Novel Continuous Column Process for As(III) Oxidation from Concentrated Acidic Solutions with Activated Carbon Catalysis

Wu, Chengqian; Mahandra, Harshit; Ghahreman, Ahmad

doi:10.1021/acs.iecr.0c00470

Cited by 13 publications

(4 citation statements)

References 39 publications

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“…An arsenic solution with a concentration of 20 mg L −1 was prepared using sodium arsenite (NaAsO 2 , Aldrich) or sodium arsenate (NaAsO 3 , Aldrich), and hydrogen chloride (HCl, Aldrich) was added to the solution to keep pH = 3 in all experiments. It is known that protons formed in As( iii ) oxidation decrease pH of the solution, 18,19 and we have confirmed the change in pH (Fig. S1†).…”

Section: Methodssupporting

confidence: 85%

As(iii) removal through catalytic oxidation and Fe(iii) precipitation

et al. 2022

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Section: Methodssupporting

confidence: 85%

As(iii) removal through catalytic oxidation and Fe(iii) precipitation

et al. 2022

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“…Arsenic is considered an element of high concern due to its toxic nature, mobilization, easy evaporation, bioaccumulation in the surrounding area, and it being a human carcinogen [1][2][3]. Naturally occurring arsenic (As) mainly exists in 60% arsenates, 20% sulfides, 10% oxides and sulfosalts, and the remaining 30% is divided between arsenites, arsenides, native elements, and metal alloys [4].…”

Section: Introductionmentioning

confidence: 99%

Comparative Study for Flue Dust Stabilization in Cement and Glass Materials: A Stability Assessment of Arsenic

2022

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Arsenic is a poisonous element and its super mobility can pose a major threat to the environment and human beings. Disposed arsenic-bearing waste or minerals over time may release arsenic into the groundwater, soil and then the food chain. Consequently, safe landfill deposition should be carried out to minimize arsenic bleeding. Cement-based stabilization/solidification and glass vitrification are two important methods for arsenic immobilization. This work compares the stability and intrinsic leaching properties of sequestered arsenic by cement encapsulation and glass vitrification of smelter high-arsenic flue dust (60% As2O3) and confirms if they meet or exceed the requirement of landfill disposition over a range of environmentally relevant conditions. The toxicity characterization leaching procedure (TCLP, 1311), synthetic precipitation leaching procedure (SPLP, 1312) and Australian standard (Aus. 4439.3) in short-term (18 h) and mass transfer from monolithic material using a semi-dynamic leaching tank (1315) in longer-term (165 days) were employed to assess arsenic immobility characteristic in three arsenic-cement (2%, 8.4% and 14.4%) and arsenic-glass (11.7%) samples. Moreover, calcium release from different matrices has been taken into consideration as a contributor to arsenic bleeding. Based on the USEPA guidelines, samples can be acceptable for landfilling only if As release is < 5 mg/L. Results obtained from short-term leaching were almost similar for both cement and glass materials. However, high calcium release was observed from the cement-encapsulated materials. The pH of leachates after the test was highly alkaline for encapsulated materials; however, in glass material it was near neutral or slightly acidic. Method 1315 tests made a huge difference between the two materials and confirmed that cement encapsulation is not the best method for landfilling arsenic waste due to the high arsenic and calcium release over time with alkaline pH. However, glass material has shown promising results, i.e., the insignificant release of arsenic over time with an acceptable change in pH value. Overall, arsenic sequestration in glass is a better option compared with the cement-based solidification process.

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“…The coupled oxidation–adsorption process, such as chemical or catalytic oxidation–adsorption coupling process, has drawn considerable attention in recent years, since it provides an alternative scenario to As(III) removal. ,− Compared with the traditional absorption process, the coupling process can further convert As(III) to As(V) and enhance the adsorption of total As. , Moreover, without using oxidizing reagents, the coupled photocatalytic oxidation–adsorption process exhibits more advantages, such as a clean process, sustainability, and the absence of secondary pollution. − At present, TiO 2 has become one of the most studied and promising materials due to its low cost, abundant raw materials, high photocatalytic activity, good chemical stability, and nontoxicity. , However, the wide band gap (3.2 eV) of TiO 2 limits its absorption of solar radiation in the UV light range, which accounts for about 4–6% of the solar spectrum . Moreover, the rapid recombination of photogenerated electrons and holes drastically reduces the efficiency of the photocatalytic process .…”

Section: Introductionmentioning

confidence: 99%

Insights into the Adsorption and Photocatalytic Oxidation Behaviors of Boron-Doped TiO₂/g-C₃N₄ Nanocomposites toward As(III) in Aqueous Solution

Ouyang

Zhang

Yuan

et al. 2021

Ind. Eng. Chem. Res.

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The coupled adsorption–photocatalytic oxidation process provides a great potential scenario to enhance the removal efficiency of arsenite contaminants by converting As(III) to As(V) and simultaneous adsorption. In this study, the boron-doped black TiO2/g-C3N4 nanocomposite is synthesized by combination of sol–gel and in situ decomposition-thermal polymerization methods as a photocatalyst for the photocatalytic oxidation and adsorption of As(III). Under dark conditions, the boron-doped samples (B-TiO2 and B-TiO2/g-C3N4) display an increase in the As(III) adsorption capacity by one order of magnitude up to circa 3.2 mg g–1 with an initial As(III) concentration of 2 mg L–1 at 298.15 K and pH 5. The adsorption kinetics of As(III) on B-TiO2/g-C3N4 conform to the pseudo-second-order kinetic model, revealing the chemical adsorption mechanism. Under visible light irradiation, the total arsenic removal capacity is substantially improved by 20% with a removal capacity of 3.9 mg g–1. The enhancement of arsenic adsorption is attributed to the chemical complexation and hydrogen bond, in which B–OH bonds play a dominant role. The photocatalytic oxidation mechanism of the as-synthesized B-TiO2/g-C3N4 is attributed to the synergism of superoxide radicals, hydroxyl radicals, and photogenerated holes.

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Novel Continuous Column Process for As(III) Oxidation from Concentrated Acidic Solutions with Activated Carbon Catalysis

Cited by 13 publications

References 39 publications

As(iii) removal through catalytic oxidation and Fe(iii) precipitation

As(iii) removal through catalytic oxidation and Fe(iii) precipitation

Comparative Study for Flue Dust Stabilization in Cement and Glass Materials: A Stability Assessment of Arsenic

Insights into the Adsorption and Photocatalytic Oxidation Behaviors of Boron-Doped TiO₂/g-C₃N₄ Nanocomposites toward As(III) in Aqueous Solution

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Novel Continuous Column Process for As(III) Oxidation from Concentrated Acidic Solutions with Activated Carbon Catalysis

Cited by 13 publications

References 39 publications

As(iii) removal through catalytic oxidation and Fe(iii) precipitation

As(iii) removal through catalytic oxidation and Fe(iii) precipitation

Comparative Study for Flue Dust Stabilization in Cement and Glass Materials: A Stability Assessment of Arsenic

Insights into the Adsorption and Photocatalytic Oxidation Behaviors of Boron-Doped TiO2/g-C3N4 Nanocomposites toward As(III) in Aqueous Solution

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Insights into the Adsorption and Photocatalytic Oxidation Behaviors of Boron-Doped TiO₂/g-C₃N₄ Nanocomposites toward As(III) in Aqueous Solution