Removal Rate Of Chromium Research Articles

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%.

Preparation of PANI-SA/CF anode to enhance the remediation and power generation capabilities of plant microbial fuel cells for chromium contaminated soil.

Plant microbial fuel cells (PMFCs) has important value for soil remediation and power generation. To improve the performance of PMFCs, a PMFC experimental system was established based on potted scindapsus aureus. Polyaniline (PANI) and sodium alginate (SA) were used as modifiers to prepare PANI-SA modified carbon felt anode. The soil remediation ability and electricity generation ability of PMFCs with four different anodes were compared and analyzed. The experimental results show that the steady-state voltage, the removal rate of hexavalent chromium, and the total chromium removal rate of PMFC using PANI-SA modified anode were 5.25mV, 98%, and 90%, respectively, which are 253%, 10.4%, and 10% higher than those of PMFCs using unmodified carbon felt anode. PMFC is effective and feasible for removing soil chromium pollution and achieving efficient soil remediation, while modifying anodes with PANI-SA can further improve the soil remediation and electricity generation capabilities of PMFC.

Iron-carbon micro-electrolysis simultaneously enhanced nutrient and heavy metal removal in constructed wetlands for purifying polluted groundwater with variable hydraulic loadings

Heavy metal and nitrate pollution, as a primary water quality issue in shallow groundwater, is posing a severe threat to public health from drinking groundwater. In this study, iron-carbon (Fe-C) fillers were applied in constructed wetlands (CWs) to enhance the nutrient and heavy metal removal simultaneously, while the interaction of effective nitrate reduction and heavy metals mitigation under variable influent hydraulic loadings was also investigated. Groundwater is not conducive to biological heterotrophic denitrification due to its low dissolved organic matter content. Fe-C fillers can form plentiful microscopic galvanic cells and act as inorganic electron donors to promote the autotrophic denitrification process. The results showed that Fe-C micro-electrolytic CWs showed excellent simultaneous removal of nutrients and heavy metals. The nitrate nitrogen (NO3–-N) removal rate was as high as 75.77% due to the increased autotrophic denitrification process, while the removal of total nitrogen (TN) and total phosphorus (TP) could reach 73.72 % and 89.04% with a low nitrous oxide (N2O) emission of 12.12 μg m-2h−1. Besides, the removal rates of chromium (Cr) and lead (Pb) reached 98.96% and 97.09%, respectively. However, the presence of heavy metals might inhibit denitrification by competing with nitrite for electrons and generating free radicals, which decreased the denitrification by 10.02–39.05% particularly with the increasing of the hydraulic loading. On the other hand, heavy metals promoted TP removal by forming metal phosphate precipitates and complexations with phosphorus. This study provides comprehensive insights into processes and mechanism of simultaneous nutrient and heavy metal removal in CW.

Engineering design of n/p-type nano heterojunctions loaded on cotton cellulose nanocrystal surface: Removal of pollutants and supercapacitors applications

The target of work illustrates the importance of obtaining clean water production via the engineering design of nano heterojunction between n/p-type nanomaterials loaded on the cellulose nanoparticles (NPs) surface. The various tools used for confirmation of the fabrication of the hybrid nanomaterials (HNM) such as electron microscopy (Transmission TEM and scanning SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In the photocatalytic and adsorption process used to clean the water from the different pollutants such as Methylene blue (MB) and Rhodamine B (RhB), the rate of photodegradation is 8.98 × 10−4 min−1 ± 1.611 × 10−4 and 0.011 min−1 ± 5.11 × 10−4 for RhB and MB dye respectively. While the mixed dye (RhB-MB) is 3.374 × 10−4 min−1 ± 1.49 × 10−4 for RhB and 0.00829 min−1 ± 4.99 × 10−4 for MB. The removal of imidacloprid insecticide under a visible light source, where the rate is 0.00835 min−1 ± 2.06 × 10−4. The removal rate of chromium (Cr+3) is 0.0034 ± 4.89 × 10−4 and the efficiency of degradation was 56 %. The supercapacitor and energy storage are detected by impedance spectroscopy via the cyclic voltammetry technique. The glucose sensor is studied via spectroscopy and electrochemical techniques, also antioxidant activity is studied with the fabricated electrode. The cytotoxicity of the fabricated material is detected with the cell line. The nanocomposite is a promising candidate for water clean production, biosensor, and energy applications.

