Biosorption of chromium(VI) from aqueous solution by cone biomass of Pinus sylvestris

Biosorption of chromium(VI) on to cone biomass of Pinus sylvestris was studied with variation in the parameters of pH, initial metal ion concentration and agitation speed. The biosorption of Cr(VI) was increased when pH of the solution was decreased from 7.0 to 1.0. The maximum chromium biosorption occurred at 150 rpm agitation. An increase in chromium/biomass ratio caused a decrease in the biosorption efficiency. The adsorption constants were found from the Freundlich isotherm at 25 degrees C. The cone biomass, which is a readily available biosorbent, was found suitable for removing chromium from aqueous solution.     

Comparative study of Cd(II) and Cr(VI) biosorption on Staphylococcus xylosus and Pseudomonas sp. in single and binary mixtures

Biosorption of Cd(II) and Cr(VI) ions in single solutions using Staphylococcus xylosus and Pseudomonas sp., and their selectivity in binary mixtures was investigated. Langmuir and Freundlich models were applied to describe metal biosorption and the influence of pH, biomass concentration and contact time was determined. Maximum uptake capacity of cadmium was estimated to 250 and 278 mg g(-1), whereas that of chromium to 143 and 95 mg g(-1) for S. xylosus and Pseudomonas sp., respectively. In binary mixtures with Cd(II) ions as the dominant species, there is a profound selectivity for cadmium biosorption, reaching 96% and 89% for Pseudomonas sp. and S. xylosus, respectively, at 10 mg l(-1) Cd(II) and 5 mg l(-1) Cr(VI). Interesting, when chromium (VI) ions are the dominant species, there is selectivity towards chromium around 92% with S. xylosus only.     

Bioaccumulation and biosorption of chromium by Aspergillus niger MTCC 2594

Chromium toxicity is of prime concern due to chrome tanning processes in the leather sector. Chrome tanning results in the discharge of toxic levels of chromium causing pollution hazards. Chromium levels of Cr(III) and Cr(VI) were high above permissible limits in chrome samples after chrome tanning. The potential of Aspergillus niger MTCC 2594 to accumulate chromium as well as its biosorption capacity is investigated in this study. Bioaccumulation of Cr(III) and Cr(VI) in the spent chrome liquor has resulted in a 75-78% reduction of the initial Cr content in 24-36 h. A. niger biomass is found to be very effective in the biosorption of Cr(III) and Cr(VI) in spent chrome liquor. Maximum adsorption of 83% for biosorption of Cr(III) at 48 h and 79% of Cr(VI) at 36 h in spent chrome liquor is observed. The biosorption characteristics fit well with Langmuir and Freundlich isotherms and the adsorption parameters are evaluated. The biosorption of Cr also follows Lagergren kinetics. A. niger biomass is effectively used for the biosorption of chromium with 79-83% Cr removal in 36-48 h.     

Biosorption of Cr (VI) with Trichoderma viride immobilized fungal biomass and cell free Ca-alginate beads

Ability of Cr (VI) biosorption with immobilized Trichoderma viride biomass and cell free Ca-alginate beads was studied in the present study. Biosorption efficiency in the powdered fungal biomass entrapped in polymeric matric of calcium alginate compared with cell free calcium alginate beads. Effect of pH, initial metal ion concentration, time and biomass dose on the Cr (VI) removal by immobilized and cell free Ca-alginate beads were also determined. Biosorption of Cr (VI) was pH dependent and the maximum adsorption was observed at pH 2.0. The adsorption equilibrium was reached in 90 min. The maximum adsorption capacity of 16.075 mgg(-1) was observed at dose 0.2 mg in 100 ml of Cr (VI) solution. The high value of kinetics rate constant Kad (3.73 x 10(-2)) with immobilized fungal biomass and (3.75 x 10(-2)) with cell free Ca- alginate beads showed that the sorption of Cr (VI) ions on immobilized biomass and cell free Ca-alginate beads followed pseudo first order kinetics. The experimental results were fitted satisfactory to the Langmuir and Freundlich isotherm models. The hydroxyl (-OH) and amino (-NH) functional groups were responsible in biosorption of Cr (VI) with fungal biomass spp. Trichoderma viride analysed using Fourier Transform Infrared (FTIR) Spectrometer.     

