Study On The Assembly Of Layered Double Hydroxide And Its Adsorption Performance For Benzene In Water

Benzene is a representative substance of benzene series among organic pollutants,and its toxicity is the strongest among benzene series.Because of its strong carcinogenicity,it has been included in the World Health Organization’s list of carcinogens.Compared with other organic pollutants,benzene has relatively stable chemical properties and has a certain degree of solubility in water.Benzene pollution in water threatens human health and the ecological environment.Therefore,the treatment of benzene-containing sewage is an important issue.Layered Double Hydroxides(LDHs)is referred to as hydrotalcite.It is a kind of anionic clay.It is widely used in the adsorption of heavy metal ions,inorganic anions,anionic dyes,cationic dyes and other pollutants because of its properties such as adjustable cations of the layers,exchange of interlayer anions,and structure memory effect.A series of hydrotalcites with different cation compositions and different cation ratios were synthesized with the help of the cation tunability of the hydrotalcite laminates.The study found that for MgAl-LDH,ZnAl-LDH,CaAl-LDH,the strength of the interaction between it and benzene The order is CaAl-LDH>ZnAl-LDH>MgAl-LDH,resulting in the order of CaAl-LDH>ZnAl-LDH>MgAl-LDH for the adsorption rate of benzene in water;for Mg2Al-LDH,Mg3Al-LDH,Mg4Al-LDH,which is the same as The order of the interaction strength between benzene is Mg4Al-LDH>Mg3Al-LDH>Mg2Al-LDH,resulting in the adsorption rate of benzene in water as Mg4Al-LDH>Mg3Al-LDH>Mg2Al-LDH.The kinetics of the adsorption process of MgAl-LDH on benzene in water can be described by a quasi-first order adsorption kinetic equation,which shows that the rate of the adsorption process is mainly controlled by the external mass transfer process,and the adsorption isotherm conforms to the Freundlich adsorption isotherm model.The adsorption process is uneven adsorption that occurs on the surface of hydrotalcite.The structure memory effect of hydrotalcite was used to synthesize organic anion intercalated hydrotalcite by roasting reduction method.The effect of interlayer guest anion on the adsorption performance of LDHs on benzene was studied.Organic anion(SDS,SA)intercalation was used to make LDHs by The hydrophilicity turns into hydrophobicity,which enhances the affinity of LDHs for benzene,thereby greatly improving the adsorption performance of hydrotalcite for benzene.The length of SA ions is longer than SDS,making the distance between SA-LDH layers larger than SDS-LDH and increasing benzene entry The probability of organic phase further improves the adsorption performance of LDHs.The adsorption process of organic intercalation modified hydrotalcite to benzene conforms to the quasi-second-order kinetic equation and linear isotherm adsorption model,indicating that the nature of the adsorption of benzene to the organic intercalation modified hydrotalcite is a distribution effect.The effect of the structure and morphology of LDHs on the adsorption performance of benzene was further studied.For hydrotalcite with different specific surface area and pore structure,because the specific surface area becomes larger and more adsorption sites are exposed,the increase in pore volume will increase the adsorption capacity,resulting in The adsorption rate and saturated adsorption capacity of benzene in water increase with the increase of the specific surface area and pore volume of the hydrotalcite;the special morphology of 3D-SDS-LDH forms a pore structure between the hydrotalcite sheets,making it more It is easy to capture benzene molecules in water,and the adsorption performance of benzene in water is significantly better than the two-dimensional sheet-shaped SDS-LDH.