Removal Of Cd Research Articles

Bioremediation of paddy soil with amphitropic mixture markedly attenuates rice cadmium: Effect of soil cadmium removal and Fe/S-cycling bacteria in rhizosphere

Cadmium (Cd) pollution in paddy soil can easily lead to excessive Cd in rice, thereby considerably threatening human health. Microbial leaching is an effective pathway for the mobilization and removal of Cd from soil. In this study, an amphitropic mixture (AM) composed of autotrophic and heterotrophic microbial strains was used to leach Cd-contaminated paddy fields. Chemical analysis showed that the AM effectively removed 52 % of the total Cd, 39 % of the available Cd, and 60 % of the exchangeable and carbonate-bound Cd from the paddy soil. After bioleaching, the Cd in the discarded AM solution was adsorbed using a metal adsorbent. Effects of remediation on the soil nutrients or secondary pollution were not significant. Microbial analysis showed that >96 % and 67 % of the indigenous bacteria and fungi, respectively, remained in the AM-remediated soil. Double-cropped rice was cultivated to evaluate the Cd removal efficiency of grains using AM remediation. The Cd in early and late brown rice decreased by 86 % and 56 %, respectively, which was higher than that found for a series of biochemical remediation materials reported in other studies. Furthermore, the AM remediation promoted the growth of iron (Fe)- and sulfur (S)-cycling bacteria in the rice rhizosphere, such as Sulfuricurvum, Desulfurivibrio and Geobacter etc., which reduced the Cd availability in the soil and rice uptake. This study shows that AM has potential applications in the remediation of Cd-contaminated paddy fields and provides a new pathway for safe rice production.

Remediation of Cd(II) contamination in aqueous solution by modified sludge biochar with molten salt-assisted pyrolysis

In this work, modified sludge biochar was prepared using molten salt-assisted pyrolysis method to remove Cd(II) from aqueous solution. The biochar was characterized using XRD, FTIR, Raman, XPS and pore structure analysis techniques, and the effects of initial pH, adsorption temperature, adsorption time and initial Cd(II) concentration on the Cd(II) removal were investigated. Compared with the virgin sludge biochar (VSBC), the modified sludge biochar (MSBC) by molten salt-assisted pyrolysis method was rougher surface, more developed pore structure and higher graphitization. The initial pH had a greater effect on the Cd(II) removal, and the high adsorption temperature promoted the Cd(II) removal. The Cd(II) removal behavior was in accordance with the pseudo-second-order kinetic model and Langmuir model, which indicated that the adsorption reaction was a single and uniform chemisorption. Thermodynamics indicated that the Cd(II) removal by VSBC and MSBC was spontaneous and heat-absorbing reaction. Additionally, the maximum adsorption capacities of Cd(II) by VSBC and MSBC were 39.02 and 101.26 mg/g at pH 5.0 and 25 °C, respectively. The mechanisms of Cd(II) removal included complexation of O-containing groups, ion exchange, precipitation, and electrostatic interaction. After three adsorption-desorption experiments, the Cd(II) removal efficiency by VSBC was maintained at 33.26%, while the Cd(II) removal efficiency on MSBC was maintained at 90.18%. This finding suggested that the modified sludge biochar using molten salt-assisted pyrolysis could be effective in remediating Cd(II)-contaminated water body.

Interpretation of the adsorption process of toxic Cd2+ removal by modified sweet potato residue.

