Biosorption Capacity Research Articles

Maize cob (Zea mays) as natural biomass sorbent for crude oil biosorptive removal from contaminated seawater: Taguchi process optimization and biosorptive removal mechanism.

Crude oil pollution poses a serious threat to the aquatic environment. Hence, there is an increasing interest in developing an efficient cleaner process technique for oil spill cleanup via agricultural biomass waste-organic sorbent utilization. This work evaluated the effects of independent biosorptive removal at three varying levels (initial concentration of crude oil (Z1, 7.8-15.6 g/L), seawater-oil temperature (Z2, 25-45 °C), sorbent dose (Z3, 1-3 g), and sorbent particle size diameter (Z4, 1.18-4.72 mm)) on the biosorptive removal efficiency and biosorptive capacity performance of maize cob sorbent for crude oil biosorptive removal from seawater. Experiments were designed based on Taguchi orthogonal array experimental design (L9(34)) to study the effects and process optimization. The results revealed that the maize cob sorbent's crude oil biosorptive removal efficiency is related to Z1, Z3, and Z4, while the biosorptive capacity is related to Z1 and Z3. The optimum biosorptive removal efficiency and the biosorptive capacity values were 96.53% and 12.64 g/g, respectively, achieved at optimum factors of Z1 (7.8 g/L), Z3 (3 g), and Z4 (1.18 mm), as well as at Z1 (15.6 g) and Z3 (1 g). The isotherm and kinetic data, respectively, followed the Langmuir isotherms and the pseudo-second-order kinetics with a maximum monolayer biosorptive capacity of 23.31 g g-1. The mechanism of biosorptive crude oil removal was by physical sorption and film diffusion control. Therefore, the maize cob represents an inexpensive and effective natural sorbent for oil spill removal from water bodies.

Mucor cells passively immobilized on rose waste phyto-biomass: An eco-friendly hybrid material for the biotreatment of reactive dye contamination

The immobilization of microbial cells on eco-friendly supports is a promising technique to obtain effectively immobilized biomaterials for the biotreatment of aquatic pollution. For the biosorption of reactive dye-contaminated water, a new immobilized biosorbent, rose waste/Mucor plumbeus cells (RWMPC) composite was designed by immobilizing the fungal cells on a process waste of the rose oil industry. Batch and continuous mode biosorption features of RWMPC under different pH, initial dye concentration, contact time, biomaterial dose, and effluent flow rate conditions were examined. Zeta potential measurements, FT-IR, and SEM analysis were used to determine the morphological features of the biomaterial and possible Reactive Blue 49 (RB49)-biomaterial interactions. Kinetic investigations revealed that Ho's pseudo-second-order kinetic model could offer the best data fitting for biosorption, while the Freudlich model best matched the equilibrium data. Immobilized biomaterial displayed a high biosorption capacity of 120.88mg g−1. With an appropriate flow rate and amount of RWMPC packed into the column, dynamic treatment tests demonstrated >90% biosorption efficiency. The breakthrough curve of the RWMPC column adequately fits Chu's simplistic model. Regeneration tests revealed that after ten consecutive cycles, the biosorption yield and recovery efficacy of RWMPC were >65 and 85%, respectively. Zeta potential tests, SEM micrographs, and FT-IR studies also verified the dye uptake. Using synthetic wastewater in a continuous system, RWMPC could remove >90% of RB49. Breakthrough and exhaustion points were identified, and the maximum exhaustion capacity value was computed as 127.6 mg g−1. The results might inspire a fresh approach to the problem of reactive dye contamination in waters.

Utilization of Low Cost Biofertilizers for Adsorptive Removal of Congo Red Dye.

