Design and optimization of a batch sequential contactor for the removal of chromium(VI) from industrial wastewater using sheep wool as a low-cost adsorbent

Ray, Priyasha; Sabri, Muhammad Ashraf; Ibrahim, Taleb H.; Khamis, Mustafa; Jumean, F.H.

doi:10.5004/dwt.2018.22365

Cited by 7 publications

(8 citation statements)

References 16 publications

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“…The following conditions from our previous work on batch sequential reactors [21] were used: Wool dosage = 8.0 g/L, contact time = 25 min, pH = 2.0, T = 25.0 • C, initial Cr(VI) concentration = 100 mg/L, and regeneration using 1.0-m KCl. For the first semi-continuous column trial shown in Figure 2, 100 mg/L Cr(VI) was fed into the adsorption column at pH 2.0.…”

Section: Resultsmentioning

confidence: 99%

“…An increase in solution pH accompanies the reduction that takes place when wastewater is processed, particularly during the 24 h dark period. Adsorption is highly dependent on pH, as results from batch studies indicate [21,23]. The optimum pH of 2.0 has led to ca.…”

Section: Resultsmentioning

confidence: 99%

“…For chromium, previous studies show very high removal efficiencies on wool when compared to other natural adsorbents such as olive cake, sawdust, pine needles, almond shells, cactus leaves, and coal [20]. Removal efficiencies ranging between 80 and 99% for Cr(VI) on wool have been demonstrated in a batch sequential reactor study, with the wool exhibiting no decline in removal efficiency even when regenerated with KCl in repeated cycles [21]. Another study reported up to 99% removal after a long residence time on sheep wool.…”

Section: Introductionmentioning

confidence: 88%

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Scale-Up of Self-Regenerating Semi-Batch Adsorption Cycles through Concurrent Adsorption and Reduction of Cr(VI) on Sheep Wool

et al. 2020

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A previous publication by our group reported that adsorption of Cr(VI) on sheep wool reached 99% when allowed a long residence time, with concurrent reduction to Cr(III). In this study, the process was scaled up by optimizing a pilot plant based on semi-batch adsorption cycles. This yielded Cr(III), which is about 300 times less toxic than Cr(VI), and can be precipitated using lime at high pH. Since the reduction step is slower than the adsorption one, an adsorption column was designed to perform semi-batch operation cycles, whereby the extended “off cycle” allows reduction to take place. Since reduction of Cr(VI) frees active sites on wool, the plant acts in lieu of in situ regeneration, accompanied by additional adsorption of Cr(VI). The results show that 97% of the column efficiency can be recovered within 24 h of “off cycle”. Wastewater from a local electroplating industry was treated by this method with high removal of Cr(VI), reaching the limit permitted by environmental standards. This study also reveals that typical concentrations of heavy metals, present in wastewater produced from electroplating, had no substantial antagonistic interference with Cr(VI) adsorption.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 88%

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Scale-Up of Self-Regenerating Semi-Batch Adsorption Cycles through Concurrent Adsorption and Reduction of Cr(VI) on Sheep Wool

et al. 2020

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“…In previous studies by our group, sheep wool has been found to be efficient in Cr(VI) removal, with subsequent reduction to Cr(III) [31,32]. This study reports on the results of using sheep wool for the removal of ARS from wastewater and the possibility of regenerating the contaminated wool.…”

Section: Introductionmentioning

confidence: 89%

Cyclic Sequential Removal of Alizarin Red S Dye and Cr(VI) Ions Using Wool as a Low-Cost Adsorbent

et al. 2020

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Alizarin red S (ARS) removal from wastewater using sheep wool as adsorbent was investigated. The influence of contact time, pH, adsorbent dosage, initial ARS concentration and temperature was studied. Optimum values were: pH = 2.0, contact time = 90 min, adsorbent dosage = 8.0 g/L. Removal of ARS under these conditions was 93.2%. Adsorption data at 25.0 °C and 90 min contact time were fitted to the Freundlich and Langmuir isotherms. R2 values were 0.9943 and 0.9662, respectively. Raising the temperature to 50.0 °C had no effect on ARS removal. Free wool and wool loaded with ARS were characterized by Fourier Transform Infrared Spectroscopy (FTIR). ARS loaded wool was used as adsorbent for removal of Cr(VI) from industrial wastewater. ARS adsorbed on wool underwent oxidation, accompanied by a simultaneous reduction of Cr(VI) to Cr(III). The results hold promise for wool as adsorbent of organic pollutants from wastewater, in addition to substantial self-regeneration through reduction of toxic Cr(VI) to Cr(III). Sequential batch reactor studies involving three cycles showed no significant decline in removal efficiencies of both chromium and ARS.

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“…That is why adsorption of metal cations is reported in several papers [6][7][8]. However, anion removal is also examined [9][10][11][12]. All the authors applied the adsorbate concentrations under 10 mmol/L probably because the increasing concentration decreases the removal percentage.…”

Section: Introductionmentioning

confidence: 99%

Radiation-modified wool for adsorption of redox metals and potentially for nanoparticles

Porubská

Jomová

Lapčík

et al. 2020

Nanotechnology Reviews

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Electron beam irradiated sheep wool with absorbed radiation doses ranging from 0 to 165 kGy showed good adsorption properties toward copper cations. The Cu(ii) being Lewis acid generated several types of complex salts based on carboxylates or cysteinates with ligands available in keratin. Under these conditions, cross-links were formed between the keratin chains. Experimental data obtained from Cu(ii) adsorption using the concentration of 800–5,000 mg/L were tested for fitting to 10 isotherm models. Various compositions and architectures of the Cu(ii)-complexes were specified to be responsible for different isotherm model fittings. The copper cation showed adherence to Langmuir, Flory–Huggins, and partially Redlich–Peterson models. The latter clearly distinguished the native wool from the modified ones. Another aim is to investigate the conditions for the adsorption of anti-microbial nanoparticles in addition to the redox-active metals on radiation-modified wool taking into account that the diffusion of nanoparticles into the modified wool is governed by electrostatic interactions.

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Design and optimization of a batch sequential contactor for the removal of chromium(VI) from industrial wastewater using sheep wool as a low-cost adsorbent

Cited by 7 publications

References 16 publications

Scale-Up of Self-Regenerating Semi-Batch Adsorption Cycles through Concurrent Adsorption and Reduction of Cr(VI) on Sheep Wool

Scale-Up of Self-Regenerating Semi-Batch Adsorption Cycles through Concurrent Adsorption and Reduction of Cr(VI) on Sheep Wool

Cyclic Sequential Removal of Alizarin Red S Dye and Cr(VI) Ions Using Wool as a Low-Cost Adsorbent

Radiation-modified wool for adsorption of redox metals and potentially for nanoparticles

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