Continuous treatment of highly concentrated tannery wastewater using novel porous composite beads: Central composite design optimization study.

This present study depicts the successful employment of fixed-bed column for total chromium removal from tannery wastewater in dynamic mode using sodium alginate-powdered marble beads (SA-Marble) as adsorbent. The SA-Marble composite beads prepared were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and Brunauer, Emmett and Teller (BET) method. The adsorption process performance of this bio-sorbent was examined in batches and columns for real effluent (tannery wastewater). After 90 min, the total chromium removal efficiency could be kept above 90% in the batch experiment. The adsorption kinetics fit better with the pseudo-second-order model, indicating the chemisorption process and the adsorption capacity of about 67.74 mg g-1 at 293 K (C0 = 7100 mg L-1) was obtained. Additionally, dynamic experiments indicate that the total chromium removal efficiency could be maintained above 90% after 120 min at 293 K and 60 min at 318 and 333 K; it's an endothermic but rapid process. The effects of two adsorption variables (Temperature and time) were investigated using central composite design (CCD), which is a subset of response surface methodology (total Cr, COD, sulfate, and total phosphorus percentage removal). This work paves a new avenue for synthesizing SA-Marble composite beads and provides an adsorption efficiency of total chromium removal from tannery wastewater.

Chromium Recovery from Chromium-Loaded Cupressus lusitanica Bark in Two-Stage Desorption Processes.

Hexavalent chromium (Cr(VI)) contamination poses serious health and environmental risks. Chromium biosorption has been employed as an effective means of eradicating Cr(VI) contamination. However, research on chromium desorption from chromium-loaded biosorbents is scarce despite its importance in facilitating industrial-scale chromium biosorption. In this study, single- and two-stage chromium desorption from chromium-loaded Cupressus lusitanica bark (CLB) was conducted. Thirty eluent solutions were evaluated first; the highest single-stage chromium desorption efficiencies were achieved when eluent solutions of 0.5 M NaOH, 0.5 M H2SO4, and 0.5 M H2C2O4 were used. Subsequently, two-stage kinetic studies of chromium desorption were performed. The results revealed that using 0.5 M NaOH solution in the first stage and 0.5 M H2C2O4 in the second stage enabled the recovery of almost all the chromium initially bound to CLB (desorption efficiency = 95.9-96.1%) within long (168 h) and short (3 h) desorption periods at each stage. This study clearly demonstrated that the oxidation state of the recovered chromium depends on the chemical nature and concentration of the eluent solution. The results suggest the possible regeneration of chromium-loaded CLB for its subsequent use in other biosorption/desorption cycles.

Indirect Competitive ELISA for the Determination of Total Chromium Content in Food, Feed and Environmental Samples.

Background: This study aimed to prepare monoclonal antibodies (mAbs) with high immunoreactivity, sensitivity, and specificity for the chelate (Cr(III)-EDTA) of trivalent chromium ion (Cr(III)) and ethylenediamine tetraacetic acid (EDTA). Further, the study established an indirect competitive enzyme-linked immunosorbent assay (icELISA) for detecting the total chromium content in food, feed, and environmental samples. Methods: Hapten Cr(III)-iEDTA was synthesized by chelating Cr(III) with isothiocyanatebenzyl-EDTA (iEDTA). Immunogen Cr(III)-iEDTA-BSA formed by chelating Cr(III)-iEDTA with bovine serum albumin (BSA), and coating antigen Cr(III)-iEDTA-OVA formed by chelating Cr(III)-iEDTA with ovalbumin (OVA) were prepared using the isothiocyanate method and identified by ultraviolet spectra (UV) and inductively coupled plasma optical emission spectrometry (ICP-OES). Balb/c mice were immunized with the Cr(III)-iEDTA-BSA, and the anti Cr(III)-EDTA mAb cell lines were screened by cell fusion. The Cr(III)-EDTA mAbs were prepared by induced ascites in vivo, and their immunological characteristics were assessed. Results: The immunogen Cr(III)-iEDTA-BSA was successfully synthesized, and the molecular binding ratio of Cr(III) to BSA was 15.48:1. Three hybridoma cell lines 2A3, 2A11, and 3D9 were screened, among which 2A3 was the best cell line. The 2A3 secreted antibody was stable after six passages, the affinity constant (Ka) was 2.69 × 109 L/mol, its 50% inhibition concentration (IC50) of Cr(III)-EDTA was 8.64 µg/L, and it had no cross-reactivity (CR%) with other heavy metal ion chelates except for a slight CR with Fe(III)-EDTA (1.12%). An icELISA detection method for Cr(III)-EDTA was established, with a limit of detection (LOD) of 1.0 µg/L and a working range of 1.13 to 66.30 µg/L. The average spiked recovery intra-assay rates were 90% to 109.5%, while the average recovery inter-assay rates were 90.4% to 97.2%. The intra-and inter-assay coefficient of variations (CVs) were 11.5% to 12.6% and 11.1% to 12.7%, respectively. The preliminary application of the icELISA and the comparison with ICP-OES showed that the coincidence rate of the two methods was 100%, and the correlation coefficient was 0.987. Conclusions: The study successfully established an icELISA method that meets the requirements for detecting the Cr(III)-EDTA chelate content in food, feed, and environmental samples, based on Cr(III)-EDTA mAb, and carried out its preliminary practical application.

