Preparation And Properties Of Sulfur-doped Clay Mineral Nano-iron Composites

Nano-zero-valent iron(nZVI)has many advatanges such as,large specific surface area,high reaction activity,low prcice,easy obtained raw materials,which is widely used in the treatment of organic pollutants and heavy metals.However,the reaction activity is usually decreased,due to easy agglomerate and oxidation characteristics of the nZVI.Herein,the supported iron sulfide was prepared by the reduction method in liquid phase using the sodium dithionite as a vulcanizing agent and three kinds of clay minerals with different structural compositions as supports.The morphology and crystal structure of the prepared composites were analyzed to study their structure characteristics.The prepared composites were used to remove tetracycline(TC)from wastewater,and the feasibility in practical applications was discussed to provide theoretical and technical support for the treatment of environmental pollution.The main findings of this experiment are as follows:(1)The nano-iron was vulcanized using sodium dithionite as a sulfurization reagent,and different structural composition clay minerals of bentonite(BT),attapulgite(APT)and halloysite(HNTs)as supports to prepare the supported composite materials: BT-S-nZVI,APT-S-nZVI,HNTs-S-nZVI.The morphological,surface area and crystal structure of the composites before and after the reaction were characterized by TEM,FTIR,BET and XRD.The results showed that BT,APT and HNTs exhibited flaky,rod-like and tubular morphology,respectively,which could provide abundant active sites.Moreover,due to the action of the support,the agglomeration of S-nZVI was effectively suppressed and the dispersion of S-nZVI was increased.(2)The composite materials were used to remove TC,typical pollutants in water.The effects of initial concentration of TC,solution pH and reaction time on the reaction activity were investigated.The results showed that the initial concentration of TC was 1500 mg/L?pH of 5?contact time of 2h,the removal amount of TC by BT-S-nZVI,APT-S-nZVI and HNTs-S-nZVI was 244.95 mg/g,256.91 mg/g and227.91 mg/g,respectively.(3)The results of adsorption isotherms and adsorption kinetics showed that theadsorption of TC on BT-S-nZVI,APT-S-nZVI and HNTs-S-nZVI composites conforms to the langmuir isotherm equation.The adsorption behavior of BT by BT-S-nZVI,APT-S-nZVI and HNTs-S-nZVI could be conformed to the equation of pseudo second-order kinetics.(4)The removal of TC in the tap water,well water and yellow river water were investigated for the BT-S-nZVI.The results showed that BT-S-nZVI exhibited excellent performace for the removal TC in the three water.Under the condition of the pH of 3?contact time of 2 h,the removal amount reached 195.54 mg/g,190.04 mg/g and 199.56 mg/g,respectively.Thus,the nanocomposite has great potential for the removal of TCs antibiotics in water.(5)The results show that the removal amount of TC still reached 119.08mg/g after 5 cycles of recycling for the BT-S-nZVI,indicating that the composite has certain application prospects for removing TCs.