Treatment Of Carmine Wastewater Using Layered Double Hydroxides(LDHs)in Situ Synthesized By Magnesia Aluminum Salt And Calcined Dolomite

Dyeing wastewater is an important source of industrial pollution.However,it's difficult to deal with dyeing wastewater because of a series of difficulties,such as high concentration pollution high-chroma product antiphotodegradation,strong resistant to biological treatment and oxidation reaction.Layered double hydroxides(LDHs)have strong anion exchange ability,and can be synthesized at room temperature.They also have structural and structural tunability and structural memory.So,they have potential applications in the treatment of anionic dye wastewater.In this paper,calcined dolomite and AICl3·6H2O were used as raw materials to treat carmine dye wastewater by the method of instant LDHs synthesis.The effects of different initial concentrations of carmine,water temperature,calcined dolomite addition and the ratio of aluminum to salt on the removal of carmine by LDHs were investigated.In order to reduce the consumption of acid in practical application,based on the above experiments,the raw materials were slightly improved,and LDHs was calcined with dolomite,magnesium salt(MgCl2·6H2O)and aluminum salt(AICl3·6H2O).The effects of different time,carmine concentration,water temperature,and dosage of medicament on the experiment were investigated.The analysis results of XRD,FT-IR,FE-SEM and TG were used to investigate the mechanism and physicochemical properties of LDHs on removal of carmine.The results show that:1.the XRD patterns of the synthesized samples showed low peak diffraction intensity,low crystallinity,poor structural regularity,and lamellar structure characteristics.The pH value,temperature,initial concentration of carmine and the ratio of magnesium and aluminum had a great influence on the removal rate of carmine,2.It shows that the best reaction conditions for calcined dolomite and aluminum salt to synthesize LDHs in real time are:the dosage is l.7g·L-1,pH=9,Mg/Al ratio is 3,temperature is 30?,under this condition,the removal rate of carmine can reach more than 89%.The best experimental conditions for the removal of cochineal from LDHs by calcined dolomite and magnesium salt are the following:the temperature 30? and the dosage of 1.8g·L-1 can make the solution pH reach 9,and the removal rate of carmine can reach over 92%under this condition.3.by adding different agents,it is found that there are two mechanisms for the high removal rate of carmine in water:first,carmine can be adsorbed onto the surface of LDHs,so that it can be removed.Another possibility is that the carmine anions are removed by embedding into the LDHs layer.Calcium and magnesium may play an auxiliary role in the precipitation of carmine.