Metal Removal Process Research Articles

Composite Treatment Module for Removing Acidity and Metal (Loid)S from Acid Rock Drainage

This study evaluates a two-stage approach for remediating acid rock drainage (AMD) generated from an abandoned coal mine site. The method combines the adsorption and chemical precipitation properties of drinking water treatment residue (WTR) in a continuous flow-through fluidized filter bed with hydroponic phytoremediation using Vetiver grass to remove dissolved metal(loid)s. In the first stage, the filter demonstrated exceptionally high removal efficiencies for several metals, including up to 99.67% of Al (<1 mg/L), 99.46% of Fe (<2 mg/L), and 92.48% of As. Significant removal efficiencies were also achieved for Zn (69.24%) and Cu (62.85%). However, relatively low removal efficiencies were observed for Mn (12.50%), Ni (26.74%), and Co (21.36%). Additionally, the system effectively reduced acidity, increasing the pH from 2.67 to a near-neutral level of 6.13. The second stage, a 30-day Vetiver grass treatment, further reduced Mn concentrations by 56.9%, improving upon the limited Mn removal observed in the fluidized filter column. This underscores the complementary role of hydroponic phytoremediation in enhancing the overall metal removal process. This innovative and cost-effective system demonstrates significant potential for AMD remediation, achieving simultaneous removal of metal(loid)s and neutralizing acidity in contaminated mine water.

Elimination of nickel ions in a packed column using clamshell waste as an adsorbent

The present investigation assessed the viability of utilizing a powdered clam shell in continuous adsorption to eliminate nickel ions from simulated wastewater. The breakthrough curves (BTC) were analyzed by altering the Q (inlet flow rate) in a glass column (ID 5 cm, H 35 cm) with a multi-port and filled with the powdered clamshell adsorbent (PCSA). The PCSA’s nickel adsorption efficiency was maximum (87.68%) with Q = 8 mL/min at a bed length (H) of 25 cm with 1.05 mg/g adsorption capacity. Moreover, the mass transfer zone (MTZ) and idle bed length (Lu) were estimated from the corresponding BTC. The values of MTZ and Lu demonstrated fluctuations in response to changes in bed length, suggesting the presence of non-ideal circumstances. The validity of the Thomas model for predicting column dynamics was established, and the associated model parameters were assessed. Additionally, the parameters of the BDST model were assessed in order to aid in calculating the sufficient depth for a packed bed column (PBC) while scaling up. Therefore, a metal removal process from industrial effluent can be efficiently achieved by utilizing a PBC of powdered clamshell adsorbent.

Application of Direct Metal Laser Sintering for the Electrode Production and Study of Associated Process Parameters

The manufacturing sector is greatly influenced by the application of modern metal removal processes for the production of complex part geometries, the processes being non-conventional, versatile and more precise. Selective laser sintering is an additive manufacturing process which produces three-dimensional objects by fusing the powdered metal layer-by-layer in the presence of laser light. This work focuses on the manufacturing of electrodes by Direct Metal Laser Sintering and evaluating the influence of process parameters on the output responses under consideration. Laser power, scan speed, laser spot size, layer thickness, porosity and hatch spacing are the process parameters affecting the electrode production process. Sintering depth, energy density, relative density and ultimate tensile strength are the output responses. The experimental analysis examines the impact of the process parameters on sintering depth for the powdered Aluminium Alloy 6061. Optimised parameters are found to be 120W laser power, 285mm/s scanning speed, 15% porosity, 0.2mm laser spot size and 2.04mm layer thickness. Taguchi method is one of the techniques to obtain optimised electrode production by Direct Metal Laser Sintering.

