Kinetic and equilibrium modeling of chromium (VI) biosorption on fresh and spent Spirulina platensis/Chlorella vulgaris biomass

Biosorption of chromium (VI) was studied using both fresh and spent algal biomass of Spirulina platensis and Chlorella vulgaris. Both showed comparable behavior suggesting that biosorption is primarily a surface phenomenon. Biosorption rate was very fast during the first five minutes, in which almost 50% of the chromium (VI) was adsorbed. Two step kinetic model was proposed for biosorption. Equilibrium data obeyed Freundlich and Langmuir adsorption isotherms. Fresh algal biomass of S. platensis gave maximum of 73.6% biosorption of chromium (VI) in 100 ppm solution at 1 g l(-1) cell loading. For improved economics, beta-carotene was extracted from S. platensis and the spent biomass was used for chromium (VI) biosorption. The maximum biosorption by spent biomass was increased to 86.2%. Thus, this two step process not only showed improved efficiency in biosorption ( approximately 17% increase) but also gave valuable byproduct, namely beta-carotene.     

The past,present, and future trends of biosorption

The discovery and further development of biosorption phenomena provide a basis for a whole new technology aimed at the removal of various pollutants or the recovery of valuable resources from aqueous systems. Today, biosorption is one of the main components of environmental and bioresource technology. Since the status of scientific development of a technology can be reflected through analyses of the literatures pertaining to it, in this review, we qualitatively examine almost all aspects of biosorption research. A range of subjects are covered, including the initial history, raw materials, mechanisms, instrumental tools, process factors, modification and immobilization methods, recovery and regeneration, continuous processes, commercial application, and modeling studies of biosorption. Finally, we summarized the important considerations of the current research on biosorption, as well as the suggestions for its future directions. We believe that this review will prove to be useful for scientists and engineers in the performance of their research into biosorption.     

Biosorption Behavior of Ciprofloxacin onto Enteromorpha prolifera: Isotherm and Kinetic Studies

The studies aimed at the feasibility of using Enteromorpha prolifera for the removal of ciprofloxacin from aqueous solutions. Batch experiments were carried out for the biosorption of ciprofloxacin onto Enteromorpha prolifera. The factors affecting the biosorption process such as the initial concentration, dosage, pH and the contact time were studied. Enteromorpha prolifera exhibited a maximum biosorption capacity of 21.7 mg/g. The pseudo-second-order kinetic model described the ciprofloxacin biosorption process with a good fitting. The optimum pH of ciprofloxacin adsorbed by Enteromorpha prolifera was 10. Biosorption equilibrium studies demonstrated that the biosorption followed Freundlich isotherm model, which implied a heterogeneous biosorption phenomenon.     

Chromium Biosorption from Cr(VI) Aqueous Solutions by Cupressus lusitanica Bark: Kinetics,Equilibrium and Thermodynamic Studies

The present study investigated the kinetics, equilibrium and thermodynamics of chromium (Cr) ion biosorption from Cr(VI) aqueous solutions by Cupressus lusitanica bark (CLB). CLB total Cr biosorption capacity strongly depended on operating variables such as initial Cr(VI) concentration and contact time: as these variables rose, total Cr biosorption capacity increased significantly. Total Cr biosorption rate also increased with rising solution temperature. The pseudo-second-order model described the total Cr biosorption kinetic data best. Langmuir´s model fitted the experimental equilibrium biosorption data of total Cr best and predicted a maximum total Cr biosorption capacity of 305.4 mg g^-1. Total Cr biosorption by CLB is an endothermic and non-spontaneous process as indicated by the thermodynamic parameters. Results from the present kinetic, equilibrium and thermodynamic studies suggest that CLB biosorbs Cr ions from Cr(VI) aqueous solutions predominantly by a chemical sorption phenomenon. Low cost, availability, renewable nature, and effective total Cr biosorption make CLB a highly attractive and efficient method to remediate Cr(VI)-contaminated water and wastewater.     

