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Modification of Sargassum angustifolium by molybdate during a facile cultivation for high-rate phosphate removal from wastewater: structural characterization and adsorptive behavior

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ABSTRACT

In this paper, a new and facile approach for molybdate loading in the brown algae of Sargassum angustifolium is introduced. The molybdate ions were entered into the algae body during a short cultivation to produce algae–Mo as a novel adsorbent for eliminating phosphate ions from synthetic and real wastewaters. Results of the surface analysis showed that molybdate loading onto the algae was successfully performed. Herein, basic variables, such as initial solution pH, adsorbent dosage, contact time, phosphate concentration, and temperature, were investigated in detail to assess the phosphate adsorption performance of algae–Mo. The pseudo-second-order kinetic model fitted our acquired experimental kinetic data most appropriately, in comparison to the use of a pseudo-first-order model. The Langmuir model appeared to fit the adsorption data more desirably than that of Freundlich and Dubnin–Radushkevich models, with a maximum phosphate adsorption capacity of 149.25 mg/g at 25 °C. The finding of the thermodynamic study revealed that the phosphate adsorption onto algae–Mo was spontaneous, feasible, and endothermic in nature. The study on Mo2+ ions leaching strongly suggested that the risk of Mo2+ leakage during phosphate adsorption was negligible at a wide pH range of 3–9. The adsorption efficiency attained was 53.4% at the sixth cycle of reusability. Two real wastewaters with different qualities were successfully treated by the algae–Mo, suggesting that the algae–Mo could be ordered for practical wastewater treatment.

No MeSH data available.


Effects of adsorbent reuse times on phosphate adsorption (adsorbent dose: 10 g/L, pH: 5, phosphate concentration: 50 mg/L, contact time: 60 min)
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Fig10: Effects of adsorbent reuse times on phosphate adsorption (adsorbent dose: 10 g/L, pH: 5, phosphate concentration: 50 mg/L, contact time: 60 min)

Mentions: To assess the recyclability of the algae–Mo in the phosphate adsorption, an experimental phase was carried out. To do this, the recyclability of the adsorbent was tested in seven consecutive cycles under identical conditions (pH 5, initial phosphate concentration of 50 mg/L, contact time 60 min, and solution temperature 25 °C) and the adsorbent was being recycled from the previous test without any modifications. The phosphate removal efficiency was determined after each test, and the results are presented in Fig. 10. As indicated, the algae–Mo preserved its adsorption capability after the sixth reuse (with efficiency >50%); thus, the algae–Mo is a stable adsorbent for attenuating phosphate-containing wastewaters. Conclusively, the recyclable properties of algae–Mo adsorbent support its commercial use. The cycle number (i.e., 6 cycles) of reusability of the adsorbent is more than that obtained by nanostructured iron(III)–copper(II) binary oxides studied by Li et al. (2014).Fig. 10


Modification of Sargassum angustifolium by molybdate during a facile cultivation for high-rate phosphate removal from wastewater: structural characterization and adsorptive behavior
Effects of adsorbent reuse times on phosphate adsorption (adsorbent dose: 10 g/L, pH: 5, phosphate concentration: 50 mg/L, contact time: 60 min)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120031&req=5

Fig10: Effects of adsorbent reuse times on phosphate adsorption (adsorbent dose: 10 g/L, pH: 5, phosphate concentration: 50 mg/L, contact time: 60 min)
Mentions: To assess the recyclability of the algae–Mo in the phosphate adsorption, an experimental phase was carried out. To do this, the recyclability of the adsorbent was tested in seven consecutive cycles under identical conditions (pH 5, initial phosphate concentration of 50 mg/L, contact time 60 min, and solution temperature 25 °C) and the adsorbent was being recycled from the previous test without any modifications. The phosphate removal efficiency was determined after each test, and the results are presented in Fig. 10. As indicated, the algae–Mo preserved its adsorption capability after the sixth reuse (with efficiency >50%); thus, the algae–Mo is a stable adsorbent for attenuating phosphate-containing wastewaters. Conclusively, the recyclable properties of algae–Mo adsorbent support its commercial use. The cycle number (i.e., 6 cycles) of reusability of the adsorbent is more than that obtained by nanostructured iron(III)–copper(II) binary oxides studied by Li et al. (2014).Fig. 10

View Article: PubMed Central - PubMed

ABSTRACT

In this paper, a new and facile approach for molybdate loading in the brown algae of Sargassum angustifolium is introduced. The molybdate ions were entered into the algae body during a short cultivation to produce algae–Mo as a novel adsorbent for eliminating phosphate ions from synthetic and real wastewaters. Results of the surface analysis showed that molybdate loading onto the algae was successfully performed. Herein, basic variables, such as initial solution pH, adsorbent dosage, contact time, phosphate concentration, and temperature, were investigated in detail to assess the phosphate adsorption performance of algae–Mo. The pseudo-second-order kinetic model fitted our acquired experimental kinetic data most appropriately, in comparison to the use of a pseudo-first-order model. The Langmuir model appeared to fit the adsorption data more desirably than that of Freundlich and Dubnin–Radushkevich models, with a maximum phosphate adsorption capacity of 149.25 mg/g at 25 °C. The finding of the thermodynamic study revealed that the phosphate adsorption onto algae–Mo was spontaneous, feasible, and endothermic in nature. The study on Mo2+ ions leaching strongly suggested that the risk of Mo2+ leakage during phosphate adsorption was negligible at a wide pH range of 3–9. The adsorption efficiency attained was 53.4% at the sixth cycle of reusability. Two real wastewaters with different qualities were successfully treated by the algae–Mo, suggesting that the algae–Mo could be ordered for practical wastewater treatment.

No MeSH data available.