Removal of Cobalt and Strontium in Aqueous Solution by Adsorption using Brewer’s Spent Grain (BSG)

Abstract

Beer is one of the most popular liquors in the world. During the beer-brewing process, the used barley, the main ingredient of beer, and little amount of other additives like hops were produced as the by-product. This by-product was called as brewer’s spent grain (BSG) and reused by animal feeding. The BSG annual production in the world was reported as 38,600,000 tons (S.I. Musaatto., 2014). However, BSG has more valuable potential than usage of animal feeding because of high contents of protein and fiber such as cellulose. Thus, BSG was used for adsorption operation in this study for valuable usage than before. Global warming is the most serious environmental problem these days. The IPCC suggests all countries should reduce CO2 production by 45 % by 2030. To reduce CO2 production, the BSG was converted to biochar by pyrolysis operation, an effective way to treat the wastes. Moreover, radioactive waste is one of the biggest concerns in Korea due to the permanent shutdown of the Gori nuclear power plant and the necessity of the safe destruction of NPP, the announcement of disposal of effluent from the Fukushima NPP accident treatment to the pacific ocean. Thus, the BSG was used for adsorption operation for Co and Sr, one of the most serious radionuclides, to resolve the radioactive waste problems. When the pyrolysis temperature was increased, the surface functional group of BSG was decreased and it makes higher pH and lower CEC value while the surface area and pore volume were increased. In the high level of pyrolysis (650 ~ 850 ºC), the BSG has properties of carbon-based material like graphite, a well-organized C Hyung-Wook Lee(이형욱). Removal of Cobalt and Strontium in Aqueous Solution by Adsorption using Brewer’s Spent Grain (BSG) (맥주박의 흡착을 이용한 수용액 내 코발트와 스트론튬의 제거). School of Earth Science and Environmental Engineering (지구환경공학부), 2023. 68 p. Professor Kyoung-Woong Kim MS/EN 20211079ii structure. Also, after higher level of pyrolysis, the C composition was increased. The BSG-850, BSG-origin biochar after 850 ºC of pyrolysis, has the adsorption capacity to Co and Sr. In 298 K, BSG-850 has 3.304 and 1.462 mg/g of adsorption capacity for Co and Sr, respectively. It means BSG can remove about 40 and 10 % of Co, Sr in 10 ppm of initial concentration. The adsorption process of BSG follows the PSO model (0.987 and 0.917 of R2 value for Co and Sr) and reached to adsorption equilibrium state within about 24 hours. The Langmuir model is the most fitted model for the adsorption isotherm of BSG to both Co and Sr (0.987, and 0.948 R2 values, respectively). At the higher temperature, BSG can uptake more Co and Sr: 4.659, 2.54 mg/g in 308K and 5.5.16, 3.036 mg/g in 318K. The reusability of BSG was confirmed as 75.3, 47.8, 43.6, and 36.2 % for Co after 1,2,3, and 4 cycles, respectively. In Sr adsorption, the capacity was also decreased to 93.6, 84.2, 57.2, and 32.7 % after 1,2,3, and 4 cycles, respectively. If the other competitive ions existed, the adsorption capacity was decreased. In terms of Co, the disturbance effect was Mn (0 %) = Na (0 %) < Cd (24.1 %) < Ni (32.2 %) while Sr was disturbed by Mn (25.2 %) < Ni (29.4 %)< Na (30.2 %) < Cd (59.7 %). Through this research, the adsorption capacity and several adsorption properties of BSG-origin biochar to Co and Sr were confirmed. Thus, it seems like BSG can be a good option for solving the global warming and radioactive waste problems for protecting the environment