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1

Elimination of Hexavalent Chromium Ions in Water Using a Manganese-Coated Pumice Adsorbent

Lestari Puji, Purwiandono Gani, Pramayshela Shike, Siswoyo Eko

Journal of Ecological Engineering

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2024

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Vol. 25, nr 1

229--235

EN

A natural pumice stone stone coated with manganese (Mn) has been prepared and utilized to remove hexavalent chromium (Cr(VI)) ions in water via adsorption process. Prior to the application, the natural pumice was ground, sieved, and immerse in a dilute HCl solution. The coating of Mn on the acid-activated pumice was carried out by soaking the powder in 0.5 M Mn(NO3)2 solution for 72 h. The characterisation of the produced pumice adsorbent was performed with scanning electron microscopy and fourier-transform infrared spectroscopy instruments. The adsorption of Cr(VI) onto Mn-coated pumices was optimum at pH 3. Both the Langmuir and Freundlich isotherm models could be used to describe the adsorption process. The rate of adsorption followed the model for pseudo- second-order kinetics. The maximum adsorption capacity of Mn-coated pumice towards Cr(VI) ions was 1.94 mg/g.

2

Biosorption of Hexavalent Chromium onto Ziziphus lotus Fruits Powder: Kinetics, Equilibrium, and Thermodynamics

El Yakoubi Nosair, El Ansari Zineb Nejjar, Ennami Mounia, El Kbiach Mohammed L’bachir, Bounab Loubna, El Bouzdoudi Brahim

Journal of Ecological Engineering

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2024

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Vol. 25, nr 2

321--332

EN

Ziziphus lotus has been the subject of several researchs because of its nutritional benefits and ecological attributes. The removal of hexavalent chromium Cr(VI) from a solution using powdered Zizphus lotus fruits, for its qualities of being inexpensive as well as environmentally friendly, was investigated. The results obtained showed that at pH = 2, at 30°C, after 600 min of adsorbent/adsorbate contact, with 100 mg/L as initial concentration of Cr(VI) and a biosorbent dosage of 5 g/L, the biosorption of Cr(VI) on Zizphus lotus fruit powder (ZLFP) is at its maximum rate. The sorption process was exothermic (∆H° = –6.69 kJ/mol), and was characterized by a positive entropy values (∆S° = 46.76 J/K mol) suggesting a high affinity of the ZLFP for Cr(VI). Given that the Gibbs free energy (∆G°) is negative and decreases as temperatures increase from 293 to 323 K, the process of biosorption is both feasible and spontaneous. The Temkin model and the Langmuir model both generated excellent fits to the equilibrium data. The maximum monolayer biosorption capacity was 36.11 mg/g. The pseudo second order model was used to fit the kinetic data relating to the adsorption of Cr(VI) on the ZLFP. The FTIR spectral analysis allowed the characterization of the biochemical groups mainly involved in the sorption of Cr(VI) ions on the ZLFP, and which are: N–C, H-O, O–C, H-C, and O=C. The capacity of Ziziphus lotus fruit as an inexpensive, effective, and ecofriendly biosorbent is confirmed through this study.

3

Fate and Management of Pollution of Hexavalent Chromium Cr(VI) and Heavy Metals in the Zarqa River Basin in Jordan

Shammout Maisa'a W., Shatanawi Muhammad, Awwad Akl M.

Journal of Ecological Engineering

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2022

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Vol. 23, nr 2

108--115

EN

This paper focused on the fate of pollution and management of hexavalent chromium Cr(VI) and heavy metals in the Zarqa River Basin in Jordan. The Zarqa River basin was selected in this research because it contains the majority of Jordanian industries, which are the main source of pollutants including Cr(VI) and heavy metals. This will help in assisting water resource management organizations in decision making when coping with pollution. Industries related to sources and impacts of Cr(VI) and heavy metals were identified, and the administration measures were highlighted according to their role in improving water quality. An analysis of water samples along the Zarqa River was conducted between 2016-2019 to evaluate the heavy metals concentrations and compare the results with the Jordanian standards. Findings showed that Cr(VI) was below the allowable limits (<5 μg/l), and the heavy metals were within the allowed limits set forth in the Jordanian Standard. The ranges of water analysis values (μg/L) were; DO 4640–6480, Fe <40–80, Mn 20–128, Co <20–30, Pb 80–190, Zn 70–100, and Cu <80–190, Al 700–730, V <70–100, B <300–351, Si 1100–1800, Ni 30, and Cd <10. These findings indicated that the quality of the Zarqa River would not cause hazardous effects. However, this was not the case few years ago due the current protection measures. At present some industries have been relocated from the Zarqa Basin to an area that does not pose any environmental hazards, while the rest of industries remained in the basin, but they have established an on-site treatment plant for industrial waste under the control of Jordanian government, and the enforcement of the environmental protection law. These measures must be monitored and updated by decision makers in a sustainable manner to prevent any water pollution.