Presence of colors, organic surface finishing agents and surfactants in textile industry effluent makes it highly detrimental for surrounding environment. Hence the effluent from textile industry needs treatment for removal of these colors, organic and inorganic components before its disposal. Hence applicability of low cost and environmental friendly biosorbents, Azospirillium biofertilizer and Rhizobium biofertilizer were investigated for removal of Congo red dye. Batch experimentation was carried out to check operating parameters like, temperature, dose of adsorbent, pH, agitation speed, contact time and initial concentration. The biosorption capacity for Congo red dye was 67.114 and 101.01mg/g, for Azospirillium biofertilizer and Rhizobium biofertilizer, respectively at optimized parameters. RL factor was 0.558 and 0.568 for Azospirillium biofertilizer and Rhizobium biofertilizer. The data showed combination of interaction-based separation through better fitting of Langmuir isotherm compared to Freundlich. Its separation is well described by Pseudo-second order and intraparticle diffusion model. Adsorption was favorable at lower temperature suggesting exothermic and spontaneous nature. Reusability for Azospirillium biofertilizer and Rhizobium biofertilizer was checked for 25mg/land. While the biological nature of Azospirillium and Rhizobium biofertilizer makes removal of Congo red dye environmentally benign.

Valorization of spent Aureobasidium pullulans for the removal of toxic pollutant in wastewater treatment

Textile industries are growing rapidly due to increased demand for textile products worldwide. The discharge of textile effluent containing synthetic dyes, chlorides, pigments, aromatic compounds, and heavy metals contributes substantially to water pollution due to its toxicity and chemical composition. This work is focused on the potential usage of treated Aureobasidium pullulans biomass (TAPB) to remove the toxic chemical pollutant, Methylene Blue (MB), from an aqueous solution. Experimental results found that maximum MB removal of 76.5% was observed using TAPB dosage of 3 ​g/L, initial pH 8.0, temperature 30 ​°C, and initial MB concentration of 50 ​mg/L. The maximum biosorption capacity of TAPB was found to be 113.75 ​mg/g using the Langmuir non-linear approach. Successive biosorption and desorption experiments showed better regeneration capacity of TAPB until the fourth trial. These results demonstrated that maximum MB removal (%) could be possible with a small quantity of biomass, consequently offering a minimum size of the contactor and less capital cost requirement for biosorption. It also showed a greater regeneration capacity biosorbent for removing MB. Hence, the feedstock consumption for MB removal could be considerably decreased in large-scale processes.

Biosorption of cadmium by Enterobacter ludwigii isolated from soil contaminated with cadmium near a coal-fired power plant in Korea

ABSTRACT This study aimed to isolate and characterize indigenous bacteria from cadmium-contaminated soil around a coal-fired power plant in Korea for their potential use in biosorption. The 16S ribosomal RNA analysis identified Enterobacter ludwigii G17–1 in the soil, exhibiting a remarkably high minimum inhibitory concentration (2,500 mg/L) for cadmium. The efficiency of cadmium biosorption was investigated under different pH levels (6–9), temperatures (15–40°C), and initial cadmium concentrations (25–100 mg/L), using both live and dead G17–1. The live G17–1 strain exhibited a maximum biosorption efficiency of 50% for 25 mg/L cadmium at 24 hours, while the highest efficiency achieved with dead G17–1 was 48% at 1 hour. The biosorption capacity decreased as the initial cadmium concentration increased. These findings suggest that the isolated bacterium, E. ludwigii G17–1, holds potential for the bioremediation of cadmium-contaminated water and wastewater.

Removing heavy metal ions from wastewater by Chlorella sorokiniana coupled to manganese-doped magnetic ferrite nanoparticles

In this study, we investigated the benefit of combining Chlorella sorokiniana with manganese-containing ferrite nanoparticles (NPs) for heavy metal removal and cell harvesting. Our results demonstrate that the combination of non-toxic nanoparticles significantly enhances the heavy metal removal capacity of C. sorokiniana without affecting its growth. The microalgae combined with NPs was able to sequester Cr6+, Co2+, and Ni2+ from aqueous solutions and could remove these metals at a higher adsorption capacity and within a relatively short time than their individual counterparts, indicating a synergistic effect between the algal cells and the nanomaterials, where bioadsorption and chemisorption were the main players. Both biosorption and chemisorption capacities were found to be the highest for single-metal systems and decreased when coexisting ions were present in the solution. The adsorption of the heavy metals evaluated was better described by the pseudo-second order model than the pseudo-first order model, indicating that chemisorption dominated over physisorption. These characteristics suggest that the combination of biosorbents with nanosorbents is a promising approach for the treatment of water contaminated with heavy metals making this process more efficient, economical, sustainable, and clean.