The Comprehensive Toxicological Assessment of Total Chromium Impurities in Traditional Herbal Medicinal Product with Thymi herba (Thymus vulgaris L. and Thymus zygis L.) Available in Pharmacies in Poland: Short Communication.

Scientific reports about elemental impurities in final pharmaceutical products are essential from a regulatory point of view; unfortunately, there is a lack of studies about this important toxicological topic. The aim of our short communication was determination of total Cr impurities in traditional herbal medicinal products (THMP) with Thymi herba (Thymus vulgaris L. and Thymus zygis L.) available in Polish pharmacies (n = 6, because only six manufacturers produce this kind of pharmaceutical products in Poland). The total content of Cr impurities was determined by atomic absorption spectrometry using electrothermal atomization (ETAAS). Applied comprehensive toxicological risk assessment was based on three main tiers: Tier 1, the comparison of raw results as total Cr impurities profile (metal per L of THMP) with ICH Q3D guideline standards; Tier 2, the estimation of total Cr exposure with a single dose; and Tier 3, the estimation of total Cr daily exposure. We confirmed that total Cr impurities were present in all analyzed THMP with thymi herba (the observed level was below 6.0 µg/L). Total Cr concentration in a single dose can be deceptively high in comparison to the raw results but is not a threat to patients (20.15-63.45 ng/single dose). Moreover, the estimation of total Cr daily exposure shows that all analyzed THMP are characterized by daily dose (40.30-181.41 ng/day) below PDE value (10,700 mg/day); hence, all products meet the standards of ICH Q3D elemental impurities guideline.

Health risk assessment of total chromium in the qanat as historical drinking water supplying system.

This study investigated the health risk assessment of total chromium (CrT) in qanats of South Khorasan, Eastern Iran. For this, concentration of CrT in a total of 83 qanats were measured in summer 2020. Samples were initially tested in the field for temperature, pH, dissolved oxygen (DO), electrical conductivity (EC), and total dissolved solids (TDS). In the lab, collected samples were filtered and fixed with nitric acid (HNO3) for the detection of CrT using inductively coupled plasma mass spectrometry (ICP-MS). Hazard quotient (HQ) and carcinogenic risk assessments were considered to evaluate the risks of CrT to inhabitants. Results showed that concentration of CrT ranged from 1.79 to 1017.05 µg L-1, and a total of 25 stations illuminated CrT concentrations above the WHO standards (50 µg L-1). HQ demonstrated HQ < 1 for 90.37% of studied samples with negligible hazard, whereas 9.63% of stations illuminated HQ ≥ 1 meaning the presence of non-carcinogenic risk for water consumers. Carcinogenic risk (CR) exhibited CR > 1.00E-04 in 81.93% of qanats while 18.07% of stations had 1.00E-06 < CR < 1.00E-04 meaning no acceptable and acceptable CR for the studied qanats, respectively. Zoning map displayed that qanats in the south of South Khorasan possessed the highest HQ, but north regions showed the lowest ones. Together, CrT in qanats of South Khorasan is above the WHO limit, which results in a high risk of carcinogenicity for residents, and in turn, more efforts should be made to provide hygienic groundwater for consumers.

Remote Investigation of Total Chromium Determination in Environmental Samples of the Kombolcha Industrial Zone, Ethiopia, Using Microfluidic Paper-based Analytical Devices.