Cadmium (Cd) is a common and toxic non-essential heavy metal that must be effectively treated to reduce its threat to the environment and public health. Adsorption with an adsorbent, such as agricultural waste, is widely used to remove heavy metals from wastewater. Sweet potato, the sixth most abundant food crop worldwide, produces a large amount of waste during postharvest processing that could be used as an economic adsorbent. In this study, the feasibility of using sweet potato residue (SPR) as an adsorbent for Cd2+ adsorption was assessed. To enhance the removal rate, SPR was modified with NaOH, and the effects of the modification and adsorption conditions on the removal of Cd2+ from wastewater were investigated. The results showed that modified sweet potato residue (MSPR) could be adapted to various pH and temperatures of simulated wastewater, implying its potential for multi-faceted application. Under optimized conditions, the removal of Cd2+ by MSPR was up to 98.94% with a maximum adsorption capacity of 19.81 mg g-1. Further investigation showed that the MSPR exhibited rich functional groups, a loose surface, and a mesoporous structure, resulting in advantageous characteristics for the adsorption of Cd2+. In addition, the MSPR adsorbed Cd2+ by complexation, ion exchange, and precipitation during a monolayer chemisorption adsorption process. This work demonstrates a sustainable and environment friendly strategy for Cd2+ removal from wastewater and a simple approach for the preparation of MSPR and also revealed the adsorption mechanism of Cd2+ by MSPR, thus providing a suitable adsorbent and strategy for the removal of other heavy metals.

A kinetic and thermodynamic investigation for adsorption of cadmium (ii) ions on the microwave modified sugar cane bagasse

In the current research work, urea-treated microwave-modified sugar cane bagasse (MSCB), an agricultural waste, is employed as low-cost adsorbent for removing Cd (II) ions from reaction media. In this research work, the comparative analysis of MSCB and unmodified sugar cane bagasse (USCB) were studied at the same time and comparison was made for investigating the better adsorption performance using Cd (II) ions as model contaminant. Different parameters affecting the removal of Cd (II) ions including time, pH, and dose were studied. Results indicate that MSCB required less extreme conditions for effective working as compared to USCB. The optimal adsorbent dose was 0.4 g while the working pH was in the range of 6–7. The MSCB showed higher calculated adsorption capacity of 37.037 mg/g while lower value of 15.384 mg/g was found for USCB. Kinetic data showed that this adsorption reaction was endothermic, feasible and spontaneous. The ∆H⁰, ∆S⁰ and ∆G⁰ values for USCB was found to be − 14.998 kJ/mol, 54.68 J/kmol and − 3.255 KJ/mol whereas, the values for MSCB were − 18.789 kJ/mol, 69.94 J/kmol, and − 2.104 KJ/mol, respectively. The higher values for MSCB showed its excellent efficiency towards removal of Cd(II). However, it has been observed that both adsorbents exhibited best correlation with the Langmuir and Freundlich model of adsorption. Hence, this work provides a novel and excellent adsorbing material for adsorption of Cd (II) ions from aqueous medium.

Elucidation of the CadA Protein 3D Structure and Affinity for Metals.

The mitigation of cadmium (Cd) pollution, a significant ecological threat, is of paramount importance. Pseudomonas aeruginosa harbors 2 Cd resistance genes, namely, cadR and cadA. Presently, our focus is on the identification and characterization of the cation-transporting P-type ATPase (cadA) in Pseudomonas aeruginosa BC15 through in silico methods. The CadA protein and its binding capacities remain poorly understood, with no available structural elucidation. The presence of the cadA gene in P aeruginosa was confirmed, showing a striking 99% sequence similarity with both P aeruginosa and P putida. Phylogenetic analysis unveiled the evolutionary relationship between CadA protein sequences from various Pseudomonas species. Physicochemical analysis demonstrated the stability of CadA, revealing a composition of 690 amino acids, a molecular weight of 73 352.85, and a predicted isoelectric point (PI) of 5.39. Swiss-Model homology modelling unveiled a 33.73% sequence homology with CopA (3J09), and the projected structure indicated that 89.3% of amino acid residues were situated favourably within the Ramachandran plot, signifying energetic stability. Notably, the study identified metal-binding sites in CadA, namely, H3, C30, C32, C35, H48, C89, and C106. Docking studies revealed a higher efficiency of Cd binding with CadA compared to other heavy metals. This underscores the crucial role of N-terminal cysteine residues in Cd removal. It is evident that CadA of P aeruginosa BC15 plays a crucial role in Cd tolerance, rendering it a potential microorganism for Cd toxicity bioremediation. The structural and functional elucidation of CadA, facilitated by this study, holds promise for advancing cost-effective strategies in the remediation of cadmium-contaminated environments.