Lead biosorption profiling of endophytic Aspergillus flavus SGE34 isolated from Cleome viscosa Linn.

ABSTRACT Lead is an environmental pollutant that causes remarkable damage to various organs in the human body, especially the nervous system. Removal of lead by conventional methods is costly, and therefore, in the current scenario, biosorption using fungi is extensively explored as they provide good metal uptake systems. The present study evaluated the Pb (II) biosorption potential of endophytic fungi Aspergillus flavus SGE34. The fungal isolate was obtained from the root of an indigenous medicinal plant of the Chhattisgarh region named Cleome viscosa Linn. The biosorption potential of dead fungal biomass was optimized at different operating parameters like contact time, pH, and temperature. The maximum biosorption values were found at pH 6.0 with an equilibrium time of 150 minutes at 350C. The Fourier transform infrared spectroscopy study revealed that the pattern of new absorption bands, altered absorption intensity, and shift in wavenumber of functional groups was deduced, due to interaction between metal ions and active sites of biosorbent. The present study concluded that A. flavus SGE34 has high metal tolerance and biosorption capacity; it could effectively remove lead from industrial effluents.

The Remediation of Dysprosium-Containing Effluents Using Cyanobacteria Spirulina platensis and Yeast Saccharomyces cerevisiae.

Dysprosium is one of the most critical rare earth elements for industry and technology. A comparative study was carried out to assess the biosorption capacity of cyanobacteria Spirulina platensis and yeast Saccharomyces cerevisiae toward dysprosium ions. The effect of experimental parameters such as pH, dysprosium concentration, time of contact, and temperature on the biosorption capacity was evaluated. Biomass before and after dysprosium biosorption was analyzed using neutron activation analysis and Fourier-transform infrared spectroscopy. For both biosorbents, the process was quick and pH-dependent. The maximum removal of dysprosium using Spirulina platensis (50%) and Saccharomyces cerevisiae (68%) was attained at pH 3.0 during a one-hour experiment. The adsorption data for both biosorbents fitted well with the Langmuir isotherm model, whereas the kinetics of the process followed the pseudo-second-order and Elovich models. The maximum biosorption capacity of Spirulina platensis was 3.24 mg/g, and that of Saccharomyces cerevisiae was 5.84 mg/g. The thermodynamic parameters showed that dysprosium biosorption was a spontaneous process, exothermic for Saccharomyces cerevisiae and endothermic for Spirulina platensis. Biological sorbents can be considered an eco-friendly alternative to traditional technologies applied for dysprosium ion recovery from wastewater.

Evaluation of Thermodynamic Parameters for Cu(II) Ions Biosorption on Algae Biomass and Derived Biochars

The removal of metal ions by biosorption on inexpensive materials is still a challenge for environmental engineering research. In this study, marine green algae biomass (Ulva lactuca sp.) and the biochars obtained from this biomass, at 320 °C (BC-320) and 550 °C (BC-550), were used as biosorbents for the removal of Cu(II) ions from aqueous solution. In addition to comparing the biosorption capacities, the determination of the thermodynamic parameters allows the choice of the most suitable material for the biosorption processes. The experimental results, obtained for Cu(II) ions biosorption on each biosorbent (algae biomass (AB), BC-320 and BC-550), at three different temperatures (10, 30 and 50 °C) were analyzed using Langmuir and Freundlich isotherm models, while pseudo-first order, pseudo-second order and intra-particle diffusions models were used to model the kinetic data. The biosorption of Cu(II) ions is best described by the Langmuir model and the pseudo-second kinetic model, regardless of the type of biosorbent. Such behavior is characteristic for the retention of metal ions on low-cost materials, and is explained in the literature using the concepts of molecular symmetry. The maximum biosorption capacity (qmax, mg/g) depends on the temperature, but also on the type of biosorbent, and follow the order: BC-320 < AB < BC-550. Using the experimental isotherms, the thermodynamic parameters (ΔG0, ΔH0 and ΔS0) for the biosorption of Cu(II) ions on each biosorbent were calculated. The analysis of the obtained values constitutes the main arguments in choosing BC-550 as the most effective biosorbent for the removal of Cu(II) ions from aqueous media.