Highly efficient adsorption of chromium on N, S-codoped porous carbon materials derived from paper sludge

The synergistic effect of heteroatoms is a viable method to enhance the adsorption performance of heavy metal onto carbon-based materials. However, the high cost, complex operation and a lot of pollution from the synthesis process have limited its development. Herein, a facile two-step pyrolysis method is used to prepare in situ N and S doped porous biochar from paper mill sludge for the removal of Cr(VI) from aqueous environment. The NSC-450 sample prepared under the optimum conditions has a large specific surface area of 3336.7 m2 g−1, an average pore size of 2.56 nm and a total pore volume of 2.10 cm3 g−1, manifesting the excellent adsorption capacity of 356.25 mg g−1 for Cr(VI). The adsorption of Cr(VI) by NSC-450 is consistent with the Langmuir isotherm and pseudo-second-order model, suggesting a spontaneous and endothermic chemisorption process. The analysis results show that the NH, graphitic nitrogen and thiophene structures have a positive effect on converting a large amount of Cr(VI) to Cr(III) by synergistic reduction, indicating obviously facilitating Cr(VI) removal compared to other sites. Therefore, in this material, the strong adsorption mechanism is mainly reductive complexation. Moreover, the effects of real water quality, anions, cations and fulvic acid on the adsorption behavior of Cr(VI) onto the NSC-450 were further investigated. The results demonstrate that the chromium removal rate remains above 82% even in actual electroplating wastewater, suggesting NSC-450 has great practical application prospect. This work offered a feasible method for high-value utilization of sludge, but also provided a novel perspective for the future design of heteroatom-doped carbon materials for promoting to eliminate hexavalent chromium from water environment.

Photolysis Effect of Muyu Stone/Magnetism Chitosan Microspheres on Chromium in Source Water

In this paper, Fe3O4 magnetism chitosan was made by emulsification crosslinking method. Muyu stone/Magnetism Chitosan Microspheres were prepared by embedding, and then used to photolysis chromium in source water. Based on single factor test, the experimental condition was optimized by quadratic regression orthogonal rotatable composite factorial design. The orthogonal regression model between the removal rate of Cr6+ (y) and microspheres dosage (x1), solution pH value (x2), reaction time (x3) was established as y=88.335+1.380x1+1.468x2+2.217x3-4.465x12-2.556x22-1.266x32+2.363x1x2+4.313x1x3-0.636x2x3. It can be inferred from the model that the removal rate of Cr6+ can reach 93.93% under these conditions of microsphere dosage of 2.444g, pH value of 4.6 and reaction time of 80.4min. Microsphere dosage of 2.444g,pH value of 4.6 and reaction time of 80.4min. Under these conditions, chromium removal rate reaches 93.13%.

Rapid adsorption of Pb (II) and Cr (VI) from aqueous solution by Aluminum hydroxide nanoparticles: Equilibrium and kinetic evaluation

Pollution of water due to excessive lead and chromium levels in groundwater and wastewater has contributed to severe health issues, which has increased concern over the provision of clean water. There is a dire need for successfully eliminating these pollutants through the use of low-cost and ecosystem-friendly materials. This paper reports the synthesis of aluminum hydroxide nanoparticles of 9.9 nm as calculated through X-Ray Diffraction (XRD) analysis. Fourier-transform infrared spectroscopy (FTIR) and pH of Point Zero Charge (pHPZC) were used to establish nanomaterial and surface charge formation on the material. The effects of the various parameters, i.e., the number of nano adsorbents, contact time, initial heavy metal concentration, and pH, were examined in detail on the lead and chromium removal rate. Kinetic studies were reported to fit better with the second-order kinetics model, and experimental adsorption equilibrium data fitted well with the Freundlich isotherm model under optimized conditions. The maximum removal of 95% for Pb(II) obtained for nano adsorbent dose was: 0.5 g/L, pH: 5.5, initial lead concentration: 10 mg/L at 30 min of contact time, and maximum removal of 97% for Cr(VI) for nano adsorbent dose: 1 g/L, pH: 5, initial: 15 mg/L and 60 min of contact time.

