Displaying publications 1 - 20 of 125 in total

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  1. Influence of alloying elements on cellular response and in-vitro corrosion behavior of titanium-molybdenum-chromium alloys for implant materials
    Mat-Baharin NH, Razali M, Mohd-Said S, Syarif J, Muchtar A
    J Prosthodont Res, 2020 Oct;64(4):490-497.
    PMID: 32063537 DOI: 10.1016/j.jpor.2020.01.004
    PURPOSE: Not all elements with β-stabilizing properties in titanium alloys are suitable for biomaterial applications, because corrosion and wear processes release the alloying elements to the surrounding tissue. Chromium and molybdenum were selected as the alloying element in this work as to find balance between the strength and modulus of elasticity of β-titanium alloys. This study aimed to investigate the effect of Titanium-10Molybdenum-10Chromium (Ti-10Mo-10Cr), Titanium-10Chromium (Ti-10Cr) and Titanium-10Molybdenum (Ti-10Mo) on the elemental leachability in tissue culture environment and their effect on the viability of human gingival fibroblasts (HGFs).

    METHODS: Each alloy was immersed in growth medium for 0-21 days, and the elution was analyzed to detect the released metals. The elution was further used as the treatment medium and exposed to seeded HGFs overnight. The HGFs were also cultured directly to the titanium alloy for 1, 3 and 7 days. Cell viability was then determined.

    RESULTS: Six metal elements were detected in the immersion of titanium alloys. Among these elements, molybdenum released from Ti-10Mo-10Cr had the highest concentration throughout the immersion period. Significant difference in the viability of fibroblast cells treated with growth medium containing metals and with direct exposure technique was not observed. The duration of immersion did not significantly affect cell viability. Nevertheless, cell viability was significantly affected after 1 and 7 days of exposure, when the cells were grown directly onto the alloy surfaces.

    CONCLUSIONS: Within the limitation of this study, the newly developed β-titanium alloys are non-cytotoxic to human gingival fibroblasts.

    Matched MeSH terms: Chromium*; Chromium Alloys
  2. Emulsion liquid membrane modeling for chromium removal from electroplating wastewater using TOMAC as a carrier
    Othman N, Noah NFM, Sulaiman RNR, Jusoh N, Tan WT
    Water Environ Res, 2021 Sep;93(9):1669-1679.
    PMID: 33704848 DOI: 10.1002/wer.1551
    Hexavalent chromium, emanating primarily from the electroplating industries, can be reduced to the less toxic trivalent variety by several methods, including emulsion liquid membrane (ELM). In this work, studies on the continuous removal of chromium from authentic electroplating wastewater by ELM are reported. The effects of treat ratio, external feed phase, and stripping agent concentration were examined. A mathematical boundary breakage model was used to study the extraction efficiency of chromium through the ELM process. The model representing the prediction of ELM extraction performance for chromium was validated through the comparison between the simulation and experimental results. The result showed the simulation model is found to be in good agreement with the experimental result. Almost 100% of 40 ppm chromium in the external feed phase was extracted within 3 to 5 min using 0.022 M TOMAC as extractant, 1.0 M acidic thiourea in the internal phase, and 1 to 5 of treat ratio. PRACTITIONER POINTS: Hexavalent chromium, emanating primarily from electroplating industries, can be reduced to the less toxic trivalent using ELM process. The developed method was tested for its applicability with predominant species of Cr2 O7 2- in real rinse electroplating wastewater. The extraction efficiency (%) of Cr (VI) was almost 100% for 40 ppm Cr in the external feed phase within 3 to 5 min. The result showed the simulation model is found to be in good agreement with the experimental result.
    Matched MeSH terms: Chromium/analysis
  3. CuO improved energy band of AgO/fibrous SiO2-ZrO2 for optimized simultaneous photocatalytic redox of chromium (VI) and p-cresol using response surface methodology
    Aziz FFA, Jalil AA, Hassan NS, Fauzi AA, Khusnun NF, Ali MW, et al.
    Environ Res, 2023 Mar 01;220:115151.
