Yong-Hui Zhang,Zuo-Bei Wang,Adenike Bernice Eloise Adeoye,Yi-Fan Wang,You-Gui Huang,Xin Ye,Wei Wang
Lanthanum (La) adsorbents are highly effective for phosphorus removal but are constrained by their high reagent cost because of their La content. By exploiting the similarity in ionic sizes between Ca 2+ and La 3+ , we develop a low-cost composite adsorbent LCCa-5@Dia by doping La 2 (CO 3 ) 3 ·8H 2 O with Ca 2+ . Our results indicate that the slow addition of NaHCO 3 during the synthetic process facilitates the incorporation of Ca 2+ into the La 2 (CO 3 ) 3 ·8H 2 O lattice, leading to an adsorption behavior nearly identical to that of the undoped adsorbents. LCCa-5@Dia demonstrates a high adsorption capacity of 60.04 mg P/g, with stable performance across a pH range of 3 to 11. Its adsorption property also exhibits excellent stability under the interference of solution pH and competing ions. Materials characterization reveals that the adsorption occurs through electrostatic attraction and ligand exchange. In continuous column-adsorption experiments, the LCCa-5@Dia adsorbent treats up to 4000 bed volumes of simulated low concentration wastewater (1.7–2.7 mg P/L). This translates to a treatment cost as low as $0.0211/m 3 . Meanwhile, the adsorbent also maintains over 80 % of the adsorption capacity after three regeneration cycles. The excellent performance and low treatment cost of the calcium-doped lanthanum carbonate adsorbents highlight its practical potential in treating low concentration wastewater.
Ibrahim El-Tantawy El-Sayed,Xingmei Lu,Jiayu Xin,Azza A. Al-Ghamdi,Enas A. Imam,Hamada B. Hawash,Ahmed A. Galhoum,S. Wageh
Two α-aminophosphonate anlages (methyl- and phenyl-derivatives, MeAP and PhAP, respectively) were synthesized via an in-situ reaction. Moreover, their corresponding sand nanocomposites, MeAPNC and PhAPNC, respectively, were prepared using an eco-friendly, inexpensive and facile solid-state synthetic route. These materials were extensively characterized by CHNSP/O, XRD, FTIR, SEM-EDX, TEM, and PZC. Lanthanum sorption characteristics were investigated and compared through the study of pH dependence (optimal pH: 4.5), equilibration time (achieved at 120 and 90 min for α-APs and nanocomposites, respectively), and sorption isotherms. The Sips isotherm and pseudo-second-order (PSORE) kinetics were the optimal models for fitting the experimental data. Sorption isotherms showed that methyl-derivatives (≈1.29–1.359 mmol/g) were more effective than their corresponding phenyl-derivatives (≈0.941–0.986 mmol/g) due to steric hindrance, acid-base differences, and inductive effects. Sorbents showed appreciated stability with just a 4.5–10.5 % loss in performance over six reuse cycles using HCl (0.2 M). Notably, sand incorporation slightly increased capacity with half-organic-portion in composites, as well as enhanced kinetics and regeneration efficiency. La(III) sorption is spontaneous, exothermic, and increases randomness across all sorbents. Finally, the prepared sorbents have proven effective sorption for Nd(III) beside La(III) with high selectivity from acidic complex monazite liquor.
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