Biosorption of Escherichia coli Using ZnO-Trimethyl Chitosan Nanocomposite Hydrogel Formed by the Green Synthesis Route.

In this study, we tested the biosorption capacity of trimethyl chitosan (TMC)-ZnO nanocomposite (NC) for the adsorptive removal of Escherichia coli (E. coli) in aqueous suspension. For the formation of ZnO NPs, we followed the green synthesis route involving Terminalia mantaly (TM) aqueous leaf extract as a reducing agent, and the formed ZnO particles were surface-coated with TMC biopolymer. On testing of the physicochemical characteristics, the TM@ZnO/TMC (NC) hydrogel showed a random spherical morphology with an average size of 31.8 ± 2.6 nm and a crystal size of 28.0 ± 7.7 nm. The zeta potential of the composite was measured to be 23.5 mV with a BET surface area of 3.01 m2 g-1. The spectral profiles of TM@ZnO/TMC NC hydrogel on interaction with Escherichia coli (E. coli) revealed some conformational changes to the functional groups assigned to the stretching vibrations of N-H, C-O-C, C-O ring, and C=O bonds. The adsorption kinetics of TM@ZnO/TMC NC hydrogel revealed the pseudo-second-order as the best fit mechanism for the E. coli biosorption. The surface homogeneity and monolayer adsorption of the TM@ZnO/TMC NC hydrogel reflects majorly the entire adsorption mechanism, observed to display the highest correlation for Jovanovic, Redlich-Peterson, and Langmuir's isotherm models. Further, with the use of TM@ZnO/TMC NC hydrogel, we measured the highest adsorption capacity of E. coli to be 4.90 × 10 mg g-1, where an in-depth mechanistic pathway was proposed by making use of the FTIR analysis.

Mass transfer limiting step determination and a new modified empirical model for Th(ІV) biosorption in a fixed-bed column

In this paper, a new empirical model for predicting breakthrough curves of Th(ІV) biosorption using Ca-pretreated Cystoseria indica alga in a fixed bed column was presented. Also, the comparison of the proposed model with the Thomas, Yoon-Nelson, and Clark models showed that the new model had better agreement with the experimental data. Furthermore, the optimum flow rate of 2.5 mL/min with a maximum biosorption capacity of 213.20 mg/g was obtained using the proposed new model. Also, four mass transfer models, including internal mass transfer, external mass transfer, biosorption on active sites, and triple resistance, were used to determine the rate-limiting step and mass transfer mechanism. The internal mass transfer was considered the mass transfer controlling step. In addition, the sensitivity analysis of the mass transfer coefficients (kf, ks, kad) again showed that the internal resistance is the governing mass transfer resistance to the Th(ІV) biosorption process. The biosorption of Th(IV) from a real effluent by Ca-pretreated Cystoseria indica alga in a fixed-bed column was investigated to validate the new empirical model. The results demonstrated that the new empirical model could describe biosorption behavior more accurately than the Thomas model.

Systematic investigation of simultaneous copper biosorption and nitrogen removal from wastewater by an aerobic denitrifying bacterium of auto-aggregation

