Removal of toxic metals from aqueous solutions by fungal biomass of Agaricus macrosporus

The environmental remediation capacity of Ulva lactuca: the potential of macroalgae to reduce the threats caused by Titanium in marine invertebrate species

As a result of the wide use of Titanium (Ti) compounds in various products, Ti and Ti nanoparticles (nTi) are released into aquatic environments, inducing varying degrees of toxicity on aquatic fauna. Ulva lactuca, green macroalgae commonly found in coastal areas, has been extensively studied due to its worldwide distribution and capacity to accumulate trace elements under toxic conditions, which makes it a good universal sorbent. The present study aimed to establish the remediation properties of U. lactuca by evaluating the toxicity of Ti and nTi in bivalves, in the presence and absence of algae. Using the bivalve species Mytilus galloprovincialis, Ti toxicity was evaluated by assessing changes in mussel's metabolic capacity and oxidative status. Results evidenced cellular damage in M. galloprovincialis exposed to Ti and nTi. This was a result of the inactivation of antioxidant defences. The presence of U. lactuca limited cellular damage, however, this was not a result of the previously demonstrated bioremediation capacity, as no accumulation of Ti was verified in algal tissues. As a metabolic depression was verified for mussels exposed to Ti/nTi in the presence of algae, we hypothesise that U. lactuca may have been responsible for changes to the water quality which induced this response.

Bioremediation potential and lead removal capacity of heavy metal-tolerant yeasts isolated from Dayet Oum Ghellaz Lake water (northwest of Algeria)

Seven metal-resistant yeast strains were isolated and selected from Dayet Oum Ghellaz Lake water (northwest of Algeria) known as a highly polluted area by lead and cadmium. The yeast strains were screened on the basis of their resistance to seven heavy metals Hg, Cr, Cd, Pb, Cu, Zn, and Fe and characterized by molecular and phylogenetic analysis. The sequencing of the D1/D2 domain of the 26S rRNA genes revealed the affiliation of the seven yeast isolates to Rhodotorula mucilaginosa, Clavispora lusitaniae, and Wickerhamomyces anomalus species. All yeast strains were halotolerant as they were able to grow in 10-15% NaCl. The yeast isolates were highly resistant to the studied heavy metals and exhibited different tolerance according to the metal type. The highest minimum inhibitory concentrations (MIC) were observed in R. mucilaginosa RO7 and W. anomalus WO2 strains which were then selected for lead removal assays. The present study is the first to investigate the lead elimination by W. anomalus. The lead uptake was significantly affected by biomass concentration in a reverse relationship, with purification percentages estimated at 98.15 ± 0.9% and 97.046 ± 0.47% and removal efficiency of 12.68 ± 0.91 and 15.55 ± 0.72 mg/g for W. anomalus WO2 and R. mucilaginosa RO7, respectively. The investigated metal-tolerant yeast strains proved to be promising candidates for bioremediation processes of heavy metals. This work amends the metal-resistant yeast bank with new strains having interesting abilities to resist to relatively high concentrations of toxic heavy metals and which can be used in the near future as low-cost biosorbents.

High affinity of 3D spongin scaffold towards Hg(II) in real waters

This study focuses on the ability of commercial natural bath sponges, which are made from the skeletons of marine sponges, to sorb Hg from natural waters. The main component of these bath sponges is spongin, which is a protein-based material, closely related to collagen, offering a plenitude of reactive sites from the great variety of amino acids in the protein chains, where the Hg ions can sorb. For a dose of 40 mg L^-1 and initial concentration of 50 μg L^-1 of Hg(II), marine spongin (MS) removed ~90% of Hg from 3 water matrixes (ultrapure, bottled, and seawater), corresponding to a residual concentration of ~5 μg L^-1, which tends to the recommend value for drinking water of 1 μg L^-1. This value was maintained even by increasing the MS dosage, suggesting the existence of a gradient concentration threshold below which the Hg sorption mechanism halts. Kinetic modelling showed that the Pseudo Second-Order equation was the best fit for all the water matrixes, which indicates that the sorption mechanism relies most probably on chemical interactions between the functional groups of spongin and the Hg ions. This material can also be regenerated in HNO₃ and reused for Hg sorption, with marginal losses in efficiency, at least for 3 consecutive cycles.

