by 0.1 mol/L NaOH solution.MAMC also showed good adsorption performance for Sb(?)and Sb(?).The adsorption of Sb in two valence states by MAMC was greatly affected by pH,and the amount of adsorption decreased with the increase of pH.The adsorption effect of MAMC on Sb(?)is better than that of Sb(?)under different concentrationbackgrounds.The initial pollution concentration has a great influence on the adsorption performance of the material.The concentration of Sb(?)and Sb(?)on the concentration gradient of 200 mg/L.The theoretical maximum adsorption capacity can reach 11.83 mg/g and 75.18 mg/g.Freundlich adsorption isotherm equation can well satisfy the adsorption process of Sb(?)by MAMC,while the adsorption process of Sb(?),MAMC can be well satisfied with two isothermal adsorption equations.The effect of 0.1 mol/L NaOH on the regeneration and desorption of the material is good.The desorption of the material after four adsorption desaturations can still keep the Sb(?)and Sb(?)removal efficiency at 85% and 59%.In the binary system of arsenic and antimony coexistence,fixing the As concentration in the solution system and increasing the concentration of Sb in the solution will not affect the adsorption of As on the material,indicating that the heavy metal Sb in the solution system cannot seize the adsorption site of As.,And the material has a preferential adsorption process for As.When the concentration of Sb was increased in the fixed solution system and the concentration of As in the solution was increased,the amount of Sb adsorbed by MAMC appeared antagonistic and extrusion(the amount of adsorption decreased from 17.78 mg/g to 6.93 mg/g),and the solution system Adsorption of As in the medium increases with increasing concentration(adsorption capacity increases from 4.96 mg/g to 23.46 mg/g).The adsorption kinetics experiment under the co-existence system and the same concentration increase experiment also confirmed the phenomenon of preferential adsorption of As by MAMC.