4

A Novel Rotating Fixed Bed Batch Reactor for Hexavalent Chromium Reduction

Sayed Doaa, Alturki Abdulaziz A., Farag Hassan, Khalifa Randa E., Abdel-Aziz Mohamed Helmy

Journal of Ecological Engineering

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2022

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Vol. 23, nr 11

273--280

EN

Hexavalent chromium reduction using iron powder has the advantages of being efficient and capable of degrading pollutants, as well as inexpensive and simple to procure. The performance of a new rotating fixed-bed batch reactor in treating aqueous solutions containing chromium hexavalent ions with iron powder was investigated. Two magnets were covered with iron powder and coupled with an isolated stainless-steel shaft in a new agitator design. Variables such as time, initial hexavalent chromium content, iron powder dose, rotational speed, and pH were investigated in order to discover the optimum chromium removal approach. The analysis of variance (ANOVA) was used to determine the experimental kinetics. Contact time of 21 minutes, initial Cr(VI) concentration of 30 ppm, iron powder dosage of 10 g, rpm of 276 and pH of 3 were determined to be the optimal conditions for removing hexavalent chromium.

5

Sorption of Cr(VI) onto hdtma modified zeolitic tuffs

Sobolewska Paulina, Chojnacka Maria, Kramski Dawid, Warchoł Jolanta

Ecological Chemistry and Engineering. A

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2020

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Vol. 27, nr 1-2

1--9

EN

The removal of Cr(VI) from aqueous solutions was investigated using clinoptilolite and phillipsite-chabazite rich tuffs. These minerals were modified using hexadecyltrimethyl – ammonium bromide (HDTMA-Br) and used for Cr(VI) ions removal. The physicochemical characteristics of zeolitic minerals were revealed by XRD, XRF, BET and FT-IR techniques. The uptake capacities of modified zeolites were compared in batch sorption experiments. To predict the sorption isotherms and to determine the characteristic parameters for process design, three isotherm models the Freundlich, the Langmuir, and the Bilangmuir, were applied to experimental data. The data obtained reveal homogeneous Cr(VI) sorption on one kind of active sites on PC-HDTMA surface and heterogeneous sorption on two kinds of active sites on CL-HDTMA surface.

6

Formation of hexavalent chromium in Cr-containing steelmaking slag

Sato Y., Ijima K., Shibayama A., Inoue R.

Archives of Materials Science and Engineering

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2018

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Vol. 94, nr 1

5--10

EN

Purpose: In present work, the mineral phases in chromium-containing slags were identified, and the formation mechanisms of Cr(VI) in Cr2O3-containing mineral phases were discussed. Design/methodology/approach: In steelmaking slag containing chromium, chromium is mainly present as spinel phases such as MgCr2O4 and (Mg,Fe)Cr2O4. When these Cr(III) oxides are oxidized to Cr(VI) oxide, the Cr(VI) is easily eluted from the slag due to its high solubility in water. Findings: The Cr (VI) adversely affects the human health and the environment. In this study, the influence of cooling rate, quenching temperature and oxidation/reduction condition during cooling on the Cr(VI) amount eluted from synthesized MgCr2O4, (Mg,Fe)Cr2O4 and CaCr2O4 were investigated. Research limitations/implications: The formation of Cr(VI) oxide in MgCr2O4 and CaCr2O4 compounds during heating under air was considered to be indispensable. The amounts of Cr(III) and Cr(VI) dissolved from MgCr2O4 were smaller than those from CaCr2O4. Since the formation of CrO3 in MgCr2O4 started at around 1400 K during cooling, slag should be cooled rapidly from the high temperature above 1400 K, or cooled in inert atmosphere in order to minimize Cr(VI) formation. FeO in (Mg,Fe)Cr2O4 solid solution suppressed Cr(VI), Cr(III) and Mg elution. Originality/value: The development of prevention method of Cr(VI) formation in the slags containing chromium is urgent in order to utilize the slags to land-fill and civil engineering works.

7

Szkodliwe substancje w materiałach włókienniczych - chrom sześciowartościowy

Chylewska K.

Przegląd Włókienniczy - Włókno, Odzież, Skóra

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2016

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nr 11

39--40

EN

The article presents information on updating of the laboratory proper testing method used for determination of hexavalent chromium in textile materials. UV-VIS spectrofotometry was described for the determination of chromium (VI) in extraction solutions.

8

Use of dead and living fungal biomass for removal of hexavalent chromium

Holda A., Mlynarczykowska A.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 2

551--563

EN

The removal of hexavalent chromium from aqueous solution was carried out in batch experiments using dead and living biomass of Aspergillus niger. The effects of the operating parameters such as influent Cr(VI) concentration, influent pH and biomass concentration on the Cr(VI) reduction were investigated. The results indicates that the removal rate of Cr(VI) increased with a decrease in pH or with increase of Cr(VI) and biomass concentrations. For chromium bioaccumulation along with nutrients the process is the most intensive within the first 5 days of mycelium formation. For biosorption, the greatest binding of this metal is achieved within the first 4 days of the process.

9

Temporal variability of sewage sludge heavy metal content from Greek wastewater treatment plants

Spanos T., Ene A., Patronidou C. S., Xatzixristou C.