Trichoderma viride involvement in the sorption of Pb(II) on muscovite, biotite and phlogopite: Batch and spectroscopic studies

In this study, batch and spectroscopic approaches were used to explore the sorption of Pb(II) on micas (i.e., muscovite, biotite and phlogopite) in the presence of Trichoderma viride (T. viride). Batch sorption showed that ion exchange, outer-sphere complexes (OSCs) and inner-sphere complexes (ISCs) contributed to Pb(II) sorption on biotite and phlogopite in the pH range of 2.0-7.4, whereas the ISCs were predominant for Pb(II) sorption on muscovite. X-ray diffraction and Fourier transform infrared (FT-IR) analyses have confirmed the changes of structure and surface properties of micas after co-culturing with T. viride, which could improve the sorption capacity of micas to Pb(II). Scanning electron microscopy revealed the bio-mineralization of Pb(II) on T. viride and mica-T. viride composites forming lead phosphates. Furthermore, FT-IR analysis showed that the groups of Si-OH, Al-OH from micas, and carboxyl, phosphate and amino groups from T. viride were synergistically contributing to Pb(II) sorption on mica-T. viride composite. X-ray photoelectron spectroscopy further confirmed that both OSCs and ISCs formed for Pb(II) sorption on micas; however, in the case of mica-T. viride composites, the synergistic effects of T. viride and micas were contributing to Pb(II) sorption through forming the ISCs and biomineralization.

Kinetic and thermodynamic studies of the biosorption of Cr (VI) in aqueous solutions by Agaricus campestris

In the present study, biomass of Agaricus campestris was tested to evaluate its effectivity as a biosorbent for the removal of Cr (VI) ions from aqueous solutions. The influence of various process parameters such as pH, temperature, contact time, biosorbent dosage and desorption were studied. Pseudo-first order, pseudo-second order, Ritchies and intraparticle diffusion model were used to present the adsorption kinetics. Results obtained indicate that the adsorption process is fast and spontaneous within the first 60 min. The experimental data supports pseudo-second order model. The sorption data conformed well to the Langmuir isotherm model. The maximum adsorption capacity (q _max) onto A. campestris was 56.21 mg g^-1 for Cr(VI) at 45°C when 0.1 g biomass was used. In addition, the mean values of thermodynamic parameters of standard free energy (ΔG⁰= -1.635 kJ mol^-1 at 45°C), standard enthalpy (ΔH⁰= -9.582 kJ mol^-1) and standard entropy (ΔS⁰= -24.992 J mol^-1K^-1) of the adsorption mechanism were determined.

Negligible effect of potentially toxic elements and rare earth elements on mercury removal from contaminated waters by green, brown and red living marine macroalgae

Mercury (Hg) removal by six different living marine macroalgae, namely, Ulva intestinalis, Ulva lactuca, Fucus spiralis, Fucus vesiculosus, Gracilaria sp., and Osmundea pinnatifida was investigated in mono and multi-contamination scenarios. All macroalgae were tested under the same experimental conditions, evaluating the competition effects with all elements at the same initial molar concentration of 1 μmol dm^-3. The presence of the main potentially toxic elements (Cd, Cr, Cu, Ni, and Pb) and rare earth elements (La, Ce, Pr, Nd, Eu, Gd, Tb, and Y) has not affected the removal of Hg. Characterizations of the macroalgae by FTIR before and after the biosorption/bioaccumulation assays suggest that Hg was mainly linked to sulfur-functional groups, while the removal of other elements was related with other functional groups. The mechanisms involved point to biosorption of Hg on the macroalgae surface followed by possible incorporation of this metal into the macroalgae by metabolically active processes. Globally, the green macroalgae (Ulva intestinalis, Ulva lactuca) showed the best performances for Hg, potential toxic elements and rare earth elements removal from synthetic seawater spiked with 1 μmol dm^-3 of each element, at room temperature and pH 8.5.

