The performance of nonviable
The release of synthetic dyestuffs into the aquatic ecosystems through the wastewater of textile industries is a global environmental concern [
Biosorption is one of the popular and attractive technologies for the removal of color contaminants from aqueous effluents. Biosorption is a process that utilizes inexpensive dead biomass to sequester inorganic [
A variety of biomasses is used by the SAIDAL antibiotic complex at Medea, (Algeria) among which the basidomycete
The sorbates used in the experiments were Basic red 46 (BR46) and Crystal violet (CV) or genetian violet which are used in textile processing Industry of Algier (Algeria). These dyes are suitable for dyeing of acrylic substrates, some polyamide and polyester types, viscose, cotton, and wool. CV is also used as an active ingredient in Gram’s stain and as a bacteriostatic agent in animal husbandry and veterinary practice [
Batch kinetic biosorption studies were conducted in a temperature-controlled stirrer using 1000 mL of adsorbate solution. Samples were withdrawn at suitable intervals and were separated from the sorbent by centrifugation for 20 min at 5000 rpm and then analyzed using a UV spectrophotometer.
For the single system, the dye concentrations were determinated by measuring the absorbance at wavelength of maximum absorbance of CV (594 nm), and BR46 (530 nm) and then calculated according to the calibration curves, respectively.
For components of a binary system, the concentrations of each dye in mixture solutions can be computed using (
Waste
Adsorption experiments were carried out by adding a fixed amount of adsorbent (0.6 and 0.7 g/L for CV and BR46, resp.) to a series of conical flasks filled with 100 mL diluted solutions (10–120 mg/L). The conical flasks were placed in a thermostatic shaker at 10, 15, 20, and 30° at pH 7.5. The removal efficiency (
Experiments were undertaken to study the effect of varying initial concentration (10–120 mg/L) at 30°C on dye removal by dead
Effect of contact time at several initial CV concentrations on sorption kinetics (30°C, pH 7,
Effect of contact time at several initial BR46 concentrations on sorption kinetics (30°C, pH 7,
After a lapse of some time, the remaining vacant surface sites are difficult to be occupied due to repulsive forces between the adsorbate on the
The sorbent concentration is another factor that influences the sorption equilibrium. In order to examine the effect of the sorbent dosage on the removal efficiency dye, adsorption experiments were set up with various amounts of dried
Effect of biosorbent dosage on BR46 and CV removal.
It followed the predicted pattern of increasing percentage sorption as the dosage was increased and reaches a saturation level at high doses, 0.6 and 0.7 g/L of biosorbent were observed to be the upper limit for the removal of CV and BR46 respectively. This is probably because of the resistance to mass transfer of dye from bulk liquid to the surface of the solid, which becomes important at high-adsorbent loading in the conical flask in which the experiment was conducted.
Adsorption equilibrium studies were conducted at initial dye concentration of 50 mg/L by adding a fixed amount of adsorbent (0.6 g and 0.7 g for CV and BR46, resp.) into a series of conical flasks each filled with 1000 mL of dye solution. Batch sorption experiments were performed at various aqueous phase pH (4.7, 5.8, 6.5, 7.5, 8.1, and 8.6). During the adsorption, the temperature of system was kept constant at 30°C.
The pH of the dye solution plays an important role in the whole biosorption process and particularly in the adsorption capacity, influencing the surface charge of the biosorbent, the degree of ionization of the dye present in the solution and the dissociation of functional groups on the active sites of biosorbent, and the solution dye chemistries. The fungal cell wall contains a high amount of polysaccharides and some of them are associated with proteins and other components. These macromolecules have several functional groups, and the biosorption phenomenon depends on the protonation or unprotonation of these functional groups on the surface of the cell wall [
Effect of pH on BR46 and CV removal.