Biosorption of Chromium(VI) and Lead(II): Role of Spirulina platensis in the Treatment of Industrial Effluent

Biosorption is the process of removal of any chemical molecules by the treatment of biological material. Industrialization resulted in the discharge of various toxic heavy metals into water bodies, which poses serious health hazards to humans and animals. In the present study, live Spirulina platensis was used as a biosorbent for the removal of the heavy metals chromium (Cr(VI)) and lead (Pb(II)) from the aqueous samples. S. platensis were cultured in the presence of different concentrations of heavy metals. The growth of the algal cells was found to be decreased by 59% and 36% in media containing 50 ppm Cr(VI) and Pb(II), respectively. To assess the biosorption of heavy metals, at different time intervals, the spent culture media were used to detect Cr(VI) by atomic absorption spectroscopy method and Pb(II) by 4-(2-pyridylazo)resorcinol indicator method. Results suggested that there was a significant uptake of Cr(VI) and Pb(II) from the medium by S. platensis, with corresponding decrease of metals in the medium. When metal salt solutions or industrial effluent samples were passed through the column containing immobilized live S. platensis in calcium alginate beads, the concentration of Cr(VI) was found to be reduced drastically. The present study indicates the application of S. platensis for the bioremediation of heavy metals from the samples obtained from industrial effluents.     

Co2+, Cu2+, and Zn2+ accumulation by cyanobacterium Spirulina platensis

The Spirulina platensis biomass was characterized for its metal accumulation as a function of pH, external metal concentration, equilibrium isotherms, kinetics, effect of co-ions under free (living cells, lyophilized, and oven-dried) and immobilized (Ca-alginate and polyacrylamide gel) conditions. The maximum metal biosorption by S. platensis biomass was observed at pH 6.0 with free and immobilized biomass. The studies on equilibrium isotherm experiments showed highest maximum metal loading by living cells (181.0 +/- 13.1 mg Co(2+)/g, 272.1 +/- 29.4 mg Cu(2+)/g and 250.3 +/- 26.4 mg Zn(2+)/g) followed by lyophilized (79.7 +/- 9.6 mg Co(2+)/g, 250.0 +/- 22.4 mg Cu(2+)/g and 111.2 +/- 9.8 mg Zn(2+)/g) and oven-dried (25.9 +/- 1.9 mg Co(2+)/g, 160.0 +/- 14.2 mg Cu(2+)/g and 35.1 +/- 2.7 mg Zn(2+)/g) biomass of S. platensis on a dry weight basis. The polyacrylamide gel (PAG) immobilization of lyophilized biomass found to be superior over Ca-alginate (Ca-Alg) and did not interfere with the S. platensis biomass biosorption capacity, yielding 25% of metal loading after PAG entrapment. The time-dependent metal biosorption in both the free and immobilized form revealed existence of two phases involving an initial rapid phase (which lasted for 1-2 min) contributing 63-77% of total biosorption, followed by a slower phase that continued for 2 h. The metal elution studies conducted using various reagents showed more than 90% elution with mineral acids, calcium salts, and Na(2)EDTA with free (lyophilized or oven-dried) as well as immobilized biomass. The experiments conducted to examine the suitability of PAG-immobilized S. platensis biomass over multiple cycles of Co(2+), Cu(2+), and Zn(2+) sorption and elution showed that the same PAG cubes can be reused for at least seven cycles with high efficiency.     