Bibliometric analysis of European publications between 2001 and 2016 on concentrations of selected elements in mushrooms

This article presents a bibliometric study of 200 European publications released between 2001 and 2016, about the contamination of mushrooms by selected elements. The analysis includes figures on the type of analyte, its concentration, the species of fungi, and its country of origin. In the literature review, 492 species of mushrooms (wild-growing and cultured) found in 26 European countries and their concentration of 74 associated elements were analysed. The papers, which dealt mainly with the heavy metal (Cd, Cu, Fe, Pb, and Zn) concentrations of mushrooms, primarily came from Turkey, Poland, Spain, and the Czech Republic. More than 50% of the publications provided data about edible mushrooms. The results of the bibliometric analysis showed that over the 16 years, European research on fungal contamination by selected analytes has not lessened in popularity and is ongoing. Many of the studies underlined the need to assess the risk to human health arising from the consumption of contaminated mushrooms taken from various habitats. These results were the effect of, among other things, the strong interest in studies carried out on edible species, in which concentrations of mainly heavy metals that are dangerous to health and are marked were indicated (Cd, Pb, and Hg).

Valuation of banana peels as an effective biosorbent for mercury removal under low environmental concentrations

The use of banana peels as biosorbent for mercury sorption from different aqueous solutions was investigated in this work. The impact of the operating conditions, such as biosorbent dosage, contact time and ionic strength was evaluated for realistic initial Hg(II) concentrations of 50 μg dm^-3. Biosorbent dosage and contact time showed more influence on Hg(II) removal than ionic strength, and their increase led to improve Hg(II) uptake achieving final concentrations with drinking water quality. The kinetic behaviour of the sorption process was assessed through the reaction-based models of pseudo-first order, pseudo-second order and Elovich, being the last two more appropriated to describe the process. The equilibrium study showed that Freundlich isotherm provided the best fit to the experimental results (R² = 0.991), which may suggest a multilayer mechanism at biosorbent surface, and the sorption capacity of banana peels obtained from Langmuir isotherm was 0.75 mg g^-1. The ability of banana peels to sorb Hg(II) was also examined under real waters, like seawater and a wastewater, which confirmed the feasibility of the biosorbent. Additionally, a counter-current two-stages unit has been proposed for the application of banana peels as biosorbent in water treatments for mercury removal.

Self-assembly biochar colloids mycelial pellet for heavy metal removal from aqueous solution

To effectively improve the heavy metal removal efficiency and stability of biomass adsorbents, a novel biochar colloids-mycelial pellets (BC-MP) composite was prepared via a biological assembly method. BC-MP was successfully produced with increased surface area and multisorption sites by physical adsorption, electrostatic interaction and hydrogen-bond formation between BC and extracellular polymers on MP. To investigate the performance and mechanisms of heavy metal adsorption by BC-MP, batch experiments were conducted with cadmium (Cd (II)) as the model pollutant. Results showed that BC-MP had higher removal efficiency (57.66%) compared to BC (5.45%) and MP (38.45%), respectively, due to the synergistic effect. The maximum adsorption capacity of Cd (II) on BC-MP was 102.04 mg/g based on Langmuir isotherm model. Adsorption kinetics analysis indicated that chemical sorption was the key factor controlling the adsorption of Cd (II) onto BC-MP. Multiple characterization tests revealed that the main mechanisms of the adsorption process were surface complexation, cation exchange and precipitation. The BC-MP composite showed excellent heavy metal removal efficiency with long-term adsorption stability, suggesting its potential as a promising biosorbent for heavy metal removal from industrial wastewater.