Effects of Phytoremediation on industrial wastewater

Due to the development of industry, there are different levels of heavy metal pollution in domestic waters, and the treatment of heavy metal pollution is also imminent. As a hot plant for phytoremediation, Leersia hexandra Swartz has a good effect on remediation of chromium, copper and nickel polluted water. The highest removal rates of chromium, copper and nickel are 100%, 93.8% and 89.3% respectively. Leersia hexandra Swartz also has good enrichment characteristics of chromium, copper and nickel in heavy metal contaminated soil. In the soil containing chromium, copper and nickel, Leersia hexandra Swartz can grow normally and has strong tolerance to high concentration of heavy metal contaminated soil, which indicates that Leersia hexandra Swartz has certain research value in the field of remediation of heavy metal contaminated soil or water.

Nanofiltration and microfiltration for the removal of chromium, total dissolved solids, and sulfate from water

This study was designed to evaluate the hybrid system performance of nanofiltration (NF) and microfiltration (MF) processes in removing the hexavalent chromium (Cr(VI)) and sulfate from water. To do so, we made a hybrid pilot, including 1 μm and 5 μm filters, sand filter, activated carbon filters, and a nanofilter. We studied the effects of various parameters on the removal of Cr(VI) from polluted water and drinking water such as pH, pressure, concentrations of chromium, concentrations of sulfate, and total dissolved solids (TDS). The selected parameters were as follows: pressure: 0.1-0.4 MPa, pH: 2–10, Cr(VI) concentration: 0.1–0.4 mg/l, and sulfate concentration: 40–500 mg/l. According to the results, the efficiency of chromium removal increased with increasing the pH, while increasing the pressure from 0.1 to 0.4 MPa decreased the removal rate of chromium. In addition, increasing the concentrations of sulfate led to a decreasing trend in the removal efficiency. According to the findings of the study, the hybrid pilot made is able to reduce the chromium and sulfate to the levels under the WHO standard (Cr(VI) = 0.05 mg/l and sulfate = 500 mg/l).•The optimal conditions for removal of Cr(VI) included the initial chromium concentration of 0.1 mg/l, pressure of 0.1 Mpa, pH of 10, and the sulfate concentration of 40 mg/l.•In general, the experimental results revealed that the fabricated hybrid system including MF, NF, sand filter, and carbon filter has the ability to remove chromium and sulfate from drinking water (tap water) at a rate of 99%.•At sulfate concentration of 40 mg/l, the TDS elimination efficiency was 97.75% and increased by 99.87% as the concentration increased to 500 mg/l. The presence of sulfate ions increases the TDS in water.

Heavy Metal Treatment of Municipal Wastewater Based on Chemical Oxidation

In this paper, based on the existing research, one innovative method for synthesizing poly(m-phenylenediamine) (PmPD) polymer using the chemical oxidation was presented, and the prepared PmPD was used for the treatment of chromium in wastewater. Then, the mechanism of PmPD in the treatment of chromium was studied. The results show that the best method for PmPD synthesis is the drop-by-drop method; 25 °C is the optimum polymerization temperature of PmPD and 5h response time is the optimal synthesis time of the polymer. At pH=2, the removal rate of chromium from wastewater by PmPD polymer reaches more than 80%, and the removal effect of PmPD(Na2CO3)2 on chromium is the best. At pH>7 (the alkaline solution), the PmPD polymer has almost no effect on the removal of chromium. With the same amount of PmPD polymer, the higher the temperature, the better the removal rate of chromium ion by PmPD polymer; the higher the initial chromium ion concentration, the lower the chromium ion removal rate.

Performances of purified indigenous Leifsonia sp. and its mechanism in the removal of Cr(VI) under shaking condition

The increasing discharge of wastewater with chromium(VI) plays adverse impacts on the environment in recent years. This study purposes to investigate the adsorption efficiency and removal mechanism of chromium(VI) via a purified indigenous bacteria (Leifsonia sp.). The effect of varying pH, initial chromium(VI) concentration, dosage of dry biosorbent, contact time and temperature on the adsorption efficiency of chromium(VI) was studied via single-factor experiment. Our results demonstrate that the strain has high efficiency of adsorbing chromium(VI) from aqueous solution. The maximum removal rate of chromium(VI) was 95.4% when pH was 2 (range 1.5–9.0), contact time was 4 h, the initial chromium(VI) concentration was 10 mg/L and the temperature was 30 °C (10–50 °C). Freundlich isotherms fit the adsorption process well, and the adsorption kinetics is consistent with the pseudo-secondary kinetic model. Furthermore, the adsorption mechanism was elucidated via FTIR and XPS, indicating that chromium precipitates on the biosorbent surfaces are a mixture of chromium(VI) and chromium(III). It is implied that physisorption and chemisorption proceed at the same time during the chromium(VI) adsorption process. These findings show that Leifsonia sp. as a biosorbent displays excellent adsorption efficiency, having the potential to remove chromium(VI) from aqueous solutions.