Research Investigates and Simulation Behavior of the Failure Characteristics of Red Mud–Loess Type Permeable Reactive Barriers PRB in Fixed‐Bed Column Experiments

Controlling and remediating water and soil pollution while efficiently utilizing solid waste is essential for comprehensive environmental protection and sustainable development, particularly in establishing green, low‐carbon economic systems in China. We evaluate the impact of initial concentration, flow rate, and bed height on breakthrough performance and adsorption capacity using the Tessier method under dynamic water flow conditions. Additionally, we analyze micromorphological changes in the red mud–loess mixture before and after breakthrough by acid mine drainage containing Pb and Cd in mining areas, employing soil column experiments and numerical simulations with COMSOL Multiphysics. Our findings suggest that reducing initial concentration and flow rate while increasing bed height leads to higher breakthrough time, saturation time, and adsorption capacity for Pb and Cd in the red mud–loess mixture (7 : 3). Furthermore, the red mud–loess blend (7 : 3) demonstrates sustained and efficient acid‐buffering capability in the presence of acid mine drainage containing Pb and Cd. Notably, under specific conditions (initial Pb content at 100 mg/L, a height of 7 cm, and flow rate set at 1 mL/min), the adsorption capacity of red mud–loess (7 : 3) reaches 17.30 mg/g. The prescribed minimum length for PRBs is 11.40 cm. Under specified conditions (Cd concentrations at 100 mg/L, a height of 5 cm, and a flow rate of 1 mL/min), the material exhibits a notable adsorption capacity of 29.91 mg/g, with a theoretical minimum length for PRBs at 8.95 cm. Increasing bed heights successfully remove Pb and Cd ions through chemical precipitation. The BDST model accurately describes the breakthrough curves of Pb and Cd and develops a correlation formula for the breakthrough time of red mud–loess PRB medium. As the saturation of Pb increases from 0.05 to 0.85, the maximum volume adsorption capacity of Pb increases from 1.78 to 2.98 mg/L, while for Cd, it increases from 4.15 to 7.87 mg/L. Elevating the bed height first triggers chemical precipitation, hence improving Pb and Cd removal. Consequently, the longevity of red mud–loess PRB in acidic mine effluent containing Pb and Cd surpasses predicted theoretical outcomes. These observations reveal correlations between the breakthrough length for red mud–loess permeable reactive barriers and the bed height. Furthermore, the distribution of Pb speciation within the red mud–loess mixture (7 : 3) is primarily governed by the presence of iron–manganese oxide, while the composition of Cd speciation is chiefly influenced by the carbonate form and iron–manganese oxide. After treating acidic mine wastewater with Pb and Cd, the red mud–loess mixed material (7 : 3) undergoes surface changes, shifting from smooth to rough due to H+ corrosion. Pores between particles enlarge, yet heavy metal ions, adsorbates, and precipitates reoccupy and cover the surface, transforming the particle morphology from dense lamellar to clustered spherical. Our innovative approach to combining waste materials for environmental remediation presents a cost‐effective and impactful solution for heavy metal pollution.

Biomass chitosan/sodium alginate colorimetric imprinting hydrogels with integrated capture and visualization detection for cadmium(II)

Due to Cd(II) with highly toxic, persistent and bioaccumulative, the discharge of it into the environment brings serious pollution. Developing strategies that are efficient, low-cost, pollution-free and specific to removing Cd(II) from wastewater is therefore of great urgency and prime importance. A novel chitosan/sodium alginate ionic imprinting(IICA) hydrogels with specific adsorption capacity for Cd(II) was prepared through freeze-thaw and ion imprinting, and finally the colorimetric sensor (IICAS) was prepared via introducing Rhodamine B(RhB) and Victoria blue(VBB) by immersion to achieve visual detection of Cd(II). The IICA hydrogels with imprinted hole structure had higher adsorption capacity and better specific selectivity for Cd(II). As well as internal diffusion, coordination, ion exchange, and hydrogen bonding influenced the adsorption rate. Moreover, the IICAS exhibited good selective detection ability and linearity for Cd(II) with the fitted correlation coefficient (R2) = 0.98, limit of detection (LOD) = 35 nmol/L. Combined with the smartphone platform, portable and quantitative detection of Cd(II) can be achieved, Within the 0–100 mg/L range, R2 remained 0.94, and LOD was 75 nmol/L. This strategy of preparing a novel whole biomass IICAS integrating capture and visual detection provides a new insight into the construction of a promising candidate sensor for the removal and detection of Cd(II).

