Removal of Cr(<scp>vi</scp>) from wastewater by a two-step method of oxalic acid reduction-modified fly ash adsorption

XiaoLing, Jiang; Fan, Wenqiang; Li, Chun‐Qing; Wang, Yong; Bai, Junbin; Yang, Heng; Liu, Xiaoli

doi:10.1039/c9ra05980f

Cited by 21 publications

(7 citation statements)

References 30 publications

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“…Thus, they concluded that Mn(II) could catalyze the reduction process of Cr(VI) with oxalic acid. Many methods had been developed to promote the reduction process of Cr(VI) with oxalic acid, like catalyzed by TiO 2 , Al 2 O 3 , FeOOH and sunlight 22 – 25 , but these methods were still not easy for the practical application, especially in groundwater remediation. This paper focused on the directional reduction behavior of Cr(VI) with oxalic acid because of the direct Cr(VI) reduction by oxalic acid was thermodynamically spontaneous 26 – 28 , the effect of dosage of oxalic acid, reaction temperature, dosage of sulfuric acid and reaction time on the reduction efficiency of Cr(VI) were investigated.…”

Section: Introductionmentioning

confidence: 99%

Reduction behavior of chromium(VI) with oxalic acid in aqueous solution

Peng

Guo

2020

Sci Rep

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The direct Cr(VI) reduction process by oxalic acid was conducted. The existence of Cr(VI) in the reaction medium was measured by software Visual MINTEQ and the concentration of Cr(VI) was measured by ICP-OES. The results showed that the Cr(VI) was efficiently reduced by oxalic acid at high reaction temperature and high dosage of oxalic acid. The reduced product, Cr(III), was easily generated stable complex compounds (Cr(HC2O4)3) with oxalate, which displayed a negative effect on the reduction process. The high reaction temperature and high acidic medium could destroy the stable structure of a complex compound to release oxalate, and facilitate the reduction of Cr(VI). Generally, the results showed in this paper provided a versatile strategy for Cr(VI) reduction and exhibited a bright application future for real wastewater treatment.

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Section: Introductionmentioning

confidence: 99%

Reduction behavior of chromium(VI) with oxalic acid in aqueous solution

Peng

Guo

2020

Sci Rep

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“…In addition, at the initial time of contact, there is a large number of vacant adsorption sites and also a high concentration gradient of Cr(VI) between the adsorbent and the bulk of the solution. As adsorption equilibrium was reached, the adsorption capacity remained unchanged because of the decrease in number of vacant sites available for adsorption and also a decrease in concentration gradient. , The kinetics data for pseudo-first-order and pseudo-second-order kinetic models are displayed in Table . As shown in Figure b, the pseudo-second-order kinetic model better defined the adsorption of Cr(VI) with R 2 values of 0.9836, 0.9868, and 0.9954 for Cr(VI) initial concentrations of 20, 50, and 75 mg/L, respectively.…”

Section: Results and Discussionmentioning

confidence: 99%

Hyperbranched-Polyethylenimine-Functionalized Coal Fly Ash as an Adsorbent for the Removal of Hexavalent Chromium and Reuse as a Dye Photocatalyst