A comprehensive review on the role of biosurfactants in remediation of heavy metals from contaminated environment

The hazardous nature of heavy metals (HMs) in the ecosystem has drawn global attention due to its emergence as a major environmental and public health concern. As toxic metals are non-degradable, they affect not only animals but also human beings and vegetation. These HMs are long-lasting pollutants that travel vast distances from their site of origin in the environment and bioaccumulate in humans and other organisms through the food chain. These pollutants can cause extensive pollution since they are frequently produced by industrial activities and inappropriate disposal procedures. Biosurfactants’ (BSs) versatility makes them an appealing category that plays an essential role in various biotechnological applications for environmental remediation. BSs have a variety of characteristics, including metal binding, solubilization, and emulsification. They remediate the HMs through processes like complexation, ion exchange, and metal solubilization. Furthermore, owing to their amphiphilic nature, they improve the sorption and solubility of hydrophobic contaminants and reduce the surface area and interfacial tension of immiscible liquids. As a result, BS-based remediation plays an important part in the heavy metal removal process in multiple ways. This review aims to provide information on the function of BSs in eliminating HMs through bioremediation processes for environmental sustainability.

Study on the Influence Law of Micro-Scale Abrasive Wear on a Wind Turbine Brake Pad

The hard particles in the copper-based powder metallurgic material of a brake pad for a wind turbine brake falls off and presses into the surface of the brake disc to form abrasive particles under high-speed and heavy-load working conditions. The presence of abrasive particles will produce abrasive wear with micro-scratch and micro-scribe on the copper-based material of the brake pad. The critical scratch depth effect in the abrasive wear process is proposed based on the critical depth effect of the metal removal process at the micro-scale. The abrasive wear is divided into two types: scratch wear and scratch wear, which is proposed according to the comparison of the actual scratch depth and the critical scratch depth. The range of braking speeds and friction coefficients in abrasive wear is determined by the recommended parameters of the disc brake. The ABAQUS2020 software is used to simulate and analyze the micro-scale abrasive wear of a brake pad. The brake strain/stress curves of the brake pad under different brake speeds and friction coefficients are compared and analyzed for two abrasive wear types based on the range of braking parameters, and the key factors affecting abrasive wear are proposed.

Detoxification and removal of heavy metal by an acid-tolerant microalgae, Graesiella sp. MA1

Detoxification and removal of heavy metal by an acid-tolerant microalgae, Graesiella sp. MA1

Performance of Teflon- reinforced Nafion against microbes and removal of heavy metal ions from aqueous environment

Performance of Teflon- reinforced Nafion against microbes and removal of heavy metal ions from aqueous environment

Performance evaluation of electrocoagulation process for removal of heavy metals from wastewater using aluminum electrodes under variable operating conditions

Performance evaluation of electrocoagulation process for removal of heavy metals from wastewater using aluminum electrodes under variable operating conditions

OPTIMISATION OF TECHNOLOGY AND SELECTION OF BIOSORBENTS BASED ON HAWTHORN, MOUNTAIN ASH AND MOTHERWORT TO IMPROVE THE QUALITY OF FERMENTED MILK PRODUCT

The accelerated development of urbanisation brings with it environmental problems and adverse effects on human health. Air pollution, water pollution and limited access to natural resources are becoming serious challenges. However, innovative products incorporating enterosorption technologies present a potential solution to improve public health. These products contribute to the effective removal of toxic substances from the body, mitigating the negative health effects of urbanisation.In the context of yoghurt with LABR, it has been found to be more stable to whey separation and moisture retention. Prebiotics have a positive effect on water retention, although this effect may diminish over time. The optimal concentration of LABR bacteria also emphasises the importance of a precise balance, after which additional increases do not bring significant improvements. These results can be used to optimise the production of yoghurt, taking into account its structure and properties over its shelf life.Considering the study data, it can be concluded that an optimal combination of L. acidophilus bacterial concentration and metal concentration, reached on the fourth day after the addition of prebiotics, is necessary to maximise the efficiency of heavy metal bioremediation. These results have practical implications for heavy metal removal processes in aqueous media, providing a basis for optimising bioremediation conditions in industrial and environmental applications.