    PMID: 36584845 DOI: 10.1016/j.envres.2022.115151
    Ternary CuO/AgO/FSZr photocatalysts were fabricated via the hydrothermal and electrochemical methods with three different CuO loading (1, 3 and 5 wt%), indicated as 1CuO/AgO/FSZr, 3CuO/AgO/FSZr and 5CuO/AgO/FSZr. The photocatalytic reaction was tested towards simultaneous chromium (VI) photoreduction and p-cresol photooxidation and the performance in order as follow: 3CuO/AgO/FSZr > 5CuO/AgO/FSZr > 1CuO/AgO/FSZr > AgO/FSZr > FSZr. CuO/AgO/FSZr photocatalysts showed an improvement in photocatalytic activity compared to AgO/FSZr and FSZr due to the reduction potential of chromium (VI) aligned closer to the conduction band of CuO and provided abundant free active electrons (e-) and holes (h+) with efficient transportation and migration. Interestingly, the 3CuO/AgO/FSZr was established as the best photocatalyst with 98% reduction of chromium (VI) and 83% oxidation of p-cresol simultaneously, owing to its strong corporation between the metal oxides and support and higher total pore volume. The Langmuir-Hinshelwood model were employed for kinetics which followed the pseudo-first-order kinetics model well. Based on the simultaneous photocatalytic mechanism, chromium (VI) and p-cresol were directly reduced and oxidized by e- and h+, respectively. The response surface methodology (RSM) discovered that the quadratic term initial concentration of chromium (VI) is the main significant factor in photocatalytic performance. The optimum parameters for simultaneous photoredox of chromium (VI) and p-cresol predicted from RSM are 9.6 mg L-1 of chromium (VI) concentration, 9.8 mg L-1 of p-cresol concentration and 0.32 g L-1 of catalyst dosage. Under these conditions the error between the predicted and experimental values is only 3.7%. The 3CuO/AgO/FSZr sustained the photocatalytic performance after reused for five cycles and could oxidized various organic pollutants as well as reduced chromium (VI) simultaneously.
    Matched MeSH terms: Chromium*
  4. Synthesis of surface-modified porous polysulfides from soybean oil by inverse vulcanization and its sorption behavior for Pb(II), Cu(II), and Cr(III)
    Lyu S, Abidin ZZ, Yaw TCS, Resul MFMG
    Environ Sci Pollut Res Int, 2024 Apr;31(20):29264-29279.
    PMID: 38573576 DOI: 10.1007/s11356-024-33152-w
    Guided by efficient utilization of natural plant oil and sulfur as low-cost sorbents, it is desired to tailor the porosity and composition of polysulfides to achieve their optimal applications in the management of aquatic heavy metal pollution. In this study, polysulfides derived from soybean oil and sulfur (PSSs) with improved porosity (10.2-22.9 m2/g) and surface oxygen content (3.1-7.0 wt.%) were prepared with respect to reaction time of 60 min, reaction temperature of 170 °C, and mass ratios of sulfur/soybean oil/NaCl/sodium citrate of 1:1:3:2. The sorption behaviors of PSSs under various hydrochemical conditions such as contact time, pH, ionic strength, coexisting cations and anions, temperature were systematically investigated. PSSs presented a fast sorption kinetic (5.0 h) and obviously improved maximum sorption capacities for Pb(II) (180.5 mg/g), Cu(II) (49.4 mg/g), and Cr(III) (37.0 mg/g) at pH 5.0 and T 298 K, in comparison with polymers made without NaCl/sodium citrate. This study provided a valuable reference for the facile preparation of functional polysulfides as well as a meaningful option for the removal of aquatic heavy metals.
    Matched MeSH terms: Chromium/chemistry
  5. Nanoporous anodic Nb2O5 with pore-in-pore structure formation and its application for the photoreduction of Cr(VI)
    Alias N, Hussain Z, Tan WK, Kawamura G, Muto H, Matsuda A, et al.
    Chemosphere, 2021 Nov;283:131231.
