Journal of Environmental Science and Health Part A, 41:2587–2606, 2006 C Taylor & Francis Group, LLC Copyright
ISSN: 1093-4529 (Print); 1532-4117 (Online) DOI: 10.1080/10934520600927989 Biosorption Potential of the Macrofungus Ganoderma carnosum for Removal of Lead(II) Ions from Aqueous Solutions Tamer Akar,1 Ahmet Cabuk,2 Sibel Tunali,1 and Mustafa Yamac2 1 Department of Chemistry, Faculty of Arts and Science, Eskişehir Osmangazi University, Eskişehir, Turkey 2 Department of Biology, Faculty of Arts and Science, Eskişehir Osmangazi University, Eskişehir, Turkey This paper reports the utilization of a macro-fungus Ganoderma carnosum as a biosorbent material for the removal of lead(II) ions from aqueous solutions. The biosorption potential of G. carnosum was investigated by batch experiments. The influences of physico-chemical parameters like pH, biosorbent dosage, contact time and initial metal ion concentration were evaluated. The biosorption equilibrium was attained in 10 minutes. Equilibrium biosorption data were analyzed by the Freundlich, Langmuir and Dubinin–Radushkevich (D–R) isotherm models. Maximum biosorption capacity of biosorbent was found to be 22.79 mg g−1 (1.10 × 10−4 mol g−1 ) at the pH value of 5.0. The biosorbent was regenerated using 10 mM HCl solution, with up to 96% recovery, and reused four times in biosorption-desorption cycles successively. Biosorption efficiency of G. carnosum was also examined in a real effluent. The mechanism of the biosorption was investigated with FTIR, SEM and EDAX analysis and the findings suggested that the biosorption process involved in ion exchange as dominant mechanism as well as complexation. The ion exchange mechanism was also confirmed by the mean free energy value obtained from D–R isotherm model. Key Words: Biosorption, Equilibrium, Ganoderma carnosum, Ion-exchange, Isotherm. Received March 30, 2006. Address correspondence to Tamer Akar, Eskişehir Osmangazi University, Faculty of Arts and Science, Department of Chemistry, 26480, Eskişehir, Turkey; E-mail: takar@ ogu.edu.tr 2587 2588 Akar et al. INTRODUCTION Heavy metals are hazardous contaminants because they cannot be broken into simpler, less toxic forms and they persist unchanged in the environment for many years.[1] The presence of heavy metal ions in the aquatic systems has been of great concern because of their toxicity even at lower concentrations.[2] Toxic metals enter waterways from two main sources: industrial waste discharges and particulates in the atmosphere that settle and are carried in runoff.[1] One of the significant toxic metal ions for human health is lead. It is the most widely distributed in the environment and the one that the average person is the most likely to encounter. The hazardous effects of lead are on central and peripheral nervous systems, haematopoietic, renal, gastrointestinal, cardiovascular and reproductive systems. The other damaging effects of lead are anaemia, tenderness, loss of cognitive abilities, nausea[1,2] and suppression of the mental capacity of children.[3] Studies have shown that infants exposed to lead have IQ scores that are 5% lower by age 7 than the scores of unexposed children; the children are six times more likely to have reading disabilities and seven times more likely to drop out of school.[1] Therefore, there is significant interest regarding lead removal from contaminated water systems. Biosorption technology has emerged as a promising alternative method over conventional treatment methods with the advantages of low operating cost, minimization of the chemical and/or biological sludge volume, high efficiency in detoxifying very dilute effluents, no nutrient requirements and regeneration of sorbent material and possibility of metal recovery. It is based on the property of microbial biomass to sequester heavy metals through interactions between toxic metal ions and the metal binding functional groups present on the cell wall structure of the microbial origin sorbents composed mainly of polysaccharides, proteins and lipids.