Potential use of green algae as a biosorbent for hexavalent chromium removal from aqueous solutions

The hexavalent chromium Cr(VI) poses a threat as a hazardous metal and its removal from aquatic environments through biosorption has gained attention as a viable technology of bioremediation. We evaluated the potential use of three green algae (Cladophora glomerata, Enteromorpha intestinalis and Microspora amoena) dry biomass as a biosorbent to remove Cr(VI) from aqueous solutions. The adsorption capacity of the biomass was determined using batch experiments. The adsorption capacity appeared to depend on the pH. The optimum pH with the acid-treated biomass for Cr(VI) biosorption was found to be 2.0 at a constant temperature, 45?°C. Among the three genera studied, C. glomerata recorded a maximum of 66.6% removal from the batch process using 1.0?g dried algal cells/100?ml aqueous solution containing an initial concentration of 20?mg/L chromium at 45?°C and pH 2.0 for 60?min of contact time. Langmuir and Freundlich isotherm equations fitted to the equilibrium data, Freundlich was the better model. Our study showed that C. glomerata dry biomass is a suitable candidate to remove Cr(VI) from aqueous solutions.     

A comparative study on heavy metal biosorption characteristics of some algae

The biosorption of copper(II), nickel(II) and chromium(VI) from aqueous solutions on dried (Chlorella vulgaris, Scenedesmus obliquus and Synechocystis sp.) algae were tested under laboratory conditions as a function of pH, initial metal ion and biomass concentrations. Optimum adsorption pH values of copper(II), nickel(II) and chromium(VI) were determined as 5.0, 4.5 and 2.0. respectively, for all three algae. At the optimal conditions, metal ion uptake increased with initial metal ion concentration up to 250 mg l⁻¹. Experimental results also showed the influence of the alga concentration on the metal uptake for all the species. Both the Freundlich and Langmuir adsorption models were suitable for describing the short-term biosorption of copper(II), nickel(II) and chromium(VI) by all the algal species.     

Removal of Chromium(VI) Ions from Synthetic Solutions by the Fungus Penicillium purpurogenum

The ability of Penicillium purpurogenum to bind high amounts of chromium(VI) from aqueous solutions is demonstrated. Cr(VI) adsorption capacity increases with time during the first four hours and then leveled off toward the equilibrium adsorption capacity. Biosorption of Cr(VI) ions reached equilibrium in four hours. Binding of Cr(VI) ions with Penicillium purpurogenum biomass was clearly pH dependent. Cr(VI) loading capacity increased with increasing pH. The adsorption of Cr(VI) ions reached a plateau value at a pH of approx. 6.0. The maximum capacity of adsorption of Cr(VI) ions onto the fungal biomass was 36.5 mg/g. Adsorption behavior of Cr(VI) ions can be approximately described with the Langmuir equation. When applying the Langmuir model, the maximum adsorption capacity (Q_max) and the Langmuir constant were found to be 40 mg/g and 3.9 × 10^–3 mg/L. Elution of Cr(VI) ions was performed by means of 0.5 M HCl. It was possible to use the biomass of Penicillium purpurogenum for six cycles for biosorption.     

Removal and recovery of uranium (VI) from aqueous solutions by immobilized Aspergillus niger powder beads

The immobilized Aspergillus niger powder beads were obtained by entrapping nonviable A. niger powder into Ca-alginate gel. The effects of pH, contact time, initial uranium (VI) concentration and biomass dosage on the biosorption of uranium (VI) onto the beads from aqueous solutions were investigated in a batch system. Biosorption equilibrium data were agreeable with Langmuir isotherm model and the maximum biosorption capacity of the beads for uranium (VI) was estimated to be 649.4?mg/g at 30?°C. The biosorption kinetics followed the pseudo-second-order model and intraparticle diffusion equation. The variations in enthalpy (26.45?kJ/mol), entropy (0.167?kJ/mol?K) and Gibbs free energy were calculated from the experimental data. SEM and EDS analysis indicated that the beads have strong adsorption capability for uranium (VI). The adsorbed uranium (VI) on the beads could be released with HNO₃ or HCl. The results showed that the immobilized A. niger powder beads had great potential for removing and recovering uranium (VI) from aqueous solutions.     

