Preparation Of Boron Adsorption Materials And Their Adsorption Effect On Boric Acid

Here,several different experimental methods were used to prepare different types of adsorbent materials.These materials were used to study the adsorption of boric acid in aqueous solution.The experiments used the TG-DSC curve to determine the optimal temperature for the calcination;Through FT-IR,XRD,SEM and EDS characterized the structure and morphology of the prepared material.The boric acid were investigated by using a static test batch of these materials,and discussed the effect of different adsorbent dosage,the initial p H value,contact time and adsorption temperature in adsorption process.The adsorption temperature data was fitted by Langmuir and Freundlich model,and the data of contact time was fitted by pseudo-first-order and pseudo-second-order.From the results of these characterized,we can inferred the adsorption mechanism in boron adsorption.The result of the experiments was as follows:(1)A magnesium aluminum cerium hydrotalcite(Mg-Al-Ce-HT)was successfully prepared by co-precipitation method for boron removal.XRD,FT-IR,SEM,EDS,and XPS analysis were employed to confirm the structure and characteristic.The adsorption efficiency of Mg-Al-Ce-HT was studied as a function of initial p H value,the amount of absorbent,the concentration of initial boric acid,temperature(adsorption isotherms)and contact time(adsorption kinetics).The p H value of the solution appeared to have little effect on boron sorption when p H value was less than 8.0.However,when the p H value exceeds 8.0,the adsorption capacity decreased and had an obvious trend.It was due to the H3BO3(B(OH)3)exchange to B(OH)4-in high p H values.The optimum amount of absorbent was 0.2 g and the concentration of boric acid was 200 mg/L in 50 m L solutions.Boron removal was reached the equilibrium in 160 min,and from the adsorption kinetics,the adsorption process was happened in the form of ion-exchange.And the data was well fitted with Langmuir model,which indicated that the adsorption was a monolayer adsorption.The adsorption isotherm showed the adsorption was a spontaneous and endothermic process.(2)The Mg-Al-Zr metal compound oxide was successfully prepared by co-precipitation.The best calcine temperature is 400?.The initial p H value of boric acid and adsorption temperature affects the adsorption behavior considerably.When the p H value in 3.0 to 6.0,with the increasing of the initial p H value,the adsorption capacity was increased.The highest point is in the initial p H value at 6.0.When the p H value above 6.0,the adsorption efficiency was decreased with the increasing of the p H values.The change of temperature has greatly effect of adsorption.When the adsorption temperature at the range of 298K~318K,with the increasing of adsorption temperature,the adsorption capacity was increased.The experiment data was fitted by Langmuir model and Freundlich model,the result shows that the data was well fitted with Langmuir model,which indicated that the adsorption was a monolayer adsorption.The best absorbent dosage is 25 mg,the concentration of boric acid is 140 mg/L;the best contact time is about 100 min.From the adsorption kinetics,the result shows the data was well fitted with pseudo-second-order model,it indicated that the adsorption was happened in the form of ion-exchange.(3)The Zn-Co MOFs was prepared by hydrothermal synthesis method successfully.The adsorption efficiency was deep affect with initial p H value of boric acid.When the acidity in the solution was in the neutral or alkaline,the adsorption has a good adsorption effect.The best dosage of absorbent is 20 mg in 10 m L 200 mg/L solutions.The adapt contact time of the adsorption is about 240 min.The temperature of adsorption also has the effect in the adsorption efficiency.With the increasing of the temperature,the adsorption capacity was increased.The data was fitted with Langmuir model and Freundlich model,calculated thermodynamic parameters.The result shows the data was well fitted with Langmuir model,and the adsorption process is a endothermic process.The adsorption kinetics shows the adsorption process was well fitted with pseudo-second-order model,it indicated the adsorption is a monolayer adsorption.