[4,5] The most of the earlier reports in the literature indicates the potential use of different types of biomass in heavy metal removal. Those include microfungi,[6−11] bacteria,[12−16] yeast[17,18] and algae[19,20] whereas there is still very little information about the use of the biomass of the macro-fungi[21−23] as a biosorbent for heavy metal removal. In the present study macro-fungi Ganoderma carnosum, was identified as a promising biosorbent for the removal of lead(II) ions from aqueous solution. To our knowledge, it has not been used for the sorption of heavy metals from aqueous solutions. The influence of initial pH, biosorbent dosage, contact time, initial lead(II) ion concentration and co-ions on biosorption was studied. Biosorption-desorption cycles were performed to determine the reusability potential of biosorbent. The biosorption equilibrium data at 20◦ C were modelled by using the Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models. The mechanism of the process was investigated by Fourier transform Ganoderma carnosum as Biosorbent for Lead Removal 2589 infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energydispersive X-ray analysis (EDAX). MATERIALS AND METHODS Preparation of the Biosorbent Material The macro-fungus used in the present study was G. carnosum, provided from fungi culture laboratory of Biology Department of Eskisehir Osmangazi University. The fungal biomass was washed with deionised water for several times in order to remove dust, cut into small pieces and then dried in an oven at 70◦ C until constant weight. The biomass was then grounded and sieved to select particle size of less than 300 µm and subsequently was used for biosorption experiments. Batch Biosorption Experiments Batch experiments were performed with a magnetic stirrer at 200 rpm and 20◦ C using 100 mL beakers containing test solutions. The stock lead(II) ion solution (1 g L−1 ) was prepared by dissolving of Pb(NO3 )2 of analytical grade in deionised water. Other concentrations were prepared by dilution of this stock solution and fresh dilutions were used in each experiment. To study the effect of initial pH on lead(II) biosorption onto G. carnosum biomass, 50 mL of 100 mg L−1 lead(II) solution was used and then the initial pH values of the contact solutions were adjusted to a value in the range of 1.0–5.0 by adding 0.1 M HCl or 0.1 M NaOH. Then 0.1 g of biomass was added to each beaker and the biosorption mixtures were stirred for 1 h, which is sufficiently long enough for biosorption equilibrium. The effect of biosorbent dosage was studied by using different dose of biomass (0.2–12 g L−1 ). The optimum pH and biosorbent concentration were determined as 5.0 and 4.0 g L−1 , respectively and used throughout all biosorption experiments. The period of contact time was varied from 5 to 120 min by using the same sorption mixture described above to determine the optimum biosorption time. The effect of the initial lead(II) concentration on the biosorption was studied at optimum conditions determined above except that the concentration of lead(II) in the biosorption mixture was varied between 30 and 300 mg L−1 . The co-ion effect on the biosorption of lead(II) was also investigated in multiple metal ion mixture containing Pb2+ , Ni2+ , Cd2+ and Mn2+ ions. The medium containing 100 mg L−1 of each metal ion was incubated with 0.2 g of biosorbent at pH 5.0 for 10 min. After biosorption, the contents of the beakers were centrifuged at 4500 rpm for 3 min and the biomass was successfully separated from aqueous solution. The supernatants were analyzed for residual lead(II) concentration using an atomic absorption spectrophotometer (Hitachi 180-70, Japan). The 2590 Akar et al. measurements were performed under the following conditions: air-acetylene flame, 7.5 mA lamp current, 1.3 nm spectral slit width and 283.3 nm wavelength. The instrument calibration was checked using a known lead standard solution in every 10 readings. The biosorption capacity, (qe ), per g of biomass, was calculated from the general mass-balance equation (Eq. 1) as follows: qe = [(Ci − Ce )]·V/M (1) where, Ci (mg L−1 ) and Ce (mg L−1 ) are the initial and equilibrium lead(II) ion concentrations of the solution; V: volume of the lead(II) solution (L); M: weight of the biomass added into reaction mixture (g). Reusability Tests of Biomass The recovery and reusability of biosorbent material are important parameters related to the application potential of biosorption technology.