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1

Czy specjacja pierwiastków w wodzie ma sens? Część l:Formy chemiczne chromu w wodzie

Zembrzuska Joanna, Kamgar Elham, Rychlewski Paweł

Technologia Wody

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2023

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Nr 1 (79)

37-40

PL

Rozwój nauki, świadomości społeczeństwa oraz wyniki prowadzonych badań toksykologicznych coraz wyraźniej wskazują, że w przypadku wielu pierwiastków nie jego całkowita zawartość lecz obecność jego form chemicznych wpływa na rozwój i stan zdrowia organizmów żywych. Z tego względu wydaje się być ważniejszym pozyskać informacje na temat form w jakich występuje od całkowitej jego zawartości. Formami chemicznymi pierwiastków, jakie wykazują aktywność biologiczną i toksyczność wobec organizmów żywych są formy jonowe. W artykule zostało poruszone zagadnienie specjacji i analizy specjacyjnej ze szczególnym zwróceniem uwagi na problem występowania chromu w wodzie do picia oraz w wodach powierzchniowych. Obecnie uregulowania prawne wskazują na monitorowanie całkowitej zawartości tego pierwiastka w wodzie. To podejście nie daje nam poczucia bezpieczeństwa, gdyż chrom ma zróżnicowane właściwości zależne od stopnia jego utlenienia. Chrom(lll) jest zaliczany do mikroelementów niezbędnych do prawidłowego funkcjonowania i rozwoju organizmu, zaś chrom (VI) ma negatywny wpływ na zdrowie człowieka. Przypisuje się mu działanie kancerogenne i mutagenne.

EN

The development of science, public awareness and the results of toxicological research show morę and more apparent that in the case of many elements, not their total content, but the presence of their chemical forms affects the development and health of living organisms. For this reason, it seems more important to obtain information on the forms in which it occurs than its total content. The chemical forms of elements that exhibit biological activity and toxicity to living organisms are ionic forms. The article deals with the issue of speciation and speciation analysis with patticular attention to the problem of the occurrence of chromium in drinking water and surface waters. Currently, legal regulations indicate the monitoring of the total content of this element in water. This approach does not give us a sense of security, because chromium has different properties depending on the degree of its oxidation. Chromium (III) is included among the microelements necessary for the proper functioning and development of the body, while chromium(VI) has a negative impact on human health. It is believed to be carcinogenic and mutagenic.

2

The effect on wear resistance of laser alloying with chromium and titanium of grey iron parts

Paczkowska Marta

Journal of Research and Applications in Agricultural Engineering

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2023

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Vol. 68, nr 2

26--35

EN

The aim of the presented study is to evaluate the influence of laser alloying with chromium and titanium on the surface layer microstructure and abrasive wear resistance of grey iron parts. A coulter flap was chosen as the object of this investigation. To produce the alloyed layer on the area of the flap that is the most exposed to wear, a diode laser was used as the heat source. The investigation demonstrated that laser alloying with chromium and titanium can increase the wear resistance of components working in abrasive conditions. A smaller mass loss after the wear tests in abrasive conditions of soil could be expected. The laser alloyed layer (with a depth of approx. 400 μm) was characterized by a martensite microstructure (mainly), homogenous morphology and fine grains. A fivefold increase in hardness (approximately 1050HV) in comparison to the hardness of the base material and twofold in comparison to the original ledeburitic surface layer of the coulter flap was noted. Some changes after laser alloying in the surface stereometry were observed (a decrease in the roughness parameters is possible). The roughness parameter values after the wear test decreased in the case of the original and alloyed coulter flaps..

3

Chromium Ions Removal by Capacitive Deionization Process: Optimization of the Operating Parameters with Response Surface Methodology

Issa Zainab M., Salman Rasha H.

Journal of Ecological Engineering

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2023

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Vol. 24, nr 1

51--65

EN

An innovative desalination method called electrosorption or capacitive deionization (CDI) has significant benefits for wastewater treatment. This process is performed by using a carbon fiber electrode as a working electrode to remove hexavalent chromium ions from an aqueous solution. The pH, NaCl concentration, and cell voltage were optimized using the Box-Behnken experimental design (BDD) in response surface methodology (RSM) to study the effects and interactions of selected variables. To attain the relationship between the process variables and chromium removal, the experimental data were subjected to an analysis of variance and fitted with a quadratic model. The optimum conditions to remove Cr(VI) ions were: pH of 2, a cell voltage of 4.3V, and NaCl concentration of 1.4 g/L. This study demonstrated that the carbon fiber electrode was very efficient in Cr(VI) ions removal and the BBD methodology was a practical and effective strategy for predicting the results of various experimental conditions during a CDI process for the removal of chromium ions.