Finding effective methods for simultaneous removal of eutrophic nutrients and heavy metals has attracted increasing concerns for the environmental remediation. Herein, a novel auto-aggregating aerobic denitrifying strain (Aeromonas veronii YL-41) was isolated with capacities for copper tolerance and biosorption. The denitrification efficiency and nitrogen removal pathway of the strain were investigated by nitrogen balance analysis and amplification of key denitrification functional genes. Moreover, the changes in the auto-aggregation properties of the strain caused by extracellular polymeric substances (EPS) production were focused on. The biosorption capacity and mechanisms of copper tolerance during denitrification were further explored by measuring changes in copper tolerance and adsorption indices, as well as by variations in extracellular functional groups. The strain showed extremely strong total nitrogen removal ability, with 67.5%, 82.08% and 78.48% of total nitrogen removal when NH4+-N, NO2−-N, and NO3−-N were used as the only initial nitrogen source, respectively. The successful amplification of napA, nirK, norR, and nosZ genes further demonstrated that the strain accomplished nitrate removal through a complete aerobic denitrification pathway. The production of protein-rich EPS of up to 23.31 mg/g and an auto-aggregation index of up to 76.42% may confer a strong biofilm-forming potential to the strain. Under the stress of 20 mg/L copper ions, the removal of nitrate-nitrogen was still as high as 71.4%. In addition, the strain could achieve an efficient removal of 96.9% of copper ions at an initial concentration of 80 mg/L. Scanning electron microscopy and deconvolution analysis of characteristic peaks confirmed that the strains encapsulate heavy metals by secreting EPS and, meanwhile, form strong hydrogen bonding structures to enhance intermolecular forces to resist copper ion stress. This study provides an innovative and effective biological approach for the synergistic bioaugmentation removal of eutrophic substances and heavy metals from aquatic environments.

Alginate modified collagen for rapid, durable and effective biosorption of Pb (II) ions from an aqueous solution

The aim of this study is to define the biosorption properties of Alginate, AC1 and AC2 beads composed of collagen obtained from sea urchin Diadema setosum and alginate obtained from Sargassum vulgare, for Pb (II) from aqueous solutions. Raw alginate beads (A), 2:1 alginate-modified-collagen beads (AC1), and 3:1 alginate-modified collagen beads (AC2) were successfully synthesized, characterized, and removal capacity of Pb (II) in aqueous solutions studied. The biosorption of Pb (II) ions by the synthesized beads was studied and the effect of parameters such as initial concentration, contact time, and solution pH on the biosorption of Pb (II) ions was investigated. Langmuir isotherm model provides satisfactory estimations of homogeneous monolayer biosorption capacity, the highest Pb (II) determined values being 248.76 mg/g for Alginate beads, 344.83 mg/g for AC1 beads, and 303.03 mg/g for AC2 beads. Moreover, AC1 beads were determined to be homogeneous monolayer and multilayer at two different stages. In the former stage, Pb (II) were quickly diffused to the outer surface of absorbent, and in the latter stage, ions were slowly biosorbed to the inner surface. The results obtained in this study showed that Alginate, AC1 and AC2 beads can be used effectively to remove Pb (II) ions from aqueous solutions. Another finding from this study was that the AC1 beads did not disintegration and significantly swelled in size relative to the other beads. Another important finding of this study was that AC1 beads were not deformed and increased in size.

Immobilization of Pseudomonas aeruginosa FNCC-0063 on Calcium Alginate and Its Application as Bioabsorbent

Biosorption of Cu (II) using bacteria Pseudomonas aeruginosa FNCC-0063 was immobilized on calcium alginate (PAI). This research examined the effect of various parameters such as pH, contact time, and initial Cu (II) concentration. The biosorption mechanism of Cu (II) was studied by sequential desorption with H2O, KNO3 1 M, HNO3 0.5 M and Na2EDTA 0.1 M. Cu (II) concentration was analyzed using atomic absorption spectrophotometer (AAS). The results showed that optimum Cu (II) ion biosorption occurred at a pH biosorption rate constant of 0.03724 g mg-1.min-1. The kinetics studies showed that Cu (II) biosorption follows pseudo-second-order. The biosorption capacities of 36.60 mg/g. Cu (II) Biosorption followed the Freundlich equation, as shown by a high correlation coefficient (R2) of about 0.99. Ionic bonds dominated the biosorption mechanism of Cu (II) ion on immobilized PAI.