Zn2+ biosorption by Oscillatoria anguistissima

Oscillatoria anguistissima showed a very high capacity for Zn²⁺ biosorption (641 mg g⁻¹ dry biomass at a residual concentration of 129·2 ppm) from solution and was comparable to the commmercial ion-exchange resin IRA-400C. Zn²⁺ biosorption was rapid, pH dependent and temperature independent phenomenon. Zn²⁺ adsorption followed both Langmuir and Freundlich models. The specific uptake (mg g⁻¹ dry biomass) of metal decreased with increase in biomass concentration. Pretreatment of biomass did not significantly affect the biosorption capacity of O. anguistissima. The biosorption of zinc by O. anguistissima was an ion-exchange phenomenon as a large concentration of magnesium ions were released during zinc adsorption. The zinc bound to the biomass could be effectively stripped using EDTA (10 mM) and the biomass was effectively used for multiple sorption–desorption cycles with in-between charging of the biomass with tap water washings. The native biomass could also efficiently remove zinc from effluents obtained from Indian mining industries.     

The mechanism of uranium biosorption by Rhizopus arrhizus

Biosorption of elements is a little understood phenomenon exhibited by some types of even nonliving microbial biomass. A common fungus Rhizopus arrhizus has been reported to take up uranium from aqueous solutions to the extent of 180 mg U(6+)/g. The mechanism of uranium sequestering by this type of biomass was studied by using experimental techniques such as electron microscopy, x-ray energy dispersion analysis, IR spectroscopy, and supporting evidence was obtained for a biosorption mechanism consisting of at least three processes. Uranium coordination and adsorption in the cell-wall chitin structure occur simultaneously and rapidly whereas precipitation of uranylhydroxide within the chitin microcrystalline cell-wall structure takes place at a lower rate. Interference of Fe(2+) and Zn(2+) coions with uranium biosorption is indicated.     

Reuse of waste beer yeast sludge for biosorptive decolorization of reactive blue 49 from aqueous solution

Reactive blue 49 was removed from aqueous solution by biosorption using powder waste sludge composed of Saccharomyces cerevisiae from the beer-brewing industry. The effect of initial pH, temperature and the biosorption thermodynamics, equilibrium, kinetics was investigated in this study. It was found that the biosorption capacity was at maximum at initial pH 3, that the effect of temperature on biosorption of reactive blue 49 was only slight in relation to the large biosorption capacity (25°C, 361 mg g⁻¹) according as the biosorption capacity decreased only 43 mg g⁻¹ at the temperature increased from 25 to 50°C. The biosorption was spontaneous, exothermic in nature and the dye molecules movements decreased slightly in random at the solid/liquid interface during the biosorption of dye on biosorbents. The biosorption equilibrium data could be described by Freundich isotherm model. The biosorption rates were found to be consistent with a pseudo-second-order kinetics model. The functional group interaction analysis between waste beer yeast sludge and reactive blue 49 by the aid of Fourier transform infrared (abbr. FTIR) spectroscopy indicated that amino components involved in protein participated in the biosorption process, which may be achieved by the mutual electrostatic adsorption process between the positively charged amino groups in waste beer yeast sludge with negatively charged sulfonic groups in reactive blue 49.     

Biosorption behavior of azo dye by inactive CMC immobilized Aspergillus fumigatus beads

The biosorption equilibria and kinetics of an azo dye (reactive brilliant red K-2BP) were examined in this study using inactive carboxylmethylcellulose (CMC) immobilized Aspergillus fumigatus beads as the biosorbent. It was found that the biosorption capacity was at maximum when dye solution pH was about 2.0, that the sorption was spontaneous and endothermic with insignificant entropy changes, and that the Freundlich isotherm model fitted well to the biosorption equilibrium data. The biosorption rates were found to be consistent with a pseudo-second-order model. An intraparticle diffusion-based Weber-Morris model was applied to evaluate rate-limiting steps of the biosorption processes. The results suggested that the diffusion controlled the overall biosorption process, but the boundary layer diffusion of dye molecules could not be neglected. External mass transfer coefficients (beta(I)S) obtained by both Mathews and Weber model and Frusawa and Smith model were consistent.     