[24] In this work consecutive biosorption and desorption cycles were repeated for four times using the same biomass in order to determine the reusability potential of G. carnosum. Following the batch biosorption process, lead(II)-loaded biomass was separated by centrifugation and suspended into 50 mL of the eluent solution (10 mM HCl). Each biosorption and desorption cycles were allowed 10 min of contact time in the solutions containing biosorbent—lead (II) ions or biosorbentdesorbent agent for achieving sorption or desorption equilibrium. The concentrations of the lead(II) ion released into eluent solutions were determined as described above. The eluted biosorbent was thoroughly washed with deionised water and placed into metal solution for the next biosorption and desorption cycles. Desorption efficiency was calculated by using the following equation. Desorption efficiency = Amount of lead(II) desorbed × 100 Amount of lead(II) biosorbed (2) Real Industrial Wastewater The industrial wastewater was collected from the main drain of the casting unit of metal processing industry from Eskişehir, Turkey. Wastewater sample was placed into a sterile container and transferred to laboratory and stored at 5◦ C. The various characteristics of wastewater were presented in Table 1. Furthermore, real wastewater sample was spiked with lead(II) and the proposed biosorption method was applied to with and without spiked samples. Statistical Analysis Data presented are the mean values from three independent experiments. Standard deviation and error bars are indicated wherever necessary. All Ganoderma carnosum as Biosorbent for Lead Removal 2591 Table 1: Chemical characteristics of wastewater sample. Parameters pH Temperature (◦ C) Suspended solid (mg L−1 ) Lead (mg L−1 ) Copper (mg L−1 ) Nickel (mg L−1 ) Cadmium (mg L−1 ) Sodium (mg L−1 ) Potassium (mg L−1 ) Calcium (mg L−1 ) Magnesium (mg L−1 ) Effluent quality 3.16 27 26 1.9 137.3 22.3 5.8 66.2 7.0 243.0 112.0 statistical analysis was done using SPSS 9.05 for Windows where it is possible to evaluate whether the effect and the interaction among the investigated factors are significant with respect to the experimental error. FTIR Spectral Analysis In an effort to find out the binding functional groups on the biomass surface that are responsible from the lead(II) biosorption, infrared analysis of unloaded and lead(II)-loaded biomass samples were carried out with a Bruker Tensor 27 FTIR spectrophotometer within the range of 400–4000 cm−1 . SEM and EDAX Analysis The porosity of biosorbent surface and possible metal-biosorbent interactions were examined with SEM and EDAX analysis. The morphological analysis of unloaded and lead(II) loaded biomass were carried out by means of a Cam Scan Oxford Link scanning electron microscope coupled with an energy dispersive X-ray analyzer. RESULTS AND DISCUSSION Effect of Initial pH The pH dependency of the biosorption of lead(II) ions was studied at a pH range of 1.0–5.0 and the results are represented in Figure 1. It was observed that biosorption was negligible at the initial pH below 2.0. When the initial pH values were increased from 3.0 to 5.0 the biosorption capacity of G. carnosum biomass was increased as much as about five fold (from 4.11 ± 0.75 to 18.79 ± 1.19 mg g−1 , P < 0.05). The higher pH values (pH > 5.5) were not used due to precipitation of lead(II) ions. The low lead(II) biosorption at highly 2592 Akar et al. Figure 1: pH effect on the lead(II) biosorption onto G. carnosum. acidic conditions may be explained by competition between lead(II) ions and protons for occupancy in the same biosorption sites. This competition creates a repulsive ionic environment, less favorable to further binding of lead(II) ions, resulting in the reduced lead(II) biosorption.[25] However, as the pH increases the concentration of H+ ions decreases and the binding groups on the biosorbent surface become negative as a result of deprotonation. Thus more negative binding sites for lead(II) ions are provided. The maximum lead(II) biosorption by G. carnosum was observed at pH 5.0 and the further experiments were performed at optimal pH. Similar pH trends for different biosorbents were reported in the literature.[7,26] Effect of Biosorbent Concentration The effect of the biosorbent concentration on the lead(II) biosorption yield was investigated by varying the biosorbent concentration between 0.2–12 g L−1 at pH 5.0 and the results are presented in Figure 2. From the figure it was observed that the biosorbent concentration played an important role in the biosorption yield of G. carnosum for lead(II) ions. The increase in the biosorbent dosage from 0.2 to 4.0 g L−1 leads to a significantly increase in the percentage of lead(II) biosorption from 5.6 ± 1.12 to 75.16 ± 1.13% (P < 0.05). So, 4.0 g Ganoderma carnosum as Biosorbent for Lead Removal 2593 Figure 2: Biosorbent dosage effect on the lead(II) biosorption onto G. carnosum. L−1 biosorbent dosage was chosen for the next experiments. The increase in the lead(II) biosorption with the biosorbent concentration can be explained by increased surface area of the biosorbent and availability of more binding sites for lead(II) ions. Effect of Contact Time To determine the appropriate contact time the