Holistic Exploitation of Spent Coffee Ground: Use as Biosorbent for Olive Mill Wastewaters After Extraction of Its Phenolic Compounds
2022
Solomakou, Nikoletta | Tsafrakidou, Panagiota | Goula, Athanasia M.
Various experiments on the isolation of phenolic components from olive mill wastewaters (OMW) have been conducted and several methods have been used separately or in combination. Adsorption is characterized by its low cost and high efficiency. Nonetheless, the high initial cost of common commercial sorbents renders their substitution and the demand for a regeneration procedure essential. The purpose of this study was the investigation of the effectiveness of a coffee industry waste, spent coffee ground (SCG), for the adsorption of OMW bioactive components, after the extraction of its phenolics using emerging methods. The novelty of the present research is based on the holistic exploitation of SCG for the waste management of another food industry by-product, both of which are being produced in high quantities, consisting a potential hazard for the environment. The effects of different factors, such as the solution’s pH (2.0–10.0), temperature (20–60 °C), initial sorbate concentration (50–500 mg/L), and sorbent mass concentration (0.01–0.05 g/mL), on adsorption efficiency, were investigated performing batch experiments. The results were correlated to the effects of the investigated factors on the adsorption of gallic acid, which is one of the most abundant phenolic species in OMW. Adsorption yield reached a maximum of 45.44% after 20 min, at 30 °C and pH of 8.0, with an initial concentration of 162.5 mg/L and sorbent ratio of 0.02 g/mL. Different effects were found during gallic acid adsorption, where the efficiency was higher (70.69%).
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