Ecological Chemistry and Engineering. S

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2016

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Vol. 23, nr 2

271--283

EN

The aim of this study was to evaluate the temporal variations of selected heavy metals level in anaerobic fermented and dewatered sewage sludge. Sewage sludge samples were collected in different seasons and years from three municipal wastewater treatment plants (WWTPs) located in Northern Greece, in Kavala (Kavala and Palio localities) and Drama (Drama locality) Prefectures. An investigation of the potential of sludge utilization in agriculture was performed, based on the comparison of average total heavy metal concentrations and of chromium species (hexavalent, trivalent) concentrations with the allowed values according to the Council Directive 86/278/EEC and Greek national legislation (Joint Cabinet Decision 80568/4225/91) guidelines. In this regard, all the investigated heavy metals (Cd, Cr, Cu, Ni, Pb, Zn, Hg) and chromium species Cr(VI) and Cr(III) have average concentrations (dry matter weight) well below the legislated thresholds for soil application, as following: 2.12 mg kg−1 Cd; 103.7 mg kg−1 Cr; 136.4 mg kg−1 Cu; < 0.2 mg kg−1 Hg; 29.1 mg kg−1 Ni; 62.0 mg kg−1 Pb; 1253.2 mg kg−1 Zn; 1.56 mg kg−1 Cr(VI) and 115.7 mg kg−1 Cr(III). Values of relative standard deviation (RSD) indicate a low or moderate temporal variability for domestic-related metals Zn (10.3-14.7%), Pb (27.9-44.5%) and Cu (33.5-34.2%), and high variability for the metals of mixed origin or predominantly resulted from commercial activities, such as Ni (42.4-50.7%), Cd (44.3-85.5%) and Cr (58.2-102.0%). For some elements the seasonal occurrence pattern is the same for Kavala and Palio sludge, as following: a) Cd and Cr: spring>summer>winter; b) Cu, Ni and Pb: winter>spring>summer. On average, in summer months (dry season) metal concentrations are lower than in spring and winter (wet seasons), with the exception of Zn. For Kavala and Palio the results demonstrate that the increased number of inhabitants (almost doubled) in summer time due to tourism does not influence the metal levels in sludge. Comparing the results obtained for similar spring-summer-winter sequences in 2007 and 2010/11 and for the spring season in 2007, 2008 and 2010, it can be noticed that, in general, the average heavy metal contents show an increasing tendency towards the last year. In all the measurement periods, the Palio sludge had the highest metal contents and Kavala sludge the lowest, leading to the conclusion that the WWTP operating process rather than population has a significant effect upon the heavy metal content of sludge. Cr(VI)/Cr(total) concentration ratios are higher for Kavala sludge in the majority of sampling campaigns, followed by Drama and Palio sludge. The metals which present moderate to strong positive correlation have common origin, which could be a domestic-commercial mixed source.

10

Removal of hexavalent chromium from aqueous solution by adsorption on γ-alumina nanoparticles

Golestanifar H., Haibati B., Amini H., Dehghani M. H., Asadi A.

Environment Protection Engineering

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2015

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Vol. 41, nr 2

133--145

EN

The use of γ-alumina (γ-Al2O3) nanoparticles as adsorbent to remove Cr(VI) from aqueous solution was investigated using batch experiments. Adsorption experiments were carried out for various initial doses of Al2O3, initial concentrations of chromium(VI), contact times and pH. The structure and morphology of the sorbent was characterized by XRD, SEM, and TEM techniques. Results demonstrated that the removal efficiency of chromium(VI) was increased by increasing the contact time, initial concentration, and pH. The results of the study showed that adsorption of chromium by γ-alumina nanoparticles reached equilibrium after 60 min and after that a little change of chromium removal efficiency was observed. Furthermore, kinetics of chromium sorption was well fitted by pseudo-second order kinetic model, and well explained by the Freundlich isotherm (R2 > 0.992). Overall, alumina nanoparticles recognized as an effective sorbent to remove chromium(VI) from aqueous solutions.

11

Photocatalytic reduction of hexavalent chromium in aqueous solutions with zinc oxide nanoparticles and hydrogen peroxide

Assadi A., Dehghani M. H., Rastkari N., Nasseri S., Mahvi A. H.

Environment Protection Engineering

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2012

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Vol. 38, nr 4

5--16

EN

Photocatalytic reduction of Cr(VI) to Cr(III) in aqueous solutions under UV irradiation and ZnO semiconductor catalyst was investigated using potassium dichromate as a model compound. The effects of pH, catalyst dose (0.05-0.15 g/dm3), Cr(VI) initial concentration (0.1-15 mg/dm3) and hydrogen peroxide concentration on photocatalytic reduction of Cr(VI) were investigated. The reduction rate of chromium was more favorable in acidic solution. Hydrogen peroxide was added as a reduction reagent for enhancement of the photoreduction. The process of photoreduction of Cr(VI) approximately followed first-order kinetics. Drinking water samples and wastewater were collected and photocatalytically treated for reduction of Cr(VI).