Biosorption of hexavalent chromium from aqueous solution by a tropical basidiomycete BDT-14 (DSM 15396)

Summary A tropical white-rot basidiomycete, BDT-14 (DSM 15396) was investigated for its chromium (VI) biosorption potential from an aqueous solution. Pre-treatment of fungal biomass with acid resulted in 100% metal adsorption compared to only 26.64% adsorption without any pre-treatment. Chromium adsorption was a rapid process at early exposure resulting in 60% chromium removal within the first 2 h of exposure. An increase in biomass showed an increase in the total metal ions adsorption but a decrease in specific uptake of metal ions. The concentrations of chromium had a pronounced effect on the rate of adsorption. The adsorption efficiency was 100% when the initial Cr (VI) concentration was 100 mg l⁻¹ with 1,000 mg biomass. Only 47.5% adsorption was observed with 500 mg l⁻¹ Cr (VI) concentration. The adsorption data fit well with the Langmuir and Freundlich isotherm models. Comprehensive characterization of parameters indicates BDT−14 biomass as a promising material for Cr (VI) adsorption.     

Biosorption of Ni, Cr and Cd by metal tolerant Aspergillus niger and Penicillium sp. using single and multi-metal solution

Fungi including Aspergillus and Penicillium, resistant to Ni2+, Cd2+, and Cr6+ were isolated from soil receiving long-term application of municipal wastewater mix with untreated industrial effluents of Aligarh, India. Metal tolerance in term of minimum inhibitory concentration (MIC) was 125-550 microg/ml for Cd, 300-850 microg/ml for Ni and 300-600 microg/ml for Cr against test fungi. Two isolates, Aspergillus niger and Penicillium sp. were tested for their Cr, Ni and Cd biosorption potential using alkali treated, dried and powdered mycelium. Biosorption experiment was conducted in 100 ml of solution at three initial metal concentrations i.e., 2, 4 and 6 mM with contact time (18 hr) and pretreated fungal biomass (0.1g) at 25 degrees C. Biosorption of all metals was found higher at 4 mM initial metal concentration as compared to biosorption at 2 and 6 mM concentrations. At 4 mM initial metal concentration, chromium biosorption was 18.05 and 19.3 mg/g of Aspergillus and Penicillium biomasses, respectively. Similarly, biosorption of Cd and Ni ions was also maximum at 4 mM initial metal concentration by Aspergillus (19.4 mg/g for Cd and 25.05 mg/g of biomass for Ni) and Penicillium (18.6 mg/g for Cd and 17.9 mg/g of biomass for Ni). In general, biosorption of metal was influenced by initial metal concentration and type of the test fungi. The results indicated that fungi of metal contaminated soil have high level of metal tolerance and biosorption properties.     

Bioremediation of cadmium-contaminated water systems using intact and alkaline-treated alga (Hydrodictyon reticulatum) naturally grown in an ecosystem

Cadmium can enter water, soil, and food chain in amounts harmful to human health by industrial wastes. The use of intact and NaOH-treated dried algal tissues (Hydrodictyon reticulatum), a major ecosystem bio-component, for Cd removal from aqueous solutions was characterized. Cadmium biosorption was found to be dependent on solution pH, bioadsorbent dose, the interaction between pH and dose, contact time, and initial Cd concentration. The experimental results indicated that the biosorption performance of alkaline-treated algal tissues was better than that of intact tissues. The maximum biosorption capacities were 7.40 and 12.74 mg g^?1 for intact and alkaline-treated bioadsorbents, respectively, at optimum operating conditions. Biosorption reaches equilibrium after 24 and 240 minutes of contact, respectively, for alkaline-treated and intact bioadsorbents. Cadmium biosorption was best fitted to Langmuir isotherm model (R² ≈ 0.99) and the kinetic study obeyed the pseudo-second-order kinetic model, which suggests chemisorption as the rate-limiting step in the biosorption process. Alkaline-treated algal tissues can be used as a new material of low-cost bioadsorbent for continuous flow rate treatment systems.     