Microfluidic paper-based analytical devices (µ-PADs) fabricated in Japan were employed for the determination of total chromium (Cr) in water, soil, and lettuce irrigated with wastewater in Ethiopia. The µ-PADs, which were printed by wax printing in Japan, were transported to Ethiopia and prepared for the determination of total Cr by adding appropriate reagents to the pretreatment and detection zones. Soil and lettuce samples were determined by the µ-PADs and a UV-Vis spectrophotometer in Ethiopia. A paired t-test showed that the mean total Cr concentrations determined in the soil and lettuce samples were not significantly different between µ-PADs and UV-Vis spectrophotometric analysis at the 5% level of significance. This implies that the µ-PADs have good accuracy and reliability, and could be employed to monitor Cr in environmental samples. We found that the total Cr concentrations in all soil and lettuce samples were above the permissible limit. Moreover, evaluating Cr contamination level using the geo-accumulation index indicated that the soils were contaminated with Cr moderately to heavily. Thus, the present work successfully demonstrated the potential of remote investigations of pollution in a less-equipped laboratory by transporting the µ-PADs fabricated in another laboratory.

Feasibility and mechanism of microbial-phosphorus minerals-alginate immobilized particles in bioreduction of hexavalent chromium and synchronous removal of trivalent chromium.

Chromium(VI) contaminated groundwater has become an increasingly prominent problem due to its extensive application in industry. Based on the easy-loss defect of microbial in practical application and previous research on the coupling enhancement of Cr(VI) bioreduction by phosphorus minerals, Microbial-Phosphorus minerals-Alginate (MPA) immobilized particles were proposed and investigated in this study. The feasibility of MPA immobilized particles were proved, with the higher reduction efficiency, lower phosphorus surplus, significant 94% of total Cr reduction and 85% of intragranular fixation. These superiorities were also obtained at different pH and initial Cr(VI) concentration conditions. Furthermore, the mechanisms of the enhancement of MPA were investigated from microbial level (microbial biomass, antioxidase, gene expression and microbial community analysis) and physics level (adsorption kinetic and isotherm), where the speculation that the reduction mainly took place outside the particles was proposed. This research provides a new approach for the practical application of Cr(VI)-contaminated groundwater in-situ bioremediation.

Effect of pH on hexavalent and total chromium removal from aqueous solutions by avocado shell using batch and continuous systems.

Solution pH appears to be the most important regulator of the biosorptive removal of chromium ions from aqueous solutions. This work presents a kinetic study of the effects of solution pH on Cr(VI) and total chromium removal from aqueous solution by Hass avocado shell (HAS) in batch and continuous packed bed column systems. Different Cr(VI) and total chromium removal performances of HAS were obtained in pH-shift batch, pH-controlled batch, and continuous systems. These results emphasize the great importance of determining the most appropriate pH for Cr(VI) and total chromium removal, considering the operational mode of the proposed large-scale treatment system. Total chromium biosorption batch kinetics was well described by the Elovich model, whereas in the continuous system, the fitness of the kinetic models to the experimental data was pH dependent. X-ray photoelectron spectroscopy and kinetic studies clearly indicated that the reaction mechanism of Cr(VI) with HAS was the reductive biotransformation of Cr(VI) to Cr(III), which was partially released to the aqueous solution and partially biosorbed onto HAS.

Avaliação dos níveis de cromo total em águas para consumo humano / Evaluation of total chromium levels in drinking water

Níveis elevados de cromo associados às águas naturais não são comuns, mas concentrações elevadas desse elemento, de ocorrência natural, têm sido relatadas nas águas subterrâneas de vários sistemas aquíferos, incluindo o Aquífero Bauru, SP, Brasil. Este fato está associado à ocorrência de rochas máficas/ultramáficas e às condições alcalinas e oxidantes. Neste estudo foi desenvolvido e aplicado um método para monitorar a concentração de cromo total em amostras de água da cidade de São José do Rio Preto. Esta cidade está localizada no estado de São Paulo, na região onde concentrações superiores ao limite estabelecido pela legislação brasileira (0,05 mg/L) foram detectadas em águas subterrâneas de poços de abastecimento. O cromo total foi determinado usando-se Espectrometria de Massas com Plasma Indutivamente Acoplado (ICPMS) em 104 amostras de água coletadas, entre 2013 e 2017, em diferentes pontos de distribuição (zona rural, residencial, distrito industrial, comercial, reservatório de distribuição e estação de tratamento de água), considerando-se 52 locais. Em 99 % das amostras as concentrações de Cr estavam acima do limite de quantificação calculado para o método (0,001 mg/L). E 15% apresentaram concentrações acima do limite de regulação na água potável (Portaria 2914/2011), sendo, portanto, consideradas impróprias para o consumo humano.

