Biosorption Of Cd Research Articles

Biosorption of cadmium from aqueous solution by combination of microorganisms and chitosan: response surface methodology for optimization of removal conditions

The food-grade adsorbents of Saccharomyces cerevisiae (108 CFU/mL), Bifidobacterium longum (108 CFU/mL) and chitosan (1%w/v) alone or in combination were used for biosorption of cadmium (Cd) from aqueous solution. Among the tested adsorbents, combination of B. longum and chitosan had the highest efficiency. Therefore, biosorption process with B. longum/chitosan as the most efficient biosorbent was optimized by variables of pH (3–6), temperature (4–37 °C), contact time (5–180 min) and Cd concentrations (0.01–5 mg/L) using RSM. Twenty-seven tests were carried out and the data fitted to the second-order polynomial models. Results revealed that 99.11% of Cd was reduced within 180 min at concentration of 2.5 mg/L, pH 6 and temperature of 20.5 °C that were considered as the optimal conditions for Cd removal. The trend of isotherm was more fitted to the Langmuir model and maximum biosorption capacity was obtained about 3.61 mg/g. The pseudo-second-order fitted the biosorption kinetics for Cd ions. The B. longum/chitosan biosorbent exhibited the high affinity to Cd ion in the presence of coexisting metal ions. It could remove 81.18% of Cd from simulated gastrointestinal tract. Thus, B. longum/chitosan can have good potential as an effective adsorbent for Cd biosorption from aqueous solutions and human body.

Isotherm and kinetic studies of cadmium biosorption and its adsorption behaviour in multi-metals solution using dead and immobilized archaeal cells

It is crucial to identify more biological adsorbents that can efficiently uptake metals from wastewater. Dry haloalkaliphilic archaea Natronolimnobius innermongolicuswas evaluated for Cd ions biosorption. The optimal operating conditions (pH, biomass dose, initial metal concentration, contact time, and isotherms models) were tested. Biosorption process is influenced by the metal's solution pH with maximum removal of 83.36% being achieved at pH 8. Cadmium ions uptake reaches equilibrium in about 5 min of biosorption process. The Langmuir model was determined to better fit the Cd(II) biosorption by dry archaea. The maximal uptake capacity (qmax) of Cd(II) was 128.21 mg/g. The effect of multi-component system on biosorption behaviour of Pb, Ni, Cu, Fe, and Cd ions by immobilized dried archaeal cells, dried archaeal cells, and dried bryozoa was studied using Plackett–Burman experimental design. The investigated biosorbents were effective at removing metals from contaminated systems, particularly for Fe, Pb, and Cd ions. Moreover, the interaction behaviour of these metals was antagonistic, synergistic, or non-interactive in multi-metals system. SEM, EDX, and FTIR spectra revealed changes in surface morphology of the biomass through the biosorption process. Finally, continuous adsorption experiment was done to examine the ability of immobilized biomass to adsorb metals from wastewater.

Biosorption of Cd(II) ions by Chlorella microalgae: isotherm, kinetics processes and biodiesel production

Biosorption of Cd(II) ions by Chlorella microalgae: isotherm, kinetics processes and biodiesel production

Improvement of Zn (II) and Cd (II) Biosorption by Priestia megaterium PRJNA526404 Isolated from Agricultural Waste Water.

Heavy metals are considered as dangerous pollutants even in relatively low concentrations. Biosorption is an ecofriendly technology that uses microbial biomasses for adsorbing heavy metals from wastewater on their surfaces based on physicochemical pathways. Ten agricultural wastewater samples were collected from different sites in Sohag Governorate, Egypt. One hundred and nineteen zinc and cadmium-resistant bacterial isolates were recovered from the water samples. Interestingly, the isolate R1 was selected as the most resistant to Zn2+ and Cd2+. This isolate was morphologically and biochemically characterized and identified by sequencing of 16S rRNA gene as Priestia megaterium, and then deposited in the GenBank database under the accession number PRJNA526404. Studying the effects of pH and contact time on the biosorption process revealed that the maximum biosorption was achieved within 50 min at pH 7 and 8 for Zn2+ and Cd2+, respectively, by the living and lyophelized biomass of Priestia megaterium PRJNA526404. The preliminary characterization of the main chemical groups present on the cell wall, which are responsible for heavy metal biosorption, was performed by Infrared analysis (IR). Kinetics studies revealed that data were fitted towards the models hypothesized by Langmuir and Freundlich isotherm equations. The maximum capacity values (qmax) for biosorption of zinc and cadmium reached by using living and lyophelized biomass were 196.08; 227.27 and 178.57; 212.777 mg/g, respectively, and it was indicated that lyophilization improved efficiency of the biomass to heavy metals compared to living cells. The results indicated that Priestia megaterium PRJNA526404 had good application prospect in cadmium and zinc water remediation.