Efficient removal and transformation of Cr(VI) from alkaline wastewater to form a ferrochromium spinel multiphase via a modified ferrite process

Chromium-containing wastewater causes serious environmental pollution due to the harmfulness of Cr(VI). The ferrite process is typically used to treat chromium-containing wastewater and recycle the valuable chromium metal. However, the current ferrite process is unable to fully transform Cr(VI) into chromium ferrite under mild reaction conditions. This paper proposes a novel ferrite process to treat chromium-containing wastewater and recover valuable chromium metal. The process combines FeSO4 reduction and hydrothermal treatment to remove Cr(VI) and form chromium ferrite composites. The Cr(VI) concentration in the wastewater was reduced from 1040mgL-1 to 0.035mgL-1, and the Cr(VI) leaching toxicity of the precipitate was 0.21mgL-1 under optimal hydrothermal conditions. The precipitate consisted of micron-sized ferrochromium spinel multiphase with polyhedral structure. The mechanism of Cr(VI) removal involved three steps: 1) partial oxidation of FeSO4 to Fe(III) hydroxide and oxy-hydroxide; 2) reduction of Cr(VI) by FeSO4 to Cr(III) and Fe(III) precipitates; 3) transformation and growth of the precipitates into chromium ferrite composites. This process meets the release standards of industrial wastewater and hazardous waste and can improve the efficiency of the ferrite process for toxic heavy metal removal.

Uranium and arsenic bioremediation potential of plastic associated multi-metal tolerant Bacillus sp. EIKU23

Uranium and arsenic bioremediation potential of plastic associated multi-metal tolerant Bacillus sp. EIKU23

Methods for Electrolyte Treatment and Hexavalent Chromium Reduction in Industrial Electrochemical Machining (ECM)

Electrochemical Machining (ECM) is a metal removal process that operates on the principle of anodic dissolution. ECM has the ability to produce complex shapes in difficult-to-machine alloys with precision and excellent surface finish. However, since most of these alloys contain chromium, one of the major challenges to ECM’s wider utilisation in industry is how to eliminate the resulting hexavalent chromium (Cr+6) from the spent electrolyte. This paper presents methods for controlling the Cr+6 level to within the permitted guidelines for an industry application of ECM, and reducing it to trivalent chromium (Cr+3), to then precipitating it from the electrolyte solution,The workpiece material – Triboloy (Co; Mo; Cr alloy) has hitherto not been machined by ECM and hence no literature exists on how to treat the by-products generated. This research involves experimental analysis of various Cr+6 to Cr+3 chemical reduction methods for ECM of Tribaloy in sodium nitrate electrolyte, using spent electrolyte samples. The reduction in Cr+6 is assessed over time. It was observed that the concentration of Cr+6 decreased within a span of two minutes. Subsequently, the solution pH level was increased by the addition of an alkali to precipitate the Cr+3 ions, which then can be filtered out from the solution. The optimum solution for hexavalent chromium is thus implemented in the industrial electrolyte system for successfully machining the Tribaloy component.

Adsorption of Pb (II) Ions in Water with Natural Kenaf Beads

The purpose of this research is to study plant-based kenaf adsorbents on the adsorption of polluted Pb (II) in aqueous solutions. CHT and KNF core powder were added to the sodium alginate solution and stirred homogeneously. The blend solution was dripped into calcium chloride to form smooth magnetic KNF-CHT-ALG beads. The functional group presence in the beads and percentage adsorption of the heavy metals were checked using Fourier Transform Infrared Spectroscopy (FTIR) and Inductively Coupling Method analyses, respectively. It was found that the surface morphology of kenaf core was rougher than that of kenaf fibre, with the presence of a larger amount of micropores as observed in the FESEM analysis. In addition, the FTIR pattern of the KNF-CHT-ALG beads had shown the existence of functional groups such as hydroxyl and carboxyl, which could attract more positively charged heavy metals. The ICP analysis confirmed the successful 95% adsorption of the heavy metals. Kenaf is an abundant crop available in Malaysia that may reduce the production cost of the adsorbents. The significant outcomes of this study would be its contribution to minimising the dependency on the chemical adsorbent and to accelerating the removal process of heavy metals in real water bodies. Thus, this study aims to create a more sustainable future, especially by reaching SDG 6: Clean Water and Sanitation.