biosorption experiments were conducted with 100 mg L−1 of lead(II) ion concentration and various contact time between 5–120 minutes at pH 5.0. The results are plotted in Figure 3. It can be seen that the biosorption rate of lead(II) ions was very fast initially (5 minutes) and the equilibrium was established rapidly within the short period of 10 min. The amount of sorbed lead(II) ions was increased from 15.49 ± 0.84 to 17.82 ± 1.62 mg g−1 (P < 0.05) during this period. After the sorption equilibrium, the lead(II) uptake values did not significantly change with the further increase in the contact time (P > 0.05). Therefore, 10 minutes was maintained as the equilibrium time for the following experiments. Saeed and co-workers reported that the rate of biosorption process in metal removal is of greatest significance for developing a biosorbent-based water-treatment technology.[27] 2594 Akar et al. Figure 3: Contact time effect on the lead(II) biosorption onto G. carnosum. Effect of Initial Lead(II) Concentrations To determine the effect of the initial metal ion concentration on the biosorption capacity of biomass the initial concentrations of lead(II) ions were varied between 30 and 300 mg L−1 at optimum conditions. The results are plotted in Figure 4 which clearly indicate that the lead(II) biosorption by G. carnosum biomass was highly depend on the initial lead(II) concentration. According to Figure 4, biosorption capacity of G. carnosum biomass increased first with increasing of the initial concentrations of lead(II) ions in the solution up to 150 mg L−1 (P < 0.05) and then did not significantly change (P > 0.05) with further increase in the initial lead(II) concentrations. The maximum lead(II) removal capacity of G. carnosum biomass was found as 22.81 ± 2.03 mg g−1 at 150 mg L−1 of initial lead(II) concentration. This trend is agreement with the previous reports in the literature.[7,8,28] An increase observed in the biosorption capacity of the biomass from beginning to the saturation value could be attributed to increase in the driving force the concentration gradient, as an increase in the initial metal ion concentrations.[29] The reason of observed constant biosorption capacity after the saturation value can be explained by the completely occupancy of binding sites on the biosorbent surface by metal ions.[6] The lead(II) ion concentration in industrial wastewaters can vary between 200 Ganoderma carnosum as Biosorbent for Lead Removal 2595 Figure 4: Initial metal ion concentration effect on the lead(II) biosorption onto G. carnosum. and 500 mg L−1 .[30] Therefore, this study can provide practical benefits on such applications when the studied range of lead(II) ion concentration was taken into account. Desorption and Reusability Studies For the more economically biosorption system in water treatment process the reusability potential of biosorbents after regeneration is very important. The results of desorption experiments of lead(II) ions by 10 mM of HCl solution are shown in Figure 5. It can be seen that desorption of lead(II) from metal-loaded biosorbent was resulted with more than 95% recovery of lead(II) ions. The biosorption efficiency did not significantly change (P > 0.05) and only a maximum 13% decrease was observed after four consecutive biosorptiondesorption cycles. These results showed that the G. carnosum biomass has a good potential for the removal of lead(II) ions repeatedly from aqueous solutions without any detectable loss in the total biosorption capacity. Co-ion Effect The co-ion effect on the biosorption of lead (II) ions by G. carnosum biomass was studied for multi-metal containing solution. Lead(II) biosorption capacity 2596 Akar et al. Figure 5: Regeneration and reusability of G. carnosum for the lead(II) biosorption. of biomass was slightly reduced from 18.79 ± 1.34 to 15.03 ± 1.15 mg g−1 by the presence of nickel(II), cadmium(II) and manganese(II) ions in the same sorption mixture. The slightly decrease in the lead(II) biosorption capacity of the biomass could be explained by the competition between metal ions for the same biosorption sites on the biomass surface. This small decrease in the biosorption capacity of the biomass in multi-metal containing systems could be an advantage for specific lead(II) sorption. Biosorption Isotherms The equilibrium sorption isotherms are one of the most important data to understand the mechanism of the sorption[31] and to evaluate the applicability of sorption process as a unit operation.[32] In the present study Langmuir (Fig. 6), Freundlich (Fig. 7) and Dubinin–Radushkevich (D–R) (Fig. 8) isotherm models were used to describe the equilibrium biosorption data. The Langmuir isotherm model assumes homogeneous type of sorption onto surface containing a finite number of binding sites. Once a metal occupies a site, no further sorption can take place at that site. The linearized Langmuir isotherm equation is represented by the following expression:[33]