4

The influence of selected transition elements on cell metabolism

Terpiłowska Sylwia, Rafińska Katarzyna, Gołębiowski Adrian, Kowalkowski Tomasz, Buszewski Bogusław

Ecological Chemistry and Engineering. S

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2023

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Vol. 30, nr 4

471--488

EN

The elements are present in the environment. Moreover, they are used in pharmacy and the production of new materials used in medical applications. They are often as environmental pollutants. They can accumulate in organisms and induce toxic effects on the cellular level. HepG2, L929 and Caco-2 cell lines were exposed to known concentrations of chromium chloride, iron chloride, nickel chloride, molybdenum trioxide and cobalt chloride (200 or 1000 μ M used alone and in combinations). Concentrations of chromium, iron, nickel, molybdenum and cobalt in the cell lysate and the culture medium were determined by ICP-MS. Moreover, sodium, potassium, calcium and magnesium concentrations were also measured. What is more, cells were observed under light and scanning electron microscope. The dose-dependent increase in the concentration of chromium, iron, nickel, molybdenum and cobalt in all cell lines after incubation with elements was observed. Potassium concentration decreases while sodium calcium and magnesium increase after incubation of cells with of mentioned elements. The incubation of cells with microelements induces cell morphology changes. The presented study shows the crucial role of tested microelements in the induction of cell death as a result of an imbalance of sodium, potassium, calcium and magnesium concentration inside the cell.

5

Characteristics and Adsorption Test of Activated Carbon from Indonesian Bituminous Coal

Kusdarini Esthi, Budianto Agus

Journal of Ecological Engineering

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2022

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Vol. 23, nr 10

129--138

EN

The fast-growing batik industry in Indonesia raises the problem of the waste containing chromium. One method to remove chromium is by the adsorption process using activated carbon. Activated carbon can be made from coal. This commodity is a mining mineral the availability of which is still abundant in Indonesia. This study aimed to obtain: 1) the best concentration of activator and activation temperature in the manufacture of activated carbon; 2) characteristics of activated carbon (moisture content, volatile matter content, ash content, fixed carbon content, iodine number, specific surface area, pore-volume, pore surface area, pore radius, and SEM photos); 3) % activated carbon removal for chromium and maximum adsorption capacity for chromium; 4) Freundlich and Langmuir isotherm adsorption equation of activated carbon to chromium. The manufacture of activated carbon was carried out by a carbonization process followed by a chemical and physical activation processes. The chemical activator was ammonium phosphate with doses of 74.5 g/L, 149 g/L, 223.5 g/L, and 298 g/L. Meanwhile, physical activation was carried out at 848 K, 948 K, 1048 K, and 1148 K. The next step was to test the adsorption capacity of activated carbon on artificial batik waste containing chromium. The results showed that: 1) activator concentration did not significantly affect the characteristics of activated carbon. Meanwhile, the optimal activation temperature is at a temperature of 1048 K and 1148 K, which can produce the activated carbon that meets the requirements of activated carbon of the Indonesian National Standard 06-3730-1995 with the following contents: air content 0.16–0.81%; volatile matter 14.62–19.31%; ash 6.48–9.97%; fixed carbon 70.60–75.79%; iodine number 1243.13–1258.65%; specific surface area 31.930 m2/g; activated carbon pore volume 0.011 cc/g; pore surface area 8.905 m2/g; activated carbon pore radius 30.614; 3) the proportion of activated carbon removal for chromium is 37–53% and the maximum adsorption capacity for chromium is 52 mg/g; 4) the Freundlich equation test resulted in a constant R2 of 0.5126, n 2.4870, KF 8.8818 mg/g, while the Langmuir equation test resulted in a constant R2 of 0.8897, b -0.0075 L/mg, qm -90.0901 mg/g.