Induction of resilience strategies against biochemical deteriorations prompted by severe cadmium stress in sunflower plant when Trichoderma and bacterial inoculation were used as biofertilizers.

Cadmium (Cd) is a highly toxic heavy metal. Its emission is suspected to be further increased due to the dramatic application of ash to agricultural soils and newly reclaimed ones. Thereby, Cd stress encountered by plants will exacerbate. Acute and chronic exposure to Cd can upset plant growth and development and ultimately causes plant death. Microorganisms as agriculturally important biofertilizers have constantly been arising as eco-friendly practices owing to their ability to built-in durability and adaptability mechanisms of plants. However, applying microbes as a biofertilizer agent necessitates the elucidation of the different mechanisms of microbe protection and stabilization of plants against toxic elements in the soil. A greenhouse experiment was performed using Trichoderma harzianum and plant growth-promoting (PGP) bacteria (Azotobacter chroococcum and Bacillus subtilis) individually and integrally to differentiate their potentiality in underpinning various resilience mechanisms versus various Cd levels (0, 50, 100, and 150 mg/kg of soil). Microorganisms were analyzed for Cd tolerance and biosorption capacity, indoleacetic acid production, and phosphate and potassium solubilization in vitro. Plant growth parameters, water relations, physiological and biochemical analysis, stress markers and membrane damage traits, and nutritional composition were estimated. Unequivocal inversion from a state of downregulation to upregulation was distinct under microbial inoculations. Inoculating soil with T. harzianum and PGPB markedly enhanced the plant parameters under Cd stress (150 mg/kg) compared with control plants by 4.9% and 13.9%, 5.6% and 11.1%, 55.6% and 5.7%, and 9.1% and 4.6% for plant fresh weight, dry weight, net assimilation rate, and transpiration rate, respectively; by 2.3% and 34.9%, 26.3% and 69.0%, 26.3% and 232.4%, 135.3% and 446.2%, 500% and 95.6%, and 60% and 300% for some metabolites such as starch, amino acids, phenolics, flavonoids, anthocyanin, and proline, respectively; by 134.0% and 604.6% for antioxidants including reduced glutathione; and by 64.8% and 91.2%, 21.9% and 72.7%, and 76.7% and 166.7% for enzymes activity including ascorbate peroxidase, glutathione peroxidase, and phenylalanine ammonia-lyase, respectively. Whereas a hampering effect mediated by PGP bacterial inoculation was registered on levels of superoxide anion, hydroxyl radical, electrolyte leakage, and polyphenol oxidase activity, with a decrease of 0.53%, 14.12%, 2.70%, and 5.70%, respectively, under a highest Cd level (150 mg/kg) compared with control plants. The available soil and plant Cd concentrations were decreased by 11.5% and 47.5%, and 3.8% and 45.0% with T. harzianum and PGP bacterial inoculation, respectively, compared with non-inoculated Cd-stressed plants. Whereas, non-significant alternation in antioxidant capacity of sunflower mediated by T. harzianum action even with elevated soil Cd concentrations indicates stable oxidative status. The uptake of nutrients, viz., K, Ca, Mg, Fe, nitrate, and phosphorus, was interestingly increased (34.0, 4.4, 3.3, 9.2, 30.0, and 1.0 mg/g dry weight, respectively) owing to the synergic inoculation in the presence of 150 mg of Cd/kg. However, strategies of microbe-induced resilience are largely exclusive and divergent. Biofertilizing potential of T. harzianum showed that, owing to its Cd biosorption capability, a resilience strategy was induced via reducing Cd bioavailability to be in the range that turned its effect from toxicity to essentiality posing well-known low-dose stimulation phenomena (hormetic effect), whereas using Azotobacter chroococcum and Bacillus subtilis, owing to their PGP traits, manifested a resilience strategy by neutralizing the potential side effects of Cd toxicity. The synergistic use of fungi and bacteria proved the highest efficiency in imparting sunflower adaptability under Cd stress.