 1 1 1 1 = + (3) qe qmax qmax KL Ce Ganoderma carnosum as Biosorbent for Lead Removal 2597 Figure 6: The Langmuir isotherm plot for the lead(II) biosorption onto G. carnosum. where qe and Ce are the amount of sorbed lead(II) ions per unit weight of biosorbent (mol g−1 ), and the equilibrium lead(II) concentration in the solution (mol L−1 ), respectively. qmax is the monolayer biosorption capacity of the biosorbent (mol g−1 ), and KL is the Langmuir constant (L mol−1 ) and is related to the free energy of biosorption which reflects quantitatively the affinity between the sorbent and sorbate. The Freundlich isotherm model assumes that the sorption process takes place on heterogeneous surfaces and sorption capacity is related to the concentration of lead(II) ions at equilibrium. The linearized Freundlich equation is expressed as follows:[34] ln qe = ln K F + 1 ln Ce n (4) where K F (L g−1 ) and n are Freundlich isotherm constants, related to the biosorption capacity and the degree of nonlinearity between solution concentration and biosorption, respectively. Langmuir isotherm parameters can be used to predict the affinity between the sorbate and sorbent using the separation factor or dimensionless equilibrium parameter, ‘RL,’ expressed as following equation:[35] RL = 1 1 + KLCo (5) 2598 Akar et al. Figure 7: The Freundlich isotherm plot for the lead(II) biosorption onto G. carnosum. Figure 8: The D–R isotherm plot for the lead(II) biosorption onto G. carnosum. Ganoderma carnosum as Biosorbent for Lead Removal 2599 where KL is the Langmuir constant as described above,Co is the initial lead(II) ion concentration in solution (mol L−1 ). The value of RL between 0 and 1 represents favorable and >1 represents unfavorable biosorption.[35,36] In this study the value of RL was found as 6.30 × 10−3 , which indicates that the biosorption process is favorable. Furthermore, the numerical value of Freundlich constant of n was 4.30. The Dubinin–Radushkevich (D–R) isotherm is more general than the Langmuir isotherm since it does not assume a homogeneous surface or constant biosorption potential. It was applied to distinguish between the physical and chemical biosorption of lead(II) ions. (D–R) isotherm model is expressed by the following equation:[37] ln qe = ln qm − βε 2 (6) where ε is the Polanyi potential, equal to RT ln(1 + C1e ), qe ,is the amount of lead (II) ions sorbed at equilibrium per unit weight of biosorbent (mol g−1 ), β is a constant related to the biosorption energy (mol2 kJ−2 ), qm is the theoretical saturation capacity (mol g−1 ), Ce is the equilibrium concentration of lead(II) ions in solution (mol L−1 ), R is the gas constant (J mol−1 K−1 ), and T is the absolute temperature (K). The slope of the plot of lnqe versus ε 2 (Fig. 8) gives the value of β (mol2 kJ−2 ) and the intercept yields the value of qm (mol g−1 ). The Polanyi sorption theory assumes that the sorbent surface closed by fixed volume of sorption site and sorption potential exists over these sites. The sorption potential is related to an excess of sorption energy over the condensation energy and is independent of temperature.[38,39] The constant β gives an idea about the mean free energy E, (kJ mol−1 ), of biosorption per mole of the biosorbate when it is transferred to the surface of the solid from infinity in the solution and can be calculated using the relationship:[40−42] 1 E= (7) (2β)1/2 The value of E gives information about the biosorption mechanism as chemical ion-exchange or physical biosorption. If its value is in the range of 8–16 kJ mol−1 the biosorption process follows chemical ion-exchange mechanism,[43] while for the values of E < 8 kJ mol−1 the biosorption process is of a physical nature.[44] The numerical value of the mean free energy of biosorption was found as 15.62 kJ mol−1 indicating that the biosorption may be occur via a chemical ion-exchange process. The Langmuir, Freundlich and D–R isotherm model parameters calculated from the corresponding plots with the regression coefficients are listed in Table 2. As shown in this table, the experimental data fitted well to all the isotherm models investigated because of high regression coefficients. This finding implies that the surface of G. carnosum is made up of homogeneous and heterogeneous biosorption patches. 