Biosorption of pharmaceutical products by mushroom stem waste

Residues from pharmaceutical products are found in effluents and in other environmental matrices such as soil and surface waters. Chitin and chitosan are highly adsorptive substances present in mushrooms such as champignon (Agaricus bisporus) and shiitake (Lentinula edodes). This study evaluated the adsorption efficiency of shiitake and champignon stalks, and shiitake substrate in water contaminated with paracetamol and 17 α-ethynyl estradiol (EE2). Stalks and substrate were dried and ground. Particles were physically evaluated and chemically characterized. Adsorption kinetic and isotherms were carried out for EE2 and paracetamol. Shiitake and champignon stalks had high percentage of porosity, closed and open pores. All bioproducts from mushroom had chemical groups similar to chitosan standard. However, the degree of deacetylation of chitosan was higher in shiitake (28.3%). In EE2 adsorption kinetics, shiitake and champignon stalks showed 100% removal in 20 and 30 min, respectively. Shiitake substrate showed 80% removal. In paracetamol adsorption kinetics, all bioproducts presented more than 95% removal. In EE2 adsorption isotherm, the maximum adsorption capacities (q_max) to shiitake and champignon stalks and shiitake substrate were 5.62, 18.95 and 0.31 mg_EE2/g, respectively. For paracetamol adsorption isotherm, q_max to shiitake and champignon stalks were 34.20 and 338.08 mg_paracetamol/g, respectively. In conclusion, shiitake and champignon stalks (specially champignon) had the best results regarding the adsorption of EE2 and paracetamol. Reuse of discarded mushroom waste reduces the environmental impact and can add value to the product.

A green l-cysteine modified cellulose nanocrystals biosorbent for adsorption of mercury ions from aqueous solutions

Using a green biosorbent to remove toxic mercury ions from aqueous solutions is a significant undertaking. In the present study, a novel biosorbent, l-cysteine modified cellulose nanocrystals (Lcys-CNCs), was prepared by functionalizing high surface area cellulose nanocrystals with l-cysteine through periodate oxidation and reductive amination reaction. Lcys-CNCs were characterized by FT-IR, ¹³C CP-MAS NMR, elemental analysis, XPS, zeta potential and SEM. As cellulose nanocrystals are the natural nanomaterial, and l-cysteine contains strong mercury chelating groups, Lcys-CNCs show excellent adsorption capacity for mercury ions. The experimental conditions such as pH, contact time, and initial mercury ion concentration are discussed. The pseudo-second order model can describe the removal kinetics of Hg(ii) more accurately than the pseudo-first order model. The adsorption isotherm study of Hg(ii) followed the Langmuir model of monolayer adsorption. The maximum uptake capacity of Lcys-CNCs was determined to be 923 mg g⁻¹. Lcys-CNCs can remove mercury ions with 93% removal efficiency within 5 min from a 71 mg L⁻¹ solution. For Cd(ii), Pb(ii), Cu(ii) and Zn(ii) ions, Lcsy-CNCs can selectively adsorb Hg(ii) ions and the removal efficiency is 87.4% for Hg(ii). This study suggests Lcsy-CNCs are a green and highly efficient biosorbent for adsorption of mercury ions from aqueous solutions.

A green biosorbent, l-cysteine modified cellulose nanocrystals, was successfully synthesized and applied to adsorb mercury ions from aqueous solutions.

Removal of cadmium from contaminated Lentinula edodes by optimized complexation and coagulation

Heavy metal pollution is a serious problem for Lentinula edodes; however, the treatment of contaminated L. edodes has seldom been studied. This study investigated the removal of cadmium (Cd) from contaminated L. edodes and its lentinan by complexation and coagulation. Some influencing factors, such as pH, medical dosage, and preoxidation were examined. Cd complexation from contaminated L. edodes was shown to be more efficient under acidic conditions (pH 5.0), with a clearance rate of 80.47% in 25 mmol/L EDTA and 78.45% in 25 mmol/L sodium citrate. The Cd content in the lentinan of the contaminated L. edodes was markedly lower than that in the powdered mushroom (2.77 mg/kg vs. 19.49 mg/kg) and was easier to remove. The maximum Cd clearance rate (96.3%) for lentinan was obtained using an optimized process that involved preoxidation with 0.5 mg/L KMnO4, complexing with 25 mmol/L EDTA and 25 mmol/L sodium citrate, and coagulation with 50 mg/L activated carbon (AC) at pH 10.0.

Highly cadmium tolerant fungi: their tolerance and removal potential

BACKGROUND

Soil and effluent of lead and zinc industries contain high concentration of cadmium. The present study was conducted to isolate tolerant fungal strains from cadmium -polluted sites in Zanjan province, Iran.

