Adsorption Of Typical Endocrine Disruptor Compounds From Water By Modified Acicular Mullite

Endocrine dirupting chemicals are widely distributed in water,and have received widespread attention due to their potential negative effects on humans and animals.However,the traditional water treatment process has low removal efficiency of EDCs in water,and the emerging water treatment processes always have higher costs during the construction and operation processes.Therefore,it is of great significance to improve the removal ability of traditional water treatment processes for EDCs.In order to improve the removal effect of EDCs in raw water by traditional water treatment process,acicular mullite ceramic granular was synthesized through in-situ reaction sintering and its performance as a filter material for water treatment was evaluated.Then the synthesized high porosity acicular mullite was introduced as a support material for the modified filter material,and was modified by metal oxide nanoparticles,surfactants,and in-situ growth of MOF-derived carbon.Clay ceramsite was selected as control.Batch adsorption tests were employed to evaluate the removal efficiency of typical endocrine disruptors BPA,EE2 and Cd?II?in water by modified acicular mullite.The adsorption kinetics,isothermal adsorption curve and adsorption thermodynamics were used to analyze the adsorption processes of BPA,EE2 and Cd?II?on the modified filter material.The intrinsic mechanism of BPA,EE2 and Cd?II?adsorption on modified acicular mullite was explored by means of the adsorption site energy distribution model.The findings obtained are mainly as follows:?High porosity acicular mullite with three-dimensional network structure was successfully synthesized by adjusting the formula,mineralizer type,pore forming agent and sintering temperature.The optimal synthesis conditions are that Shanghai kaolin,none mineralizer,pore former was selective,and calcined at 1400 ^oC for two hours under unsealed conditions.The volume density,apparent porosity,flexural strength,hydrochloric acid solubility,wear rate and breaking rate of the synthesized needle cluster mullite can meet the demand of ceramsite for water treatment.?The iron oxyhydroxide and iron oxide were uniformly embedded into the acicular mullite and the clay ceramsite by the slow hydrolysis method.After iron embedment,the iron content,specific surface area,pore volume and isoelectric point of the two ceramsites were increased.The results of adsorption experiments showed that the remove efficiency of BPA and EE2 by iron-modified acicular mullite was low,while the remove efficiency of Cd?II?increased with the increase of iron content.The Langmuir-Freundlich model well fitted the isothermal adsorption data of Cd?II?.The kinetic study showed that the pseudo second-order kinetic model is suitable for describing the adsorption behavior of Cd?II?on iron embedded acicular mullite.The adsorption amount of Cd?II?increases with the increase of the pH value of the solution.Iron modification effectively increased the adsorption capacity of Cd?II?on two kinds of ceramsite filter materials and iron-modified acicular mullite could effectively remove Cd?II?in water.?In order to effectively remove BPA and EE2 in water,the Mn-Fe binary metal oxide modified acicular mullite?Mn-Fe-M?was synthesized.The results show that the manganese loading on acicular mullite is manganite with an average particle size of 450nm.After modification by ferromanganese,the specific surface area,manganese content,cumulative pore volume and mesoporous specific surface area of the acicular mullite were increased significantly.Embedding iron into mullite is beneficial to load more manganese,and its removal efficiency for BPA and EE2 is further improved.The adsorption kinetics of BPA and EE2 on Mn-Fe-M fits well with the intraparticle diffusion model.The isothermal adsorption data was best fitted to the Langmuir-Freundlich model.The maximum adsorption capacities of BPA and EE2 were calculated to be 5.043 and 3.990 mg/g,respectively.Thermodynamic studies show that the adsorption of BPA and EE2 by Mn-Fe-M is an endothermic reaction.The adsorption amount of BPA and EE2 on Mn-Fe-M decreased with the increase of pH value.The increase of ionic strength is beneficial to the adsorption removal of BPA and EE2.The coexisting anion of SO₄^2-promotes the adsorption of BPA and EE2,while CO₃^2-and PO₄^3-inhibit the adsorption of BPA and EE2 on Mn-Fe-M.The adsorbent regeneration test showed that Mn-Fe-M was reproducible and reusable.Acicular mullite is more suitable as a carrier material for modified filter media and Mn-Fe-M has a better removal effect for BPA and EE2 from water.?CTMAB was used as a modifier to synthsized hydrophobic acicular mullite.The higher the contact angle,the better the adsorption effect of BPA and EE2 by CTMAB-M.The adsorption amount of BPA and EE2 on CTMAB-M increase with the increase of ionic strength.The adsorption kinetics of BPAand EE2 adsorption on CTMAB-M could be best described by the pseudo second-order kinetics model,while for CTMAB-C it is more suitable by the intraparticle diffusion model.Thermodynamic analysis showed that the low temperature favored the adsorption of BPA and EE2 on CTMAB-M.Site energy studies indicated that the average adsorption site energy of BPA and EE2 on CTMAB increased with increasing temperature,but the number of adsorption sites decreased significantly with increasing temperature.CTMAB-M regeneration experiments showed that the regeneration effect was poor.There may be loss of modifier during use.CTMAB-M is only suitable use at low temperature.?The MOF?Zn/Co-ZIF?was successfully loaded into acicular mullite?MOF-M?by liquid phase synthesis method,and further carbonized into MOF-M-C.The adsorption of BPA and EE2 is consistent with the pseudo-secondary kinetic model,followed by the intraparticle diffusion model.The adsorption of BPA and EE2 by MOF-M-C tends to be chemisorbed.Isothermal adsorption experiments showed that the adsorption amount of BPA and EE2 by MOF-M-C were 14.425 and 8.919 mg/g,which are the maximum values in this study.The adsorption amount of BPA and EE2 by MOF-M-C increases with the increase of temperature.The pH value of the solution had a great influence on the adsorption amount of BPA on MOF-M-C,as for EE2 the pH influence was not significant.The adsorption of BPA and EE2 by MOF-M-C is a spontaneous process with increasing entropy.The adsorption amount of BPA and EE2on MOF-M-C increased with the increase of ion concentration.The adsorbent regeneration test showed that MOF-M-C was easy to regenerate.?The relationship between the adsorption mechanism of BPA and EE2 adsorbed by modified acicular mullite,model parameters and adsorption energy shows that the site energy distribution can obtain the average adsorption site energy,and visually see the values of various adsorption affinity.The adsorption coupling oxidation reaction greater than hydrogen bonds,?-?interactions,and all are greater than hydrophobic interactions.The study found that the average adsorption site energy??E^*?,separation factor?R_L?,average adsorption energy?E?and 1/n value,these parameters of the adsorption affinity,in addition to the adsorption force is also affected by the number of adsorption sites,so the particle size and specific surface area of the adsorbent affect these parameters.The isosteric heat of adsorption(Q_st)could provide more valuable information than the thermodynamic parameters.The difference of Q_st value between various adsorption affinity is obvious,and it can be roughly judged whether the adsorption is physical adsorption or chemical adsorption.The Q_st value can also see whether the surface of the adsorbent is uniform and the distribution of adsorption energy.