Isolation and Screening of Microorganisms from Waste Dumping Sites for Biosorption of Cadmium and Lead

Heavy metal poisoning of the environment poses a serious threat to ecosystems and human health. Landfills have been found to harbor diverse microbial communities capable of bioremediating such contaminants via biosorption. Unlike traditional methods of heavy metal remediation, which often involve costly and resource-intensive techniques, biosorption offers a promising alternative that harnesses the natural capabilities of microorganisms. The objective of this research was to identify and screen microorganisms from landfills for their ability to bio-sorb cadmium (Cd) and lead (Pb). The present study deals with the isolation and screening of the microorganisms capable of removing heavy metals from the area near Dehradun Municipal Solid Waste Management Pvt. Ltd. Among the 17 bacterial isolates and 2 fungal isolates, only 7 bacteria and one fungal strain were able to absorb the heavy metal concentration. Among the 7 bacterial strains, the percentage of microbes with the ability to absorb Pb ranged from 35% to 70%, while the percentage of microbes with the ability to absorb Cd ranged from 20% to 50%. On the other hand, the fungal strain had an absorption capacity of about 80% for both Pb and Cd. This study emphasizes the potential of microorganisms isolated from landfills as attractive candidates for Cd and Pb biosorption. These isolates show significant tolerance and efficient biosorption capacities, making them good candidates for further exploration and prospective application in the bioremediation of heavy metal-contaminated environments.

Evaluation of adsorptive performance of Adhatoda vasica on lead by batch process

AbstractPowdered leaves of Adhatoda vasica are used to investigate the adsorptive capacity of lead in a batch system. The conventional heavy metal removal approaches like ion exchange, membranes, precipitation, adsorption, etc. are proven, but are costly and harmful to the environment. The proposed approach explores the possibility of a biosorption technique for removing lead from aqueous solutions using A. vasica leaf powder. It is a low‐cost, non‐conventional, readily, and abundantly available plant‐based material. The equilibrium biosorption data was analyzed using the Langmuir, Freundlich, and Temkin isotherm models, with the Freundlich model providing the best description of the equilibrium dynamics. The kinetic analysis shows pseudo‐second order to be the best fit, revealing the spontaneous and endothermic nature of adsorption. The maximum biosorption capacity for lead is 5.903 mg g−1 indicating the adsorptive capacity of A. vasica under favorable process conditions.

Removal of toxic metal Cd (II) by Serratia bozhouensis CdIW2 using in moving bed biofilm reactor (MBBR)

The use of bioreactor technology to treat industrial wastewater containing heavy metals has created new perspectives. Cadmium metal is one of the toxic heavy metals that have harmful effects on human health and the environment. This research work presents a comprehensive approach for aqueous cadmium removal through biosorption in a moving bed biofilm reactor (MBBR). The bacterium resistant to Cd(II) (350 mg/L) CdIW2 was selected among 8 cadmium tolerant bacteria isolated from the industrial wastewater of the metal industry. 16S rRNA gene and phenotypic analysis showed that the bacterium CdIW2 is similar to Serratia bozhouensis. The highest biosorption capacity of 65.79 mg/g was acquired in optimal conditions (30 min, pH = 6, 0.5 g/L, and 35 °C). The biosorption of the CdIW2 strain was consistent with the Langmuir isotherm and the pseudo-second order kinetic and showed the process's spontaneous thermodynamic and endothermic results. The removal rate 91.74% of MBBR in batch mode was obtained in 72 h and 10 mg/L of Cd(II). Furthermore, continuous mode bioreactor analysis has shown high efficiency at intel loading rates of 6–36 mg/L. day for cadmium removal. The second order kinetic (Grau) was chosen as the suitable model for modeling the MBBR process. Although several studies have evaluated the removal of various types of heavy metals, none of the studies involved the use of a metal-resistant strain in an MBBR bioreactor.

