Synthesis And Adsorption Property Of Magnetic Magnesium Oxide Composites

Organic dyes are the primary contaminant in effluent. Among a variety of conventional methods for treating organic dyes wastewater, adsorption plays a dominant part due to its simplicity, high efficiency and low-energy cost. In recent years, people has devoted to develop materials for adsorbing organic dyes, aiming to find adsorbent with the properties of excellent adsorption capacity, environmentally friendly and easy to recycle. As a kind of high efficient, non-toxic and accessible adsorbent, MgO was widely used in organic dyes wastewater treatment. Particularly, MgO with micro-nano hierarchical structures showed superb adsorption performance for some anionic organic dyes due to its high specific surface area and multiple reaction channels. However, to separate adsorbents from wastewater using traditional methods such as sedimentation, filtration and centrifugation is not applicable, for it’s not simple and the operation cost is expensive. In this paper, in order to separate MgO adsorbent from effluent, MgO-Fe and MgO-MgFe2O4composite were respectively synthesized by an ion exchange route using hierarchical magnesium carbonate as templates, aiming to develop adsorbent with magnetism and adsorption capacity. The influence of adding amount of FeCl2and annealing temperature on the properties of products were investigated to find the optimal synthesis technology, and the adsorption property of the optimized MgO-Fe and MgO-MgFe2O4composite toward a series of anionic organic dyes was also explored. The main contents are as follows:(1) Synthesis and adsorption performance of MgO-Fe composite. Hierarchical flowerlike MgO-Fe composite was synthesized via an ion exchange route and subsequent calcination by H2reduction using magnesium carbonate as templates (MCH). The influence of adding amount of FeCl2on the properties of product such as crystalline structure, morphology and magnetism was discussed, and the adsorption performance of optimized MgO-Fe composite for anionic organic dyes was investigated. The results showed that the saturated adsorption capacity of MgO-Fe composite toward Congo red is up to1921mg/g, which is higher than other adsorbents reported in the literature.(2) Synthesis and adsorption performance of MgO-MgFe2O4composite. By partly etching the precursor of MgFe2O4on MCH and heat treatment, Hierarchical flowerlike MgO-MgFe2O4was readily prepared by an ion exchange route using magnesium carbonate as templates. Two key synthetic factors (the adding amount of FeCl2and annealing temperature) that affect crystalline structurer, morphology, magnetic property and adsorption capacity were carefully studied, in order to determine the optimum synthetic conditions. MgO-MgFe2O4composite synthesized under optimized conditions showed excellent adsorption capacity toward Congo red (498mg/g), in addition, other anionic organic dyes such as acid fuchsine and methyl orange can also be adsorbed well.