Removal Of Chromium Research Articles

Removal of lead (II) and chromium (VI) from simulated wastewater using extracellular polymeric substances from Penicillium expansum

Removal of lead (II) and chromium (VI) from simulated wastewater using extracellular polymeric substances from Penicillium expansum

Utilization of Base and Acid Modified Rice Husk-Corncobs Composite for Removal of Chromium (VI) Ion in Simulated Tannery Wastewater

In the ever-increasing blind race of industrialization and urbanization environmental contamination by toxic heavy metal ions is becoming a serious issue for both scientists and masses. Hence, the objective of this paper was to evaluate the utilization of base (BMOD) and acid (AMOD) modified rice husk-corncobs composite for the removal of chromium (VI) Ion in simulated tannery wastewater using appropriate standard techniques. SEM-EDX, XRD and FTIR characterizations revealed the elemental composition, crystallographic structures and the chemical bonds respectively. The results of the sorption kinetic study showed that the data fitted well with the pseudo-second order model for both acid modified (AMOD) and base modified (BMOD) biosorbent with a maximum adsorption of 28.46 mg/g and 39.66 mg/g respectively. The results of the sorption isotherm study showed that they both fitted Freundlich isotherm model. From the results obtained, rice husk and corn cob were effective biosorbent for the removal of Cr (VI) ion from tannery effluent.

Removal of Chromium Contaminated Soils by Electro-Kinetic Method

Removal of Chromium Contaminated Soils by Electro-Kinetic Method

Composite sorbent based on Fe3O4 with Fe(N2H4)xCly for the removal of Chromium(VI) from wastewater

Composite sorbent based on Fe3O4 with Fe(N2H4)xCly for the removal of Chromium(VI) from wastewater

Application of biohybrid membranes for arsenic and chromium removal and their impact on pollutant accumulation in soybean (Glycine max L.) seedlings.

Chromium and arsenic are among the priority pollutants to be controlled by regulatory and health agencies due to their ability to accumulate in food chains and the harmful effects on health resulting from the ingestion of food contaminated with metals and metalloids. In the present work, four biohybrid membrane systems were developed as alternatives for the removal of these pollutants, three based on polyvinyl alcohol polymeric mesh (PVA, PVA-magnetite, PVA L-cysteine) and one based on polybutylene adipate terephthalate (PBAT), all associated with bioremediation agents. The efficiency of the bioassociation process was assessed through count methods and microscopy. The removal capacity of these systems was evaluated in synthetic liquid medium, both in the absence and in the presence of soybean (Glycine max L.) seedlings. The content of chromium and arsenic was also analyzed in aerial and hypogeous tissues of seedlings grown on contaminated solid substrate. PVA and PVA-magnetite biohybrid membranes showed the highest removal rates, between 57 and 75% of the initial arsenic content and more than 80% of the initial chromium content after 48h of treatment, when evaluated in synthetic liquid media with initial concentrations of 2.5ppm of pentavalent arsenic and 5ppm of hexavalent chromium, both in presence and absence of seedlings. PVA and PBAT promoted a significant reduction of arsenic translocation to the aerial parts, generally edible, of this crop of agronomic interest. The systems tested showed a high potential for biotechnological applications in matrices affected by the presence of arsenic and chromium.

Complete chromium removal via photocatalytic reduction and adsorption using bimetallic UiO-66(Zr/Al)

Photocatalytic reduction is a widely researched method for removing heavy metal ions from water. This study successfully synthesized Zr-based bimetallic UiO-66(Zr/Al) materials via a solvothermal method, incorporating aluminum (Al) into the Zr-UiO-66 lattice. Characterization confirmed successful Al(III) doping without altering the fundamental framework. Among the synthesized materials, UZA-6 exhibited remarkable photocatalytic activity, achieving a 99.25 % removal rate of hexavalent chromium (Cr(VI)) from water within 60 min under simulated solar irradiation. Additionally, the catalyst effectively adsorbed the reduced trivalent chromium (Cr(III)) and maintained a removal rate of 97.73 %, thereby achieving complete removal of Cr element in water. Photoluminescence and electrochemical analyses revealed that the enhanced photocatalytic performance was due to improved separation of photogenerated electron-hole pairs and facilitated charge transfer, attributed to Al doping. This research offers valuable insights into developing effective MOF-based catalysts for water purification, highlighting the potential of UZA-6 for efficiently removing both Cr(VI) and Cr(III) from contaminated water.