The results of percentage of dye removal versus equilibrium pH increased with increasing pH. Further the variation in pH (7.5–8.6) did not cause any disintegration of the biosorbent, and the extent of adsorption was observed to become nearly constant at pH values greater than 7.5. As the initial pH of the dye solution decreased, the number of negatively charged adsorbent sites decreased and positively charged sites increased which did not favor the adsorption of positively charged dye cation due to electrostatic repulsion [
The lower uptake of dye adsorption at acidic pH is also due to the presence of excess of H+ ions competing with dye cation for the adsorption sites. Therefore, ionic exchange, electrostatic repulsion, structural properties of the dye and
All the two dyes found to follow the similar trend with low percentage of removal at low pH (pH = 4.7). At pH 7.5 and 8.1, the maximum adsorption onto
There were many factors responsible for this difference in dye uptake, such as their structure, molecular size, and functional groups.
The effect of temperature on BR46 and CV uptake capacity (
CV adsorption on
BR46 adsorption on
In order to optimize the design of a sorption system to remove dyes from aqueous solutions, it is important to establish the most appropriate correlation for the equilibrium curves. The isotherms data were analyzed using two of the most commonly used equilibrium models, Langmuir [
The effects of temperature on biosorption were studied at initial dye concentration (10 mg/L), fixed initial pH (7.5 and 8.1 for CV and BR46, resp.) and biomass concentration (0.6 and 0.7 g/L for CV and BR46, resp.) for 90 min. Adsorption isotherms in single-component systems are presented in Figures
Biosorption isotherm parameters for the biosorption of CV and BR46 onto
Parameters | Temperature | |||
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10°C | 15°C | 20°C | 30°C | |
BR46 | ||||
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Freundlich constants | ||||
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2.18 | 2.25 | 2.47 | 2.60 |
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6.38 | 7.47 | 9.50 | 10.91 |
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0.99 | 0.983 | 0.995 | 0.996 |
Langmuir constants | ||||
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62.5 | 66.66 | 71.43 | 76.92 |
|
0.046 | 0.054 | 0.06 | 0.065 |
|
0.98 | 0.977 | 0.963 | 0.959 |
| ||||
CV | ||||
| ||||
Freundlich | ||||
|
2.82 | 2.77 | 2.38 | 2.35 |
|
11.26 | 13 | 19 | 22.35 |
|
0.96 | 0.97 | 0.96 | 0.986 |
Langmuir | ||||
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71.43 | 90.91 | 142.85 | 166.66 |
|
0.058 | 0.054 | 0.0625 | 0.089 |
|
0.932 | 0.907 | 0.829 | 0.934 |
Langmuir adsorption isotherm for CV on
Langmuir adsorption isotherm for BR46 on
Freundlich adsorption isotherm for CV on
Freundlich adsorption isotherm for BR46 on
The studies of adsorption equilibrium are important in determining the effectiveness of adsorption; however, it is also necessary to identify the types of adsorption mechanism in a given system.
The kinetic of biosorption of CV and BR46 had been modeled using ( Pseudo-second order
Intraparticle diffusion
Pore diffusion coefficient
where
Parameters of Pseudo-second-order and Weber-Morris model for biosorption of CV and BR46 onto
Single system | |||||||
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(g·/mg/min) | (mg/g) | (mg/g·min) | (g/mg·min0.5 ) | (cm2/s) | |||
CV | |||||||