Biosorption of di(2-ethylhexyl)phthalate by seaweed biomass

Samples of various Sargassum species were collected in the Hong Kong marine environment and used for studies on biosorption of di(2-ethylhexyl)phthalate (DEHP). Batch adsorption experiments were carried out to determine the removal capacity and removal efficiency of the biosorbents. The DEHP removal ability was similar among beached seaweed and three freshly collected Sargassum species. Different physico-chemical factors were evaluated in order to enhance the performance of the biosorbents. Under optimized conditions (25 mg biomass, initial pH 4, 25 °C, 40 mg L^–1 DEHP), the mean removal capacity of beached seaweed and Sargassum siliquastrum was 5.68 and 6.54 mg g^–1, respectively. Examination of the Langmuir and Freundlich adsorption isotherms showed that the biosorption phenomenon by these biosorbents could well be described by these models. Desorption of DEHP was also assessed with methanol, which showed the most satisfactory desorbing ability. Further study in multiple adsorption–desorption of DEHP by the biosorbents demonstrated the reusability of both beached seaweed and S. siliquastrum for biosorption of DEHP.     

Characterization of various functional groups present in the capsule of Microcystis and study of their role in biosorption of Fe, Ni and Cr

This study demonstrates highest biosorption of Fe followed by Ni and Cr by Microcystis in single, bi and trimetallic combination. Fe was not only preferentially adsorbed from the metal mixtures but Ni and Cr failed to decrease its biosorption. The agreement of the data of Fe biosorption with the Langmuir model suggested monolayer sorption and existence of constant sorption energy during the experimental conditions. In contrast to Fe biosorption, Ni and Cr sorption followed the Freundlich isotherm; this demonstrates a multilayer biosorption of the two metals. IR analysis of Microcystis cells confirmed the presence of a large number of -COO(-) and some amino groups in the Microcystis cell wall. The oxygen and nitrogen donor atoms from carboxyl and amino groups were found to play a vital role in metal biosorption by Microcystis cell walls, and ion exchange mechanisms were involved in the biosorption of test metals. Extra peaks present in Ni and Cr treated cells implied that amino groups are more responsible for Ni and Cr biosorption.     

Surface treated Pteris vittata L. pinnae powder used as an efficient biosorbent of Pb(II), Cd(II), and Cr(VI) from aqueous solution

Biosorption is a surface-dependent phenomenon. Surface modifications by chemical treatment methods could either improve or reduce the biosorption capacity of potential biosorbents. In the present work, pristine Pteris vittata L. pinnae (PPV) powder was treated separately with sodium hydroxide (NaOH), calcium chloride (CaCl₂), and nitric acid (HNO₃). The pristine and treated biosorbents were used to assess the biosorption of Pb(II), Cd(II), and Cr(VI) as a function of pH. Kinetics and adsorption isotherms were studied. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscope combined with energy dispersive x-ray (SEM-EDX) spectroscopic techniques were used to characterize the biosorbents before and after chemical treatments. The possible functional groups contributing to the metal sorption were identified. Results revealed favorable biosorption of Pb(II), Cd(II), and Cr(VI) described by pseudo-second order kinetics. NaOH-treated P. vittata (NPV) showed higher biosorption capacity for Pb(II) and Cd(II) compared to that of PPV. ATR-FTIR studies indicated that -OH, -COOH, and -NH₂ groups were mainly involved in Cr(VI) and -OH in Pb(II) and Cd(II) biosorption. The enhanced efficiency of NPV and CaCl₂ treated P. vittata (CPV) in the uptake of Pb(II) and Cd(II) compared to PPV can be associated with their altered physicochemical characters.     

An ecofriendly approach for bioremediation of contaminated water environment: Potential contribution of a coastal seaweed community to environmental improvement

High levels of heavy metals like copper ions in many industrial based effluents lead to serious environmental and health problems. Biosorption is a potential environmental biotechnology approach for biotreatment of aquatic sites polluted with heavy metal ions. Seaweeds have received great attention for their high bioremediation potential in recent years. However, the co-application of marine macroalgae for removal of heavy metals from wastewater is very limited. Thus, for the first time in literature, a coastal seaweed community composed of Chaetomorpha sp., Polysiphonia sp., Ulva sp. and Cystoseira sp. species was applied to remove copper ions from synthetic aqueous medium in this study. The biosorption experiments in batch mode were conducted to examine the effects of operating variables including pH, biosorbent amount, metal ion concentration and contact time on the biosorption process. The biosorption behavior of biosorbent was described by various equilibrium, kinetic and thermodynamic models. The biosorption of copper ions was strongly influenced by the operating parameters. The results indicated that the equilibrium data of biosorption were best modeled by Sips isotherm model. The values of mean free energy of biosorption computed from Dubinin-Radushkevich isotherm model and the standard Gibbs free energy change indicated a feasible, spontaneous and physical biotreatment system. The pseudo-second-order rate equation successfully defined the kinetic behavior of copper biosorption. The pore diffusion also played role in the control of biosorption process. The maximum copper uptake capacity of biosorbent was found to be greater than those of many other biosorbents. The obtained results revealed that this novel biosorbent could be a promising material for copper ion bioremediation implementations.     