METHODS

Cadmium tolerance and bioremediation capacity of seven isolates including Aspergilus versicolor, Aspergillus fumigatus, Paecilomyces sp.9, Paecilomyces sp.G, Terichoderma sp, Microsporum sp,Cladosporium sp were determined.

RESULTS

Minimum inhibitory concentration values among 1,000-4,000 mg l-(1)proved great ability of isolated strains to survive in cadmium polluted environments. The most tolerant fungi, Aspergilus versicolor, showed tolerance index of 0.8 in 100 mg l-(1) cadmium agar media. Fungal resistance against cadmium is depended directly on strain's biological function. A. versicolor was found to bioaccumulate over7 mg of cadmium per 1 g of mycelium, followed by 5.878, 5.243, and 5.075, 4.557 by Paecilomyces sp, Aspergilus fumigatus, Microsporum sp and Terichoderma sp, respectively.

CONCLUSION

It can be noted that tolerance of the strains appears to be independent from bioaccumulation capacity. Finally, the results indicated that A. versicolor could be a prospective candidate for bioremediation processes.

Efficient removal of Cd(ii) and Cu(ii) from aqueous solution by magnesium chloride-modified Lentinula edodes

To enhance metal biosorption capacity, magnesium chloride-modifiedLentinula edodes(MMLE) was prepared by treatingLentinula edodeswith a mixture of NaOH, ethanol and MgCl₂.

Biosorption of Elements

Biosorption is a unique ability of living or dead biomass to interact with substances such as metals where reduction of sorbate concentration can be achieved. Thus, it has been widely proposed as a promising alternative for metal remediation and recovery owing to its low cost and sustainable “green” nature. Despite considerable biosorption‐related research performed in the past few decades, no significant commercial success has been achieved so far. This chapter starts with discussion of the basic science of biosorption and the potential of some selected biomasses such as yeast, algae, agro‐based waste and vermicompost to be used as biosorbent material. Following this, some important issues regarding the practical application of biosorption are highlighted, including the advantages and disadvantages of using dead or living biomass, the availability of biosorption reactors, immobilization techniques, metal recovery and post‐treatment of spent biosorbent. Lastly, current challenges that limit the commercial success of biosorption as well as the direction of future research are discussed.

Biosorption of lead(II) in aqueous solution by spent mushroom Tricholoma lobayense

The biosorption of lead(II) ions in both simulated and real wastewater by spent mushroom Tricholoma lobayense, was studied in this work. The results show a biomass with a high potential for removing lead ions from wastewater. The optimum pH for the adsorption is 4, and the adsorption process is fast. The best sorbent mass of the biomaterial is 5 g/L with an initial lead(II) concentration of 1 mmol/L. The process follows the Langmuir isotherm model, and the biosorption capacity of lead ions reaches to 210 mg/g, which is higher than many biosorbents previously studied. The mechanism of biosorption may be mainly attributed to ion exchange. The FT-IR study identifies the functional groups responsible for this process. A scanning electron microscope showed a significant change of the sorbent surface after the biosorption process. The energy dispersive elemental analysis also confirmed the adsorption of lead(II) ions.

Evaluation of copper resistant bacteria from vineyard soils and mining waste for copper biosorption

Vineyard soils are frequently polluted with high concentrations of copper due application of copper sulfate in order to control fungal diseases. Bioremediation is an efficient process for the treatment of contaminated sites. Efficient copper sorption bacteria can be used for bioremoval of copper from contaminated sites. In this study, a total of 106 copper resistant bacteria were examined for resistance to copper toxicity and biosorption of copper. Eighty isolates (45 from vineyard Mollisol, 35 from Inceptisol) were obtained from EMBRAPA (Empresa Brasileira de Pesquisa Agropecuária) experimental station, Bento Gonçalves, RS, Brazil (29°09′53.92″S and 51°31′39.40″W) and 26 were obtained from copper mining waste from Caçapava do Sul, RS, Brazil (30°29′43.48″S and 53′32′37.87W). Based on resistance to copper toxicity and biosorption, 15 isolates were identified by 16S rRNA gene sequencing. Maximal copper resistance and biosorption at high copper concentration were observed with isolate N2 which removed 80 mg L⁻¹ in 24 h. Contrarily isolate N11 (Bacillus pumilus) displayed the highest specific copper biosorption (121.82 mg/L/OD unit in 24 h). GenBank MEGABLAST analysis revealed that isolate N2 is 99% similar to Staphylococcus pasteuri. Results indicate that several of our isolates have potential use for bioremediation treatment of vineyards soils and mining waste contaminated with high copper concentration.