Removal of Chromium and Arsenic from Water Using Polyol-Functionalized Porous Aromatic Frameworks.

Chromium and arsenic are two of the most problematic water pollutants due to their high toxicity and prevalence in various water streams. While adsorption and ion-exchange processes have been applied for the efficient removal of numerous toxic contaminants, including heavy metals, from water, these technologies display relatively low overall performances and stabilities for the remediation of chromium and arsenic oxyanions. This work presents the use of polyol-functionalized porous aromatic framework (PAF) adsorbent materials that use chelation, ion-exchange, redox activity, and hydrogen-bonding interactions for the highly selective capture of chromium and arsenic from water. The chromium and arsenic binding mechanisms within these materials are probed using an array of characterization techniques, including X-ray absorption and X-ray photoelectron spectroscopies. Adsorption studies reveal that the functionalized porous aromatic frameworks (PAFs) achieve selective, near-instantaneous (reaching equilibrium capacity within 10 s), and high-capacity (2.5 mmol/g) binding performances owing to their targeted chemistries, high porosities, and high functional group loadings. Cycling tests further demonstrate that the top-performing PAF material can be recycled using mild acid and base washes without any measurable performance loss over at least ten adsorption-desorption cycles. Finally, we establish chemical design principles enabling the selective removal of chromium, arsenic, and boron from water. To achieve this, we show that PAFs appended with analogous binding groups exhibit differences in adsorption behavior, revealing the importance of binding group length and chemical identity.

Fungal carbonatogenesis process mediates zinc and chromium removal via statistically optimized carbonic anhydrase enzyme

IntroductionWith rapid elevation in population, urbanization and industrialization, the environment is exposed to uncontrolled discharge of effluents filled with broad-spectrum toxicity, persistence and long-distance transmission anthropogenic compounds, among them heavy metals. That put our ecosystem on the verge or at a stake of drastic ecological deterioration, which eventually adversely influence on public health. Therefore, this study employed marine fungal strain Rhodotorula sp. MZ312369 for Zn2+ and Cr6+ remediation using the promising calcium carbonate (CaCO3) bioprecipitation technique, for the first time.ResultsInitially, Plackett–Burman design followed by central composite design were applied to optimize carbonic anhydrase enzyme (CA), which succeeded in enhancing its activity to 154 U/mL with 1.8-fold increase comparing to the basal conditions. The potentiality of our biofactory in remediating Zn2+ (50 ppm) and Cr6+ (400 ppm) was monitored through dynamic study of several parameters including microbial count, CA activity, CaCO3 weight, pH fluctuation, changing the soluble concentrations of Ca2+ along with Zn2+ and Cr6+. The results revealed that 9.23 × 107 ± 2.1 × 106 CFU/mL and 10.88 × 107 ± 2.5 × 106 CFU/mL of cells exhibited their maximum CA activity by 124.84 ± 1.24 and 140 ± 2.5 U/mL at 132 h for Zn2+ and Cr6+, respectively. Simultaneously, with pH increase to 9.5 ± 0.2, a complete removal for both metals was observed at 168 h; Ca2+ removal percentages recorded 78.99% and 85.06% for Zn2+ and Cr6+ remediating experiments, respectively. Further, the identity, elemental composition, functional structure and morphology of bioremediated precipitates were also examined via mineralogical analysis. EDX pattern showed the typical signals of C, O and Ca accompanying with Zn2+ and Cr6+ peaks. SEM micrographs depicted spindle, spherical and cubic shape bioliths with size range of 1.3 ± 0.5–23.7 ± 3.1 µm. Meanwhile, XRD difractigrams unveiled the prevalence of vaterite phase in remediated samples. Besides, FTIR profiles emphasized the presence of vaterite spectral peaks along with metals wavenumbers.ConclusionCA enzyme mediated Zn2+ and Cr6+ immobilization and encapsulation inside potent vaterite trap through microbial biomineralization process, which deemed as surrogate ecofriendly solution to mitigate heavy metals toxicity and restrict their mobility in soil and wastewater.