Utilization potential of poultry litter ash as phosphorus-based fertilizer

A large quantity of poultry litter is globally generated as a result of expanding poultry industry. From several alternative technologies, one of the most feasible management for this waste is com-bustion, which exhausts poultry litter ash (PLA) as the main by-product. In this study, a PLA sample was examined for its utilization potential as a raw material for phosphorus-based fertilizer. According to the experimental results, Ca, P and K were determined as the major elements in the PLA sample with 29.54, 6.13 and 4.96%, respectively. Although the sample contains 2472 ppm Zn and 922 ppm Cu, their solubility determined by the leaching test is below the toxicity limit for haz-ardous waste. In terms of the major elements, about 290 mg/l Ca was detected in the leachate, re-sulting in a pH value higher than 13, whereas P concentration was found only 0.0092 mg/l. These two crucial results constitute the major difficulties for direct use of the PLA as a fertilizer. On the other hand, a usable P-rich product with low heavy metal contents and neutral pH can be obtained through acidification, heavy metal removal and neutralization processes. However, in this case, the feasibility of processes to be used should be carefully considered in economic point of view. In conclusion, direct application of the PLA sample examined as P-based fertilizer is not possible without any pre-treatments mainly due to its very high alkalinity and the low water solubility of P.

Sequestration of cobalt and nickel by biofilm forming bacteria isolated from spent nuclear fuel pool water

In the current study, six bacterial types, isolated from spent nuclear fuel (SNF) pool facility, were investigated for their ability to sequester heavy metals (cobalt and nickel). Biofilm formation by the six bacterial isolates, viz., Bacillus subtilis, Staphylococcus species, Staphylococcus arlettae, Staphylococcus epidermidis, Staphylococcus auricularis, and Chryseobacterium gleum, were assayed, and they were found to have significant biofilm forming property. Their biofilms were characterised using confocal scanning laser microscopy, and their potential to accumulate Co2+ and Ni2+ from bulk solutions was analysed with respect to time. A comparative assessment of bioaccumulation capacity was done using biofilms, planktonic cells, and live vs dead cells. The strains accumulated Co2+ and Ni2+ in the range of 4 × 10-4 to 1 × 10-5g/mg of cell biomass. It is interesting to note that dead biomass also showed significant removal of the two metal ions, suggesting an alternative process for metal removal. This study suggests that hostile environments can be a repertoire of putative bacterial species with potential heavy metals and other contaminants remediation properties.

Integrated application of green zero-valent iron and electrokinetic remediation of metal-polluted sediment.

In recent years, more focus has been placed on integrated metal removal processes. Electrokinetic (EK) treatment is superior to other technologies because it can be applied to a variety of mediums. Green nanoparticles, on the other hand, have the potential to significantly reduce pollutant concentrations in a short period of time. In this study, we investigated the possibility of combining green zero-valent iron (nZVI) with EK on Cd and Zn-contaminated sediment. For green synthesis, extracts of dry leaves of mulberry (ML-nZVI) and oak (OL-nZVI) were used, both abundantly present in the Republic of Serbia. The results show that, despite the fact that their availability was greatly reduced, the metals were concentrated and stabilized to a significant extent in the middle of the EK cell (z/L 0.5) after all treatments. When the results were compared, OL-nZVI proved to be a more effective nanomaterial even with smaller doses of OL-nZVI, which is important in terms of achieving better economic benefits. This study identified green nano zero-valent iron as a powerful tool for metal removal when combined with electrokinetic (EK) treatment, which improves green nZVI longevity and migration. This study of the combined green nZVI-EK remediation treatment, in particular, will have an impact on future research in this field, given the achieved efficiency.

