Elimination Of Chromium Research Articles

Exclusion of Chromium(VI) Ion in Grueling Activated Carbon Fabricated from Manilkara zapota Tree Wood by Adsorption: Optimization by Response Surface Methodology

The current paper makes obvious the elimination of chromium(VI) ion, from wastewater via adsorption technique with activated carbon generated from Manilkara zapota tree (MZTWAC). Preliminarily MZTWAC has undergone characterization studies which uncovered the suitability of MZTWAC to expel chromium(VI) from aqueous solution. Batch adsorption experimentation was premeditated with the competence of central composite design (CCD) and it was executed. Response surface methodology (RSM) was the key optimization software to appraise the adsorptive chattels of MZTWAC engaged in removing chromium(VI) ion in aqueous solution which explored the interactions flanked between four expounding variables explicitly initial concentration of chromium(VI) ion, pH of the solution, MZTWAC dose and time of exposure, and contact time. The response variable that was concentrated in the study was adsorption capacity. It was deduced a polynomial in quadratic equation was documented amid the adsorption capacity and variables influencing the adsorption with R2 = 0.9792 which was projected as the best suit for the adsorption process. ANOVA that is expanded as analysis of variance judged the connotation of adsorption process variables. 0.2 g of MZTWAC dosage has removed 87.629% chromium(VI) from aqueous solution. The enhancement of adsorption process reclined on the attainment of maximum adsorption capacity which further depends on the optimization of variables under consideration. This criterion was accomplished by the desirability function optimizing the process variables.

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

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

Recyclable process modeling study of hexavalent chromium elimination by thiol-based electron donor: Implications for practical applicability

Recently, extensive researches implemented to decontaminate hexavalent chromium from industrial effluents. Even though, these processes were not comprehensively addressed in various environmental conditions. This paper investigated the reduction plus adsorption mechanism of [Cr2O7]2- by thiol-based composite in wide range pHs. In this system, firstly the reduction of [Cr2O7]2- to Cr3+ occurred and Cr species adsorbed by -SH, -NH2, -OH functional groups in different degrees. The pH 2.0 medium underwent partial reduction of [Cr2O7]2- to Cr3+, besides three-quarter of [Cr2O7]2- were reduced to Cr3+ and also Cr species adsorbed onto the composite in pH 3.0 medium. The extremely fast reduction occurred within 5 min, which helped the application in the fixed-bed column while diminished the column’s residual time. Interestingly, mild acidic pHs have prompted the composite to a well-expanded structure, which further controlled the hydraulic resistance and column blockage. Inspiringly, the [Cr2O7]2-- composite system can be treated 13 L of 19.87 mg L−1 [Cr2O7]2- to the Environmental Protection Agency’s (EPA) discharge limit by 2.27 g of composite in pH 3.0 with 383 mL of an eluent. As per the Bohart-Adams model, a liter of a fixed-bed column may effectively capture around 60 g of Cr from industrial effluent in pH 2.0 – 3.0. This collective system is an efficient catalytic cycle technique to treat oxyanions from wastewater where replacing toxic oxidants with environmentally friendly catalytic wastewater treatment processes.

Investigation the Effects of Green-Synthesized Copper Nanoparticles on the Performance of Activated Carbon-Chitosan-Alginate for the Removal of Cr(VI) from Aqueous Solution.

In the present investigation, green nano-zerovalent copper (GnZVCu), activated carbon (AC), chitosan (CS) and alginate (ALG) nanocomposites were produced and used for the elimination of chromium (VI) from a polluted solution. The nanocomposites GnZVCu/AC-CS-alginate and AC-CS-alginate were prepared. Analysis and characterization were performed by the following techniques: X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The SEM analysis revealed that the nanocomposites are extremely mesoporous, which leads to the greatest adsorption of Cr+6 (i.e., 97.5% and 95%) for GnZVCu/AC-CS-alginate and AC-CS-alginate, respectively. The adsorption efficiency was enhanced by coupling GnZVCu with AC-CS-alginate with a contact time of 40 min. The maximum elimination of Cr+6 with the two nanocomposites was achieved at pH 2. The isotherm model, Freundlich adsorption isotherm and kinetics model and P.S.O.R kinetic models were discovered to be better suited to describe the exclusion of Cr+6 by the nanocomposites. The results suggested that the synthesized nanocomposites are promising for the segregation of Cr+6 from polluted solutions, specially the GnZVCu/AC-CS-alginate nanocomposite.