Efficient chromium(VI) removal using trioctylmethylammonium salicylate as the carrier in polymer inclusion membranes.

In this study, the ionic liquid (IL) trioctylmethylammonium salicylate (TOMAS) was prepared and incorporated into a polymer inclusion membrane (PIM) based on cellulose triacetate (CTA) as the polymer for the removal of Cr(VI). Various parameters including the effect of membrane composition (plasticizer and carrier concentration) as well as variables affecting both the feed phase and receiving solution have been investigated. Optimal results were achieved with a PIM made of 50% CTA and 50% TOMAS (% in mass) without the addition of any plasticizer. Using this PIM, Cr(VI) was effectively transported from a feed solution consisting of 10mg L-1 Cr(VI) in 0.01mol L-1 NaNO3 at pH = 2, to a receiving solution containing 0.1mol L-1 NaOH. The transport of Cr(VI) was not affected by the presence of other metals, such as Cr(III), Cd(II), Zn(II), Cu(II), and Ni(II), and a selective recovery rate of 93.61% for both single-ion and mixed-ion solutions after 24h of processing was obtained. Finally, the stability of the membrane was also investigated, with a slight decrease in efficiency observed after 5days of reuse.

Modeling of hexavalent chromium removal onto natural zeolite from air stream in a fixed bed column

The increasing use of hexavalent chromium (Cr(VI)) has exposed large populations to this environmental and occupational carcinogenic agent. Therefore, researchers have been interested in removing this substance through adsorbents. This study aimed to investigate the efficiency of natural zeolite in the direct adsorption of Cr(VI) from airflow and its adsorption modeling. In this study, a nebulizer device produced the Cr(VI) mist. The efficiency of natural zeolite in Cr(VI) adsorption from airflow, modeling of fixed column adsorption, and the effective parameters on adsorption efficiency including the initial concentration of chromium, airflow rate, and adsorption bed depth were studied. To facilitate the prediction of the performance of natural zeolite’s adsorption column, Yoon–Nelson, Thomas, BDST, and Buhart–Adams models were used. The results showed that the adsorption capacity diminished with increased airflow rate and initial concentration, while it increased with elevated height of the adsorption bed. Yoon–Nelson, Thomas, and BDST models corresponded to experimental data with a correlation coefficient of 0.9933, but the information of the Buhart–Adams model had a lower correlation coefficient (around 0.6677). In conclusion, natural zeolite can be used as an efficient low-cost adsorbent for directly Cr(VI) removing from the airflow in a fixed bed column.

Chromium removal from concentrated ammonium-nitrate solution: Electrocoagulation with iron in a plug-flow reactor

Highly concentrated ammonium nitrate (AN) solutions are characteristic of explosives manufacturing wastewaters and liquid fertilizer commodities, but chromium (Cr) contamination from corroding metal infrastructure or source impurities can pose problems. Technologies are needed to decontaminate AN from Cr without chemical alterations if AN is to be recovered as a resource. Iron-based electrocoagulation is a proven way to produce Fe(II) for reducing dissolved Cr(VI) to the less soluble and less toxic form of Cr(III), but is an untested technology for AN brines. This work examined Cr removal from synthetic wastewater with high concentrations of AN (400 g/L) by electrocoagulation in a flow-through reactor, where the effects of time, solution flow rate, applied current, and coexisting ions were analyzed. This method not only reduces Cr(VI) to Cr(III) using the produced Fe(II), but also promotes complete Cr removal from solution with the formation of insoluble Fe-Cr precipitates. A slower flow rate and higher applied current increased the removal efficiency of the reactor; furthermore, the reactor took up to one hour to reach steady state conditions, depending on the flow rate. Cr concentrations along the anode length were modeled using a simplified advection–dispersion-reaction model, providing reaction rate coefficients for various flow rates and currents. Overall, the results of this work showed that electrocoagulation with iron can be used for treatment of AN solution contaminated with Cr(VI). This work also provides design guidelines with a corresponding model for field applications in future work.

