Polysaccharides Used in Biosorbents Preparation for Organic Dyes Retaining from Aqueous Media

Abstract

Natural polymers can themselves be efficient as materials with biosorptive properties but can also be used to transform microbial biomass into an easy-to-handle form, respectively, into biosorbents, through immobilization. The article aims to study biosorbents based on residual microbial biomass (Saccharomyces pastorianus yeast, separated after the brewing process by centrifugation and dried at 80 °C) immobilized in sodium alginate. The biosorptive properties of this type of biosorbent (spherical particles 2 and 4 mm in diameter) were studied for removal of reactive dye Brilliant Red HE-3B (with concentration in range of 16.88–174.08 mg/L) from aqueous media. The paper aims at three aspects: (i) the physico-chemical characterization of the biosorbent (Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) and Fourier Transform Infrared (FTIR) spectra); (ii) the modeling of biosorption data in order to calculate the quantitative characteristic parameters using three equilibrium isotherms (Langmuir, Freundlich, and Dubinin–Radushkevich—DR); and (iii) the evaluation of thermal effect and the possible mechanism of action. The results of the study showed that biosorption capacity evaluated by Langmuir (I) model is 222.22 mg/g (ϕ = 2 mm) and 151.51 mg/g (ϕ = 4 mm) at 30 °C, and the free energy of biosorption (E) is in the range of 8.45–13.608 KJ/mol (from the DR equation). The values of thermodynamic parameters suggested an exothermic process due the negative value of free Gibbs energy (ΔG0 = −9.031 kJ/mol till −3.776 kJ/mol) and enthalpy (about ΔH0 = −87.795 KJ/mol). The obtained results underline our finding that the immobilization in sodium alginate of the residual microbial biomass of Saccharomyces pastorianus led to an efficient biosorbent useful in static operating system in the case of effluents with moderate concentrations of organic dyes.

Empirical Modeling and Optimization by Active Central Composite Rotatable Design: Brilliant Red HE-3B Dye Biosorption onto Residual Yeast Biomass-Based Biosorbents

“…Moreover, the prepared biosorbent material was commonly physico-chemically characterized before and after the biosorption process of the reactive Brilliant Red HE-3B dye to demonstrate that dye biosorption takes place and to underline the biosorption progress and efficiency. These experimental data were already reported in previous authors' articles [10,11].…”

“…Biomass. In the brewing processes, a few by-products are formed, which are available in large amounts, e.g., residual Saccharomyces pastorianus yeasts (Saccharomycetaceae family) [11]. We tested the residual Saccharomyces pastorianus biomass at the finishing of brewing process organized at an industrial company (Albrau, Ones , ti, Romania).…”

“…We tested the residual Saccharomyces pastorianus biomass at the finishing of brewing process organized at an industrial company (Albrau, Ones , ti, Romania). The residual yeast-based biomass was separated by centrifugation (8000 rpm), dried at 80 • C and then immobilized in sodium alginate (using two different practice techniques) [10,11].…”

“…Brilliant Red HE-3B is a reactive dye and its biosorption from wastewater resulting from the process of dyeing textiles, by using a residual Saccharomyces pastorianus yeast (available at large scale, easy and safe to use) immobilized in sodium alginate (using two different practice techniques) as biosorbent has been analyzed and reported, as corresponding to a maximum biosorption capacity of around 224.47-555.55 mg/g [10,11]. The process is influenced by some operating factors: temperature, pH, S/L phases contact time (biosorption time period), biosorbent and adsorbate concentration and other particular characteristics such as the diameters of the biosorbent granules depending on the immobilization techniques used.…”

Modified Polymeric Biosorbents from Rumex acetosella for the Removal of Heavy Metals in Wastewater

“…The determination of the PCZ was carried out to know the pH value from which the metallic cations (As, Cd, Pb and Zn) could be adsorbed. In Figure 3 , it can be verified that pH 4.8 was the neutral charge point of the untreated biomass for both fractions; in the case of solutions with values higher than PCZ, the adsorption of cations would be favored due to the presence of negative charges [ 39 , 40 , 41 , 42 , 43 , 44 ]. Natural fibers have acid groups on their surface; they completely dissociate above pH 4.0, which would favor the adsorption of different molecules.…”