6

Active Capping Treatment of Copper and Chromium Contaminated Sediment with Bentonite Kaolin and Sand to Inhibit their Release to the Overlying Water

Aliyu Mohammed Kabir, Abd Karim Ahmad Tarmizi Bn, Chan Chee Ming, Abdulkadir Aeslina, Bin Daud Zawawi, Oyekanmi Adeleke Abdulrahman

Journal of Ecological Engineering

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2022

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Vol. 23, nr 12

264--272

EN

The public concern over sediment contamination brought on by mining operations, excessive use of chemical fertilisers or pesticides, industrial, agricultural, and municipal effluent, is increasing. Dredging is a more expensive treatment option than in situ capping of polluted sediment for immobilising pollutants in sediments on site. In order to stop the release of Cr and Cu from chemically contaminated sediments, this study aimed to evaluate the efficiency of utilising active capping materials such as bentonite (B), kaolin (K), and a 1:1 combination of bentonite and kaolin (BK) as capping materials. In a 90-day laboratory experiment carried out in glass tanks with a 1 cm thickness cover of capped material plus sand spread over the polluted sediment, the efficacy of B, K, and BK in inhibiting trace metal leachability was examined. The findings demonstrated that B and BK decreased the ability of sediments to leach Cr and Cu. The results suggest that BK and B should be considered as a suitable active material for capping treatment of polluted sediment sites because of their high Cu and Cr trapping. According to an analysis of adsorption kinetics, chemisorption was the adsorption process. The outcomes of this study demonstrated the potential for using kaolin, a bentonite-kaolin clay mixture covered with sand, and bentonite as capping materials for the in-situ treatment of Cr and Cu polluted coastal sediments.

7

High Structural Stability and Adsorption Capacity of Zn/Al-Biochar and Cu/Al-Biochar Toward Adsorption of Cr(VI)

Palapa Neza Rahayu, Taher Tarmizi, Siregar Patimah Mega Syah Bahar Nur, Normah, Juleanti Novie, Wijaya Alfan, Badri Arini Fousty, Lesbani Aldes

Journal of Ecological Engineering

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2021

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Vol. 22, nr 4

213--223

EN

Layered double hydroxide (LDH) Zn/Al and Cu/Al was synthesized by using the coprecipitation method under base condition at pH 10 following with formation of composites based on biochar (BC) to form Zn/Al-BC and Cu/ Al-BC. The materials were characterized by XRD, FTIR, BET, and thermal analyses. Furthermore, materials was applied as adsorbent of Cr(VI) on aqueous solution. The performance of composites as adsorbent was evaluated by reusability of adsorbent toward Cr(VI) adsorption process. The results showed that Cu/Al-BC and Zn/Al-BC can reuse the re-adsorption process with the adsorption ability of more than 60%. The adsorption capacity of Cu/ Al-BC and Zn/Al-BC was higher than that of starting materials and up to 384.615 mg/g for Cu/Al-BC and 666.667 mg/g for Zn/Al-BC. Both composites showed the potential adsorbents to remove Cr(VI) from aqueous solution.

8

Chromium Elimination from Contaminated Soil by Electro-Kinetic Remediation, Using Garlic Peels Powder

Hawal Laith Hamdan, Al-Sulttani Ali Omran, Kariem Nagam Obaid

Journal of Ecological Engineering

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2021

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Vol. 22, nr 7

252--259

EN

In this paper, an electro-kinetic technique was applied to remove chromium from contaminated soil. This technique is appropriate for the soils with low permeability. Various experiments were carried out under different operating conditions, including various purging solutions. Garlic peels powder (GPP) was used in this study as a cheap adsorbent substance to avert the flow of reverse osmosis, which may affect the removal percentage. The results proved that the removal percentage increased as the pH of the purging solutions decreased. The first three experiments were performed with purging solution at pH of 4, 6, and 8 respectively. The highest removal percentage was 66.3% at pH of 4 compared to the other two experiments at pH of 6 and 8, where the removal percentages were 53.3% and 49.7%, respectively. This paper showed that the percentage of chromium removal decreased along with the voltage. The removal percentage at 1.5 V/cm was 66.3%, while at 1 V/cm was 61%. Garlic peels powder (GPP) is considered as an effective adsorbent material to avert the reverse osmosis flow. Therefore, the use of this material in this study will give a new impression on the application of these products as an absorbent medium.

