Selectivity of SO2 and H2S removal by ethanol-treated calcined eggshell at low temperature

• Published in: Environmental science and pollution research international 2020-06, Vol.27 (17), p.22065-22080
• Main Authors: Ahmad, Waseem, Sethupathi, Sumathi, Kanadasan, Gobi, Iberahim, Nursashabila
• Format: Article
• Language: English
• Subjects: Adsorption; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Design of experiments; Earth and Environmental Science; Ecotoxicology; Egg shells; Environment; Environmental Chemistry; Environmental Health; Environmental science; Ethanol; Experimental design; Food waste; Gases; Hydrogen sulfide; Low temperature; Reaction time; Relative humidity; Research Article; Response surface methodology; Roasting; Selectivity; Sorbents; Sulfur dioxide; Variance analysis; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-020-08671-x

Eggshell is a food waste produced worldwide in substantial amount with very limited recycling activity. In this study, the potential of ethanol-treated calcined eggshell was tested as sorbent for SO 2 and H 2 S. Three variables were selected in the preparation of sorbents via response surface methodology (RSM), i.e., concentration of ethanol in water (50%, 70%, 90%), reaction temperature (20 °C, 40 °C, 60 °C), and contact time (30, 60, 90 min). Central composite design (CCD) was used to develop a quadratic model to correlate the operating variables with the adsorption capacity. Analysis of variance (ANOVA) was performed to identify the significant factors of the experimental design. It was found that the reaction temperature during the sorbent preparation was the most significant factor. The optimum preparation conditions using RSM were found at 20 °C of reaction temperature with 76.37% of ethanol concentration for 67 min of reaction time. The maximum adsorption capacity for the optimized sorbent was found to be 27.75 mg/g and 9.55 mg/g for SO 2 and H 2 S, respectively. The prepared sorbent was more selective towards SO 2 compared with H 2 S. Moreover, the presence of 40% of relative humidity in the inlet gas further enhanced the adsorption capacity of both gases. The ethanol-treated calcined eggshell was further substantiated by FESEM, BET, FTIR, XRD, and XRF. Results showed potential usage of eggshell as a sorbent for SO 2 and H 2 S gases.