Enhanced Phosphate Removal from Water by Honeycomb-Like Microporous Lanthanum-Chitosan Magnetic Spheres

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 NO 3 − had little effect on adsorption capacity to phosphate, while CO 3 2− 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.

Recovery of Phosphate(V) Ions from Water and Wastewater Using Chitosan-Based Sorbents Modified—A Literature Review

“…92 mg/g. Lanthanum(III) ions were also added to the MCS composite [52]. La-chitosan magnetic spheres showed a high adsorption rate for phosphate at a pH of 3.0.…”

Lake and River Restoration: Method, Evaluation and Management

“…The removal of P from the water column is crucial and effective for the control of eutrophication, and adsorption is one of the most effective treatment processes. Cheng et al [20] synthesised a P adsorbent of lanthanum-chitosan magnetic spheres, and evaluated its capability under different conditions. A superior P adsorption ability was demonstrated and, furthermore, the adsorption kinetics, isotherms, and thermodynamic analyses of P by as-prepared adsorbents were studied to reveal the underpinning mechanisms.…”

Pretreatment by recyclable Fe3O4@Mg/Al-CO3-LDH magnetic nano-adsorbent to dephosphorize for the determination of trace F− and Cl− in phosphorus-rich solutions

“…8 and 9 in Section 3.2, respectively). According to the literature, phosphate adsorption by some non-LDH adsorbents [66][67][68][69][70] and some LDH adsorbents [23][24][25][26]31,33 is greatly affected by F À or Cl À due to their adsorption. For LDHs, considering the bonding strength between the layers and interlayer anions in aqueous solution, 17 the strength of phosphates is generally higher than that of F À and Cl À .…”