Aqueous phosphate removal using nanoscale zero-valent iron

Almeelbi, Talal; Bezbaruah, Achintya N.

doi:10.1007/s11051-012-0900-y

Cited by 149 publications

(75 citation statements)

References 38 publications

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“…Besides organic (halogenated) compounds, nZVI can reduce and/or immobilize harmful metals and metalloids [2,3] and other ions: PO4 3- NO3 -, NO2 - [4]. Depending on the nature of the contaminant, there are many proposed mechanisms and pathways of iron action: reduction, adsorption, reduction and adsorption, adsorption and precipitation or oxidation [5,6].…”

Section: Introductionmentioning

confidence: 99%

Activation process of air stable nanoscale zero-valent iron particles

Ribas

Černík

Benito

et al. 2017

Chemical Engineering Journal

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Nanoscale Zero Valent Iron (nZVI) represents a promising material for subsurface water remediation technology. However, dry, bare nZVI particles are highly reactive, being pyrophoric when they are in contact with air. The current trends of nZVI manufacturing lead to the surface passivation of dry nZVI particles with a thin oxide layer, which entails a decrease in their reactivity. In this work an activation procedure to recover the reactivity of air-stable nZVI particles is presented. The method consists of exposing nZVI to water for 36 hours just before the reaction with the pollutants. To assess the increase in nZVI reactivity based on the activation procedure, three types of nZVI particles with different oxide shell thicknesses have been tested for Cr(VI) removal. The two types of air-stable nZVI particles with an oxide shell thickness of around 3.4 and 6.5 nm increased their reactivity by a factor of 4.7 and 3.4 after activation, respectively. However, the pyrophoric nZVI particles displayed no significant improvement in reactivity. The improvement in reactivity is related mainly to the degradation of the oxide shell, which enhances electron transfer and leads secondarily to an increase in the specific surface area of the nZVI after the activation process. In order to validate the activation process, additional tests with selected chlorinated compounds demonstrated an increase in the degradation rate by activated nZVI particles.

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Section: Introductionmentioning

confidence: 99%

Activation process of air stable nanoscale zero-valent iron particles

Ribas

Černík

Benito

et al. 2017

Chemical Engineering Journal

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“…As a result, removal of excessive phosphorus is important for controlling water eutrophication. A number of methods and techniques have been developed for phosphorus removal, including chemical precipitation, adsorption, and biological treatments345. Among these available methods, chemical precipitation (with aluminum, iron and calcium salts) caused sludge handling, where the biological treatments were found unsuitable for removal of low phosphate concentrations from the water.…”

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confidence: 99%

Adsorption of phosphate in water using one-step synthesized zirconium-loaded reduced graphene oxide

Luo

Wang

Shu

et al. 2016

Sci Rep

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In this account, a one-step green hydrothermal method for zirconium-loaded reduced graphene oxide (RGO-Zr) adsorbent was developed in pure water. It is based on the formation of initially strong-coupling RGO-Zr nanocomposites followed by in situ reduction of GO to RGO during the hydrothermal treatment. The phosphate adsorption performance of the as-prepared nanocomposites was investigated in aqueous environment under various conditions. The characterization results of RGO-Zr nanocomposites showed that ZrO2 was successfully integrated onto the RGO sheets in amorphous. The data from equilibrium phosphate adsorption on RGO-Zr revealed that the adsorption kinetics followed a pseudo-second-order kinetic model, where the adsorption isotherm fitted the Langmuir isotherm model with a maximum adsorption capacity of 27.71 mg P/g at pH 5 and 298 K. The improved phosphate adsorption on RGO-Zr was caused by the dispersion of ZrO2 on the RGO surface. Furthermore, the phosphate adsorption was found insensitive to the increase in pH while it was sensitive to the increase in temperature. The coexisting anions of SO42−, F−, Cl−, NO3− and CO32− affected the phosphate adsorption in a different way. Results suggest that the present RGO-Zr adsorbent has the potential for controlling phosphorus pollution in water.

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“…Further, most of the secondary calcite began forming only after the effluent was exposed to atmospheric CO 2 . Iron phases in the slag may also provide sorption sites; however, sorption of phosphate would likely be limited under these high-pH conditions [48,49]. Additionally, phases not in the thermodynamic database such as amorphous Ca phosphate, Ca-phosphate-carbonates, or Ca-deficient hydroxylapatite may also play a role.…”

Section: Phosphate Removal Mechanisms and Chemistry Of Reacted Solutionsmentioning

confidence: 99%

Geochemical Characterization of Iron and Steel Slag and Its Potential to Remove Phosphate and Neutralize Acid

et al. 2019

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Iron and steel slags from legacy and modern operations in the Chicago-Gary area of Illinois and Indiana, USA, are predominantly composed of Ca (10–44 wt. % CaO), Fe (0.3–28 wt. % FeO), and Si (10–44 wt. % SiO2), with generally lesser amounts of Al (<1–15 wt. % Al2O3), Mg (2–11 wt. % MgO), and Mn (0.3–9 wt. % MnO). Mineralogy is dominated by Ca ± Mg ± Al silicates, Fe ± Ca oxides, Ca-carbonates, and high-temperature SiO2 phases. Chromium and Mn concentrations in most samples may be environmentally significant based on comparison with generic soil contaminant guidelines. However, simulated weathering tests suggest these elements are present in generally insoluble phases making their use in water treatment applications possible; however, the generation of high pH and alkaline solutions may be an issue. As for possible water treatment applications, batch and flow-through experiments document effective removal of phosphate from synthetic solutions for nearly all slag samples. Air-cooled fine fractions (<10 mm) of modern slag were most effective; other types, including modern granulated, modern air-cooled coarse fractions (>10 mm), and legacy slag removed phosphate, but to a lesser degree. An additional water treatment application is the use of slag to neutralize acidic waters. Most slag samples are extremely alkaline and have high net neutralization potentials (NNP) (400–830 kg CaCO3/t), with the highest approximately equivalent to 80% of the neutralization potential of calcite. Overall, phosphate removal capacity and NNP correlate positively with total Ca content and the dissolution of Ca minerals facilitates secondary Ca phosphate formation and consumes acid during hydrolysis. Utilizing locally available slag to treat waste or agricultural waters in this region may be a higher value alternative than use in construction, potentially offsetting restoration costs to degraded legacy areas and decreasing steel manufacturers’ current waste footprint.

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Aqueous phosphate removal using nanoscale zero-valent iron

Cited by 149 publications

References 38 publications

Activation process of air stable nanoscale zero-valent iron particles

Activation process of air stable nanoscale zero-valent iron particles

Adsorption of phosphate in water using one-step synthesized zirconium-loaded reduced graphene oxide

Geochemical Characterization of Iron and Steel Slag and Its Potential to Remove Phosphate and Neutralize Acid

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