Deep Eutectic Solvent Assisted Facile and Efficient Synthesis of Nitrogen-Doped Magnetic Biochar for Hexavalent Chromium Elimination: Mechanism and Performance Insights

Deep Eutectic Solvent Assisted Facile and Efficient Synthesis of Nitrogen-Doped Magnetic Biochar for Hexavalent Chromium Elimination: Mechanism and Performance Insights

Sustainable removal of anodized aluminum dye by groundwater treatment waste: experimental and modeling

Groundwater treatment waste (GWTW), as an environmentally friendly renewable nanomaterial, was implemented for the removal of anodized aluminum dye Sanodure Green (SG) from aqueous solutions. The capability of the SG metal complex dye removal was assessed by measuring solution decoloration and chromium elimination degree. GWTW was characterized using FTIR, SEM, EDX, TEM, XPS and surface area measurements. Kinetic curves were obtained by changing initial dye concentration, pH, temperature and adsorbent dose. Kinetic studies showed that up to 90 % of SG dye was removed within a contact time of 20 min. The adsorption of the dye was favourable at 293 K temperature in the acidic pH region (pH 1.5–2.0) with maximum adsorption capacity 185 mg g−1. Langmuir-Freundlich isotherm model as well as hyperbolic tangent, diffusion-chemisorption and Elovich kinetic models accurately describe the dye removal process. The calculated thermodynamic parameters confirmed that SG dye removal occurred spontaneously and exothermically. The magnitude of enthalpy change (ΔH° = −35.80 kJ mol−1) was in agreement with the electrostatic interaction. The adsorption potential of GWTW for SG dye removal was also evaluated using a real wastewater produced after dyeing of anodized aluminum.

Using spent tea residue to elimination of chromium in aqueous liquid

In this work, spent red and black tea form leaves were assessed for their ability to doff expel chromium ion from aqueous solutions at various values of PH. Classification adsorption experiments indebted at choice temperature and showed cruise the adsorption of Cr ion decrease more the increase of temperature. In successive lyrics, the adsorption fight is exothermic and the enthalpy is fatal, at long last the unconventional ways and the entropy are positive. The matter copied at equal stat was compared with Langmuir, Freundlich models, and the inference efficiencies for Cr ion higher than 99% and can easily be achieved. It was hinge saunter the brilliant hatch is reform than hyacinthine cause in adsorption of chromium ion.

Development of eco-friendly, self-cleaning, antibacterial membrane for the elimination of chromium (VI) from tannery wastewater.

Hydrophobic polyvinylidene fluoride membrane was reformed to the hydrophilic membrane by incorporating synthesized titanium dioxide nanoparticles using Cajanus cajan seed extract. Spectroscopic and microscopic techniques characterized the composite membrane. The X-ray diffraction confirms the anatase phase of titanium dioxide nanoparticles of crystalline size 15.89 nm. The effect of titanium dioxide concentration on the thermodynamical and rheological properties on the polyvinylidene fluoride casting solution was investigated by the triangle phase diagram and viscosity measurement. It was concluded that titanium dioxide introduction caused thermodynamic enhancement, but the impact of rheological hinderance was higher at high concentrations. The polyvinylidene fluoride/titanium dioxide membranes were used as a bi-functional membrane to evaluate the rejection of chromium (VI) from wastewater; then, they were applied as sunlight-active catalyst membrane to reduce the concentrated chromium (VI) to chromium (III) by reduction. It was concluded that at 0.02 wt% of titanium dioxide, the maximum rejection of 85.59% and a% reduction of 92% was achieved with enhanced flux.

Hexavalent chromium sequestration from electronic waste by biomass of Aspergillus carbonarius

ABSTRACT The idea of eliminating noxious metal ions from electronic waste contaminated water has led to the use of the metal adsorbing ability of biological matter. The principle of an ion exchanger of biological origin is the key in exhibiting this metal binding feature of microbial biomass. In this study, dead biomass of Aspergillus carbonarius was immobilized using sodium alginate and tested as a biosorbent for hexavalent chromium elimination from effluent. Size and functional groups were characterized for the immobilized bead containing biomass. Optimization of boundary variables like bead size, biosorbent dosage, contact time, pH, and temperature were performed. Maximum elimination of 92.43% hexavalent chromium was achieved at pH 2.0 for 12 h at 37°C, with 20 g/25 mL adsorbent dosage. On application of adsorption isotherms, the data were found to fit Freundlich isotherm and exhibited a high value of correlation coefficient proving the ability of A. carbonarius biomass to act as an effective quencher of hexavalent chromium from electronic waste contaminated water.

