engleski

Desorption of synthetic dye congo red from dye- loaded biosorbent using organic solvents

Synthetic dyes, widely used in many industries, are a heterogeneous group comprised of structurally very diverse compounds. Coloured industrial effluents represent the most common sources of water pollution with dyes. The most often used method for the removal of dyes from industrial effluents is adsorption, which is efficient but costly method due to the price of conventional adsorbents. Therefore, different lignocellulosic waste materials have been examined, as possible adsorbents. Dye-loaded lignocellulosic materials after adsorption process has to be adequately disposed of, so the treatment through solid state fermentation (SSF) by white-rot fungi is proposed in order to degrade both the material and dye. To measure the extent of the Congo Red (CR) dye degraded from biosorbent for future analysis of samples after SSF, individual solvents were used to extract CR adsorbed onto brewers’ spent grain (BSG). Nonpolar solvents (dichloromethane, benzene, chloroform, toluene, and xylene), polar aprotic solvents (ethyl acetate, acetone, tetrahydrofuran, dimethylformamide, acetonitrile, dimethyl sulfoxide), and polar protic solvents (water, ethanol, methanol, and amyl alcohol) were used. A two-component solvent system and three- component solvent system were also tested. Taking into account the new solvents introduced in the last decades as an alternative to traditional organic solvents, deep eutectic solvents (DESs) were also evaluated in the present study. The effect of molar ratio choline chloride and different hydrogen bond donor in DESs on extraction efficiency of CR from dye-adsorbed BSG was investigated. Out of the tested polar protic solvents, methanol showed the highest extraction efficiency of CR from dye-loaded BSG. When polar aprotic solvents were used, the highest extraction efficiency was achieved using acetonitrile. Compared to individual solvents, the extraction efficiency was significantly increased when multicomponent solvents were used. DESs were less efficient than both the polar protic and polar aprotic solvents.

spent grain ; Congo Red ; desorption ; organic solvents

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