9

Badanie wpływu czasu składowania hałd szlamu z mokrego oczyszczania spalin z pieców hutniczych, na zawartość wybranych pierwiastków metali ciężkich

Czekaj Karolina, Klaper Natalia, Kozieł Tomasz

Analit

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2021

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Nr 10

3--12

PL

W niniejszej pracy dokonano analizy wpływu czasu składowania hałd na zawartość wybranych pierwiastków metali ciężkich. Badanym materiałem były dwie hałdy szlamów i osadów pofiltracyjnych z oczyszczania gazów odlotowych, które różniły się czasem składowania. Analizowano je pod kątem wilgotności oraz zawartości cynku, manganu i chromu wykorzystując metodę absorpcyjnej spektroskopii atomowej. Hałda "Dąbrowa Stara", która pochodzi z przełomu roku 2020/2021 wykazała wilgotność na poziomie 39%. Natomiast hałda "Dąbrowa Nowa" została dostarczona we wrześniu 2021 r. i charakteryzowała się wilgotnością 47%. Otrzymane zawartości wody w próbkach zgadzają się z przedziałem otrzymanym przez firmę dla tego rodzaju surowca (30-50%). Badanie zawartości metali ciężkich wykazało największe stężenie cynku ze wszystkich oznaczanych pierwiastków, wyniosło ono dla próbki „Dąbrowa Stara” 17119 [μg/g], a dla próbki „Dąbrowa Nowa” 20385 [μg/g]. Najmniejszą ilość w badanych materiałach stanowił chrom, którego zawartość była nieznaczna. Dla próbki „Dąbrowa Stara” wartość oznaczonego stężenia wyniosła 127 [μg/g], a dla „Dąbrowa Nowa” 150 [μg/g]. Wykazano, że hałda "Dąbrowa Nowa" jest bardziej bogata w cynk, chrom i mangan niż hałda "Dąbrowa Stara". Różnice w zawartościach wykrywanych składników mogły być efektem wymywania ich np. poprzez opady deszczu co było spowodowane różnym czasem składowania obu hałd.

EN

In this publication, the effect of heap storage time on the content of the selected heavy metals was analysed. Two heaps of sludges and filter sludges from waste gas treatment, which differed in storage time, constituted the studied material. They were analyzed for moisture content and zinc, manganese and chromium concentrations using atomic absorption spectroscopy. „Dąbrowa Stara” heap, which dates back to the turn of 2020/2021, showed moisture content of 39%. The „Dąbrowa Nowa” heap, on the other hand, was delivered in September 2021 and had a moisture content of 47%. The obtained water contents in the samples agreed with the range obtained by the company for this type of raw material (30- 50%). The analysis of heavy metal contents showed the highest concentration of zinc of all determined elements, which was 17119 [μg/g] for the sample "Dąbrowa Stara" and 20385 [μg/g] for the sample "Dąbrowa Nowa". Chromium was the least abundant in the studied materials and its content was insignificant. For the sample "Dąbrowa Stara" the value of determined concentration was 127 [μg/g], and for "Dąbrowa Nowa" 150 [μg/g]. It was shown that the „Dąbrowa Nowa” is richer in zinc, chromium and manganese than the „Dąbrowa Stara”. The differences in the contents of the detected components could be the effect of their leaching e.g. by rainfall, which was caused by the different time of storage of the two heaps.

10

Związki kompleksowe chromu(III), wanadu(IV) i kobaltu(II) jako nowe prekatalizatory polimeryzacji olefin