    PMID: 34144283 DOI: 10.1016/j.chemosphere.2021.131231
    An anodic film with a nanoporous structure was formed by anodizing niobium at 60 V in fluorinated ethylene glycol (fluoride-EG). After 30 min of anodization, the anodic film exhibited a "pore-in-pore" structure; that is, there were smaller pores growing inside larger pores. The as-anodized film was weakly crystalline and became orthorhombic Nb2O5 after heat treatment. The energy band gap of the annealed nanoporous Nb2O5 film was 2.9 eV. A photocatalytic reduction experiment was performed on Cr(VI) under ultraviolet (UV) radiation by immersing the nanoporous Nb2O5 photocatalyst in a Cr(VI) solution at pH 2. The reduction process was observed to be very slow; hence, ethylenediaminetetraacetic acid (EDTA) was added as an organic hole scavenger, which resulted in 100% reduction after 45 min of irradiation. The photocatalytic reduction experiment was also performed under visible light, and findings showed that complete reduction achieved after 120 min of visible light exposure.
    Matched MeSH terms: Chromium
  6. A comparative study of experimental optimization and response surface optimization of Cr removal by emulsion ionic liquid membrane
    Goyal RK, Jayakumar NS, Hashim MA
    J Hazard Mater, 2011 Nov 15;195:383-90.
    PMID: 21920664 DOI: 10.1016/j.jhazmat.2011.08.056
    A comparative study on the optimization of process parameters of an emulsion ionic liquid membrane (EILM) by experimental work and response surface methodology (RSM) has been carried out. EILM was prepared by using kerosene as solvent, Span 80 as surfactant, NaOH as internal reagent, a hydrophobic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM](+)[NTf(2)](-)) as a stabilizer and a second ionic liquid tri-n-octylmethylammonium chloride (TOMAC) as a carrier. The prepared EILM was used to separate and concentrate Cr from wastewaters. The comparison between the experimentally optimized and the RSM optimized values was accomplished by optimizing the following parameters: homogenization speed, carrier concentration, internal phase concentration, agitation speed, treat ratio, internal to membrane phase ratio, surfactant concentration and pH of the feed phase. The comparison showed that all the values were in good agreement except for the internal phase concentration and the treat ratio. It was observed that the stability provided by [BMIM](+)[NTf(2)](-) decreased as the extraction progressed due to its high density. Nevertheless, a good stability could be obtained by the combination of [BMIM](+)[NTf(2)](-) and Span 80 during extraction process.
    Matched MeSH terms: Chromium/isolation & purification*
  7. Modelling and optimization of hexavalent chromium removal from aqueous solution by adsorption on low-cost agricultural waste biomass using response surface methodological approach
    Rzig B, Guesmi F, Sillanpää M, Hamrouni B
    Water Sci Technol, 2021 Aug;84(3):552-575.
    PMID: 34388119 DOI: 10.2166/wst.2021.233
    In this study, a response surface methodology (RSM) approach using central composite design (CCD) was investigated to develop a mathematical model and to optimize the effects of pH, adsorbent amount and temperature related to the hexavalent chromium removal by biosorption on peanut shells (PSh). The highest removal percentage of 30.28% was found by the predicted model under the optimum conditions (pH of 2.11, 0.73 g of PSh and 37.2 °C) for a 100 mg/L initial Cr(VI) concentration, which was very near to the experimental value (29.92%). The PSh was characterized by SEM, EDX, FTIR, BET, XRD analyses. Moreover, a Langmuir isotherm fitted well (R2 = 0.992) with the experimental data, and the maximum adsorption capacity was discovered to be 2.48 and 3.49 mg/g respectively at 25 and 45 °C. Kinetic data were well foreseen by pseudo second order. Thermodynamic study depicted that biosorption of Cr(VI) onto PSh was spontaneous and endothermic. Regeneration of the PSh using NaOH showed a loss <5% in the Cr(VI) removal efficiency up to three recycle runs. In summary, the Cr(VI) removal onto economic, sensitive and selective biosorbent (PSh) was optimized using CCD to study biosorption behaviors.
    Matched MeSH terms: Chromium/analysis
  8. Fulltext Adsorption and Kinetics Studies of Cr (VI) by Graphene Oxide and Reduced Graphene Oxide-Zinc Oxide Nanocomposite
    Naseem T, Bibi F, Arif S, Waseem M, Haq S, Azra MN, et al.
