Synthesis Of MgAl-LDH/NiFe₂O₄ And Its Adsorption, Photocatalytic Properties

Hydrotalcite(LDH) having the performance of high surface area, good thermal stability and the interlayer anionic exchangeability was widely used as an adsorbent. But LDH also exist a problem such as difficult to recycle after use.In this paper, NiFe2O4 magnetic materials were successfully prepared by using absorbent cotton as the biological template, and as prepared NiFe2O4 remained the morphology of the original cotton. Specific surface area of NiFe2O4 was 121.655m2/g. Then MgAl-Ni Fe2O4/LDH composite materials were synthesized by hydrothermal method with NiFe2O4 as a carrier, and their morphology, phase composition and physical properties were analyzed by SEM, TEM,XRD, IR spectroscopy and surface area test. Experimental results indicated that MgAl-LDH/Ni Fe2O4 composite materials were successfully prepared and remained the morphology of the original cotton. And flaky MgAl-LDH evenly distributed on Ni Fe2O4 fiber materials. Specific surface area of MgAl-LDH/NiFe2O4 was 115.494m2/g. Then the study about their adsorption properties of Congo red solution and doxycycline solution were carried.Adsorption experiments showed that the process of MgAl-LDH/NiFe2O4 adsorbing Congo red solution and doxycycline solution followed the pseudo-second-order kinetic model, and the absorption process of Congo red solution and doxycycline solution followed the Langmuir isotherm model and Freundlich isotherm model, repectivity. Their maximum adsorption capacities were 255.7545mg/g and 751.8797mg/g, respectively. Among them, pH=3 was the best condition in adsorption process of Congo red solution to MgAl-LDH/NiFe2O4, but the best adsorption of doxycycline solution was at pH=5. Morever, the adsorption process of them to MgAl-LDH/NiFe2O4 was a spontaneous and endothermic reaction. The recycling experiment indicated that MgAl-LDH/NiFe2O4 was an excellent adsorbent.In the paper, by hydrothermal method, MgZnAl-LDH/NiFe2O4 composite materials were with NiFe2O4 as the carriers. The morphology, phase composition and physical properties of MgZnAl-LDH/NiFe2O4 composite materials were analyzed. The result showed that MgZnAl-LDH/NiFe2O4 composites were successfully prepared and remained the morphology of the original cotton. And flaky MgZnAl-LDH evenly distributed on NiFe2O4 fiber materials.Specific surface area of MgZnAl-LDH/NiFe2O4 was 129.726m2/g. Then the study about theiradsorption properties of Congo red solution and doxycycline solution were carried. The results showed that the absorption process of Congo red solution and doxycycline solution followed the pseudo-second-order kinetic model, and the absorption process of Congo red solution and doxycycline solution followed the Langmuir isotherm model and Freundlich isotherm model, repectivity. Their maximum adsorption capacities were 704.2254mg/g and421.9409 mg/g, respectively. Among them, pH=3 was the best conditions in adsorption process of Congo red solution to MgZnAl-LDH/NiFe2O4, but the best adsorption of doxycycline solution was at pH=5. Morever, the adsorption process of them to MgZnAl-LDH/NiFe2O4 was a spontaneous and endothermic reaction. The recycling experiment also indicated that MgZnAl-LDH/NiFe2O4 was an excellent adsorbent.Finally, MgZnAl-CLDH/NiFe2O4 was synthesized by calcining MgZnAl-LDH/NiFe2O4.The morphology, phase composition and physical properties of MgZnAl-CLDH/NiFe2O4 composites were analyzed. The results showed that MgZnAl-CLDH/Ni Fe2O4 still retained the morphology of cotton, but the amellar structure on the fiber surface became the oxide and spinel phase. Specific surface area of MgZnAl-CLDH/NiFe2O4 was 63.774m2/g. Subsequently,the study about their adsorption and catalytic properties of Congo red solution and doxycycline solution were carried. The results showed that the absorption process of Congo red solution and doxycycline solution followed the pseudo-second-order kinetic model. The best adsorption properties of Congo red solution and doxycycline solution to MgZnAl-CLDH/NiFe2O4 were at pH=3 and pH=5, respectively. And the adsorption of Congo red solution and doxycycline solution was spontaneous and endothermic process. Degradation rates of Congo red and doxycycline rate were 94.56% and 93.17%, respectively. The photocatalytic process followed first order kinetics, so catalytic reaction is a fast process. The recycling and repeated experiments indicated that MgZnAl-CLDH NiFe2O4 materials were excellent adsorbents and catalysts.In this paper, MgAl-LDH/NiFe2O4, MgZnAl-LDH/NiFe2O4 and MgZnAl-CLDH/NiFe2O4 composite materials prepared were green, efficient, fast recovery of adsorbents, and MgZnAl-CLDH/NiFe2O4 was an efficient catalyst that could be quickly recycled.