Potential Use of Low-Cost Agri-Food Waste as Biosorbents for the Removal of Cd(II), Co(II), Ni(II) and Pb(II) from Aqueous Solutions

We evaluated the potential use of agri-food waste for the removal of heavy metal ions from aqueous solutions and its application in different processes (e.g., water remediation, in the production of biomass enriched in nutritionally significant elements, etc.). Biomasses from grape seed, grape pomace, loquat seed, Calabrese broccoli stem, empty pods of carob and broad bean pods, unripe bitter orange peel, kumquat, orange pulp and Canary Island banana pulp were prepared. The percentages and biosorption capacities were evaluated and compared with those refe-renced using Valencia orange peel (Citrus sinensis Valencia late). These studies allow for easily providing added value to different agri-food wastes. The results show that the proposed biomasses were able to retain the studied metal ions and obtained different percentages, being in some cases above 90%. The highest values were obtained using broad bean pod (Pb(II) (91.5%), Cd(II) (61.7%), Co(II) (40.7%) and Ni(II) (39.7%)). Similar values were observed using grape seed, broccoli stem, carob pod and unripe bitter orange peel. Carob pod for biosorption of Cd(II) is also of great interest. These studies suggest that the agri-food residues evaluated can be applied to prepare effective biosorbents of divalent metal ions from aqueous solutions.

Adsorption of Cd2+ from synthetic wastewater by modified leaves of Eupatorium adenophorum and Acer oblongum: thermodynamics, kinetics and equilibrium studies

AbstractHeavy metals cause outrageous ecological risks when released into the environment from many point and non-point sources. Biosorbents prepared from the leaves of Eupatorium adenophorum (AEA) and Acer oblongum (AAO) were used as practical solutions to remove the toxic heavy metal cadmium (Cd2+) from wastewater. Biosorption of Cd2+ was investigated using AEA and AAO biomass under batch conditions. The effect of operating variables like temperature, contact time, the pH impact, and initial metal concentration and biosorbent portion on Cd2+ removal has been studied. The optimal pH and the sorbent dosage were found to be 7.0 and 2.0 g L−1, respectively, and removal efficiency attained was 93.3% with an equilibrium removal time of 90 min. The equilibrium uptake of Cd2+ was evaluated by Freundlich, Langmuir, and Temkin isotherm models. The Langmuir isotherm model was proved fit confirming single layer of sorption. The biosorption of Cd2+ onto activated AEA and AAO biomass achieved were 45.45 mg g−1 and 44.64 mg g−1 respectively. The adsorption affinity of AEA toward Cd2+ was discovered a lot more prominent than AAO biomass. The kinetic data of Cd2+ biosorption onto activated AEA and AAO, fitted with a pseudo-second-order well with higher values of R2 (> 0.99). Thermodynamics disclosed that the adsorption process was spontaneous (∆G0 < 0), endothermic (∆H0 > 0), and feasible (ΔS0 > 0). The adsorption of Cd2+ onto AEA was more exothermic and spontaneous than the AAO biosorbent. Additionally, FT-IR and SEM analysis uncovered that Cd2+ were adsorbed onto selected biomassdue to –NH–, –COOH, –OH, and –NH2 groups. Ionic, coordination bond formation, and electrostatic interaction with Cd2+ demonstrated that they were promising biosorbent for wastewater treatment.

Local fruit peel biosorbents for lead(II) and cadmium(II) ion removal from waste aqueous solution: A kinetic and equilibrium study