Investigation on the adsorption of cationic dyes and heavy metal ions on zeolite HY from aqueous solution

Every living creature on the earth needs access to clean water. Water is being contaminated by humans in numerous ways. Heavy metals and textile dyes are two of the major contaminants in wastewater. Dyes and heavy metals are harmful to human health and have negative effects on the environment as well. Zeolites are excellent adsorbent materials for various types of pollutants including organic and inorganic such as dyes, heavy metals, ammonium ions, etc. In this study, we have presented the synthesis, characterizations, and application of zeolite HY for the extraction of cationic dyes and heavy metal ions. Zeolite Y was synthesized by hydrothermal approach and converted to its H-form. Different characterization techniques such as Fourier Transform Infra-Red (FTIR), Field-Emissions Scanning Electron Microscope (FE-SEM), and X-ray diffraction (XRD) were utilized for the characterization of zeolite HY. The synthesized material zeolite HY (ZHY) was then employed for the adsorption of two cationic dyes i.e., MB and CV, heavy metal ions i.e., cadmium (Cd+2) and chromium (Cr+6) and ammonium (NH4+) ions from its aqueous solution. The adsorption data showed 97.2 % removal of MB 49 % removal of CV, 0 % removal of both Cd+2 and Cr+6 heavy metal ions and 5 % removal of NH4+ ions.

Resource utilization of oak fruit peel as biomass waste for the synthesis of carbon with graphene oxide-like composition and its composite with Mg1−xCaxFe2O4 for Cd(ii) removal from water: characterization, magnetic properties, and potential adsorption study

In this study, carbon with graphene oxide (GO)-like composition (CGO) was prepared from oak fruit peel (OFP) using a room-temperature method.

BIOADSORVENTES DE RESÍDUOS DA AGROINDÚSTRIA UTILIZADOS NA REMOÇÃO DE Cd(II)

BIOADSORBENTS FROM AGROINDUSTRIAL WASTE USED IN Cd(II) REMOVAL. The use of agroindustry waste in the synthesis of bioadsorbents provides a solution to reduce the disposal of solid waste in the environment while increasing the added value of recovering locally sourced waste. However, technical and environmental issues must be considered when selecting the appropriate synthesis method to avoid creating a new environmental impact and evaluate the feasibility of applying the method. In this work, yellow mombin, guava and mango seeds were used to synthesize bioadsorbents capable of removing cadmium(II) in solution. The materials were characterized according to their chemical composition, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and evaluated by adsorption kinetics tests. Energy analysis of biomass processing was performed by life cycle analysis (LCA). The bioadsorbents presented typical characteristics of lignocellulosic biomass, with the presence of functional groups favorable to the adsorption of metals and were effective in removing cadmium(II), with efficiency of 95.7, 92.4 and 60.2%, for BSG (guava seed bioadsorbent), BSC (yellow mombin seed bioadsorbent) and BSM (mango seed bioadsorbent), respectively. The error functions provided a more appropriate criterion for analyzing the kinetic data. The methodology proposed in this work is simple to implement and has a low estimated energy demand, therefore being promising for application in small fruit processing industries in the semi-arid region of Bahia.

Performance and mechanism of a bioelectrochemical system for reduction of heavy metal cadmium ions.