High-efficiency recovery of cerium ions from monazite leach liquor by polyamines and polycarboxylates chitosan sorbents prepared from marine industrial wastes

Rare earth elements have received a lot of attention in recent years due to their increasing demand in high-tech industries. Cerium is of current interest and is commonly used in different industries and medical applications. Cerium's uses are expanding due to its superior chemical characteristics over other metals. In this study, different functionalized chitosan macromolecule sorbents were developed from shrimp waste for cerium recovery from a leached monazite liquor. The process involves demineralization, deproteinization, deacetylation, and chemical modification steps. A new class of two-multi-dentate nitrogen and nitrogen‑oxygen donor ligand-based macromolecule biosorbents was synthesized and characterized for cerium biosorption. The crosslinked chitosan/epichlorohydrin, chitosan/polyamines, and chitosan/polycarboxylate biosorbents have been produced from marine industrial waste (shrimp waste) using a chemical modification approach. The produced biosorbents were used to recover cerium ions from aqueous mediums. The affinity of the adsorbents towards cerium was tested in batch systems under different experimental conditions. The biosorbents showed high affinities for cerium ions. The percentage of cerium ions removed (%) from its aqueous system by polyamines and polycarboxylate chitosan sorbents is 85.73 and 90.92 %, respectively. The results indicated that the biosorbents have a high biosorption capacity for cerium ions from aqueous and leach liquor streams.

Hungarian and Indonesian rice husk as bioadsorbents for binary biosorption of cationic dyes from aqueous solutions: A factorial design analysis

The wastewater of the dye industry can be characterized by a complex chemical composition and consists of numerous dyes. Bioadsorbents are increasingly applied for the biosorption of dyes because they are inexpensive and environmentally friendly. Rice husk (RH) is a potential agricultural waste that can be converted into a bioadsorbents for the biosorption of cationic dyes. Herein, the removal of methylene blue (MB) and basic red 9 (BR9) dyes by Hungarian rice husk (HRH) and Indonesian rice husk (IRH) using binary biosorption was investigated. Adsorbents were characterized by zeta potential, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Batch biosorption evaluated the influence of different variables, including pH, adsorbent dose, contact time, and initial concentrations. Several factors that influence the biosorption of MB and BR9 onto rice husk were assessed using main effect, Pareto charts, normal probability plots, and interaction effect in a factorial design. The optimum contact time was 60 min. Isotherm and kinetic models of MB and BR9 in binary biosorption fitted to the Brunauer–Emmett–Teller multilayer and the Elovich equation based on correlation coefficients and nonlinear chi-square. Results showed that the biosorption capacity of HRH was 10.4 mg/g for MB and 10 mg/g for BR9; values for IRH were 9.3 mg/g and 9.6 mg/g, respectively. Therefore, HRH and IRH were found to be effective adsorbents for removing MB and BR9 via binary biosorption.

Hybrid biosorbents from exopolymeric substances immobilized in Ca-alginate and their biosorption mechanisms in single and multi-metal systems

ABSTRACT This study developed a hybrid biosorbent consisting of exopolymeric substances (EPS) from Bacillus cereus immobilized in the gelling agent Ca-alginate. Metal removal tests revealed that the hybrid EPS beads showed significantly higher metal removal compared to plain alginate beads. This higher removal efficacy in hybrid biosorbents was attributed to the increased number of functional groups detected via FTIR analysis. Hybrid EPS beads bind metals via the formation of strong covalent bonds (chemisorption), rather than through weak van der Waals forces (physisorption), complying with the pseudo-second order model. This was consistent in both single and multi-metal systems. For adsorption isotherm, metal removal (pH 5, 25ºC, 120 rpm) by hybrid biosorbents in single metal systems fits the Langmuir isotherm (monolayer adsorption). In multi-metal systems, however, the removal of Zn and Cd demonstrated a better fit to the Freundlich isotherm (multilayer adsorption) compared to the typical Langmuir isotherm (for Cu, Pb and Cr). The isotherm models indicated that the maximum biosorption capacity for Cu, Pb, Zn, Cd and Cr was at 34.97, 156.24, 19.19, 11.66 and 38.61 mg g−1, respectively. The hybrid EPS beads are superior for the biosorption of Cu, Pb and Cr compared to existing biosorbents.