Drzeżdżon Joanna

Wiadomości Chemiczne

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2020

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[Z] 74, 5-6

423--437

EN

The olefin polymerization catalysts constitute a large group of various compounds. Metallocene complexes are the largest part of this group. However, due to the instability at industrial plastics temperatures and the decomposition of complexes after MAO (or MMAO) activation, they have been partly replaced by non-metallocene compounds. This article concerns the studies on new non- metallocene precatalysts for the olefin polymerization and oligomerization. The report focuses on the structure and the catalytic activities of the complexes of chromium(III), vanadium(IV) and cobalt(II) with the following ligands: dipicolinate, 2-pyridinecarboxylate, oxalate, oxydiacetate, iminodiacetate, 2,2’- bipyridine, 4,4’-dimethoxy-2,2’-bipyridine, 1,10-phenantroline. These complex compounds are highly active precatalysts for olefin polymerization and oligomerization. The complexes: [Cr(dipic)2][Cr(bipy)(dipic)H20] 2H20 and [Cr(dipic) 2]Hdmbipy 2.5H20 deserve special attention because they are new type of the precatalysts i.e. organic salt type complexes composed both of organic cations and anions. These compounds are not only interesting because of their structure but also because of their high catalytic activity.

11

Selective solvent extraction of some heavy metal ions from aqueous solutions by octafunctionalized resorcin[4]arenes

Kończyk Joanna, Dlugosz Jan

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 2

271--285

EN

This paper presents the results of the study on the extraction capacity of 1,8,15,22-tetra(1- heptyl)resorcin[4]arene and its octasubstituted derivatives containing thiophosphoryl, ester and amide groups in the presence of Pb(II), Zn(II), Cd(II) and Cr(III) in solvent extraction process. Effects of the structure and concentration of the resorcinarene extractant and the composition of the aqueous phase as well as its acidity on the efficiency and selectivity of removal of the examined metal ions from model aqueous solutions were determined. The 1:1 stoichiometry for complexes formed between Pb(II) and Cr(III) and the octasubstituted resorcin[4]arenes was determined by classical slope analysis and loading test.

12

Effective Removal of Iron (II) from Aqueous Solution by Adsorption using Zn/Cr Layered Double Hydroxides Intercalated with Keggin Ion

Oktriyanti Melantina, Palapa Neza Rahayu, Mohadi Risfidian, Lesbani Aldes

Journal of Ecological Engineering

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2020

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Vol. 21, nr 5

63--71

EN

Zn/Cr and Zn/Cr layered double hydroxides (LDHs) intercalated with Keggin ion [α-SiW12O40]4-were successfully synthesized at room temperature and pH value of 10. The synthesized materials were characterized by means of the XRD, BET, and FT-IR analyses and used as an adsorbent iron(II). The adsorption process was investigated by studying pH, the kinetics, and thermodynamic properties of the adsorption process. The results showed the interlayer Zn/Cr LDHs was 7.53 Å and increase to 10.26 Å on Zn/Cr LDHs intercalated with Keggin ion [α-SiW12O40]4-. The BET analysis showed that the pore volume of both materials increased from 0.063 cm3 g-1 to 0.163 cm3 g-1. The pH point zero charge measurement for the Zn/Cr LDHs material was 10 while LDHs Zn/Cr intercalated with Keggin ion [α-SiW12O40]4- was 8. Zn/Cr LDHs intercalated with Keggin ion [α-SiW12O40]4- has higher adsorption capacity than Zn/Cr LDHs without intercalation. Desorption of iron (III) was successfully conducted using HCl as reagent showing the involvement of ion exchange in the adsorption.

13

Combined Adsorption of the Copper and Chromium Cations by Clinoptilolite of the Sokyrnytsya Deposit

Sabadash Vira, Gumnitsky Jaroslaw, Lyuta Oksana

Journal of Ecological Engineering

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2020

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Vol. 21, nr 5

42--46

EN

In the paper, the assessment of the impact of heavy metals on water objects, namely copper and chromium was performed, and the methods for their neutralization were defined. A scientifically grounded method for the selection of natural zeolite for the purification of wastewater from heavy metals has been developed, provided that they are jointly present. The physicochemical characteristics of two metals related to heavy metals are presented: copper and chromium. The methods for determining the sorption capacity of natural zeolite for copper and chromium compounds, as well as the methods of analytical control of the wastewater components were presented. The results of the experimental studies on the combined adsorption of copper and chromium cations by natural zeolite under static conditions were presented. The changes in the chemical composition of the zeolite surface as a result of heavy metal sorption have been investigated. The influence of the nature of the ions and the pH of the adsorption medium on the selectivity of the heavy metal ions extraction by zeolite was analyzed. A diagram of the composition of the solution, depending on the pH values, was constructed. The pH of the beginning of deposition of the corresponding heavy metal hydroxides on the zeolite surface was calculated. While analyzing the results of experimental studies on the combined adsorption of copper and chromium ions, it was found that the copper ions are significantly better adsorbed by the sorbent than the chromium ions. Despite the same concentration of the chromium and copper ions in solution, Cu2+ is extracted selectively. As can be seen from the results of experimental studies, the concentration of copper on the surface of the sorbent increases from 0.628% mass at a concentration of 0.01 g/dm3 to 47.380% mass at a concentration of 1 g/dm3. The studies on the static activity of clinoptilolite for the copper and chromium ions indicate a simultaneous mechanism of the process, which involves ion exchange and physical adsorption. The concentration of the chromium ions on the surface of the sorbent after adsorption depends on the increase of the concentration of Cr3+ in the original solution to a lesser extent. The results of the studies on the combined adsorption of the Cu2+ and Cr3+ ions indicate the possibility of their chromatographic separation, which makes their further use possible.