Heavy metals are serious causes of water pollution affecting both living organisms and human life. This research focuses on the removal of Pb(II) and Cd(II) ions from waste aqueous solution through adsorption process using natural biosorbents chemically modified from three local fruit peels comprising dragon fruit peel (DFP), rambutan peel (RP), and passion fruit peel (PFP). Their surface morphologies and functional groups were consecutively determined using scanning electron microscope and Fourier transform infrared spectrometer. Concentrations of the adsorbed metal ions were quantified using atomic absorption spectrometer. Adsorption experiments were carried out with varying adsorbent dosages, pH values, contact time, and initial lead(II) and cadmium(II) concentrations. An adsorbent dosage of 0.25 g, a pH of 4, a contact time of 180 min, and an initial concentration of 100 mg/L were found to be the optimal set of conditions for biosorption of Pb(II) and Cd(II) ions. The chemically modified groups showed the highest percentages of Pb(II) and Cd(II) removal at 97.867% and 97.100% for RP, respectively. The adsorption proceeded according to the pseudo-second-order kinetic model. The adsorption data were consistent with the Langmuir and Freundlich isotherm models, but the Langmuir model provided the best fit. The Langmuir monolayer adsorption capacity values of biosorbents were determined to be 97.087 mg(Pb2+)/g, 114.943 mg(Pb2+)/g, 103.093 mg(Pb2+)/g, and 86.207 mg(Cd2+)/g, 102.041 mg(Cd2+)/g, 89.286 mg(Cd2+)/g for DFP, RP, and PFP, respectively. The results indicate that these biosorbents could be able to efficiently remove Pb(II) and Cd(II) and serve as economic and promising adsorbents for heavy metal removal from contaminated wastewater.

Potentiality of phosphorus-accumulating organisms biomasses in biosorption of Cd(II), Pb(II), Cu(II) and Zn(II) from aqueous solutions: Behaviors and mechanisms.

Heavy metal pollution is consistently a critical global issue, and bioremediation is regarded as one of the most promising approaches. In this work, the biosorption characteristics of Cd(II), Pb(II), Cu(II) and Zn(II) from aqueous solutions using three phosphorus-accumulating organisms (PAOs) biomasses, Ochrobactrum cicero (PAB-006), Stenotrophomonas maltophilia (PAB-009), and Pseudomonas putida (PAB-0031), as biosorbents were investigated. Results indicated that the equilibrium biosorption capacities of biosorbents to heavy metal ions were sensitive to the solution pH, and increased with increasing pH values. The experimental data of Cd(II), Pb(II), Cu(II) and Zn(II) biosorption were in good agreement with the Pseudo-second-order, Redlich-Peterson and Temkin models, implying that the biosorption was a hybrid chemical reaction-biosorption process. In addition, the theoretical maximum biosorption capacities of Cd(II), Pb(II), Cu(II) and Zn(II) were calculated to be 67.84, 80.23, 50.56 and 63.07mg/g for PAB-006, 59.99, 87.71, 39.26 and 64.00mg/g for PAB-009 and 68.31, 85.43, 38.97 and 62.85mg/g for PAB-031, respectively (pH=5.0±0.1, T=25°C), according to the parameters of the Langmuir model. Moreover, ionic strength had negligible influences or slight promoting effects, while humic acid exhibited positive effects on the removal of heavy metals. Further, PABs were stable and displayed excellent reusability. Characterization techniques of FTIR and XPS revealed that surface complexation, ion exchange, hydrogen bonding and electrostatic interaction were the main mechanisms involved in the biosorption process. In summary, the biosorbent PABs possessed high biosorption performance with excellent reusability, and which hold the great application prospect in the treatment of heavy metal contaminated water.

Voltammetric detection of biosorption of Co, Ni, Zn, Cd, Pb, and Cu on Hypnum cupressiforme Hedw. in aquatic media

Voltammetric detection of biosorption of Co, Ni, Zn, Cd, Pb, and Cu on Hypnum cupressiforme Hedw. in aquatic media

Risk of low stability Saccharomyces cerevisiae ATCC 9763-heavy metals complex in gastrointestinal simulated conditions

The biosorption of heavy metals by microorganisms has attracted the interest of food researchers as the last approach to reduce the risk of their absorption in the human body. But the stability of yeast-metal complexes under simulated gastrointestinal conditions has not been investigated. In this study stability of complex as well as isotherm and kinetic models of biosorption have been studied. Also, the impact of some pretreatment on yeast biosorption was studied to check the possible impact of different environmental conditions in food processing. Data showed a risk of heavy metal release in simulated gastrointestinal conditions. The best biosorption of metals from aqueous solutions by Saccharomyces (S.) cerevisiae may be achieved after NaOH pretreatment for Mercury (Hg) 92.7%. While biosorption of Lead (Pb) 37.48%, Arsenic (As) 19.44%, and Cadmium (Cd) 39.9% by untreated yeast were better. In gastrointestinal conditions, Hg and Cd-yeast complexes were more stable and biosorption of Cd and Pb increased. Bonds of As and Hg-yeast complexes in digestion conditions were reversible. The metals biosorption by untreated yeast followed the pseudo-second-order kinetic and the Langmuir isotherm model for Hg, Pb, and Cd and Freundlich for As. Results showed that biosorption of heavy metals by S. cerevisiae, although may decrease metal bioavailability in fermented foods, the complex is not enough stable in gastrointestinal conditions.