A self-gating proton-coupled electron transfer reduction of hexavalent chromium by core-shell SBA-Dithiocarbamate chitosan composite

We have proposed a novel strategy for the reduction plus adsorption process for hexavalent chromium elimination by thiol functional hybrid materials through a self-gating process. Namely, we exploit that coating dithiocarbamate chitosan at the surface of SBA-15 affords a core-shell composite that undergoes reversible shape transformations while thiol functional groups acted as proton-coupled electron donor for [Cr2O7]2−. The reduction of [Cr2O7]2− to Cr3+ was highly efficient and exceptionally rapid, occurred within 5 min with the reduction amount of 899.66 mg of [Cr2O7]2− / 1 g of nanocomposite as a record high value. During the reduction of [Cr2O7]2−, thiol functional groups (-SH) were oxidized into disulfide linkages (SS), and simultaneously chitosan matrix turned into shrunken structure because of the consuming of protons, preventing any release of Cr3+. Disulfides can also be reversely reduced to thiols by thiosulphates (S2O32−), which was attractive for regeneration and recyclability of the nanocomposite. Moreover, the [Cr2O7]2− elimination through self-gating process was highly selective against a huge concentration of background electrolytes. This alternative strategy ensures the outstanding and stable performance in applied fields, and could be conducted in various pollution control techniques like permeable reactive barriers.

Elimination of Chromium (VI) by Adsorption onto Natural and/or Modified Kaolinite

The purpose of this study is to compare the effectiveness of a natural and / or modified kaolinite to adsorb chromium-containing aqueous effluents in its most toxic form (the hexavalent chromate ion (Cr (VI)). Adsorbant used in the present study is a kaolinite of hydrothermal origin. The modified kaolinite has been prepared by insertion of a cationic surfactant DTAC in interlayer space of this clay. The modification method is generally performed by the cation exchange reaction in the liquid state. The specific surface areas determined by nitrogen adsorption at 77 K for the two samples of kaolinite (natural and modified) are succinctly 48.75 and 63.72 m2/g. Scanning electron microscopy has shown that the used clay is in tubular form. The treatment of natural kaolin by the intercalation of cationic surfactant increased its specific surface of about 18 %. Therefore its power sorptif increased which was found by a comparative study of adsorption of Cr (VI) on natural kaolin and / or modified.

Valorisation des coques de noyaux de Balanites aegyptiaca (L.) Del. et Hyphaene thébaica (L.) Mart. pour l’élaboration et caractérisation de Charbons Actifs; application pour l’élimination du chrome

This paper focuses on the development and characterization of activated carbons to agro-food waste by activation with ortho phosphoric acid, and its application in the elimination of chromium in solution. The functions were determined by Bohem's method. The thermal analysis was carried out on the hulls of waste. The specific surface area and the pore volume are determined according to the method of Brunauer, Emmet and Teller and the method of Barret, Joyner and Halenda respectively. The Lagergren and Ho and McKay models were used for the kinetic study of chromium removal. Those of Langmuir and Freundlich have to do with the study of isotherms and the law of Van't Hoff and Gibbs in relation to the determination of thermodynamic parameters. The results obtained show that the surface functions are acidic in nature. Activated carbon from balanites aegyptiaca has developed a specific surface (1560.7401 m2 g -1 ) that exceeds that of Hyphaene thebaica (722.1510 m2 g -1 ). The pseudo-order 2 kinetics (Ho and McKay) better describe the adsorption with correlation coefficients close to unity. Adsorption capacities and rate constants prove rapid adsorption at the early stages. For the isotherms, the calculated parameter values are much more consistent with those of the Langmuir isotherm. ∆Gads 0 < 0 ; the adsorption process is spontaneous. Moreover, the values are in the range of a physisorption.

From the iron boring scraps to superparamagnetic nanoparticles through an aerobic biological route

A straightforward, highly efficient, and low-cost biological route was introduced for the synthesis of magnetic nanoparticles. Three urease-positive bacteria namely, Bacillus subtilis, B. pasteurii, and B. licheniformis were used to biosynthesize ammonia and biosurfactants required for the nanoparticle production. Also, the features of the applied biological approach was compared with a chemical co-precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), vibrating-sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR) were applied to characterize the synthesized nanoparticles. Results indicated that the biologically fabricated powders had a single domain structure, and their mean particle size was in the range of 37 to 97 nm. The production capacity of the biological processes was double the chemical method, and the biosynthesized superparamagnetic nanoparticles had higher saturation magnetization up to 132 emu/g. Finally, the removal of Cr(VI) from a synthetic solution was investigated using the four products. The maximum elimination of chromium (over 99%) was achieved by the particles synthesized by B. pasteurii, with the adsorption capacity of 190 mg/g.