This study explores the removal of Cd(ii) from wastewater using a microbial electrolysis cell (MEC) to investigate the electrochemical performance and removal kinetics of an anodic polarity reversal biocathode and the mechanism of action of electrochemically active bacteria. Comparative electrochemical methods showed that using an anodic polarity reversal biocathode resulted in greater than 90% removal of different concentrations of Cd(ii) within three days, which may be related to the catalytic effect of anodic electrochemically active bacteria. However, due to the ability of bacteria to regulate, up to nearly 2 mg L-1 of Cd(ii) ions will remain in solution. As shown by the linear fitting relationship between scanning speed and peak current, the removal process was dominated by adsorption control for 20-80 mg L-1 Cd(ii) and diffusion control for 100 mg L-1 Cd(ii). The analysis of raw sludge and sludge containing Cd(ii) showed that Arcobacter and Pseudomonas were the primary cadmium-tolerant bacteria, and that the ability to remove Cd(ii) was the result of a synergistic collaboration between autotrophic and heterotrophic Gram-negative bacteria.

High-efficiency removal of Cd(ii) and As(iii) from irrigation water using a S–Fe–C composite: performance and mechanisms

SFC showcased exceptional Cd(ii) and As(iii) removal capacities of 405 mg g−1 and 349 mg g−1, respectively, while preserving magnetic recovery properties after repeated adsorption cycles, making it an environmentally sustainable functional material.

Remediation of Pb- and Cd-contaminated clayey soil via magnetic-enhanced washing

The mass transfer efficiency between the contaminant and the washing eluent is the fundamental factor that limits the efficiency of chemical washing. In this study, the magnetization technique was employed to improve the physicochemical properties of eluent and cross-tests were conducted on clayey soils samples contaminated with lead (Pb) and cadmium (Cd). Furthermore, eluent concentration, magnetization strength, and magnetization time were varied as parameters for enhancing mass transfer efficiency. Results showed that after magnetization, the viscosity, surface tension, and contact angle of ethylene diamine tetraacetie acid (EDTA) decreased, whereas conductivity and pH increased. In particular, the viscosity of high-concentration EDTA increased with higher magnetic field strength and longer magnetization time. The maximum removal of Cd and Pb increased by 64.46% and 35.49%, respectively, compared with the unmagnetized lysate. This result highlighted the efficient mass transfer and synergistic mechanism of the magnetization technique, facilitating better contact between the eluent and the contaminants. Magnetization eluent has been proven to be an efficient, cost-effective, and easily implementable method for enhancing mass transfer efficiency, providing a valuable reference for improving the efficiency of chemical washing for heavy metal-contaminated clayey soil.

Enhanced microalgal biomass and lipid production with simultaneous effective removal of Cd using algae-bacteria-activated carbon consortium added with organic carbon source

Recently, using microalgae to remediate heavy metal polluted water has been attained a huge attention. However, heavy metals are generally toxic to microalgae and consequently decrease biomass accumulation. To address this issue, the feasibility of adding exogenous glucose, employing algae-bacteria system and algae-bacteria-activated carbon consortium to enhance microalgae growth were evaluated. The result showed that Cd2+ removal efficiency was negatively correlated with microalgal specific growth rate. The exogenous glucose alleviated the heavy metal toxicity to algal cells and thus increased the microalgae growth rate. Among the different treatments, the algae-bacteria-activated carbon combination had the highest biomass concentration (1.15 g L−1) and lipid yield (334.97 mg L−1), which were respectively 3.03 times of biomass (0.38 g L−1) and 4.92 times of lipid yield (68.08 mg L−1) in the single microalgae treatment system. Additionally, this algae-bacteria-activated carbon consortium remained a high Cd2+ removal efficiency (91.61%). In all, the present study developed an approach that had a great potential in simultaneous heavy metal wastewater treatment and microalgal lipid production.