A novel adsorbent for the removal of chromium form aqueous solution by Acacia Fumosa seed shell activated carbon

In this experimental study, the activated carbon was synthesized by acid impregnation and digestion methods using Acacia Fumosa seed shell. The chromium removal was examined by altering the process conditions like carbon dose, chromium concentration, pH, and temperature and interaction time. The viability of the sorption process was examined using Freundlich and Langmuir equations. Evaluating the isotherm equations, the Langmuir equation shows more concordance compared with Freundlich equation. The feasibility of the adsorption was studied using Lagergren's kinetics equations of pseudo order equations of first and second order equations. Experimental investigation implies that the chromium removal follows pseudo-second order equation and it confines the investigation was subjected to time and concentration of chromium. The temperature effect was checked by chromium with Acacia Fumosa seed shell carbon. The Acacia Fumosa seed shell carbon alone was firmed using Gibbs free energy, enthalpy and entropy equations. The FTIR study of the synthesized activated carbon of before and after spectrum confirms the chromium adsorption. The SEM surface of the superficial layer change of carbon of initial and after chromium loaded state show viable change.

Electron beam synergetic removal of microplastics and hexavalent chromium: Synergetic removal process and mechanism

Microplastics are ubiquitous in the environment and aged microplastics are highly susceptible to absorbing pollutants from the environment. In this study, electron beam was innovatively used to treat PVC composite Cr(VI) pollutants (Composite contaminant formed by polyvinyl chloride microplastics with the heavy metal hexavalent chromium). Experiments showed that electron beam was able to achieve synergistic removal of PVC composite Cr(VI) pollutants compared to degrading the pollutants alone. During the electron beam removal of PVC composite Cr(VI) pollutants, the reduction efficiency of Cr(VI) increased from 57% to 92%, Cl− concentration increased from 3.52 to 12.41 mg L−1, and TOC concentration increased from 16.72 to 26.60 mg L−1. The research confirmed that electron beam can effectively promote the aging degradation of PVC, alter the physicochemical properties of microplastics, and generate oxygen-containing functional groups on the surface of microplastics. Aged microplastics enhanced the adsorption capacity for Cr(VI) through electrostatic and chelation interactions, and the adsorption process followed second-order kinetics and the Freundlich model. Theoretical calculations and experiments demonstrated that PVC consumed oxidizing free radical through dechlorination and decarboxylation processes, generating inorganic ions and small organic molecules. These inorganic ions and small organic molecules further reacted with oxidizing free radical to produce reducing free radicals, facilitating the reduction of Cr(VI). Cr(VI) continuously consumed the educing free radicals to transform into Cr (Ⅲ), enhancing the system oxidative atmosphere and promoting the oxidation degradation of PVC. This study investigated the formation and synergistic removal processes of PVC composite pollutants, offering new insights for controlling microplastics composite pollution.

The application of Rumex Abysinicus derived activated carbon/bentonite clay/graphene oxide/iron oxide nanocomposite for removal of chromium from aqueous solution

Rapid industrialization has significantly boosted economic growth but has also introduced severe environmental challenges, particularly in water pollution. This study evaluates the effectiveness of a nanocomposite composed of Rumex Abyssinicus Activated Carbon/Acid Activated Bentonite Clay/Graphene Oxide, and Iron Oxide (RAAC/AABC/GO/Fe3O4) for chromium removal from aqueous solutions. The preparation of the nanocomposite involved precise methods, and its characterization was performed using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) surface area analysis, and the point of zero charge (pHpzc). Batch adsorption experiments were designed using Design Expert software with a central composite design under response surface methodology. The factors investigated included pH (3, 6, and 9), initial Cr (VI) concentration (40, 70, and 100 mg/L), adsorbent dose (0.5, 0.75, 1 g/200 mL), and contact time (60, 90, and 120 min). Adsorption isotherms were analyzed using nonlinearized Langmuir, Freundlich, and Temkin models, while pseudo-first-order and pseudo-second-order models were applied to adsorption kinetics. Characterization revealed a pHpzc of 8.25, a porous and heterogeneous surface (SEM), diverse functional groups (FTIR), an amorphous structure (XRD), and a significant surface area of 1201.23 m2/g (BET). The highest removal efficiency of 99.91% was achieved at pH 6, with an initial Cr (VI) concentration of 70 mg/L, a 90 min contact time, and an adsorbent dose of 1 g/200 mL. Optimization of the adsorption process identified optimal parameters as pH 5.84, initial Cr (VI) concentration of 88.94 mg/L, contact time of 60 min, and adsorbent dose of 0.52 g/200 mL. The Langmuir isotherm model, with an R2 value of 0.92836, best described the adsorption process, indicating a monolayer adsorption mechanism. The pseudo-second-order kinetics model provided the best fit with an R2 value of 0.988. Overall, the nanocomposite demonstrates significant potential as a cost-effective and environmentally friendly solution for chromium removal from wastewater.

