“…Because the coagulation and precipitation processes in the natural waters are accompanied by co-precipitation and adsorption processes of different forms of phosphorus (Xiong and Peng 2011), a variety of adsorbents are added to water, for instance, iron oxide in order to increase their rate and to decrease the desorption of phosphorus compounds from the bottom sediments (Geelhoed et al 1997; Zeng and Li 2004; Chitrakar et al 2006). Other widely promoted adsorbents are lanthanum-modified bentonite (Haghseresht et al 2009), natural zeolite (Tian et al 2009; Dionisiou et al 2013; Meng et al 2013), mesoporus silicate material (Zhang et al 2011), composite adsorbents containing two (or more) different metal oxides (Long et al 2011; Li et al 2014), and poly (vinyl alcohol) hydrogel beads with aluminum (Hui et al 2014). Tian et al (2009) recommended adsorption as one of the most effective removal processes for the low concentration of phosphorus.…”
Binding phosphate at participation of alginate/FeCl3 capsules was studied with laboratory experiments. The hydrogel microcapsules were obtained with the dropping-in method, by gelation of sodium alginate water solution by iron (III) chloride solution. Phosphate adsorption characteristics were studied in a static batch system with respect to changes in contact time, initial phosphates concentration, pH of solution, and temperature. After 24 h of the tests, average 87.5% of phosphate ions were removed from the natural water solutions; after 48 h, an equilibrium was reached. The adsorption data were well fit by the Freundlich isotherm model. Parameter k of the isotherms amounted from 43.4 to 104.7, whereas parameter n amounted from 0.362 to 0.476. The course of processes of phosphate adsorption and iron desorption to aquatic phase, as well as changes in pH, suggests that phosphate adsorption is a major mechanism of phosphate removal, whereas simultaneously, but at a much lower degree, a process of precipitation of phosphate by iron (III) ions released from the capsules to the solution takes its place. Parameters calculated in the Freundlich isotherm equation show that by using several times smaller amounts of iron, it is possible to remove similar or bigger amounts of phosphorus than with other adsorbents containing iron. The alginate/FeCl3 adsorbent removes phosphate in a wide pH spectrum—from 4 to 10. Results suggest that the proposed adsorbent has potential in remediation of contaminated waters by phosphate.
“…Because the coagulation and precipitation processes in the natural waters are accompanied by co-precipitation and adsorption processes of different forms of phosphorus (Xiong and Peng 2011), a variety of adsorbents are added to water, for instance, iron oxide in order to increase their rate and to decrease the desorption of phosphorus compounds from the bottom sediments (Geelhoed et al 1997; Zeng and Li 2004; Chitrakar et al 2006). Other widely promoted adsorbents are lanthanum-modified bentonite (Haghseresht et al 2009), natural zeolite (Tian et al 2009; Dionisiou et al 2013; Meng et al 2013), mesoporus silicate material (Zhang et al 2011), composite adsorbents containing two (or more) different metal oxides (Long et al 2011; Li et al 2014), and poly (vinyl alcohol) hydrogel beads with aluminum (Hui et al 2014). Tian et al (2009) recommended adsorption as one of the most effective removal processes for the low concentration of phosphorus.…”
Binding phosphate at participation of alginate/FeCl3 capsules was studied with laboratory experiments. The hydrogel microcapsules were obtained with the dropping-in method, by gelation of sodium alginate water solution by iron (III) chloride solution. Phosphate adsorption characteristics were studied in a static batch system with respect to changes in contact time, initial phosphates concentration, pH of solution, and temperature. After 24 h of the tests, average 87.5% of phosphate ions were removed from the natural water solutions; after 48 h, an equilibrium was reached. The adsorption data were well fit by the Freundlich isotherm model. Parameter k of the isotherms amounted from 43.4 to 104.7, whereas parameter n amounted from 0.362 to 0.476. The course of processes of phosphate adsorption and iron desorption to aquatic phase, as well as changes in pH, suggests that phosphate adsorption is a major mechanism of phosphate removal, whereas simultaneously, but at a much lower degree, a process of precipitation of phosphate by iron (III) ions released from the capsules to the solution takes its place. Parameters calculated in the Freundlich isotherm equation show that by using several times smaller amounts of iron, it is possible to remove similar or bigger amounts of phosphorus than with other adsorbents containing iron. The alginate/FeCl3 adsorbent removes phosphate in a wide pH spectrum—from 4 to 10. Results suggest that the proposed adsorbent has potential in remediation of contaminated waters by phosphate.
“…Among 21 various available technologies for phosphate decontamination, the 22 adsorption method is relatively simple, economical, and highly 23 efficient [5,6]. Various types of materials have been used as 24 adsorbents, such as Fe-Mn binary oxide [7], a metal oxide 25 adsorbent derived from manganese ore tailings [8], nanostruc- 26 tured Fe(III)-Cu(II) binary oxides [9], mesoporous Cr-Zr binary 27 oxide nanoadsorbent [10], magnetic Fe-Zr binary oxide [11], 28 aluminum compounds [12][13][14], and hydrous zirconium oxide- 29 based nanocomposites [4]. Composite metal oxides may show 30 physicochemical properties different from those of their single- 31 component oxide counterparts.…”
“…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.…”
Section: Resultsmentioning
confidence: 75%
“…The decrease of k
2 values with increase in the initial phosphate concentration showed a good concordance between the experimental data and the pseudo-second-order kinetic model. A review of the recently published literature (Hamoudi and Belkacemi 2013; Li et al 2014; Riahi et al 2013) on the phosphate adsorption showed that most researchers reported that the pseudo-second-order model satisfactory fits the experimental data.Fig. 9Kinetic models of a pseudo-first-order model, b pseudo-second-order model (adsorbent dose 10 g/L, pH 5)
…”
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.
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