Lagenaria siceraria peel biomass as a potential biosorbent for the removal of toxic metals from industrial wastewaters

The discharge of toxic metals from industries is a major environmental problem. It is, therefore, crucial to find efficient methods for their removal. The present study analysed the Lagenaria siceraria (LS) peel biomass for the elimination of chromium, cobalt, copper, iron, mercury, silver and zinc from wastewaters. Formaldehyde treated and untreated biomass was also tested. The ability of the biomass to adsorb metal ions was found to depend on pH, the original concentration of ions, and the biomass treatment. With untreated biomass, the order of adsorption was copper > zinc > cobalt > iron > silver > chromium > mercury, with treated biomass, the order was copper > mercury > iron > chromium > cobalt > silver > zinc, and at pH 4–5, the order was copper > iron > cobalt > chromium > silver > zinc > mercury. The biomass had remarkable affinity for copper under all the conditions. Since LS is a vegetable cultivated on a large scale, adsorption strategies based on its biomass are expected to be convenient, eco-friendly and cost effective.

Effect of Trichoderma-enriched organic charcoal in the integrated wood protection strategy.

The gradual elimination of chromium from wood preservative formulations results in higher Cu leaching and increased susceptibility to wood decay fungi. Finding a sustainable strategy in wood protection has become of great interest among researchers. The objective of these in vitro studies was to demonstrate the effect of T-720-enriched organic charcoal (biochar) against five wood decay basidiomycetes isolated from strongly damaged poles. For this purpose, the antagonistic potential of Trichoderma harzianum (strain T-720) was confirmed among other four Trichoderma spp. against five brown-rot basidiomycetes in dual culture tests. T-720 was genetically transformed and tagged with the green fluorescent protein (GFP) in order to study its antagonistic mechanism against wood decay basidiomycetes. It was also demonstrated that T-720 inhibits the oxalic acid production by basidiomycetes, a well-known mechanism used by brown-rot fungi to detoxify Cu from impregnated wood. Additionally, this study evaluated the effect of biochar, alone or in combination with T-720, on Cu leaching by different preservatives, pH stabilization and prevention of wood decay caused by five basidiomycetes. Addition of biochar resulted in a significant Cu binding released from impregnated wood specimens. T-720-enriched biochar showed a significant reduction of wood decay caused by four basidiomycetes. The addition of T-720-enriched biochar to the soil into which utility poles are placed may improve the efficiency of Cr-free wood preservatives.

Sunlight active PSf/TiO 2 hybrid membrane for elimination of chromium

Abstract The report aims to develop and use sunlight-active catalyst-membrane to reduce toxic Cr (VI) to less toxic Cr (III) and to reject Cr (III) from Cr contaminated water. Polysulfone and TiO2 nanoparticles were hybridized, to induce a bifunctional efficacy of metal ion reduction and separation. Reduction of Cr (VI) results in the formation of Cr (III), which is larger in size facilitating rejection. Hybrid membranes possess superior hydrophilicity and permeability with an added advantage of enhanced metal ion reduction and rejection. Photoreduction of Cr (VI) requires the presence of acid to avoid accumulation of holes and hydroxyl radicals in the reaction medium. Cr (III) solution obtained after photoreduction was subjected to direct filtration without any pretreatment, so as to obtain complete Cr-free water.

Zinc and Chromium elimination from complex aqueous matrices using a unique aminopropyl-modified MCM-41 sorbent: Temperature, kinetics and selectivity studies

An aminopropyl-modified MCM-41 sorbent obtained by grafting amino groups on the surface of a previously synthesized MCM-41, was used for the removal of Cr(VI) and Zn(II) from different aqueous matrices: solutions of Zn(II) and Cr(VI) in distilled water, in distilled water with high-salt content, and in a natural river water sample. The sorbent particles are spherical with a mean diameter of ≈500nm, surface area >600m2g−1 and uniform aminopropyl function distribution. Single component adsorption batch experiments, fitted with the Langmuir model, show that MCM-41-NH2 has high removal capacity for Cr(VI) and for Zn(II), 87.5 and 58.9mgg−1, respectively. Binary component adsorption experiments show that the selectivity toward chromium oxyanions or zinc cations could be adjusted by changing the pH of the solution to be treated. When pH was fixed at acidic conditions chromium was preferentially removed, while the MCM-41-NH2 sorbent retained selectively zinc species when pH was increased up to 7. The presence of salts, either added (i.e. KCl) or natural as those present in river water, resulted in an improvement in the selectivity for both metals removal reaching values of up to 97%. The obtained results indicate that MCM-41-NH2 is an efficient and selective sorbent capable of removing Cr(VI) oxyanions and/or Zn(II) cations from complex polluted water matrices.