    Molecules, 2022 Oct 22;27(21).
    PMID: 36363976 DOI: 10.3390/molecules27217152
    In this work, graphene oxide (GO) and its reduced graphene oxide-zinc oxide nanocomposite (rGO-ZnO) was used for the removal of Cr (VI) from aqueous medium. By employing a variety of characterization techniques, morphological and structural properties of the adsorbents were determined. The adsorption study was done by varying concentration, temperature, pH, time, and amount of adsorbent. The results obtained confirmed that rGO-ZnO is a more economical and promising adsorbent for removing Cr (VI) as compared to GO. Kinetic study was also performed, which suggested that sorption of Cr (VI) follows the pseudo-first-order model. For equilibrium study, non-linear Langmuir was found a better fitted model than its linearized form. The maximum adsorption capacity calculated for GO and rGO-ZnO nanocomposite were 19.49 mg/g and 25.45 mg/g, respectively. Endothermic and spontaneous nature of adsorption was detected with positive values of ΔS (change in entropy), which reflects the structural changes happening at the liquid/solid interface.
    Matched MeSH terms: Chromium/chemistry
  9. Investigation of optimal conditions for production of highly crystalline nanocellulose with increased yield via novel Cr(III)-catalyzed hydrolysis: Response surface methodology
    Chen YW, Lee HV, Abd Hamid SB
    Carbohydr Polym, 2017 Dec 15;178:57-68.
    PMID: 29050615 DOI: 10.1016/j.carbpol.2017.09.029
    For the first time, a highly efficient Cr(NO3)3 catalysis system was proposed for optimization the yield and crystallinity of nanocellulose end product. A five-level three-factor central composite design coupled with response surface methodology was employed to elucidate parameters interactions between three design factors, namely reaction temperature (x1), reaction time (x2) and concentration of Cr(NO3)3 (x3) over a broad range of process conditions and determine the effect on crystallinity index and product yield. The developed models predicted the maximum nanocellulose yield of 87% at optimum process conditions of 70.6°C, 1.48h, and 0.48M Cr(NO3)3. At these conditions, the obtained nanocellulose presented high crystallinity index (75.3%), spider-web-like interconnected network morphology with the average width of 31.2±14.3nm. In addition, the yielded nanocellulose rendered a higher thermal stability than that of original cellulosic source and expected to be widely used as reinforcement agent in bio-nanocomposites materials.
    Matched MeSH terms: Chromium Compounds/chemistry*
  10. Risk analysis of inhaled hexavalent chromium (Cr6+) exposure on blacksmiths from industrial area
    Oginawati K, Susetyo SH, Rosalyn FA, Kurniawan SB, Abdullah SRS
    Environ Sci Pollut Res Int, 2021 Mar;28(11):14000-14008.
    PMID: 33201502 DOI: 10.1007/s11356-020-11590-6
    Chromium (Cr) is used as a mixture to improve strength and corrosion resistance. Milling and welding processes can expose workers to Cr through dermal exposure and inhalation. Cr exposure can be determined by urine testing. The purpose of this study was to analyze the concentration of Cr in urine (UCr) of workers. This study was carried out using a cross-sectional method. Sampling was conducted in the village of Mekarmaju, Bandung, Indonesia. The number of respondents included 30 blacksmiths, and the control group comprised 10 people who were not blacksmiths. Cr6+ exposure was measured using a personal sampling pump placed on the collar of the worker's shirt as a breathing zone and then analyzed using a UV-visible spectrophotometer. UCr was measured with a graphite furnace atomic absorption spectrophotometer. The measured Cr6+ concentration in the exposed working area ranged from 0.03 to 0.63 mg/m3, whereas that in non-exposed area ranged from 0.02 to 0.04 mg/m3. Results showed that 16 out of 30 blacksmiths had a UCr concentration above the biological exposure index (BEI) value, 21 had a higher value than the threshold limit value (TLV), and 22 had hazard index (HI) values > 1, which indicated that Cr has a hazardous potential in the body. The analysis of the exposed and control groups showed a significant difference with a p value of 0.000 for TLV, chronic daily intake, and UCr. These results clearly showed that Cr6+ exposure may harm the health of these workers in the future. The results obtained in this study can be used to promote workers' awareness on the potential health risk caused by Cr6+ exposure in the working environment.