Effective mitigation of Cadmium contamination in soil through Sawdust Biochar application

Cadmium (Cd) contamination in soil is a serious environmental concern, and this study examines the effectiveness of sawdust biochar in reducing Cd contamination over three months. The study explores different sawdust biochar application rates and their effects on the amount of extractable Cd in the soil. According to the study, sawdust biochar has a high potential for addressing Cd pollution. Importantly, over the duration of the investigation, extractable Cd concentrations gradually decreased as a result of the use of biochar. In particular, compared to lesser application rates of 2.5% and 1.25%, the highest biochar application rate (5%) resulted in a significant reduction in cumulative leachable Cd content. Additionally, compared to the control group, all biochar-amended soils showed considerably decreased cumulative leachable Cd levels. The leachate study demonstrated the time-dependent efficiency of biochar in lowering Cd concentrations, with Cd concentration declining from 14 mg/L in August 2023 to a meager 0.004 mg/L in October 2023. Diffusion within the porous structure of biochar was determined to be the main process underlying heavy metal adsorption. However, the observed decrease in the effectiveness of heavy metal removal with biochar may be explained by surface oxidation, which creates a greater number of accessible adsorption sites. Furthermore, the soil's capacity to absorb Cd2+ was greatly improved by the raised pH brought on by biochar application, further enhancing Cd removal. The study also showed the importance of pyrolysis temperature on biochar characteristics, with higher temperatures greatly improving Cd adsorption capability. This study's findings highlighted the significant potential of sawdust biochar as a powerful technique for reducing soil Cd pollution. These results highlighted the potential of biochar for Cd remediation and crucial role that pyrolysis temperature plays in determining biochar's characteristics and adsorption capacity.

Application of the Biomass of Leaves of Diospyros kaki L.f. (Ebenaceae) in the Removal of Metal Ions from Aqueous Media

Using straightforward and cost-effective methods, persimmon leaves were converted into high-quality powder. This powder was applied as an adsorbent for the removal of Cu(II) and Cd(II) from aqueous solutions. Scanning electron microscopy (SEM) revealed the presence of particles with non-homogeneous sizes and rough textures. The biosorbent exhibited a specific surface area of approximately 0.44 ± 0.015 m2 g−1. Elemental analysis and energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of elements such as sulfur, phosphorus, nitrogen, and oxygen. The results of 13C nuclear magnetic resonance (13C-NMR), obtained using the cross-polarization technique, show the presence of groups containing sulfur and oxygen. Infrared spectroscopy (FTIR) indicated the existence of amine and hydroxyl groups. The material was used in the solid-phase extraction of Cu(II) and Cd(II) in batch experiments, and its adsorption capacity was evaluated as a function of time, pH, and analyte concentration. The fraction with a diameter between 63 and 106 μm was selected for the adsorption tests. Kinetic equilibrium was reached within 5 min, and the experimental data were fitted to the pseudo-second-order kinetic model. The optimum pH for the adsorption of both metal species was approximately 5.0. The adsorption isotherms were adjusted using the modified Langmuir equation, and the maximum amount of metal species extracted from the solution was determined to be 0.213 mmol g−1 for Cu(II) and 0.215 mmol g−1 for Cd(II), with high linear correlation coefficients for both metals. Persimmon leaves are typically abundant during the growing season, and because they are seasonal, the Diospyros kaki L.f. tree undergoes the natural process of leaf abscission, ensuring the availability of leaves for application.

EDTA functionalized Mg/Al hydroxides modified biochar for Pb(II) and Cd(II) removal: Adsorption performance and mechanism

This study has successfully synthesized layered double hydroxide (LDH) biochar (E-Mg/Al-LDH BC) with ethylenediaminetetraacetic acid (EDTA) and examined its adsorption capabilities towards Pb(II) and Cd(II). The results demonstrate that the kinetics of heavy metal removal can be well described by the pseudo-second-order model. The intraparticle diffusion model indicates that the controlling steps for Pb(II) and Cd(II) are not uniform. The adsorption isotherm for Cd(II) conforms to the Langmuir model, while for Pb(II), it adheres to the Freundlich model. The distribution coefficient (Kd) shows that Pb has a significantly higher competitive adsorption capacity than Cd(II). Therefore, in comparison to single adsorption, the maximum adsorption capacity of Cd(II) in competitive adsorption decreased by 58.86%, while Pb(II) only decreased by 13.54%. Surface complexation, cation exchange, chemical precipitation, electrostatic interaction, and cation-π bonding are the inherent mechanisms by which E-Mg/Al-LDH BC removes heavy metal ions. E-Mg/Al-LDH BC has the potential to remediate heavy metal-contaminated water, and it also provides insights for the application of modified biochar in the treatment of multi-metal water pollution.