14

Chromium Accumulation by Avicennia alba Growing at Ecotourism Mangrove Forest in Surabaya, Indonesia

Titah Harmin Sulistiyaning, Pratikno dan Herman

Journal of Ecological Engineering

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2020

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Vol. 21, nr 2

222--227

EN

The Ecotourism Mangrove Forest at Wonorejo in East Coast Surabaya area is one of large mangrove forests inside in the metropolitan city in Indonesia. There are many ecological values of the mangrove forest in most tropical countries such as sea fisheries, place of sea and coastal animals, sea and brackish water quality protecting the endangered mangrove coastlines and development of human life. The role of mangrove in increasing the sea and brackish water quality can be shown through many processes such as cycling of nutrients, particulate matter and some pollutants in water and sediment around the mangrove plants. One of the inorganic pollutants that can be removed by mangrove are heavy metals, such as chromium (Cr). The Wonorejo River is one of the rivers that receive the disposal of wastewater in Surabaya East Coast area. Large quantitites of wastewater from industries and households were released to this river. The concentration of Cr at the Wonorejo Estuary reached 0.0325 mg/L and 2.7761 mg/L in sediments. The purpose of this research was to determine the potency of Cr accumulation by Avicennia alba that was grown for ten years at Wonorejo Ecotourism Mangrove Forest. The sampling activities were conducted using a transect quadrat sampling method with a 10x10 m dimension. The sediment and mangrove root samples were extracted before being analysed using an atomic absorption spectrophotometer (AAS). The results showed that the Cr accumulation by roots of A. alba reached 25.4 ± 1.6 to 55.3 ± 1.1. The BCF value in A. alba were 0.32 ± 0.01 to 0.83 ± 0.5 with the concentration Cr in sediment were 60 ± 1.4 to 79.3 ± 1.1. A. alba showed potential as a moderate accumulator for Cr. In conclusion, A. alba can be considered for use in phyto-monitoring and phytoremediation of Cr in coastal areas.

15

Oznaczanie form specjacyjnych chromu w próbkach wód głębinowych metodą katalityczno-adsorpcyjnej woltamperometrii stripingowej

Ciężkowska Magda, Rudy Aneta

Analit

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2020

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Nr 9

19--26

PL

W pracy opisano metodę oraz wyniki oznaczenia dwóch form specjacyjnych chromu w wodach, pochodzących z sześciu artezyjskich studni głębinowych, znajdujących się na terenie miasta Krakowa. Powodem celowości oznaczenia chromu w wodach głębinowych, przeznaczonych do spożycia są silnie zróżnicowane właściwości jonów chromu (III) i chromu (VI) szczególnie jeżeli chodzi o ich wpływ na organizm ludzki. Chrom(III) jest zaliczany do mikroelementów niezbędnych do prawidłowego funkcjonowania i rozwoju organizmu. Chrom (Vl) ma negatywny wpływ, gdyż przypisuje się mu działanie mutagenne, a nawet kancerogenne. Jako metodę specjacyjnego oznaczania obu form jonów chromu wybrano katalityczno-adsorpcyjną woltamperometrię stripingową (CAdSV) połączoną z rejestracją katodowych woltamogramów techniką impulsej woltamperometrii różnicowej (DPV). Spośród wielu znanych metod instrumentalnych metoda DP CAdSV cechuje się największą precyzją, dokładnością i czułością pomiaru. Co szczególnie ważne próbki wody przeznaczone do analizy woltamperometryczej nie wymagają wstępnego przygotowania, w efekcie metoda spełnia rygorystyczne wymagania zielonej chemii analitycznej (ang. Green Analytical Chemistry).