Isotherm Modelling,Kinetic Study and Optimization of Batch Parameters Using Response Surface Methodology for Effective Removal of Cr(VI) Using Fungal Biomass

Biosorption is a promising alternative method to replace the existing conventional technique for Cr(VI) removal from the industrial effluent. In the present experimental design, the removal of Cr(VI) from the aqueous solution was studied by Aspergillus niger MSR4 under different environmental conditions in the batch systems. The optimum conditions of biosorption were determined by investigating pH (2.0) and temperature (27°C). The effects of parameters such as biomass dosage (g/L), initial Cr(VI) concentration (mg/L) and contact time (min) on Cr(VI) biosorption were analyzed using a three parameter Box–Behnken design (BBD). The experimental data well fitted to the Langmuir isotherm, in comparison to the other isotherm models tested. The results of the D-R isotherm model suggested that a chemical ion-exchange mechanism was involved in the biosorption process. The biosorption process followed the pseudo-second-order kinetic model, which indicates that the rate limiting step is chemisorption process. Fourier transform infrared (FT-IR) spectroscopic studies revealed the possible involvement of functional groups, such as hydroxyl, carboxyl, amino and carbonyl group in the biosorption process. The thermodynamic parameters for Cr(VI) biosorption were also calculated, and the negative ∆Gº values indicated the spontaneous nature of biosorption process.     

Biosorption of chromium(VI) by spent cyanobacterial biomass from a hydrogen fermentor using Box-Behnken model

The study explores utilization of waste cyanobacterial biomass of Nostoc linckia from a lab-scale hydrogen fermentor for the biosorption of Cr(VI) from aqueous solution. The biomass immobilized in alginate beads was used for removal of the metal in batch mode optimizing the process conditions adopting response surface methodology (RSM). Kinetic studies were done to get useful information on the rate of chromium adsorption onto the cyanobacterial biomass, which was found to follow pseudo second-order model. Four important process parameters including initial metal concentration (10-100 mg/L), pH (2-6), temperature (25-45 °C) and cyanobacterial dose (0.1-2.0 g) were optimized to obtain the best response of Cr(VI) removal using the statistical Box-Behnken design. The response surface data indicated maximum Cr(VI) biosorption at pH 2-4 with different initial concentrations of the metal in the aqueous solution. The biosorbent could remove 80-90% chromium from solutions with initial metal concentration of 10-55 mg/L. Involvement of the surface characteristics of the biomass was studied through its scanning electron micrographs and Fourier transform infrared (FTIR) analysis.     

Application of dried sewage sludge as phenol biosorbent

The aim of this work was to determine the potential application of dried sewage sludge as a biosorbent for removing phenol from aqueous solution. Results showed that biosorption capacity was strongly influenced by the pH of the aqueous solution with an observed maximum phenol removal at pH around 6-8. Biosorption capacity increased when initial phenol concentration was increased to 110 mg/L but beyond this concentration, biosorption capacity decreased suggesting an inhibitory effect of phenol on biomass activity. Biosorption capacity decreased from 94 to 5 mg/g when biosorbent concentration was increased from 0.5 to 10 g/L suggesting a possible competitive effect of leachable heavy metals from the sludge. The effect of Cu2+ on biosorption capacity was also observed and the results confirmed that the phenol biosorption capacity decreased when concentration of Cu2+ in the sorption medium was increased up to 15 mg/L. Desorption of phenol using distilled deionized water was less than 2% suggesting a strong biosorption by the biomass.     

The effect of pulse voltage and capacitance on biosorption of uranium by biomass derived from whiskey distillery spent wash

Biosorption of uranium by residual biomass from The Old Bushmill's Distillery Co. Ltd., Bushmills, Co. Antrim, Northern Ireland, following exposure to short and intense electric pulses has been examined. The biomass was prepared from the distillery spent wash and consisted of non-viable yeast and bacterial cells. As shown previously, untreated biomass had a maximum biosorption capacity of 170?mg uranium/g dry weight biomass. When biosorption reactions were placed between two electrodes and exposed to electric pulses with field strengths ranging from 1.25–3.25?kV/cm at a capacitance of 25?μF, biosorption increased from 170?mg of uranium to 275?mg uranium/g dry weight biomass. The data were obtained from biosorption isotherm analyses and taken as the degree of biosorption at residual uranium concentrations of 3?mM. In addition, when the capacitance of the electric pulses increased from 0.25?μF to 25?μF at a fixed pulse field strength the degree of biosorption increased from 210?mg uranium to 240?mg uranium/g dry weight biomass. The results suggest that application of short and intense electric pulses to biosorption reactions may play an important role in enhancing microbial biosorption of toxic metals/radionuclides from waste water streams.     

