A process monitoring/controlling system for the treatment of wastewater containing chromium(VI)

Zhou, Xiaojing; Korenaga, Takashi; Takahashi, Terüo; Moriwake, Tosio; Shinoda, Sumió

doi:10.1016/0043-1354(93)90069-t

Cited by 119 publications

(42 citation statements)

References 7 publications

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“…The data reveal no dicsernible effect of particle size (original vs. powdered wool) on Cr(VI) removal efficiency. Furthermore, there is no apparent distinction between Cr(VI) and total chromium concentrations, indicating that Cr(VI) is virtually the only species present The maximum removal efficiency is ca 88%, in conformity with our previous findings [5] [6]. Figure 2 shows the effect of contact time on Cr(VI) removal in the long term mode (0 -165 h).…”

Section: Methodssupporting

confidence: 70%

Concurrent Removal and Reduction of Cr(VI) by Wool: Short and Long Term Equilibration Studies

Jumean

Khamis²,

Sara³

et al. 2015

AJAC

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Hexavalent chromium removal from wastewater using sheep wool was investigated at several equilibration periods. The influence of contact time, pH, adsorbent dosage and initial concentration was investigated. Adsorption isotherms for long and short periods were fitted to the Langmuir and Freundlich isotherms. For short contact times, the Langmuir adsorption isotherm was obeyed with no detectable change in the oxidation state but removal percentages did not exceed 90%. Long contact times resulted in more than 99% removal of Cr(VI). A 2-step mechanism for the removal is proposed. Free wool and wool loaded with Cr(VI) were characterized by FTIR and SEM.

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Section: Methodssupporting

confidence: 70%

Concurrent Removal and Reduction of Cr(VI) by Wool: Short and Long Term Equilibration Studies

Jumean

Khamis²,

Sara³

et al. 2015

AJAC

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“…2 4 SO  A number of treatment methods for removal of metal ions from aqueous solutions have been reported mainly reduction, ion exchange, solvent extraction, reverse osmosis, chemical precipitation and adsorption [10]. In the reduction followed by chemical precipitation method [11], Cr(VI) is reduced to Cr(III) first, then lime is added to precipitate chromium as hydroxide.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Studies on Hexavalent Chromium Reduction

Basu¹,

Saha²

2010

AJAC

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Cr(VI) is a known human carcinogen. It is a wide spread environmental contaminant as it is extensively used in different industry. The kinetic study of reduction of Cr(VI) by a known organic substance, 1-butanol in micellar media have been studied spectrophotometrically. The reduction of Cr(VI) to Cr(III) occurs in a microheterogeneous system in cell cytoplasm. As micelles are considered to mimic the cellular membranes, the reduction process occurring in the micellar system is considered as a model to obtain insight in to the reduction process prevailing in body systems. Micellar media is also a probe to establish the mechanistic paths of reduction of Cr(VI) to Cr(III) and the effects of some electrolytes common to a biological systems are studied to establish the proposed reaction mechanism strongly. The overall reaction follows a first order dependency on substrate and hexavalent chromium and second order dependency on hydrogen ion. Suitable surfactant & suitable concentration of electrolyte enhance the rate of the reaction.

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“…There are several tested methods for the removal of chromium from aquatic environments, including precipitation (Zhou et al 1993), chemical reduction (Seaman et al 1999), ion exchange (Petruzzelli et al 1995), electrochemical precipitation (Kongsricharoern and Polprasert 1996), membrane separation (Kozlowski and Walkowiak 2002), adsorption (Srivastava et al 1997), biosorption (Aravindhan et al 2004), and photocatalytic reduction (Testa et al 2004). Most of these techniques have drawbacks such as high costs and/or the incomplete removal of toxic metals (Demirbas et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Alkali-treated Carbonized Rice Husk for the Removal of Aqueous Cr(VI)

et al. 2016

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Rice husk was chemically modified for the preparation of activated carbon. Rice husk was treated with nitric acid and carbonized at 700 C. After carbonization, the resulting rice husk char was treated with NaOH at room temperature. The 5 M NaOH-treated rice husk had the highest surface area (750 m 2 /g). Proximate analysis of activated carbon confirmed that NaOH treatment removed silica completely. Temperature programmed decomposition (TPD) graphs showed that the total gas contents (CO and CO2) liberated by CRH and H2O-treated CRH and CRH5M were 2l5 μmol/g, 390 μmol/g, and 970 μmol/g, respectively. The adsorption studies of the activated carbon during Cr(VI) removal from the aqueous medium indicated that CRH5M showed the highest rate of adsorption. The effect of adsorbent dosage, Cr(VI) concentration, pH, and temperature were studied to determine the best removal efficiency. With a decrease in pH from 4.4 to 2, the adsorption capacity increased from 3 mg/g to 25.2 mg/g. The adsorption of Cr(VI) followed pseudo-second-order behaviour. The changes in Gibbs free energy, enthalpy, and entropy affected by thermodynamic parameters were found to be negative, which confirmed that the adsorption of Cr(VI) on CRH5M is spontaneous, exothermic, and favours low temperatures.

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A process monitoring/controlling system for the treatment of wastewater containing chromium(VI)

Cited by 119 publications

References 7 publications

Concurrent Removal and Reduction of Cr(VI) by Wool: Short and Long Term Equilibration Studies

Concurrent Removal and Reduction of Cr(VI) by Wool: Short and Long Term Equilibration Studies

Kinetic Studies on Hexavalent Chromium Reduction

Alkali-treated Carbonized Rice Husk for the Removal of Aqueous Cr(VI)

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