Removal of As(III) in a column reactor packed with iron-coated sand and manganese-coated sand

Chang, Yoon-Young; Song, Ki‐Hoon; Yang, Jae‐Kyu

doi:10.1016/j.jhazmat.2007.05.005

Cited by 55 publications

(32 citation statements)

References 17 publications

(21 reference statements)

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“…Figure 7b shows the removal trends for As(III) onto IMCS(7:3) as a function of time. Initial adsorption was fast and efficient compared to previous studies, 22,36,37 around 50% removal was obtained within 60 min, and stabilized at 66% removal after 24 h. The amount of As(III) removed by IMCS(7:3) was 151.5 mg/kg at pH 6.5. This value was smaller than the q e value (322.6 mg/kg) for phosphate using IMCS(7:3) at pH 4.5 (Table 4).…”

Section: Removal Of As(iii) By Ics Mcs and Imcs In A Batchmentioning

confidence: 63%

Removal of Arsenic and Phosphate from Aqueous Solution by Metal (Hydr-)oxide Coated Sand

Huang

Yang

Keller

2014

ACS Sustainable Chem. Eng.

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Arsenic contamination is a major concern in many drinking water supplies around the world. One low-cost approach for removing arsenic and other oxyanions such as phosphate is to use metal (hydro-)oxide coated sands. In this study, solution pH, sand grain size, coating efficiency, and mineral type for iron-coated sand (ICS), manganese-coated sand (MCS), and iron-and manganese-coated sand (IMCS) were evaluated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis were used to investigate the surface properties of the coated layer. The mineral type of ICS prepared at different solution pH was identified as a mixture of FeOOH and Fe 2 O 3 . The mineral type of MCS prepared at pH 4 and 7 was identified as MnO 2 and changed to ramsdellite (γ-MnO 2 , a mixture of α-MnO 2 and β-MnO 2 ) at pH 10. ICS exhibited a greater phosphate removal capacity, and phosphate removal increased with increasing iron oxide on the sand. ICS was also shown to have a greater removal capacity for phosphate than chemical precipitation methods by FeCl 3 , especially below neutral pH. In contrast, IMCS(Fe:Mn = 7:3) was better for removing As(III), which occurs through oxidation to As(V) and adsorption of As(III) and As(V) and can reach >98% removal rate (residual concentration <0.02 mg/L) at neutral pH. IMCS(7:3) is an efficient adsorbent for arsenic, as >50% can be removed within 60 min; 66% adsorption was reached after 24 h. Removal of arsenic and phosphate by these metal (hydro-)oxide coated sand adsorbents followed a pseudo-second-order rate and Langmuir as well as Freundlich adsorption isotherms. Removal under different conditions (e.g., pH, ionic strength) was also evaluated to provide information to optimize the process.

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Section: Removal Of As(iii) By Ics Mcs and Imcs In A Batchmentioning

confidence: 63%

Removal of Arsenic and Phosphate from Aqueous Solution by Metal (Hydr-)oxide Coated Sand

Huang

Yang

Keller

2014

ACS Sustainable Chem. Eng.

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“…Among a variety of technologies (including precipitation coagulation, membrane separation, ion exchange, lime softening and adsorption), adsorption and coagulation are believed to be the cheapest As removal methods (Guo et al 2010). Some recent treatment technologies based on oxidation and adsorption are iron oxidecoated sand (Gupta et al 2005;Nguyen et al 2010), manganese dioxide-coated sand (Chang et al 2008), clay minerals (Jeon et al 2009), and zerovalent iron (Tyrovola et al 2007). Adsorption still remains an attractive and promising technology, because of its simplicity, ease of operation and handling, and sludge-free operation and regeneration capacity.…”

Section: Introductionmentioning

confidence: 99%

Arsenite removal by adsorption onto iron oxide-coated pumice and sepiolite

2014

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The present study describes the removal of arsenite by iron oxide-coated pumice and iron oxide-coated sepiolite. Pumice and sepiolite were coated with iron oxide and used as adsorbents for the removal of arsenite from aqueous solution in batch experiments. Arsenite concentration decreased exponentially with time, and equilibrium was attained in 84 h. The kinetics of the adsorption process was tested for the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The adsorption of arsenite onto iron oxide-coated pumice and iron oxidecoated sepiolite followed the pseudo-second-order model. Freundlich, Dubinin-Radushkevitch, and Temkin isotherm models were applied to the experimental equilibrium data. The adsorption of arsenite fit these isotherm models. The results indicated that the iron oxide-coated pumice and iron oxide sepiolite could be alternative adsorbents for arsenite removal. Among the adsorbents, iron oxide-coated pumice was found to be more effective than iron oxide sepiolite in the removal of arsenite.

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“…Generally, inorganic arsenic has two different oxidation states, that is, trivalent and pentavalent, in natural aqueous systems [8]. The speciation of arsenic highly depends on solution pH.…”

Section: Introductionmentioning

confidence: 99%