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13 Biosorption of Heavy Metals and Metal-Complexed Dyes Under the Influence

complex adsorbed by the sawdust was 25.1 and 62.5 mg of dye per gram with respect

to metal complexed blue (MCB) and metal complexed blue (MCY). Additionally,

there is a possibility of intraparticle diffusion because of the movement of adsorbed

molecules through the porous medium present in the sawdust. The adsorption

density of sawdust reduces with increased adsorbent dose and due to the presence

of unsaturated adsorption active sites on the surface of the sawdust [40]. Erden et al.

carried out an experiment for the removal of Siris blue KFCN dye by the lyophilized

Trametes versicolor biomass. The obtained results revealed that the maximum

adsorption capacity of the respective biomass is around 62.62 mg/g. The kinetic and

the equilibrium data show that the adsorption process followed the pseudo-second

model and Langmuir isotherm model. It is stated that the biosorption followed the

biomass concentration and time. Additionally, the Langmuir adsorption defined

that the process followed monolayer coverage of adsorption. This biosorption

process depicted that the biomass is more effective than the well-known adsorbents

such as activated carbon and amberlite. Likewise, the potential of Aspergillus

parasiticus for the decolorization of textile reactive dye was tested by varying

various parameters such as ionic strength, reaction time, biomass concentration,

and initial metal concentration in batch studies. The obtained results showed that

the highest adsorption capacity achieved by the biomass is around 1.03 × 10⁻⁴ mol/g

at pH 2.0 with 2.0 g/l of biosorbent concentration. Additionally, the recent studies

showed that the material like fly ash shows a noteworthy effect on the removal

of several dyes such as methylene blue, rhodamine B, and malachite green from

the artificial textile wastewater. The obtained result delineated that the removal

of malachite green, rhodamine B, and methylene blue by the selective microbial

species is around 0.228–0.814, 0.184–0.618, and 0.219–0.644 mg/1, respectively,

when the initial dye concentration increased from 5 to 38 mg/l. The maximum time

taken to remove malachite green and rhodamine was around 80 minutes and it was

100 minutes for the methylene blue. Additionally, the Brewer spent grain (BSG)

was used as a material for the removal of Acid green (AG 25) by varying different

parameters such as initial pH, temperature, initial dye concentration, biosorbent

dosage, and contact time. The maximum amount of dye was adsorbed by the

biomass at pH 7 and 30 ^∘C, the initial concentration was around 90 mg/l, and the

biomass concentration and time were found to be 0.2 g and 75 minutes, respectively.

The observed result depicted that the amount of dye removed increased with respect

to time and biomass concentration and decreased with respect to the temperature.

In the case of isotherm study, the equilibrium sorption capacity increased when

the initial dye concentration increased till 90 mg/l. Later, the adsorption capacity

was decreased due to the less availability of active sites. Likewise, the ability of

adsorption capacity of Ganoderma lucidum was tested with dyes present in the

wastewater by varying different parameters in response surface methodology. From

the results, the optimized conditions are observed at acidic pH of 6.6, temperature

of 26.5 ^∘C, agitation speed of 200 rpm, and dye to wastewater ratio of 1 : 2. Under

these optimized conditions, the maximum dye decolorized is 81.4% and chemical

oxidation demand (COD) reduction is about 90.3%.