Sebabi,

Mabuba,

Pillay

et al. 2024

ACS Omega

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Coal fly ash (CFA) has been extensively researched as an adsorbent for heavy metals, but its application is limited by its low adsorption capacity. The modification of CFA with hyperbranched polymers results in improved adsorption capacities. Hyperbranched polyethylenimine (HPEI) is a hyperbranched polymer containing NH 2 groups that can bind with heavy metal ions through complexation or electrostatic interactions. In this study, CFA−HPEI adsorbents with various HPEI loadings (1−5%) were prepared and evaluated for the removal of Cr(VI). The successful incorporation of HPEI onto CFA was confirmed using Fourier transform infrared, elemental analysis, and X-ray photoelectron spectroscopy (XPS). The 3% CFA−HPEI loaded adsorbent resulted in optimum results when the effect of pH and adsorbent dosage was studied. The pseudo-second-order kinetics model best described the adsorption kinetics at an initial concentration of 20 mg/L. The Freundlich adsorption isotherm model best fitted the equilibrium adsorption data with a maximum adsorption capacity of 85.93 mg/g. The Cr-loaded adsorbent was reused as a photocatalyst to degrade methylene blue (MB) in the presence of visible light. The loaded adsorbent degraded 98.9% of MB (5 mg/L) within 180 min and was accompanied by compounds with m/z of 173 and 234, corresponding to the intermediate degradation of Azure A. The XPS analysis confirmed the coexistence of Cr(III) and Cr(VI) on the surface of the adsorbent. In addition, the loaded adsorbent exhibited good stability following MB degradation with no structural changes observed. Thus, CFA−HPEI adsorbents can be utilized as low-cost adsorbents for the remediation of toxic Cr(VI) from water and wastewater. The Cr-loaded CFA−HPEI adsorbent can be effectively reused as a photocatalyst, thus reducing environmental pollution.

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“…The second stage demonstrates that as the concentration gradient driving movement of ions decreases, ammonium ions progressively diffuse into the channels of the BNPP and reach equilibrium. 77,78 The larger k 1d value represents the ratecontrolled intra-particle diffusion process, while the small/ negligible k 2d value indicates that the diffusion rate corresponding to the final equilibrium stage is slow. 78 The larger values of C 2 than C 1 suggest that the diffusion boundary layer during stage 2 became thicker.…”

Section: Elovich Modelmentioning

confidence: 99%

“…77,78 The larger k 1d value represents the ratecontrolled intra-particle diffusion process, while the small/ negligible k 2d value indicates that the diffusion rate corresponding to the final equilibrium stage is slow. 78 The larger values of C 2 than C 1 suggest that the diffusion boundary layer during stage 2 became thicker. 75 The fitting parameters for a two-stage intra-particle diffusion mechanism are consistent with the results showing the possible best fit with pseudo-first-order and pseudo-second-order kinetics and highlight the surface-mediated ammonium ion adsorption process by BNPP.…”

Section: Elovich Modelmentioning

confidence: 99%

Banana Peel Powder as an Effective Multilayer Adsorbent of Ammonium Ions

Singh

Datta

2022

Ind. Eng. Chem. Res.

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The recovery of ammonium ions or ammonia from wastewater using bioadsorbents offers an attractive sustainable route to nitrogen reuse and environmental remediation. In this work, we have studied the ability of banana peel powder (BNPP) for adsorption of ammonium ions. The prepared BNPP was characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. Structural and morphological features of BNPP were connected to the observed NH 4 + adsorption. The adsorption kinetics was found to fulfil pseudo-first-order and pseudo-second-order models while adsorption isotherms were fit adequately by Langmuir and Freundlich models. Accordingly, the adsorption of NH 4 + on BNPP is predominantly controlled by physical adsorption that enables chemisorption in a time-bound manner. The maximum adsorption capacity of BNPP was 34.48 mg/g and is superior to several prominent biomass candidates that have been reported for adsorption of NH 4 + . BNPP was also deployed on artificial urine, and the results suggest that it is an attractive bioadsorbent for harvesting nitrogen from liquid waste.

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Removal of Cr(vi) from wastewater by a two-step method of oxalic acid reduction-modified fly ash adsorption

Abstract: Removal of Cr(vi) from wastewater using a two-step method.

Cited by 21 publications

References 30 publications

Reduction behavior of chromium(VI) with oxalic acid in aqueous solution

Reduction behavior of chromium(VI) with oxalic acid in aqueous solution

Hyperbranched-Polyethylenimine-Functionalized Coal Fly Ash as an Adsorbent for the Removal of Hexavalent Chromium and Reuse as a Dye Photocatalyst

Banana Peel Powder as an Effective Multilayer Adsorbent of Ammonium Ions

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