Rose and lavender industrial by-products application for adsorption of Acid Orange 7 from aqueous solution.

Lavender (L) and Rosa damascena (RD) industrial solid by-products were used as biodegradable adsorbents for the removal of the azo dye Acid Orange 7 from aqueous solutions. The equilibrium for the adsorption (1 g of adsorbent, 20 mL aqueous solution of dye, pH 7.05) occurred at the 60 min and at 100 mg/L initial concentration of azo dye. The adsorbed amount of Acid Orange 7 was 1.63 mg/g (81.50% removal efficiency) for L and 1.74 mg/g (87% removal efficiency) for RD at 293 K. The effectiveness of the adsorption increased decreasing the pH medium: for L at pH 1.5, the removal was 1.975 ± 0.08 mg/g (98.75%), and for RD at pH 3.5, it was 1.975 ± 0.08 (98.75%). The removal behavior for Acid Orange 7 fitted the Freundlich model and suggested a diffusion process related to physical adsorption. For the three investigated temperatures (293 K, 303 K, and 313 K) negative values for Gibb's free energy ΔG⁰ were observed revealing the spontaneous character of the adsorption processes. The observed decrease of ΔG⁰ (ranging from − 18 to − 21 kJ/mol) implies a physical nature of the adsorption. The post-adsorption L and RD residues were subjected to solid-state cultivation using the fungus Ganoderma resinaceum GA1M yielding mycelium-based biocomposites. The investigations revealed that the biocomposites were free from Acid Orange 7. The approaches presented here demonstrate that L and RD industrial by-products can be successfully applied for the adsorption of Acid Orange 7 while producing harmless mycelium-based biocomposites through solid-state fermentation using G. resinaceum GA1M. [ABSTRACT FROM AUTHOR]