| |||||||
|
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10 | 7.39 × 10−2 | 16.13 | 18.67 | 0.999 | 0.522 | 0.889. | 3.29 × 10−8 |
25 | 2.05 × 10−2 | 38.46 | 30.30 | 0.997 | 1.66 | 0.943 | 2.21 × 10−8 |
50 | 0.93 × 10−2 | 76.92 | 55.55 | 0.998 | 2.37 | 0.916 | 2.03 × 10−8 |
120 | 0.82 × 10−2 | 142.85 | 166.66 | 0.998 | 4.31 | 0.852 | 3.28 × 10−8 |
|
|||||||
10 | 7.2 × 10−2 | 13.89 | 11.9 | 0.999 | 0.394 | 0.818 | 2.81 × 10−8 |
15 | 5.18 × 10−2 | 15.15 | 13.8 | 0.999 | 0.460 | 0.900 | 2.21 × 10−8 |
20 | 8.12 × 10−2 | 15.38 | 19.2 | 0.999 | 0.377 | 0.830 | 3.51 × 10−8 |
30 | 7.39 × 10−2 | 16.13 | 19.23 | 0.999 | 0.522 | 0.889 | 3.29 × 10−8 |
| |||||||
BR46 | |||||||
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10 | 7.91 × 10−2 | 12.05 | 11.49 | 0.999 | 0.376 | 0.865 | 2.89 × 10−8 |
25 | 2.59 × 10−2 | 20.83 | 11.23 | 0.999 | 0.88 | 0.874 | 1.51 × 10−8 |
50 | 0.92 × 10−2 | 40.00 | 14.7 | 0.998 | 1.94 | 0.931 | 1.03 × 10−8 |
120 | 0.95 × 10−2 | 52.63 | 26.31 | 0.999 | 3.35 | 0.917 | 3.4 × 10−8 |
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10 | 6.34 × 10−2 | 11.36 | 8.19 | 0.999 | 0.502 | 0.815 | 2.03 × 10−8 |
15 | 6.45 × 10−2 | 11.76 | 8.92 | 0.999 | 0.424 | 0.882 | 2.13 × 10−8 |
20 | 7.58 × 10−2 | 11.9 | 10.75 | 0.999 | 0.401 | 0.874 | 2.54 × 10−8 |
30 | 7.91 × 10−2 | 12.05 | 11.49 | 0.999 | 0.376 | 0.865 | 2.89 × 10−8 |
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Binary system ( |
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(g·/mg/min) | (mg/g) | (mg/g·min) | (g/mg·min0.5 ) | (cm2/s) | |||
| |||||||
CV | 6.50 × 10−2 | 13.69 | 12.19 | 0.998 | 0.376 | 0.889. | 2.5 × 10−8 |
BR46 |
2.93 × 10−2 | 8.93 | 2.34 | 0.994 | 0.640 | 0.930 | 0.74 × 10−8 |
According to this model, the plot of uptake,
The thermodynamic parameters of the adsorption process were determined from the experimental data obtained using the following equations [
Figure
Arrhenius plots for the adsorption of CV and BR46 on to
The
Thermodynamic parameters.
Temperatures (°C) |
|
|
|
---|---|---|---|
CV | |||
| |||
10 | 5.10 | 2.29 | 59.60 |
15 | 6.18 | 3.43 | |
20 | 7.58 | 4.57 | |
30 | 9.62 | 6.86 | |
| |||
BR46 | |||
| |||
10 | 2. 79 | 0.5 | 34.75 |
15 | 3.47 | 0.75 | |
20 | 4.58 | 1 | |
30 | 5.39 | 1.5 |
Figure
Biosorption kinetics in binary systems for CV and BR46.
From Table
The relative adsorptions of CV and BR46 on
Relative biosorption and biosorption selectivity for CV and BR46 in binary system.
This suggests that
To investigate the effect of initial dye concentration on binary biosorption, experiments were divided into two stages. In the first part,
Biosorption isotherm of BR46 in the presence of CV.
Biosorption isotherm of CV in the presence of BR46.
Various researchers have developed models in binary systems. In this study, the model chosen refers to theories developed by Sheindrof at al. (1981) derived a Freundlich-type multicomponent adsorption isotherm. The sheindorf-Rebhun-Sheintuch (SRS) equation was based on assumption that there is an exponential distribution of adsorption energies available for each solute [
SRS competitive isotherm plots for (a) CV biosorption in the presence of BR46 and (b) BR46 biosorption in the presence of CV.
The present study shows that the
In single system, the Freundlich isotherm model yielded the concentration range. Batch studies show that a simple model of pseudo-second-order kinetic equation can adequately predict the adsorption of BR46 and CV on dead
In this study, the ability of