An Analysis of the Factors Influencing Cadmium Removal in Aquatic Environments by Chlorella vulgaris-Derived Solids

Chlorella vulgaris is an inexpensive microalga that could be employed for environmental remediation, but further investigations are needed to assess its suitability and optimal treatment methodology. With this aim in mind, this study focused on the raw biomass and the biochar and hydrochar obtained from it, analyzing their physicochemical properties and testing them to capture cadmium from an aqueous environment. The adsorption/absorption tests assessed the effect of adsorbent dosage, pH, Cd concentration, and contact time, and the results were analyzed through a structural equation model. Biochar and hydrochar performed similarly and better than the raw biomass, with the highest Cd removal observed at an adsorbent dosage of 0.8 g L−1, an initial concentration of Cd solution of 30 mg L−1, a pH of 6, and a contact time of 30 min. The adsorption isotherm data for Cd could be well-described by the Langmuir and Temkin models. The results from the structural equation modeling revealed that the variables material type, dosage, and concentration all contributed to Cd removal in water, with time mediating these effects.

Eco-friendly magnetic biochar from Leb Mu Nang banana peel: Response surface methodology optimization for Cd(II) adsorption from synthetic wastewater

Magnetic biochar derived from Leb Mu Nang banana peel waste is introduced as a novel precursor for Cd(II) removal from synthetic wastewater. This study comprehensively evaluates and optimizes variable factors, including initial Cd(II) concentration, magnetic biochar (MLP) dosage, adsorption time, and initial pH level, using the Response Surface Methodology (RSM). A Cd(II) removal efficiency of up to 93.4 % is reached under the conditions of a 50 mg/L initial concentration, 5 g/L MLP dosage, 24 h of adsorption time, and a solution pH of 8. The pseudo-second-order and Langmuir models accurately represent the kinetics and isotherm adsorptions, highlighting ion exchange, surface complexation, and precipitation as primary adsorption mechanisms. The magnetic biochar derived from Leb Mu Nang banana peels shows promise for efficient Cd(II) removal with easy post-adsorption separation.

The role of alkalinity on metals removal from petroleum produced water by dolomite

Alkalinity is a critical parameter for describing the composition, pH buffer capacity, and precipitation potential of petroleum produced water (PW). Besides salinity, alkalinity and metal concentrations are generally greater in PW than in freshwater (FW) and seawater. This study presents batch reaction experimental and simulation results showing that the removal of Ba, Sr, and Cd from PW by dolomite is mostly due to sorption reactions, with sorption reactions and thus removal levels being higher for Cd than for Ba and Sr. In contrast, we found that the removal of Pb and As from PW by dolomite is largely due to precipitation and coprecipitation reactions of carbonate minerals on dolomite. Analyses of changes in the morphology as well as in the elemental and mineral composition of dolomite surface, along with pH, alkalinity, and Ba, Sr, Cd, Pb, and As removal measurements using synthetic PW and FW containing high concentrations (∼100 mg/L) of single and mixture toxic metals and metalloids (Ba, Sr, Cd, Pb, and As) at different initial alkalinity and pH conditions, indicate that in addition to salinity, alkalinity and pH generated from the dissolution of dolomite controls the removal of Ba, Sr, Cd, Pb, and As from PW by dolomite. However, we found that their impact is different for each metal in PW and FW. Ba, Sr, and Cd removal by dolomite is 10, 2, and 4 times smaller in PW than in freshwater (FW), respectively. Whereas As removal is practically the same regardless of salinity. Moreover, this study reveals the need of thermodynamic data of complex carbonate minerals formed from the precipitation of Ba, Sr, Cd, Pb, and As to capture the effect of alkalinity on their removal from PW by dolomite.