Characteristics of Cd(II) Biosorption into Streamer Biofilm Matrices

This study analyzed the characteristics of Cd(II)[MOU1] biosorption into the natural streamer biofilm matrices collected from the Brantas River in Indonesia to develop streamer biofilms as biosorbent pollutant ions. The biosorption features w

Modeling the Biosorption Process of Heavy Metal Ions on Soybean-Based Low-Cost Biosorbents Using Artificial Neural Networks

Pollution of the environment with heavy metals requires finding solutions to eliminate them from aqueous flows. The current trends aim at exploiting the advantages of the adsorption operation, by using some low-cost sorbents from agricultural waste biomass, and with good retention capacity of some heavy metal ions. In this context, it is important to provide tools that allow the modeling and optimization of the process, in order to transpose the process to a higher operating scale of the biosorption process. This paper capitalizes on the results of previous research on the biosorption of heavy metal ions, namely Pb(II), Cd(II), and Zn(II) on soybean biomass and soybean waste biomass resulting from biofuels extraction process. The data were processed by applying a methodology based on Artificial Neural Networks (ANNs) and evolutionary algorithms (EAs) capable of evolving ANN parameters. EAs are represented in this paper by the Differential Evolution (DE) algorithm, and a simultaneous training and determination of the topology is performed. The resulting hybrid algorithm, hSADE-NN was applied to obtain optimal models for the biosorption process. The expected response of the system addresses biosorption capacity of the biosorbent (q, mg/g), the biosorption efficiency (E, %), as functions of input parameters: pH, biosorbent dose (DS, mg/g), the initial concentration of metal in the solution (c0, mg/L), contact time (tc, h), and temperature (T, °C). Models were developed for the two output variables, for each metal ion, finding a high degree of accuracy. Furthermore, the combinations of input parameters were found which can lead to an optimal output in terms of biosorption capacity and biosorption efficiency.

Modeling and Optimization of Heavy Metals Biosorption by Low-Cost Sorbents Using Response Surface Methodology

This paper exploits, through modeling and optimization, the experimental laboratory data on the biosorption of heavy metal ions Pb(II), Cd(II), and Zn(II) from aqueous media using soybean and soybean waste biomasses. The biosorption modeling was performed using the Response Surface Methodology, followed by optimization based on numerical methods. The aim of the modeling was to establish the most probable mathematical relationship between the dependent variables (the biosorption efficiency of the biosorbents when adsorbing metal ions, R(%), and the biosorption capacity of sorbents, q(mg/g)) and the process parameters (pH; sorbent dose, DS (g/L); initial metal ion concentration in solution, c0 (mg/L); contact time, tc (min); temperature, T (°C)), validated by methodologies specific to the multiple regression analysis. Afterward, sets of solutions were obtained through optimization that correlate various values of the process parameters to maximize the objective function. These solutions also confirmed the performance of soybean waste biomass in the removal of heavy metal ions from polluted aqueous effluents. The results were validated experimentally.

Process optimization and modeling of Cd2+ biosorption onto the free and immobilized Turbinaria ornata using Box\u2013Behnken experimental design