Zinc removal from model solution and wastewater by Arthrospira (Spirulina) Platensis biomass

The biosorption of zinc from model solution as well as wastewater by Arthrospira (Spirulina) platensis biomass was studied. Adsorption capacity of the biosorbent was investigated as a function of contact time between adsorbent and zinc, the initial metals and sorbent concentration, pH value, and temperature. The ability of Arthrospira biomass for zinc biosorption exhibited a maximum at the pH range 4–8. Equilibrium data fitted well with the Langmuir model as well as the Freundlich model with maximum adsorption capacity of 7.1 mg/g. The pseudo second-order model was found to correlate well with the experimental data. Different thermodynamic parameters, ΔG°, ΔH° and ΔS° were evaluated and it has been found that the sorption was feasible, spontaneous, and endothermic in nature. The process of zinc removal from industrial effluent was studied at different time of sorbat–sorbent interaction and different sorbent dosage. Maximum zinc removal (83%) was obtained at sorbent concentration 60 g/L during 1-h experiment. The results indicate that Arthrospira platensis biomass could be effectively used for zinc removal from industrial effluents.     

Effects of electromagnetic field on the batch cultivation and nutritional composition of Spirulina platensis in an air-lift photobioreactor

Spirulina platensis was batch cultivated in a novel 3.5l magnetic air-lift photobioreactor with external-loop on which 0-0.55 T electromagnetic field (EMF) was imposed to investigate the EMF effects on the algal growth and nutrition composition. At the same time, the correlative mechanism was discussed mainly based on C, N, P uptake. It was found that, EMF has double-side effects on S. platensis cultivation depend on EMF intensity. 0.25 T EMF stress was found to be suitable for the algal cultivation enhancement increasing the maximum cell dry weight by 22% in a time period two days less than that of the control at 35 degrees C and 252 micromol photonsm(-2)S(-1). In addition, the nutritional composition of S. platensis was improved in both essential amino acids such as histidine and trace elements Ni, Sr, Cu, Mg, Fe, Mn, Ca, Co and V. It was suggested it was possible to optimize the cultivation process of S. platensis by imposing suitable weak EMF which may enhance the nutrition assimilation e.g. C, N, P and minerals by S. platensis.     

Accumulation of selenium in mixotrophic culture of Spirulina platensis on glucose

Accumulation of Se in mixotrophic culture of Spirulina platensis was investigated in this study. Results indicated that glucose was better than acetate as an organic carbon source for mixotrophic culture of S. platensis. Supplementation of glucose (2 gL(-1)) significantly enhanced the biomass concentration (2.57 gL(-1)) and the production of phycocyanin (0.279 gL(-1)) and allophycocyanin (0.126 gL(-1)) in S. platensis, which were much higher than those of photoautotrophic culture (1.08 gL(-1), 0.119 gL(-1) and 0.042 gL(-1), respectively). Stepwise addition of Se during the growth phase avoided the inhibitory effect of high Se concentration on the growth of S. platensis. The Se enrichment favored the production of phycocyanin and allophycocyanin in the algal cells. The highest Se yield (1033 microgL(-1)) was obtained at an accumulative Se concentration of 250 mgL(-1), with organic Se percentage, biomass concentration, phycocyanin and allophycocyanin yields of 92.3%, 2.55 gL(-1), 0.295 gL(-1) and 0.153 gL(-1), respectively. These results indicated that the application of mixotrophic culture S. platensis with stepwise addition of Se to the medium could offer an effective and economical way for the production of high Se-enriched algal products.