    Matched MeSH terms: Chromium/analysis
  11. Biosorption and bioreduction of Cr(VI) by locally isolated Cr-resistant bacteria
    Zakaria ZA, Aruleswaran N, Kaur S, Ahmad WA
    Water Sci Technol, 2007;56(8):117-23.
    PMID: 17978439
    Cr(VI) biosorption and bioreduction ability of locally isolated Cr-resistant bacteria was investigated using the shake-flask technique. A mixture of S. epidermidis and B. cereus showed the highest minimum inhibitory concentration (MIC) level at 750 mg/L Cr(VI) followed by S. aureus and Bacillus sp. of 250 mg/L, and A. haemolyticus of 70 mg/L. From the Langmuir adsorption isotherm, the treatment of cells with heat-acid resulted in the highest amount of Cr(VI) adsorped (78.25 mg/g dry wt. for S. epidermidis) compared to heat-acetone (67.93 mg/g dry wt. Bacillus sp.), heat only (36.05 mg/g dry wt. S. epidermidis) or untreated cells (45.40 mg/g dry wt. S. epidermidis and B. cereus). FTIR analysis showed the involvement of amine groups in Cr(VI) adsorption. In the bioreduction study, A. haemolyticus was able to completely reduce Cr(VI) up to 50 mg/L.
    Matched MeSH terms: Chromium/metabolism*; Chromium/chemistry
  12. The adsorptive removal of chromium (VI) in aqueous solution by novel natural zeolite based hollow fibre ceramic membrane
    Adam MR, Salleh NM, Othman MHD, Matsuura T, Ali MH, Puteh MH, et al.
    J Environ Manage, 2018 Oct 15;224:252-262.
    PMID: 30055458 DOI: 10.1016/j.jenvman.2018.07.043
    Adsorption is one of the most efficient ways to remove heavy metal from wastewater. In this study, the adsorptive removal of hexavalent chromium, Cr (VI) from aqueous solution was investigated using natural zeolite, clinoptilolite, in the form of hollow fibre ceramic membrane (HFCM). The HFCM sample was prepared using phase inversion-based extrusion technique and followed by sintering process at different sintering temperatures in the range of 900-1050 °C. The fabricated HFCM was characterised using scanning electron microscopy (SEM), contact angle, water permeability, and mechanical strength for all HFCMs sintered at different temperatures. The adsorption and filtration test of Cr (VI) were performed using an in-house water permeation set up with a dead-end cross-flow permeation test. An asymmetric structure with sponge- and finger-like structures across the cross-section of HFCM was observed using SEM. Based on the characterisation data, 1050 °C was chosen to be the best sintering temperature as the water permeability and mechanical strength of this HFCM were 29.14 L/m2∙h and 50.92 MPa, respectively. The performance of the HFCM in adsorption/filtration was 44% of Cr (VI) removal at the Cr (VI) concentration of 40 mg/L and pH 4. In addition, the mathematical model was also performed in simulating the experimental data obtained from this study. All in all, the natural zeolite-based HFCM has a potential as a single-step Cr (VI) removal by membrane adsorption for the wastewater treatment.
    Matched MeSH terms: Chromium/isolation & purification*; Chromium/chemistry
  13. Biosorption performance of date palm empty fruit bunch wastes for toxic hexavalent chromium removal
    Rambabu K, Bharath G, Banat F, Show PL
    Environ Res, 2020 08;187:109694.