The release of effluents containing cadmium ions into aquatic ecosystems is hazardous to humans and marine organisms. In the current investigation, biosorption of Cd2+ ions from aqueous solutions by freely suspended and immobilized Turbinaria ornata biomasses was studied. Compared to free cells (94.34%), the maximum Cd2+ removal efficiency reached 98.65% for immobilized cells obtained via Box–Behnken design under optimized conditions comprising algal doses of 5.04 g L−1 and 4.96 g L−1, pH values of 5.06 and 6.84, and initial cadmium concentrations of 25.2 mg L−1 and 26.19 mg L−1, respectively. Langmuir, Freundlich, and Temkin isotherm models were suitably applied, providing the best suit of data for free and immobilized cells, but the Dubinin–Radushkevich model only matched the immobilized algal biomass. The maximum biosorption capacity of Cd2+ ions increased with the immobilized cells (29.6 mg g−1) compared to free cells (23.9 mg g−1). The Cd2+ biosorption data obtained for both biomasses followed pseudo-second-order and Elovich kinetic models. In addition, the biosorption process is controlled by film diffusion followed by intra-particle diffusion. Cd2+ biosorption onto the free and immobilized biomasses was spontaneous, feasible, and endothermic in nature, according to the determined thermodynamic parameters. The algal biomass was further examined via SEM/EDX and FTIR before and after Cd2+ biosorption. SEM/EDX analysis revealed Cd2+ ion binding onto the algal surface. Additionally, FTIR analysis confirmed the presence of numerous functional groups (hydroxyl, carboxyl, amine, phosphate, etc.) participating in Cd2+ biosorption. This study verified that immobilized algal biomasses constitute a cost-effective and favorable biosorbent material for heavy metal removal from ecosystems.

Pitahaya Fruit (Hylocereus spp.) Peels Evaluation for Removal of Pb(II), Cd(II), Co(II), and Ni(II) from the Waters

The present study investigated the performance of Pitahaya (Hylocereus spp.) peel (PP) as a low-cost biosorbent in the removal of Co(II), Cd(II), Pb(II), and Ni(II) from single and multi-component solutions. The characterization of the samples was carried out by pHpzc, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS). Biosorption was carried out by batch experimental procedure to examine the effects of contact time, solution pH, initial concentration of metal ions, and biosorbent dosage. The results indicate that the biosorption of Pb(II), Cd(II), Co(II), and Ni(II) Pitahaya peels followed pseudo-second-order kinetics, and equilibrium adsorption followed the Langmuir model. The maximum sorption capacities of PP for the metallic species were found to be as follows: Pb (82.64 mg g−1) > Cd (17.95 mg g−1) > Co (6.013 mg g−1) > Ni (5.322 mg g−1). However, the efficiency of the biosorption change when the metallic species are mixed. The re-generation of the PP after the adsorption of the metallic species was done using 0.1 M HNO3 solution, and the reusability of the biomass was carried out using two adsorption and desorption cycles.

Curvularia coatesiae XK8, a Potential Bioadsorbent Material for Adsorbing Cd(II) and Sb(III) Compound Pollution: Characteristics and Effects.

Soil heavy metal pollution is a common problem in mining areas. The soil of the Xikuangshan located in Lengshuijiang, Hunan Province, China contains various excessive heavy metals, especially antimony and cadmium. Previous studies have shown that heavy metal-tolerant microorganisms screened from mining areas have the potential to adsorb heavy metals. In this study, we screened out a cadmium and antimony tolerant fungus named XK8 from the slags collected from the Xikuangshan. Then, we explored the single and binary biosorption characteristics of Cd(II) and Sb(III) on it. In our results, the fungus XK8 was identified as Curvularia coatesiae XK8 by ITS sequencing analysis. Under the optimal conditions, in binary biosorption of the XK8, the main effect of the initial cadmium concentration on the cadmium removal rate of XK8 is negative, while the main effect of the initial antimony concentration, biosorption time, and initial pH on the cadmium removal rate of XK8 is positive. The initial pH has the greatest impact on the biosorption of cadmium on XK8, followed by the biosorption time; moreover, the effects of both are stronger than the coexisting ions. SAS analysis shows that under the optimal conditions, the theoretical maximum cadmium removal rate of XK8 is 100%, and the actual removal rate is 67.57%. Compared to the single biosorption with binary biosorption, the maximum biosorption capacity of XK8 for cadmium in the composite biosorption system increased to 23.6 mg g–1. It shows that under the background of high antimony, Sb(III) has a promoting effect on the biosorption of Cd(II) on XK8. In summary, a cadmium and antimony tolerant fungus with strong cadmium biosorption ability under the background of high antimony was screened out. It provides a potential microbial material for the bioremediation of heavy metal pollution.