Chromium removal from solution by five photosynthetic bacteria isolates.

Biological method has been recognized as a low-cost and ecofriendly approach for removing heavy metals from aqueous wastes. In this study, the ability of five photosynthetic bacteria isolates (strains labeled SC01, HN02, SC05, JS01, and YN01) was examined for their ability to remove Cr from Cr-containing solutions. Furthermore, the possible removal mechanisms were elucidated by comparing chromium removal rates, antioxidant reaction, and accumulation of reactive oxygen species (ROS). Among the five bacteria, strains SC01 and SC05 presented the highest removal rates of chromium ions and the activity of cysteine desulfhydrase under Cr stress. They also showed lower levels of ROS and cell death than the other three bacteria strains under Cr stress. In addition, total bacteriochlorophyll content and activities of six antioxidant enzymes in SC01 were highest among these selected strains. On the contrary, strain HN02 presented the lowest level of Cr removal and the lowest activities of antioxidant enzymes. It also exhibited the highest level of ROS under Cr(VI) stress. Overall, these results show that the strains SC01 and SC05 have good Cr removal ability and could be used for removal of Cr in industrial effluents.

Removal of Cr(VI) ions from waste water by electrocoagulation using iron electrode

The performance of electrocoagulation using iron electrodes for the treatment of aqueous solutions containing chromium hexavalent ions using fixed bed electrochemical batch reactor was studied. A new anode design consisting of hex nuts was connected together with a thin rode of iron. The helical shape in the nuts increases the anode surface area allowing high chromium removal rate within very short coagulation time. The effect of different parameters affecting the electrocoagulation process, such as initial hexavalent chromium concentration, applied current, electrolyte type [sodium chloride and sodium sulfate] concentration and initial pH of the solution was investigated. The optimum conditions for the EC process by using the present cell based on minimum initial hexavalent chromium concentration, energy consumption and operating cost were 100mg of Cr(VI)/l, 0.55A, 1.5g of sodium chloride/land pH of 1.

Study on Treatment of Chromium(VI) Wastewater by Cuprous Oxide

Cuprous oxide catalyst was prepared and applied as photocatalist to treat chromium (VI) in wastewater, and the photocatalytic activity of the cuprous oxide was studied. The optimal conditions for the treatment was as follows: the pH of wastewater was 3, the amount of catalysts was 0.3 g/L, the reaction temperature was 60°C. Under the optimal conditions, the removal rate of chromium (IV) in wastewater reached 50% in the presence of cuprous oxide catalyst.

Study on the Removal Effect of Chromium(VI) in Wastewater by Rice Husk

Rice husk was used as an adsorbent to study the adsorption of Cr (VI) from wastewater, Based on the experimental studies on influences of the particle size of rice husk, solution pH value, adsorption time, temperature and rice husk dose, the optimal conditions of the adsorption were determined as follows: temperature of 35°C, pH of 2, the particle size of rice husk in the range of 80-100 mesh, adsorption time of 3h, dose of 30g/0.2g. Under the optimal conditions, the removal rate of chromium from wastewater by rice husk can reach 91%.

Desalination combined with hexavalent chromium reduction in a microbial desalination cell

The microbial desalination cell (MDC) was a novel technology to desalinate saline water, simultaneously producing electricity and treating wastewater. In our research, an MDC using a synthetic Cr (VI)-containing wastewater as the catholyte was used to desalinate brine in the desalination chamber and simultaneously to reduce Cr (VI) in cathode chamber. Below a pH value of 2.0 with an initial Cr (VI) concentration of 100mg/L, the hexavalent chromium removal rate was 75.1±3.8% with a current density 760mA/m2, and the desalination rate was 2.1mg/h. As the initial concentration of chromium increased from 200 to 1000mg/L, the current density also increased from 884.8mA/m2 to 1339.8mA/m2, with an increase in the salt removal rate from 2.2mg/h to 3.0mg/h. The analyses of scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) indicated that the Cr (VI) was reduced to Cr2O3 and deposited on the cathode surface. The deposition of Cr2O3 on the cathode surface would affect the performance of the MDCs. These results suggested that an MDC using Cr (VI) as an electron acceptor could further enlarge the application range of MDCs.