    PMID: 32485359 DOI: 10.1016/j.envres.2020.109694
    Biosorption ability of date palm empty fruit bunch (DPEFB) was examined for the removal of toxic hexavalent chromium (Cr6+) ions from synthetic wastewater. The pretreated DPEFB biosorbent was studied for its morphology and surface chemistry through Scanning electron microscopy, Energy dispersive elemental analysis and Fourier transform infrared spectroscopy. Effect of biosorption parameters such as pH, biosorbent dosage, contact time, temperature, initial feed concentration and agitation speed on the Cr6+ ions removal efficiency by DPEFB was critically evaluated. The isoelectric point for the DPEFB sorbent was observed at pH 2, above which it was dehydronated to capture the positively charged Cr6+ ions. Batch biosorption studies showed that an optimal chromium removal efficiency of 58.02% was recorded by the DPEFB biosorbent for pH 2, dosage 0.3 g, 100 rpm agitation speed, 120 min contact time, 50 mg/L initial feed concentration and 30 °C operational temperature. Thermodynamic analysis showed that the binding of Cr6+ ions on DPEFB surface was exothermic, stable and favorable at room temperature. Equilibrium behavior of chromium binding on DPEFB was more aligned to Temkin isotherm (R2 = 0.9852) highlighting the indirect interactions between Cr6+ ions and the biosorbent. Kinetic modeling revealed that the biosorption of Cr6+ ions by DPEFB obeyed pseudo-second order model than the pseudo-first order and intra-particle diffusion models. Reusability studies of the DPEFB sorbent showed that NaNO3 was an effective regenerant and the biosorbent can be efficiently reused up to three successive biosorption-desorption cycles for chromium removal. In summary, the results clearly showed that the DPEFB biowaste seems to be an efficient, economic and eco-friendly biosorbent for sustainable removal of toxic hexavalent chromium ions from domestic and industrial wastewater streams.
    Matched MeSH terms: Chromium/analysis; Chromium/toxicity
  14. Emulsion stabilization using ionic liquid [BMIM]+[NTf2]- and performance evaluation on the extraction of chromium
    Goyal RK, Jayakumar NS, Hashim MA
    J Hazard Mater, 2011 Nov 15;195:55-61.
    PMID: 21962862 DOI: 10.1016/j.jhazmat.2011.03.024
    This study focuses on the role of a hydrophobic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [BMIM](+)[NTf(2)](-) in the preparation of emulsion liquid membrane (ELM) phase containing kerosene as solvent, Span 80 as surfactant, NaOH as internal phase and TOMAC (tri-n-octylmethylammonium chloride) a second ionic liquid as carrier. The first time used [BMIM](+)[NTf(2)](-) in ELM was found to play the role of a stabilizer. The emulsion prepared using [BMIM](+) [NTf(2)](-) has a long period of stability of about 7h (at 3% (w/w) of [BMIM](+)[NTf(2)](-)) which otherwise has a brief stability up to only 7 min. The stability of the emulsion increases with the increase in concentration of [BMIM](+)[NTf(2)](-) up to 3% (w/w). Nevertheless, with further increase in concentration of [BMIM](+)[NTf(2)](-), a reduction in the stability occurs. The extraction experiments were carried out after holding the ELM for 2h after the preparation and a removal efficiency of approximately 80% was obtained for Cr. The destabilization of the emulsion was studied by observing the change in the interface height. An empirical correlation for the stability of the emulsion has been proposed.
    Matched MeSH terms: Chromium/isolation & purification*
  15. Removal of chromium (VI) from aqueous solution using treated oil palm fibre
    Isa MH, Ibrahim N, Aziz HA, Adlan MN, Sabiani NH, Zinatizadeh AA, et al.
    J Hazard Mater, 2008 Apr 1;152(2):662-8.
    PMID: 17714862
    This study proposed an oil palm by-product as a low-cost adsorbent for the removal of hexavalent chromium [Cr (VI)] from aqueous solution. Adsorption of Cr (VI) by sulphuric acid and heat-treated oil palm fibre was conducted using batch tests. The influence of pH, contact time, initial chromium concentration and adsorbent dosage on the removal of Cr (VI) from the solutions was investigated. The optimum initial pH for maximum uptake of Cr (VI) from aqueous solution was found to be 1.5. The removal efficiency was found to correlate with the initial Cr (VI) concentration, adsorbent dosage as well as the contact time between Cr (VI) and the adsorbent. The adsorption kinetics tested with pseudo first order and pseudo second order models yielded high R(2) values from 0.9254 to 0.9870 and from 0.9936 to 0.9998, respectively. The analysis of variance (ANOVA) showed significant difference between the R(2) values of the two models at 99% confidence level. The Freundlich isotherm (R(2)=0.8778) described Cr (VI) adsorption slightly better than the Langmuir isotherm (R(2)=0.8715). Difficulty in desorption of Cr (VI) suggests the suitability of treated oil palm fibre as a single-use adsorbent for Cr (VI) removal from aqueous solution.