Bioremediation of heavy metals in liquid media through fungi isolated from contaminated sources

Wastewater particularly from electroplating, paint, leather, metal and tanning industries contain enormous amount of heavy metals. Microorganisms including fungi have been reported to exclude heavy metals from wastewater through bioaccumulation and biosorption at low cost and in eco-friendly way. An attempt was, therefore, made to isolate fungi from sites contaminated with heavy metals for higher tolerance and removal of heavy metals from wastewater. Seventy-six fungal isolates tolerant to heavy metals like Pb, Cd, Cr and Ni were isolated from sewage, sludge and industrial effluents containing heavy metals. Four fungi (Phanerochaete chrysosporium, Aspegillus awamori, Aspergillus flavus, Trichoderma viride) also were included in this study. The majority of the fungal isolates were able to tolerate up to 400 ppm concentration of Pb, Cd, Cr and Ni. The most heavy metal tolerant fungi were studied for removal of heavy metals from liquid media at 50 ppm concentration. Results indicated removal of substantial amount of heavy metals by some of the fungi. With respect to Pb, Cd, Cr and Ni, maximum uptake of 59.67, 16.25, 0.55, and 0.55 mg/g was observed by fungi Pb3 (Aspergillus terreus), Trichoderma viride, Cr8 (Trichoderma longibrachiatum), and isolate Ni27 (A. niger) respectively. This indicated the potential of these fungi as biosorbent for removal of heavy metals from wastewater and industrial effluents containing higher concentration of heavy metals.

Characterization of copper bioreduction and biosorption by a highly copper resistant bacterium isolated from copper-contaminated vineyard soil

Copper is an essential but toxic heavy metal that negatively impacts living systems at high concentration. This study presents factors affecting copper bioremoval (bioreduction and biosorption) by a highly copper resistant monoculture of Pseudomonas sp. NA and copper bioremoval from soil. Seven bacteria resistant to high concentration of Cu(II) were isolated from enrichment cultures of vineyard soils and mining wastes. Culture parameters influencing copper bioreduction and biosorption by one monoculture isolate were studied. The isolate was identified by 16S rRNA gene sequence analysis as a Pseudomonas sp. NA (98% similarity to Pseudomonas putida, Pseudomonas plecoglossicida and other Pseudomonas sp.). The optimal temperature for growth was 30 degrees C and bioremoval of Cu(II) was maximal at 35 degrees C. Considerable growth of the isolate was observed between pH 5.0 and 8.0 with the highest growth and biosorption recorded at pH 6.0. Maximal bioreduction was observed at pH 5.0. Cu(II) bioremoval was directly proportional to Cu(II) concentration in media. Pseudomonas sp. NA removed more than 110mg L(-1) Cu(II) in water within 24h through bioreduction and biosorption at initial concentration of 300mg L(-1). In cultures amended with 100mg L(-1), 20.7mg L(-1) of Cu(II) was biologically reduced and more than 23mg L(-1) of Cu(II) was biologically removed in 12h. The isolate strongly promoted copper bioleaching in soil. Results indicate that Pseudomonas sp. NA has good potential as an agent for removing copper from water and soil.