Study on Adsorption of Chromium in Wastewater by Diatomite

Adsorption ability of chromium in wastewater by purified diatomite as the adsorbent material was studied. The influence of the diatomite dosage, adsorption time, chromium concentration, pH value and reaction temperature to chromium removal rate was got. The results show that under the condition of the diatomite dosage of 9.0g, adsorption time of 90 min, chromium concentration in wastewater of 5mg/L, wastewater pH of 6, and temperature of 30°C, diatomite adsorption removal rate to hexavalent chromium can reach 91.6%. The main adsorption mechanism is the combination of physical adsorption and chemical adsorption, and the latter is dominant. The cost of diatomite as adsorbent is low, and a good removal rate of chromium can be reached, which provides a solid theoretical basis for the removal of chromium in wastewater.

REMOVAL OF HEXAVALENT AND TOTAL CHROMIUM FROM AQUEOUS SOLUTIONS BY PLUM (P. domestica L.) TREE BARK

The main purpose of the present work was to evaluate the potential of plum (P. domestica L.) tree bark (PDB) to remove Cr(VI) and total chromium from aqueous solutions in batch systems. Experimental data showed that the Cr(VI) and total chromium removal capacity was dependent on operating variables such as PDB particle size, PDB pretreatment, solution pH, initial Cr(VI) concentration, and contact time. The mechanism of Cr(VI) removal by PDB implies two simultaneous processes: 1) the reduction of Cr(VI) to Cr(III), and 2) the biosorption of chromium ions. Cr(VI) and total chromium removal rates were affected to a significant extent by PDB particle size. Hydrochloric acid pretreatment proved to be optimum to increase the total chromium biosorption capacity of PDB, whilst also reducing the time needed to reach equilibrium. The optimum pH value for removal of Cr(VI) and total chromium was 1.0-2.0 and 2.0, respectively. Significant enhancement of Cr(VI) and total chromium removal was observed by increasing initial Cr(VI) concentration. The biosorption kinetic data of total

Treatment of chromium‐bearing wastewaters with constructed wetlands

AbstractChromium can have detrimental effects on most organisms, including humans. The present study focused on the effect of treating chromium‐bearing, organic‐rich wastewater on constructed wetland performance. Eight laboratory‐scale systems were used to study organic matter and chromium removals, with three features tested in duplicate: media with proven chromium sorption capacity, vegetation presence and intermittent influent loading. A set of two wetlands acted as the base design. Average BOD5 and chromium removal rates were 13.4 g/m2 day and 135 mg Cr/m2 day, respectively. From an influent chromium concentration of 5 mg/L, <0.5 mg/L could be detected at the outlet during the study in all systems. Chromium removal efficiencies were statistically different for all systems (P<0.01), except when comparing the base design against the intermittent feed systems (P>0.05). Overall treatment performance of all systems was remarkably good in spite of significant chromium content and salinity.

Hexavalent chromium sorption by biomass of chromium tolerant Pythium sp.

The removal of Cr(VI) from aqueous solutions by live and pretreated fungal biomass of Pythium sp was investigated in a batch mode. The influence of biomass dose, solution pH, initial metal ion concentration, temperature and pretreatment of biomass on biosorption efficiency was studied. The acid pretreated biomass adsorbed 1.7 times more hexavalent chromium in comparison to untreated biomass. The chromium removal rate increased with decrease in pH and increase in Cr(VI) concentration, biomass dose and temperature. The adsorption data was described well by Freundlich isotherm model. Evaluation of biosorption mechanism using infrared spectroscopy showed the involvement of positively charged amino groups in Cr(VI) biosorption. The biosorption of Cr(VI) by Pythium sp. followed second order kinetics, the biosorption process was found to be spontaneous and endothermic with high affinity of biomass for Cr(VI).