    Matched MeSH terms: Chromium/isolation & purification*
  16. Selective adsorption and ultrafast fluorescent detection of Cr(VI) in wastewater using neodymium doped polyaniline supported layered double hydroxide nanocomposite
    Wani AA, Khan AM, Manea YK, Salem MAS, Shahadat M
    J Hazard Mater, 2021 08 15;416:125754.
    PMID: 33813294 DOI: 10.1016/j.jhazmat.2021.125754
    Neodymium-doped polyaniline supported Zn-Al layered double hydroxide (PANI@Nd-LDH) nanocomposite has been prepared via an ex-situ oxidative polymerization process. The as-prepared nanocomposite shows selective fluorescence detection and adsorption of hexavalent chromium Cr(VI) within a short period. The fluorescence intensity of PANI@Nd-LDH decreases linearly with Cr(VI) concentrations ranging from 200 ppb to 1000 ppb with a limit of detection (LOD) of 1.5 nM and a limit of quantification (LOQ) of 96 nM. The sensing mechanism can be ascribed by the inner filter effect of Cr(VI), the intercalation of Cr(VI) within the intergallery region of LDH, and the synergistic affinity of metal ions along with the polymer chain for Cr(VI). The adsorption performance of PANI@Nd-LDH nanocomposite is evaluated for Cr(VI) from wastewaters, which displayed high removal capacity towards Cr(VI) (219 mg/g) as compared on bare Nd-LDH (123 mg/g) and LDH (88 mg/g) respectively. The adsorption of Cr(VI) on PANI@Nd-LDH depends on the pH of the aqueous solution. The adsorption isotherm and kinetics are supported by the Langmuir model and pseudo-second-order model, respectively. Owing to the highly sensitive detection and adsorption of Cr(VI) from aqueous water samples demonstrated the potential application of PANI@Nd-LDH as an excellent environmental probe can be exploited.
    Matched MeSH terms: Chromium/analysis
  17. Fulltext Assessing Cadmium and Chromium Concentrations in Drinking Water to Predict Health Risk in Malaysia
    Ahmed MF, Mokhtar MB
    Int J Environ Res Public Health, 2020 04 24;17(8).
    PMID: 32344678 DOI: 10.3390/ijerph17082966
    Although toxic Cd (cadmium) and Cr (chromium) in the aquatic environment are mainly from natural sources, human activities have increased their concentrations. Several studies have reported higher concentrations of Cd and Cr in the aquatic environment of Malaysia; however, the association between metal ingestion via drinking water and human health risk has not been established. This study collected water samples from four stages of the drinking water supply chain at Langat River Basin, Malaysia in 2015 to analyze the samples by inductivity coupled plasma mass spectrometry. Mean concentrations of Cd and Cr and the time-series river data (2004-2014) of these metals were significantly within the safe limit of drinking water quality standard proposed by the Ministry of Health Malaysia and the World Health Organization. Hazard quotient (HQ) and lifetime cancer risk (LCR) values of Cd and Cr in 2015 and 2020 also indicate no significant human health risk of its ingestion via drinking water. Additionally, management of pollution sources in the Langat Basin from 2004 to 2015 decreased Cr concentration in 2020 on the basis of autoregression moving average. Although Cd and Cr concentrations were found to be within the safe limits at Langat Basin, high concentrations of these metals have been found in household tap water, especially due to the contamination in the water distribution pipeline. Therefore, a two-layer water filtration system should be introduced in the basin to achieve the United Nations Sustainable Development Goals (SDGs) 2030 agenda of a better and more sustainable future for all, especially via SDG 6 of supplying safe drinking water at the household level.
    Matched MeSH terms: Chromium/toxicity
  18. Fulltext Enhancing chromium removal and recovery from industrial wastewater using sustainable and efficient nanomaterial: A review
    Irshad MA, Sattar S, Nawaz R, Al-Hussain SA, Rizwan M, Bukhari A, et al.