Removal of mercury(II) from aqueous solution using moss (Drepanocladus revolvens) biomass: equilibrium, thermodynamic and kinetic studies

The equilibrium, thermodynamics and kinetics of the biosorption of Hg(II) onto moss (Drepanocladus revolvens) biomass from aqueous solution were investigated. Optimum experimental parameters were determined to be pH 5.5, contact time 60min, biomass concentration 4 g L(-1) of solution, and temperature 20 degrees C. From the Langmuir model the maximum biosorption capacity of the moss biomass was found to be 94.4 mg g(-1). The mean free energy value (10.2 kJ mol(-1)) evaluated by using the Dubinin-Radushkevich (D-R) model indicated that the biosorption of mercury ions onto D. revolvens was taken place by chemical ion-exchange. The kinetic studies indicated that the biosorption process of mercury ions followed well pseudo-second-order model. The calculated thermodynamic parameters (DeltaG degrees , DeltaS degrees , DeltaH degrees ) showed the biosorption to be exothermic and spontaneous with decreased randomness at the solid-solution interface. The recovery of the Hg(II) from D. revolvens biomass was found to be 99% using 1M HCl. It was concluded that the D. revolvens biomass can be used as biosorbent for the treatment of wastewaters containing Hg(II) ions.

Assessment of the biosorption characteristics of a macro-fungus for the decolorization of Acid Red 44 (AR44) dye

This study focuses on the possible use of macro-fungus Agaricus bisporus to remove Acid Red 44 dye from aqueous solutions. Batch equilibrium studies were carried out as a function of pH, biomass amount, contact time and temperature to determine the decolorization efficiency of biosorbent. The highest dye removal yield was achieved at pH 2.0. Equilibrium occurred within about 30 min. Biosorption data were successfully described by Langmuir isotherm model and the pseudo-second-order kinetic model. The maximum monolayer biosorption capacity of biosorbent material was found as 1.19 x 10(-4) mol g(-1). Thermodynamic parameters indicated that the biosorption of Acid Red 44 onto fungal biomass was spontaneous and endothermic in nature. Fourier transform infrared spectroscopy and scanning electron microscopy were used for the characterization of possible dye-biosorbent interaction and surface structure of biosorbent, respectively. Finally the proposed biosorbent was successfully used for the decolorization of Acid Red 44 in synthetic wastewater conditions.

Biosorptive removal of mercury(II) from aqueous solution using lichen (Xanthoparmelia conspersa) biomass: kinetic and equilibrium studies

The potential use of the lichen biomass (Xanthoparmelia conspersa) to remove mercury(II) ions from aqueous solution by biosorption was evaluated using the batch method. Effects of pH, contact time, biomass concentration and temperature on the removal of Hg(II) ions were studied. The Langmuir isotherm models defined the equilibrium data precisely compared to Freundlich model and the maximum biosorption capacity obtained was 82.8 mg g(-1). From the D-R isotherm model, the mean free energy was calculated as 9.5 kJ mol(-1). It shows that the biosorption of Hg(II) ions onto X. conspersa biomass was taken place by chemical ion-exchange. Experimental data were also performed to the pseudo-first-order and pseudo-second-order kinetic models. The results indicated that the biosorption of Hg(II) on the lichen biomass followed well the second-order kinetics. Thermodynamic parameters, DeltaG(o), DeltaH(o) and DeltaS(o) indicated the Hg(II) sorption to be exothermic and spontaneous with decreased randomness at the solid-solution interface. Furthermore, the lichen biomass could be regenerated using 1M HCl, with up to 85% recovery, which allowed the reuse of the biomass in ten biosorption-desorption cycles without any considerable loss of biosorptive removal capacity.

Chromium removal from a real tanning effluent by autochthonous and allochthonous fungi

Heavy metals represent an important ecological and health hazard due to their toxic effects and their accumulation throughout the food chain. Conventional techniques commonly applied to recover chromium from tanning wastewaters have several disadvantages whereas biosorption has good metal removal performance from large volume of effluents. To date most studies about chromium biosorption have been performed on simulated effluents bypassing the problems due to organic or inorganic ligands present in real industrial wastewaters that may sequestrate the Cr(III) ions. In the present study a tanning effluent was characterized from a mycological point of view and different fungal biomasses were tested for the removal of Cr(III) from the same tanning effluent in which, after the conventional treatments, Cr(III) amount was very low but not enough to guarantee the good quality of the receptor water river. The experiments gave rise to promising results with a percentage of removed Cr(III) up to 40%. Moreover, to elucidate the mechanisms involved in biosorption process, the same biomasses were tested for Cr(III) removal from synthetic aqueous solutions at different Cr(III) concentrations.