Use of Paliurus spina-christi Mill. as a novel biosorbent: efficient biosorption of Pb(II) and Cd(II) ions from aqueous solution

Use of Paliurus spina-christi Mill. as a novel biosorbent: efficient biosorption of Pb(II) and Cd(II) ions from aqueous solution

Effects of Cd-resistant fungi on uptake and translocation of Cd by soybean seedlings

In this study, three cadmium (Cd)-resistant fungal strains, temporarily named as F1, F2 and F3 were isolated from the roots of Cd-tolerant soybean cultivars, rhizosphere and bulk soils, respectively, in contaminated sites. Cd-resistant strains F1, F2 and F3 were characterized for their effect on biomass, Cd uptake and translocation of two soybean cultivars (Liaodou36 and Liaodou33) grown in Cd-contaminated soils. The results showed that Cd concentration decreased significantly in Cd-supplemented culture solutions inoculated with strains F1, F2 and F3 compared to non-inoculated controls, while cell counts significantly increased during the incubation. The increase in shoot biomass of two soybean cultivars inoculated with strains F1, F2 and F3 ranged from 13% to 29%, 16%–27% and 15%–32%, respectively, compared to controls. Strain F2 had a higher potential to reduce the water-soluble Cd content (23% and 40%) and EDTA-extractable Cd content in the rhizosphere soil of Liaodou36 and Liaodou33 seedlings compared to strains F1 and F3. A significant decrease of Cd contents was observed in the root and shoot of Liaodou33 inoculated with strain F2 compared to non-inoculated controls, and inoculation with strain F2 significantly reduced the TF and BCF of Liaodou33 in comparison with controls. Based on ITS rRNA gene sequence analyses, the strains F1, F2 and F3 were identified as Mucor circinelloides (similarity 99.81%), Curvularia lunata (similarity 99.31%) and Clonostachys rosea (similarity 99.17%). The results of our study demonstrated that the strain F2 had a higher Cd biosorption and immobilization potential than strains F1 and F3. The strain F2 promoted the growth and reduced Cd uptake and translocation of Liaodou33 in Cd-polluted soils. It is worth noting that our results might provide an effective technical support for Cd immobilization remediation and safe soybean production by inoculating moderate Cd-accumulating soybean cultivars with strain F2 in Cd-contaminated soils.

Biosorption of Cd(II) by Nordic microalgae: Tolerance, kinetics and equilibrium studies

The amount of heavy metals released into the environment has significantly increased. Industrial wastewaters, e.g. from mining or battery manufacturing, are often polluted with heavy metals such as Cd, Cr or Pb. These metals threat the environment and can cause health problems even at low concentrations. Therefore, their proper removal from industrial wastewater before its disposal is of paramount importance (Javanbakht et al. [1]). Here the ability of fourteen wild Nordic microalgal strains to remove cadmium (Cd(II)) from aqueous solutions has been studied. Three of the chosen strains, namely Chlorella vulgaris (13-1), Coelastrella sp. (3-4) and Scenedesmus obliquus (13-8), demonstrated high tolerance towards Cd(II) concentrations up to 2.5 mg L−1 and their sorption kinetics and equilibrium were studied. Metal sorption by Chlorella vulgaris (13-1) and Coelastrella sp. (3-4) was described best by pseudo-second order kinetics, whereas the removal kinetics of Scenedesmus obliquus (13-8) was best fitted by the intraparticle diffusion model. Starting from an initial concentration of 2.5 mg L−1Chlorella vulgaris (13-1) and Coelastrella sp. (3-4) removed 72% and 82%, respectively, of the Cd(II) within only 24 h. Modeling their Cd(II) sorption equilibria revealed that the SIPS- and Dubinin-Radushkevich models were best suited for living microalgae, and the maximum adsorption capacity (qmax) was calculated. While Chlorella vulgaris (13-1) and Coelastrella sp. (3-4) were able to remove about 49 mg g−1 and 65 mg g−1 Cd(II), respectively, Scenedesmus obliquus (13-8) only removed around 25 mg g−1. Fourier-Transform Infrared Spectroscopy (FTIR) analyses of the biomass revealed the carboxylic moieties of the cell wall to be the key player in Cd(II) removal. This study demonstrates the high potential of Nordic microalgae to remove heavy metals at conditions relevant for an industrial tertiary wastewater treatment unit and will support the development of new, biobased, innovative technologies for the bioremediation of heavy metal polluted streams.