Biosorption of heavy metals by distillery-derived biomass

Biomass derived from the Old Bushmill's Distillery Co. Ltd., Northern Ireland was harvested and examined for its ability to function as a biosorbent for metals such as Cu, Zn, Fe, Pb and Ag. Binding studies were carried out using biosorption isotherm analysis. Although the material had previously been shown to be capable of efficient U biosorption, its affinity for Cu, Zn, Fe was lower. However, binding studies with Pb demonstrated that it had a maximum biosorption capacity for that metal of 189?mg/g dry weight of the biomass. In addition, the biomass exhibited a maximum biosorption capacity of 59?mg/g dry weight for Ag and this compared very favourably with previously quoted values for other industrial sources of Saccharomyces cerevisiae. On the basis of the biosorption isotherm analyses carried out in this study, preference for this series of metals by the biomass was found to be Pb?>?U?>?Ag?>?Zn?≥?Fe?>?Cu.     

Microbial biomass: an economical alternative for removal of heavy metals from waste water

Today indiscriminate and uncontrolled discharge of metal contaminated industrial effluents into the environment has become an issue of major concern. Heavy metals, being non-biodegradable and persistent, beyond a permissible concentration form unspecific compounds inside the cells thereby causing cellular toxicity. The only alternative to remove them from the wastewater is by immobilizing them. The conventional methods adopted earlier for this purpose included chemical precipitation, oxidation, reduction, filtration, electrochemical treatment, evaporation, adsorption and ion-exchange resins. These methods require high energy inputs especially when it refers to dilute solutions. Here microbial biomass offers an economical option for removing heavy metals by the phenomenon of biosorption. Non-living or dead biomass sequester metal(s) on their cell surface due to certain reactive groups available like carboxyl, amine, imidazole, phosphate, sulphydryl, sulfate and hydroxyl. The process can be made economical by procuring spent biomass from industry or naturally available bulk biomass. A batch or a continuous process of removal of heavy metals directly from effluents can be developed in a fixed bed reactor using the immobilized biomass. Further biosorption potential of the biomass can be improved by various physical and chemical treatments. The availability of variety of microbial biomass and their metal binding potential makes it a economical and sustainable option for developing effluent treatment process for removal and recovery of heavy metals.     

Biosorption behavior of heavy metals in bioleaching process of MSWI fly ash by Aspergillus niger

In this study, it was considered that the biosorption of heavy metals by biomass might occur during the bioleaching of fly ash. This work is focused on the biosorption behavior of Al, Fe, Pb and Zn by Aspergillus niger during the bioleaching process. The fungal biomass was contacted with heavy metals solution which extracted from fly ash by using gluconic acid as leaching agent. The equilibrium time for biosorption was about 120 min. The biosorption experiment data at initial pH 6.5 was used to fit the biosorption kinetics and isotherm models. The results indicated that the biosorption of Al, Fe and Zn by A. niger biomass were well described by the pseudo-first order kinetic model. The pseudo-second order kinetic model was more suitable for that of Pb. The Langmuir isotherm model could well describe the biosorption of Fe, Pb and Zn while the Freundlich model could well describe the biosorption of Al. Furthermore, the biosorption of metal ions decreased evidently in the presence of fly ash as compared to that in the absence of fly ash. This research showed that although the biomass sorption occurred during the bioleaching process, it did not inhibit the removal of Al, Fe, Pb and Zn evidently from fly ash.     