    Ecotoxicol Environ Saf, 2023 Sep 15;263:115231.
    PMID: 37429088 DOI: 10.1016/j.ecoenv.2023.115231
    Water contamination can be detrimental to the human health due to higher concentration of carcinogenic heavy metals such as chromium (Cr) in the wastewater. Many traditional methods are being employed in wastewater treatment plants for Cr removal to control the environmental impacts. Such methods include ion exchange, coagulation, membrane filtration, and chemical precipitation and microbial degradation. Recent advances in materials science and green chemistry have led to the development of nanomaterial that possess high specific surface areas and multiple functions, making them suitable for removing metals such as Cr from wastewater. Literature shows that the most efficient, effective, clean, and long-lasting approach for removing heavy metals from wastewater involves adsorbing heavy metals onto the surface of nanomaterial. This review assesses the removal methods of Cr from wastewater, advantages and disadvantages of using nanomaterial to remove Cr from wastewater and potential negative impacts on human health. The latest trends and developments in Cr removal strategies using nanomaterial adsorption are also explored in the present review.
    Matched MeSH terms: Chromium/analysis
  19. Conversion of seaweed waste to biochar for the removal of heavy metal ions from aqueous solution: A sustainable method to address eutrophication problem in water bodies
    Ravindiran G, Rajamanickam S, Ramalingam M, Hayder G, Sathaiah BK, Gaddam MKR, et al.
    Environ Res, 2024 Jan 15;241:117551.
    PMID: 37939801 DOI: 10.1016/j.envres.2023.117551
    The present study investigated the sustainable approach for wastewater treatment using waste algal blooms. The current study investigated the removal of toxic metals namely chromium (Cr), nickel (Ni), and zinc (Zn) from aqueous solutions in batch and column studies using biochar produced by the marine algae Ulva reticulata. SEM/EDX, FTIR, and XRD were used to examine the adsorbents' properties and stability. The removal efficiency of toxic metals in batch operations was investigated by varying the parameters, which included pH, biochar dose, initial metal ion concentration, and contact time. Similarly, in the column study, the removal efficiency of heavy metal ions was investigated by varying bed height, flow rate, and initial metal ion concentration. Response Surface Methodology (Central Composite Design (CCD)) was used to confirm the linearity between the observed and estimated values of the adsorption quantity. The packed bed column demonstrated successful removal rates of 90.38% for Cr, 91.23% for Ni, and 89.92% for Zn heavy metals from aqueous solutions, under a controlled environment. The breakthrough analysis also shows that the Thomas and Adams-Bohart models best fit the regression values, allowing prior breakthroughs in the packed bed column to be predicted. Desorption studies were conducted to understand sorption and elution during different regeneration cycles. Adding 0.3 N sulfuric acid over 40 min resulted in the highest desorption rate of the column and adsorbent used for all three metal ions.
    Matched MeSH terms: Chromium/analysis
  20. Optimization of kretschmann based on surface plasmon resonance sensor using taguchi method
    Gan SM, Najmiah Radiah Mohamad, Nur Akmar Jamil, Burhanuddin Yeop Majlis, Susthitha Menon P
    Sains Malaysiana, 2018;47:2565-2571.
    In this paper, Taguchi experimental design technique was applied for optimization of chromium (Cr)/silver (Ag)/indium
    tin oxide (ITO) SPR sensor for operation in near infrared region. Four factors were considered which include wavelength,
    thickness of Cr, thickness of Ag, and thickness of ITO. Finite-difference-time-domain (FDTD) method was used in numerical
    analysis for minimum reflectance (Rmin) and full-width-at-half-maximum (FWHM) performance parameters. The results
    obtained from the Taguchi method shows that the optimized parameter for Rmin was 785 nm of wavelength, Cr (1 nm),
    Ag (40 nm) and ITO (20 nm), whereas the optimized parameter for FWHM was 785 of wavelength, Cr (0 nm), Ag (40 nm)
    and ITO (0 nm). In short, the optimum parameters for achieving the desired performance of sensor were successfully
    predicted using Taguchi optimization method.
    Matched MeSH terms: Chromium
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