EN

The publication describes the method and results of determination of chromium speciation forms in deep-water samples. The samples came from six deep wells located in the city of Cracow. The reason for the determination of chromium in water is the different properties of Cr(III) and Cr(Vl) ions, especially their effect on the human body. Chromium (III) is essential for the proper functioning and development of the organism. Chromium (VI) has a negative effect because it acts mutagenically and even carcinogenically. The catalytic adsorptive stripping voltammetry (CAdSV) has been chosen as the method of chromium quantitative determination. Differential pulse voltammetry (DPV) technique was used to record cathodic voltammograms. Among the many instrumental methods, the DP CAdSV is characterized by the highest precision, accuracy, and sensitivity of measurements. It is important that the water samples intended for this analysis do not require any preliminary preparation, so the method meets the requirements of Green Analytical Chemistry.

16

Badanie akumulacji wybranych metali w wodzie z różnych ujęć rzeki Wisły

Matysiak Sabina, Słowik Martyna

Analit

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2020

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Nr 9

41--52

PL

Celem niniejszej pracy było zbadanie stężeń różnych ujęciach rzeki. Oznaczenie stężenia manganu i żelaza wykonano wykorzystując metodę absorpcyjnej spektrometrii atomowej (ASA), a stężenie chromu oznaczono przy użyciu metody impulsowej woltamperometrii różnicowej adsorpcyjnej strippingowej (DP-AdSV) w układzie z elektrodą rtęciową jako elektrodą pracującą. Przeprowadzone badania nie wykazały przekroczenia dopuszczalnych stężeń oznaczanych pierwiastków w wodzie. Szczególną uwagę zwrócono na próbkę wody pobraną tuż za miejscem zrzutu nieoczyszczonych ścieków komunalnych do rzeki po awarii oczyszczalni ścieków „Czajka" w Warszawie, jednak nie wykazała ona odstępstw od normy. Uzyskane wyniki porównano z obowiązującymi normami.

EN

The aim of this work was to determine the chosen metals concentration in water derived from Vistula River in Cracow and Warsaw. Three water samples were collected from different parts of the river. Atomic Absorption Spectrometry (AAS) was used to determine the concentrations of manganese and iron, whereas measurements of chromium concentration were carried out using differential voltammetry in the system with the CGMDE electrode as a working electrode. The conducted research did not show that the permissible concentrations of the elements in water were exceeded. Particular attention was paid to the water sample collected just after the discharge site of untreated municipal sewage to the Vistula river after the failure of the "Czajka" sewage treatment plant in Warsaw, but it did not show any deviation from the norm. The obtained results were compared with the applicable standards.

17

Teoretyczne badania katalizatora CrOx/SiO2

Gierada Maciej, Handzlik Jarosław

Wiadomości Chemiczne

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2019

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[Z] 73, 1-2

97--114

EN

The Phillips CrOx/SiO2 catalyst is one of the most commonly used system in the industrial production of high-density polyethylene (HDPE). This system has been extensively studied since decades, mainly by means of experimental techniques. However, the progress in determination of the nature of the chromium sites and understanding of surface reactions occurring has been rather not satisfying and many issues are still under debate. Among others, structure of the chromium oxide species on the surface of the reduced catalyst is not well defined. Likewise, the mechanism of the catalyst reduction and active site formation is not well established. Many experimental studies indicate that chromium exists on the surface of amorphous silica in a wide variety of different forms including monomeric, dimeric and polymeric species. Different oxidation states are also possible, as Cr(VI), Cr(V), Cr(IV), Cr(III), Cr(II) were detected. There is a general consensuses that Cr(VI) dominates at the surface after the catalyst preparation, while Cr(II) and Cr(III) are mainly formed after contact with a reducing agent, like ethylene or CO. Nevertheless, the detailed structure of these oxide species, as well as the active sites, is still strongly discussed. As experimental studies do not show a clear picture about the nature of silica-supported chromium catalyst, very helpful can be computational approach which can provide complementary information, not accessible by experimental techniques. In this short review we summarize the recent progress in the field of the Phillips (CrOx/SiO2) catalyst focusing on the most relevant theoretical papers that were published within last couple of years. We also highlight the need of applying advanced models if realistic theoretical description of the CrOx/SiO2 system is to be achieved. Additionally, different computational approaches in modeling of heterogenous catalysts are discussed.