Characteristics of Removal of Lead, Cadmium and Chromium from Soil Using Biosorbent and Biochar

The study proposed the use of aspen wood sawdust and biochar derived from this sawdust for the removal of Pb(II), Cd(II), and Cr(VI) ions from soil in systems containing single metals as well as a mixture of all the studied metals. The effectiveness of the applied sorbents was compared with the sorptive properties of activated carbon. The results showed that all the tested materials reduced the metal content in the soil, and the obtained biochar was able to sorb lead, cadmium, and chromium ions in both studied systems. The influence of the type of sorbent, its dose, process duration, and the impact of metal on the removal efficiency and sorption capacity was analyzed. A statistical analysis of the obtained results was also conducted, determining the influence of process parameters on the removal capabilities of metal ions. The highest Pb, Cd and Cr ion removal efficiencies were obtained in a 36-day process at a sorbent dose of 10%. Aspen sawdust, biochar and activated carbon removed 46%, 50% and 71% of Pb(II), 35%, 43% and 53% of Cd(II) and 15%, 27% and 38% of Cr(VI), respectively. In turn, the highest sorption capacity values were achieved in a 36-day process at a sorbent dose of 2%, obtaining results of 20.2 mg/g, 22.3 mg/g and 23.2 mg/g of Pb(II), 5.1 mg/g, 7.9 mg/g and 11.7 mg/g of Cd(II) and 3.8 mg/g, 5.8 mg/g and 8.5 mg/g of Cr(VI), respectively. It was found that both raw aspen wood sawdust and biochar derived from this wood are effective in removing toxic metal ions from soil, which presents a potential solution to their presence in the natural environment.

Design of biocompatible gelatin hydrogels reinforced with magnetite nanoparticles: Effective removal of chromium from water environment

The development of biocompatible adsorbents is vital for environmental remediation to control and reduce pollution and waste accumulation in ecosystems. Biocompatible hydrogels represent an innovative class of materials that are primarily composed of polymer chain units forming their structural framework. They have a high affinity for water molecules. This research thus aims to incorporate iron oxide particles into the gelatin matrix to produce gelatin hydrogel beads to remove hexavalent chromium from an aqueous solution. The synthesized beads, known for their consistent size, low friction, high specific surface area, mechanical stability, and lightweight characteristics, demonstrated their suitability for various industrial applications. The effectiveness of these hydrogels in removing hexavalent chromium ions was confirmed through a thorough analysis using techniques such as FTIR, TGA, SEM, EDX, VSM, and XPS. Batch experiments revealed that the gelatin-based nanocomposite beads exhibited optimal adsorption efficiency under acidic conditions, lower initial concentrations of chromium ions, extended contact time, and elevated temperature (50–60 °C). The composite achieved a maximum removal efficiency of 99% at pH 1, with an adsorbent dose of 0.5 g at 50 °C, and an initial concentration of 50 mg per liter. The use of 0.7 N NaOH in the regeneration process resulted in a commendable 70.5% desorption efficiency, enabling potential reuse and regeneration. Significantly, the desorption efficiency remained consistently high even after four desorption-readsorption cycles, contributing to the economic and environmental sustainability of chromium removal. Additionally, the study determined that the sorption process was feasible, spontaneous, and endothermic. These collective findings suggest that magnetic gelatin hydrogel beads could serve as a cost-effective alternative adsorbent for the efficient removal of chromium ions from aqueous solutions.