Removal of Ni(II) and Cu(II) in Aqueous Solutions Using Treated Water Hyacinth (Eichhornia crassipes) as Bioadsorbent

Phytoremediation consists of taking advantage of the capacity of certain plants to absorb, accumulate, or metabolize contaminants. In this study, Eichornia crassipes (water lily) treated with water (WLW) and NaOH (WLN) was investigated as an adsorbent for removal of Ni(II) and Cu(II) present in aqueous solution, focusing on determining the most efficient conditions (adsorbent concentration, contact time, pretreatment, temperature). The results showed that equilibrium adsorption was favorable and carried out by a multilayer physical process with both bioadsorbents. The maximum adsorption at 30 °C in WLW and WLN was 349 and 293.8 mg/g of Ni(II), respectively, and 294.1 and 276.3 mg/g of Cu(II), respectively. The thermodynamic analysis indicated that the removal in both metals was spontaneous and exothermic. The Avrami model was the most adequate in the kinetic study of Ni(II) and Cu(II) removal in both treatments, which revealed that the adsorption process was carried out by several mechanisms. In the characterization of the adsorbents, it was determined that the functional groups of WL as well as the attractive forces on the surface of the materials participated in the metal removal process.

Towards energy efficient milling of variable curved geometries

Towards energy efficient milling of variable curved geometries

Conversion of corn shell as biomass solid waste into carbon species for efficient decontamination of wastewater via heavy metals adsorption

Biomass-based solid residuals can be of serious hazardous environmental impacts if left for natural degradation. Thus, the proper utilization of such residuals is highly recommended. Therefore, one of solid residuals: namely, corn shell, was used in this study to synthesize carbon species (labeled as CS-C) as an adsorbent for efficient removal of heavy metal ions from aqueous solution. The structural properties and the textural characteristics of the prepared carbon species were verified. The present charges on the carbon surface were acquired via zeta potential analysis. The performance of CS-C, as adsorbent, was investigated through batch technique. Adsorption isotherm was optimally described using the Langmuir model reflecting that the removal process occurs at the homogenous surface of CS-C through a chemical reaction (surface complexation mechanism). The equilibrium state for the sorption process was reached after 4 h of interaction. The kinetic studies revealed the nice fit of heavy metal removal process to Pseudo-second-order model and the thermodynamics is matched to endothermic, spontaneous, and feasible sorption process. The displayed results could emphasize the high potentiality of CS-C to act as a remarkable sorbent for efficient tackling of water contaminants.

Estimation of phytoextraction potential of selected halophytes for accumulation of heavy metals from wetland saline soil

The phytoremediation is a significant natural clean-up process for removal of heavy metals from wetland saline soils (WS) for the sustainable environmental pollution control. Therefore, the phytoremediation potential of Typha domingensis (southern cattail) and Phragmites australis (common reed) has been evaluated for absorption and accumulation of salts and heavy metals growing at two sites of WS samples coded as BS1 and BS2 (“BS” the soil that is not adjoining to root of plants) in Hyderabad Sindh, Pakistan. The three parts (root, stems, and leaves) of both Plants were obtained from several of locations oxidized the matrices of each part of plants and the corresponding soil samples using acid mixture. A variety of techniques were used to identify the metals by atomic absorption spectrometry. The average values of heavy metals, Co, Cd, Cr, Cu, Pb, and Zn in BS1 and BS2 were found to be (8.53, 14.4, 8.88, 64.3, 13.3, and 142) and (12.4, 18.2, 13.6, 89.4, 14.4, and 124) µg/g, respectively. The data of bioconcentration (BCF) and translocation factors (TF) of the research showed that the studied halophytes showed a high accumulation potential (> 1) for heavy metals from WS. The metal content in plants and rhizospheric soil have a strong relationship (p < 0.01). The screening data based on classical methods and GC–MS indicated that the studied phyto extractants have many phytochemicals. These phytochemicals may have the capability to accumulate heavy metals from contaminated soils. The roots and their rhizospheric soil (RS1 and RS2) have a highly significant relationship of accumulation potential with the selected heavy metals (RS is soil adjoining to roots of plants) (p < 0.01). These halophytes are able to remove heavy metals directly from salty metal-contaminated soil in wetland environments.