Elevated chromium levels in the natural waters are not common, but the high concentrations of naturally occurring Cr have been reported in the groundwater of several aquifer systems. This finding is linked with the occurrence of mafic/ultramafic rocks and associated with the alkaline and oxidizing conditions. This study aimed at monitoring the total chromium concentration in drinking water samples from São José do Rio Preto city. Cr concentrations higher than the limit established by the Brazilian Legislation (0.05 mg/L) were detected in the groundwater from the deep supply wells. Total chromium was determined by using an Inductively Coupled Mass Spectrometer (ICP-MS) in 104 samples collected from the public drinking water distribution networks in 52 sites, from 2013 to 2017. Cr concentrations above the method limit of quantification (0.001 mg/L) were found in 99% of the analyzed samples. Approximately 15% of the collected samples presented Cr in concentrations above the established legislation limit for drinking water (Ordinance 2914/2011), that should be considered as improper for consumption.

Method for the determination of chromium in feed matrix by HPLC.

An improved method for the chromatographic separation and determination of chromium (III) and (VI) [ CRIII AND CRVI: ] in mineral mixtures and feed samples has been developed. The method uses precolumn derivatization using ammonium pyrrolidinedithiocarbamate ( APD: ) followed by reversed-phase liquid chromatography to separate the chromium ions. Both Cr(III) and Cr(VI) species are chelated with ammonium pyrrolidinedithiocarbamate prior to separation by mixing with acetonitrile and 0.5 mmol acetate buffer (pH 4.5). Optimum chromatographic separations were obtained with a polymer-based reversed-phase column (Kinetex, 5 µ, 250 × 4.5 mm, Phenomenex, Torrance, CA) and a mobile phase containing acetonitrile and water (7:3). Both Cr(III) and Cr(VI) ion concentrations were directly determined from the corresponding areas in the chromatogram. The effect of analytical parameters, including pH, concentration of ligand, incubation temperature, and mobile phase, was optimized for both chromium complexes. The range of the procedure was found to be linear for Cr(III) and Cr(VI) concentrations between 0.125 and 4 µg/mL (r² = 0.9926) and 0.1 and 3.0 µg/mL (r² = 0.9983), respectively. Precision was evaluated by replicate analysis in which the percentage relative standard deviation values for chromium complex were found to be below 4.0. The recoveries obtained (85-115%) for both Cr(III) and Cr(VI) complexes indicated the accuracy of the developed method. The degradation products, as well as the excipients, were well resolved from the chromium complex peak in the chromatogram. Finally, the new method proved to be suitable for routine analysis of Cr(III) and Cr(VI) species in raw materials, mineral mixtures, and feed samples.

Cromo (III), cromo (VI) e cromo total em alguns vinhos brasileiros / Chromium (III), chromium (VI) and total chromium in some brazilian wines

Cromo(III), Cromo(VI) e Cromo total foram analisados em cento e quatro (104) vinhos comerciais brasileiros, brancos, rosados e tintos. Espectrometria de absorção atômica em forno de grafite foi utilizada nas determinações. Herquat 464 (Aliquat 336), uma mistura de cloreto de metil-tricaprilil amônio (CH3N[(CH2)7CH3]3Cl-) com grupos alquil consistindo principalmente em cadeias C8 - C10, foi utilizado como catalisador de transferência de fase. Valores médios (ug/l) encontrados em vinhos brancos, rosados e tintos foram respectivamente: Cr(III): 11,02 , 12,53 e 8,06; Cr(VI): 8,81 , 26,56 e 5,94; Cr total: 18,14 , 39,08 e 14,00.

Chromium(III), Cr(VI) and Cr total were analyzed in one hundred and four (104) white, pink and red commercial brazilian wines. Atomic Absorption Spectrometric with Graphite Furnace was used for the analysis. Herquat 464 (Aliquat 336), a mixture of methyl trycaprillyl ammonium chioride (CH3N[(CH2)7CH3]3Cl-) with alkyl groups of C8 - C10 chains, was used as a transfer phase catalizer. Mean values (ug/l) found in white, pink and red wines were respectively: Cr(III): 11.02, 12.53 and 8.06; Cr(VI): 8.81, 26.56 and 5.94; Cr total: 18.14, 39.08 and 14.00.