Design and Synthesis of Imidazole‐Modified Reduced Gaphene Oxide Possessing More Ligands for Removal of Methylene Blue and Chromium

AbstractA new imidazole‐modified reduced graphene oxide was synthesized through a substitution reaction between amino imidazole and chlorographene. Functional groups and material composition were characterized by using several methods. The N content of product is high, it possesses more ligands. These ligands still combine metal ions under acidic conditions. Adsorption for methylene blue can be fitted by quasi‐second‐order kinetics and Langmuir isotherm model, physical adsorption is the predominant adsorption mechanism. Adsorption capacity (350.7 mg/g) of product for Cr (III) is about fourfold higher than that (74.7 mg/g) of reduced graphene oxide.

Two-dimensional MXene and molybdenum disulphide for the removal of hexavalent chromium from water: A comparative study

Chromium is a carcinogenic heavy metal that accumulates in plant and animal bodies. New materials for efficient removal of chromium from water bodies are in high demand. MXene was synthesized from MAX phase by using ammonium fluoride as an etching agent while molybdenum disulphide was synthesized by hydrothermal method. The pseudo-second order kinetic model described the adsorption of hexavalent chromium on MXene and molybdenum disulphide whereas the Freundlich Isotherm model best fitted for Mxene, and Langmuir Isotherm model was more suitable in case of molybdenum disulphide. The adsorption capacity obtained by MXene for hexavalent chromium was 59.8 mg/g (At Dosage = 1 g/L, T = 298 K, Time = 9 h, pH = 2, Co = 30 mg/L) and 113.7 mg/g in case of molybdenum disulphide (At Dosage = 0.5 g/L, T = 298 K, Time = 1.5 h, pH = 2, Co = 30 mg/L). Thermodynamic investigations showed that the process was endothermic and spontaneous. The coexisting ions showed a decrease in removal percentage up to 70 % and 79 % in case of MXene and molybdenum disulphide, respectively, after fifth cycle. It can be inferred that these developed materials have the advantages of simplicity for reducing heavy metal pollution.

Phytoremediation of Cr(VI)-rich wastewater using Water Hyacinth, Water Lettuce and Duckweed

Chromium(VI) contamination is carcinogenic and largely anthropogenic, stemming from specific industries. With Bangladesh experiencing rapid industrialization, the increasing number of industries necessitates an economic and sustainable secondary treatment process to maintain acceptable chromium levels. Phytoremediation, an environmentally friendly biochemical technique, has been extensively researched, particularly in the context of constructed wetlands. However, due to land scarcity and legal issues a constructed wetland is not the most viable option. In this study, three native aquatic plants—Eichhornia crassipes (Water Hyacinth), Pistia stratiotes (Water Lettuce), and Lemna minor (Duckweed)—were chosen to evaluate their effectiveness in removing chromium from wastewater. These plants underwent testing with five different chromium concentrations (1 mg/L, 2 mg/L, 3 mg/L, 4 mg/L, 5 mg/L) and two pH values (6 and 8) using natural ditch water as the feed solution. All the experiments were performed for 7 days in duplicate, along with a control experiment of chromium without plants. The study was conducted at Shahjalal University of Science and Technology campus, Bangladesh, from May 25 to June 1, 2023. Atomic Absorption Spectrometer was employed to measure Cr(VI) concentration, revealing average chromium removal rates of 29.4%, 81.1%, and 81.5% for Eichhornia crassipes, Pistia stratiotes, and Lemna minor, respectively, after seven days. Notably, on day three, Lemna minor exhibited the highest average removal efficiency at 84.7%.

Energy cost prediction for chromium removal by nanofiltration membrane

Abstract This paper aims to investigate the energy cost of eliminating Cr(VI) by nanofiltration membranes (NF). The modified pore flow model was utilized to predict the performance of NF membrane in terms of ion retention and water productivity. Then, the energy cost was estimated according to the obtained results from this model as well as available data from literature. The effect of feed flow, applied pressure, and temperature on energy cost were highlighted and thoroughly assessed. It is shown that high retention values can be achieved with relatively high energy cost. Nonetheless, energy cost of 0.04 $/m3 have been estimated for Cr retention less than 95 % at a pressure of 5 bar. It is also assessed that feed flow has a significant influence on energy cost relative to other operating parameters. In particular, increasing feed flow from 40 to 760 L/h leading the energy cost to be increased by twelve times. At high feed flow, however, energy cost can be largely reduced by applying pressure higher than 10 bar. It is concluded that high feed temperature is favored if there is no need for heating equipment.