Catalytical efficiency, mechanism and characterization of hydrolysed waste eggshell in the subcritical water oxidation of pistachio processing wastewater. (1st September 2022)

• Record Type: Journal Article
• Authors: Yabalak, Erdal; Isik, Zelal; Dizge, Nadir
• Is Part Of: Journal of environmental management. Volume 317(2022)
• Publication Date: 2022-09-01
• Subjects: Waste eggshell -- Subcritical water oxidation -- Pistachio -- Wastewater -- Catalyst; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2022.115326
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Sustainable, effective and environmentally friendly methods are needed in wastewater treatment as quality water is necessary for a healthy life. Valorisation of solid food waste is also of great importance. This study examines the effectiveness of hydrolysed waste eggshells (HES), a green catalyst, in pistachio processing wastewater (PPWW) treatment using subcritical water oxidation (SWO). HES was prepared in the subcritical water medium (513 K, 100 bar of N2, 2 h) with a 92.3% yield. 88.8% of COD, 100% of both TPC and color removals of PPWW were achieved. The effects of independent variables such as temperature (363–403 K), treatment time (20–100 min), the concentration of H2 O2 (0.25–1.25 M) and amount of catalyst (0–100 mg/100 mL) on the responses were investigated using response surface methodology (RSM). SEM, EDX and XRD were used to investigate the characterization of the waste eggshells. The percentage of Ca in HES increased with the hydrolysis, thus CaO increased the catalysis of hydrogen peroxide to form hydroxyl radicals. Graphical abstract: Image 1 Highlights: Waste chicken eggshells was hydrolysed in subcritical water medium and used as a catalyst. Hydrolysed waste eggshell provided high efficiency in subcritical water oxidation method. Pistachio processing wastewater was treated by SWO method using hydrolysed waste eggshell. Characterization of raw and hydrolysed eggshell was performed. 88.8% of COD removal was achieved and the process was optimised using RSM.