Abstract
The removal of phosphate in water is crucial and effective for control of eutrophication, and adsorption is one of the most effective treatment processes. In this study, microporous lanthanum-chitosan magnetic spheres were successfully synthetized and used for the removal of phosphate in water. The characterization results show that the dispersion of lanthanum oxide is improved because of the porous properties of the magnetic spheres. Moreover, the contact area and active sites between lanthanum oxide and phosphate were increased due to the presence of many honeycomb channels inside the magnetic spheres. In addition, the maximum adsorption capacity of the Langmuir model was 27.78 mg P·g−1; and the adsorption kinetics were in good agreement with the pseudo-second-order kinetic equation and intra-particle diffusion model. From the results of thermodynamic analysis, the phosphate adsorption process of lanthanum-chitosan magnetic spheres was spontaneous and exothermic in nature. In conditional tests, the optimal ratio of lanthanum/chitosan was 1.0 mmol/g. The adsorption capacity of as-prepared materials increased with the augmentation of the dosage of the adsorbent and the decline of pH value. The co-existing anions, Cl− and NO3− had little effect on adsorption capacity to phosphate, while CO32− exhibited an obviously negative influence on the adsorption capacity of this adsorbent. In general, owing to their unique hierarchical porous structures, high-adsorption capacity and low cost, lanthanum-chitosan magnetic spheres are potentially applicable in eutrophic water treatment.
Highlights
The eutrophication of water bodies has become one of the major ecological environmental issues all over the world [1,2,3]
The structure of as-prepared spheres is similar to honeycomb-like shape, which is similar to what is reported in the literature [22]
It’s obvious and intuitive that the lamellar surface of La-chitosan magnetic spheres is uniformly covered with a mesh of rod-like particles (Figure 1b,e), which is more favorable for adsorption of phosphate
Summary
The eutrophication of water bodies has become one of the major ecological environmental issues all over the world [1,2,3]. Phosphorus, an essential element for the growth of aquatic organisms, is one of the limiting elements for the eutrophication of water bodies [4]. The presence of excess phosphorus in water further results into the outbreak of algal blooms, death of aquatic organisms, and sharp deterioration of water quality. Cyanobacterial blooms, caused by an excess phosphorus in water, generally poses many difficult challenges to the stability of aquatic. The removal of excess phosphate in water is of great significance for controlling and preventing the deterioration of water bodies
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