Evaluation for biosorption of rare earth elements from gebel serbal granite using different types of algae

The Serbal granites are located in the southern Sinai Peninsula, Egypt .they are characterized by the high content of Rare earth elements (REEs), in this study different types of algae like Phaeophyta represented by C. osmundacea and Rhadophyta represented by Palmaria elegans and Chondrus Crispus have been chosen for their higher capacity of biosorption. Infrared analysis data indicate that biosorption depends especially on the components of the cell wall of the three algae, the metal biosorption process by Palmaria elegans give a great variety for complete biosorption for Samarium (Sm) in all samples except one while Europium (Eu) was absorbed totally by Chondrus Crispus and Palmaria elegans in one sample than the five samples. On the other hand, C. osmundacea and Palmaria elegans give complete biosorption for Europium in the six samples. From these data, we can conclude that the adsorption process could be efficient and economical by using Palmaria elegans for the removal of Sm and Eu from Serbal granites.     

Metal biosorption by surface-layer proteins from Bacillus species

Bacillus species have been involved in metal association as biosorbents, but there is not a clear understanding of this chelating property. In order to evaluate this metal chelating capacity, cultures and spores from Grampositive bacteria of species either able or unable to produce surface layer proteins (S-layers) were analyzed for their capacity of copper biosorption. Only those endowed of S-layers, like Bacillus sphaericus and B. thuringiensis, showed a significant biosorption capacity. This capacity (nearly 50%) was retained after heating of cultures, thus supporting that structural elements of the envelopes are responsible for such activity. Purified Slayers from two Bacillus sphaericus strains had the ability to biosorb copper. Copper biosorption parameters were determined for strain B. sphaericus 2362, and after analyses by means of the Langmuir model, the affinity and capacity were shown to be comparable to other bacterial biosorbents. A competitive effect of Ca2+ and Zn2+, but not of Cd2+, was also observed, thus indicating that other cations may be biosorbed by this protein. Spores that have been shown to be proficient for copper biosorption were further analyzed for the presence of Slayer content. The retention of S-layers by these spores was clearly observed, and after extensive treatment to eliminate the S-layers, the biosorption capacity of these spores was significantly reduced. For the first time, a direct correlation between S-layer protein content and metal biosorption capacity is shown. This capacity is linked to the retention of S-layer proteins attached to Bacillus spores and cells.     

Localization effect on the metal biosorption capability of recombinant mammalian and fish metallothioneins in Escherichia coli

In this study, we examined the expression of mammalian and fish metallothioneins (MTs) in Escherichia coli as a strategy to enhance metal biosorption efficiency of bacterial biosorbents for lead (Pb), copper (Cu), cadmium (Cd), and zinc (Zn). In addition, MT proteins were expressed in either the cytoplasmic or periplasmic compartment of host cells to explore the localization effect on metal biosorption. The results showed that MT expression led to a significant increase (5-210%) in overall biosorption efficiency (eta(ads)), especially for biosorption of Cd. The MT-driven improvement in metal biosorption relied more on the increase in the biosorption rates (r(2), a kinetic property) than on the equilibrium biosorption capacities (q(max), a thermodynamic property), despite a 10-45% and 30-80% increase in q(max) of Cd and Zn, respectively. Periplasmic expression of MTs appeared to be more effective in facilitating the metal-binding ability than the cytoplasmlic MT expression. Notably, disparity of the impacts on biosorption ability was observed for the origin of MT proteins, as human MT (MT1A) was the most effective biosorption stimulator compared to MTs originating from mouse (MT1) and fish (OmMT). Moreover, the overall biosorption efficiency (eta(ads)) of the MT-expressing recombinant biosorbents was found to be adsorbate-dependent: the eta(ads) values decreased in the order of Cd > Cu > Zn > Pb.     

Entrapment of white-rot fungus Trametes versicolor in Ca-alginate beads: preparation and biosorption kinetic analysis for cadmium removal from an aqueous solution

The biosorption of cadmium ions onto entrapped Trametes versicolor mycelia has been studied in a batch system. The maximum experimental biosorption capacities for entrapped live and dead fungal mycelia of T. versicolor were found as 102.3 +/- 3.2 mg Cd(II) g(-1) and 120.6 +/- 3.8 mg Cd(II) g(-1), respectively. Biosorption equilibrium was established in about 1 h and biosorption was well described by the Langmuir and Freundlich biosorption isotherms. The change in the biosorption capacity with time was found to fit the pseudo-second-order equation. Since the biosorption capacities were relatively high for both entrapped live and dead forms, those fungal forms could be considered as suitable biosorbents for the removal of cadmium in wastewater-treatment systems. The biosorbents were reused in three consecutive adsorption/desorption cycles without a significant loss in the biosorption capacity.