PNIPAm grafted amino-functionalized mesoporous silica for thermo-responsive chromium elimination

In this study, the effective elimination of Cr(VI) was achieved by thermo-responsive polymer-grafted amino-functionalized mesoporous silica (MS@APTES@PNIPAm) in aqueous solution. The MS@APTES@PNIPAm was successfully synthesized by the coupling of 3-MOP and N-isopropyl acrylamide (NIPAm) in 3-aminoproyltriethoxysilane (APTES) grafted mesoporous silica surface. The thermo-responsive elimination of Cr(VI) was demonstrated at various pH levels and at room temperature and 40°C, respectively. The characterization of the synthesized materials was achieved by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and nitrogen (N2) adsorption-desorption. The maximum adsorption of hexavalent chromium on MS@APTES@PNIPAm in aqueous solution was 123.8mgg−1 at 40°C in pH 2.5. Furthermore, the results of isotherm and kinetic experiments demonstrated that the adsorption behavior of Cr(VI) on MS@APTES@PNIPAm was well fitted to a Langmuir plot with a pseudo-second-order and intra-particle diffusion model.

Refinement of contaminated water by Cr(VI), As(V) and Hg(II) using N-donor ligands arranged on SBA-15 platform; batch and fixed-bed column methods

SBA-15 particles bearing N-donor functionalities, ethylenediaminopropyl and ethylenediaminepropylesalicylaldimine ligands (SBA/En and SBA/EnSA, respectively), were prepared and their potentials for elimination of chromium(VI), arsenic(V) and mercury(II) ions from aqueous solutions through batch adsorption experiments were studied. The adsorption processes were investigated by studying the parameters affecting the adsorption process including pH of the aqueous solutions, contact time, adsorbent dose, initial concentration of the ions, and temperature. The isotherms of the adsorption process were studied and discussed in detail. The Langmuir isotherm predicted the maximum adsorption capacities of SBA/En and SBA/EnSA for Cr(VI), As(V) and Hg(II) to be 67.1, 41.5 and 6.3mgg−1 and 76.9, 43.5 and 8.3mgg−1, respectively. It was shown that, pseudo second-order model described well the kinetics of the processes. A part of this study concerned on the evaluation of the efficiency of SBA/EnSA for removal of Cr(VI), As(V) and Hg(II) from their ternary aqueous solutions in fixed-bed column method. The effect of parameters affecting this process such as sample and eluent flow rates, bed height, sample volume, type and concentration of the eluent used, for desorption of the studied ions, on the process were assessed and discussed. The applicability of the proposed methods was examined by using them for decontamination of water samples containing the target ions.

Human biomonitoring of chromium and nickel from an experimental exposure to manual metal arc welding fumes of low and high alloyed steel.

The uptake and elimination of metals from welding fumes is currently not fully understood. In the Aachen Workplace Simulation Laboratory (AWSL) it is possible to investigate the impact of welding fumes on human subjects under controlled exposure conditions. In this study, the uptake and elimination of chromium or chromium (VI) respectively as well as nickel was studied in subjects after exposure to the emissions of a manual metal arc welding process using low or high alloyed steel. In this present study 12 healthy male non-smokers, who never worked as welders before, were exposed for 6h to welding fumes of a manual metal arc welding process. In a three-fold crossover study design, subjects were exposed in randomized order to either clean air, emissions from welding low alloyed steel, and emissions from welding high alloyed steel. Particle mass concentration of the exposure aerosol was 2.5mg m(-3). The content of chromium and nickel in the air was determined by analysing air filter samples on a high emission scenario. Urine analysis for chromium and nickel was performed before and after exposure using methods of human biomonitoring. There were significantly elevated chromium levels after exposure to welding fumes from high alloyed steel compared to urinary chromium levels before exposure to high alloyed welding fumes, as well as compared to the other exposure scenarios. The mean values increased from 0.27 µg l(-1) to 18.62 µg l(-1). The results were in good agreement with already existing correlations between external and internal exposure (German exposure equivalent for carcinogenic working materials EKA). The variability of urinary chromium levels was high. For urinary nickel no significant changes could be detected at all. Six-hour exposure to 2.5mg m(-3) high alloyed manual metal arc welding fumes lead to elevated urinary chromium levels far higher (7.11-34.16 µg l(-1)) than the German biological exposure reference value (BAR) of 0.6 µg l(-1) directly after exposure. On the other hand mean urinary nickel concentrations slightly increased, but did not exceed background levels due to lower bioavailability. We could underline with our single exposure experiment that a welding work related chromium exposure can be measured immediately after the work shift, while the same is not possible for nickel exposure due to lower nickel bioavailability. The data provide useful information for real occupational welding work places.