2600 Akar et al. Table 2: Biosorption isotherm constants for the biosorption of lead(II) onto G. carnosum at 20◦ C. Langmuir Isotherm Freundlich Isotherm D–R Isotherm qmax (mol g−1 ) 1.10 × 10−4 n 4.30 qmax (mol g−1 ) 2.38 × 10−4 KL (L mol−1 ) 1.09 × 105 KF (L g−1 ) 6.89 × 10−4 β (mol2 kJ−2 ) 4.53 × 10−5 r L2 RL 0.972 r F2 6.30 × 10−3 0.962 2 r D−R 0.987 E (kJ mol−1 ) 15.62 Application of Biosorbent to Real Wastewater To evaluate the potential performance of G. carnosum biomass for the removal of lead(II) ions from real wastewater, optimized biosorption procedure was tested with model wastewater samples with and without spikes at optimum experimental conditions. The results are shown in Table 3. As can be seen from the table the lead(II) removal yields of biomass were varied from 28.99 to 75.29% for real and spiked wastewater samples, respectively. The results showed that the proposed method could be successively applied for the treatment of real wastewater for the removal of lead(II) ions. Mechanism of the Biosorption The SEM microscopic photos of G. carnosum biomass at magnifications of 70x, 200x and 500x were given in Figure 9. As shown in these pictures, irregular cavities in fibrous network were observed on the biomass surface, which is considered helpful for the accessibility of heavy metals to the biosorbent surface. The mechanism of the lead(II) biosorption by G. carnosum biosorbent was elucidated on the basis of FTIR and EDAX analysis. To identify the type of possible lead(II) binding sites of G. carnosum, the FTIR spectra were recorded before and after biosorption and presented in Figure 10. The spectrum of the biomass is complex due to many functional groups existed in the surface of the biomass. The broad stretching absorption peak at 3383 cm−1 represents bonded –OH and –NH groups. The band observed at 2922 cm−1 could Table 3: The application of the proposed method in wastewater sample. Sample Real wastewater Spiked sample Spiked sample Concentration of added lead(II) (mg L−1 ) qe (mg g−1 ) Biosorption yield (%) 0 5.0 10.0 0.14 ± 0.03 1.22 ± 0.31 2.25 ± 0.20 28.99 70.19 75.29 Ganoderma carnosum as Biosorbent for Lead Removal Figure 9: Typical SEM micrographs of G. carnosum, at magnifications of 70× (a), 200× (b) and 500× (c). 2601 2602 Akar et al. Figure 10: FTIR spectra of G.carnosum before (a) and after (b) lead(II) biosorption. be assigned to symmetric and asymmetric stretching vibrations of the –CH3 and –CH2 groups. The band at 1642 cm−1 corresponds to carbonyl stretching vibrations of amide considered to be due to the combined effect of double bond stretching vibrations.[45] The 1042 cm−1 band is caused by C OH stretching [46] and the band 569 cm−1 can be assigned to P O vibrations.[47] After the interaction of biomass with lead(II) ions the spectrum exhibits changes of the peaks at 3383 and 569 cm−1 , which shift to 3393 and 574 cm−1 , respectively. This changes may suggest that the involvement of OH, NH and P O groups in biosorption process. Figure 11 shows the typical EDAX patterns for G. carnosum biomass before and after biosorption. The EDAX pattern (a) for unloaded biomass did not show the characteristic signal of lead and for lead(II) loaded biomass (b) showed clearly the signals of lead at about 2.4, 10.5, and 12.7 keV. Also the intensity of the peak at about 2.1 keV corresponding to phosphorus, significantly reduced after biosorption process. This could be indicated the involvement of phosphate group in biosorption process. Furthermore, potassium, which is capable of ion exchange with metal ions, was observed at about 3.2 keV in the spectra of unloaded biomass and disappeared after the biosorption process. These findings indicated that the biosorption process also included ion exchange mechanism for the removal of lead(II) ions by this strain, which is confirmed by the E value obtained by the D–R isotherm model. Ganoderma carnosum as Biosorbent for Lead Removal 2603 Figure 11: Typical EDAX spectra of G.carnosum before (a) and after (b) lead(II) biosorption. CONCLUSION The experimental results show that G. carnosum, a macrofungus, can be effectively used as a promising biosorbent for the removal of lead(II) ions from aqueous solution with the advantage of short biosorption time. The maximum biosorption capacity was obtained at pH value of 5.0 and 4.0 g L−1 of biosorbent concentration. The experimental data could be well modelled with the Langmuir, Freundlich and D–R sorption isotherm equations. 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