18

Removal of Hexavalent Chromium from Aqueous Solution by the Pod of Acacia gerrardii

Abdulaziz Mohammed A., Bakri Abdulrahman A., Al-Zahrani Saleh A., Al-Zahrani Majed S., Al-Lehebi Abdulrahman N., Banjar Fadil M., Nabag Mohand I.

Polish Journal of Chemical Technology

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2019

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Vol. 21, nr 2

14--19

EN

This study aims at investigating the potential of Acacia gerrardii pod for the removal of Cr(VI) in batch system. Effect of solution pH, biosorbent dosage, initial concentration of Cr(VI), contact time on the removal process was examined. Complete removal of hexavalent chromium was achieved at pH values 1.0 and 2.0 whereas maximum removal of total chromium was obtained at pH of 3.0. The study showed that the biosorption and bioreduction mechanisms were involved in the removal process. The time required for complete removal of Cr(VI) using the pod of Acacia gerrardii was shortened with an increase in biomaterial dosage and decrease in Cr(VI) concentration. Kinetic data was well described using Park kinetic model. Freundlich isotherm model adequately fitted the equilibrium data indication multilayer adsorption of total chromium on the surface of biomaterial. The pod of Acacia gerrardii could be used efficiently for the removal of hexavalent chromium from aqueous solutions.

19

Reduction of Total Chromium Levels from Raw Tannery Wastewater via Electrocoagulation using Response Surface Methodology

Aguilar-Ascón Edwar, Marrufo-Saldaña Liliana, Neyra-Ascón Walter

Journal of Ecological Engineering

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2019

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Vol. 20, nr 11

217--224

EN

This study focused on reducing total chromium levels in raw wastewater from the leather tanning industry via electrocoagulation to comply with maximum permissible limits (MPL) and to determine the effects of main process parameters. An electrocoagulation reactor was built using aluminum electrodes as an anode and cathode. Then, the response surface methodology was applied using a 3k factorial design considering three factors, namely current intensity, treatment time, and pH. The total chromium removal percentage was considered as a response variable. 99% of the total chromium found in wastewater could be removed after 14-min treatment at 2-A current intensity and pH 5.5. Similar amount of chromium was removed at pH of 8.5 and 7. Statistical analysis performed at a confidence level of p < 0.05 revealed that all three factors influenced electrocoagulation. Total chromium could be efficiently removed from raw wastewater at a current intensity of 2.9 A, a pH of 8.4, and a treatment time of 21 min, suggesting that electrocoagulation using aluminum electrodes is an efficient method for total chromium removal. Thus, this process must be considered as a solution to the problems caused by the leather tanning industry and for better compliance with the MPL established in the Peruvian environmental standards.

20

Biosorption of Heavy Metals from Synthetic Wastewater by Using Macro Algae Collected from Iraqi Marshlands

Bahaa Shaymaa, Al-Baldawi Israa Abdulwahab, Yaseen Safaa Rasheed, Abdullah Siti Rozaimah Sheikh

Journal of Ecological Engineering

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2019

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Vol. 20, nr 11

18--22

EN

Biosorption is fast, effective and low cost process. It takes place in a wide range of temperature and it can be used for almost all types of heavy metals. The aim of this study was to investigate the ability of locally collected green macro algae to remove copper, chromium and cadmium from synthetic wastewater. The fresh algae were converted into dry powder as biosorbent. In the investigations, 1 g of macro algae powder was exposed to synthetic waste water contaminated with 10 mg/L concentration of copper, chromium and cadmium in separate exposure for 2 hours. The best removal efficiency for copper, chromium and cadmium were 70%, 80% and 85%, respectively, from the initial concentration of 10 mg/L. While macro algae are abundantly available in marshlands of south Iraq, it can be preferably utilized as biosorbent to remove heavy metals from the industrial wastewater.