Large-scale comprehensive utilization of coal fly ash (CFA) has become an inevitable issue. In this study, one-step mixed alkali (KOH + CaO) hydrothermal extraction of alumina and synergistic preparation of soil amendment from CFA was developed. The Al 2 O 3 and SiO 2 in CFA were dissolved rapidly under the action of KOH, and the dissolved silicate was transformed into tobermorite under the action of CaO. This approach realized efficient separation of aluminum and silicon with simultaneous regeneration of KOH. The optimum leaching ratio of Al 2 O 3 was 56.44 %, while the leaching ratio of SiO 2 was 3.38 %. The dealuminated CFA (DACFA) was simultaneously transformed into porous aggregates intertwined with tobermorite fibers, which are rich in Si, Ca and K 2 O nutrients due to the excellent cation exchange of tobermorite or formation of tobermorite and leucite minerals. The effective Si, Ca, and K 2 O in F90 were 16.19 %, 20.45 % and 5.31 %, respectively, which met the primary standard of fertilizer. The pot experiment showed that DACFA effectively improved soil quality and immobilized soil heavy metals, thereby accelerating the growth of pakchoi. Through this technology, the high-value transformation from CFA to alumina and soil amendments is expected to facilitate large-scale utilization of CFA and enhance agricultural productivity.
Man Zhang,Rubo Tian,Siyang Tang,Kejing Wu,Binshen Wang,Yingying Liu,Yingming Zhu,Houfang Lu,Bin Liang
Bamboo pulp and papermaking produce a lot of bamboo powder waste, and its resource utilization is of great significance for biomass refining and environmental protection. Here, we propose an integrated approach involving mechanical activation, hydrothermal extraction, and deep eutectic solvents (DESs) multiple delignification for the efficient separation of bamboo powder. Among seven carboxylic acids based DESs, choline chloride (ChCl)-lactic acid (La) DES (1:1) is the most effective, with over 78.0% lignin removal and 88.9% cellulose retained after mechanical-hydrothermal (180 °C, 5 h)-DES (110 °C, 12 h) treatment. Notably, 84.7% of delignification is achieved after three times of ChCl-La DES treatment at 70, 90, and 110 °C respectively. The delignification rate is negatively correlated with the amount of carboxyl group in the DESs. The lower the p K a value, the higher the delignification rate. Additionally, the selectivity for lignin is improved with decreasing solvent polarity. DES treatment effectively degrades the guaiacyl unit lignin fractions and disrupts several β-aryl-ether bonds (e.g., β-O-4, β-β, and β-5). Furthermore, DESs exhibit good recyclability, with less than 10% reduction in delignification after three cycles. Theory calculations confirm that ChCl-carboxylic acid DESs could compete with lignin to break hydrogen bonds in lignocellulosic biomass by providing their chloride, hydroxyl, and carboxyl groups. Overall, this study demonstrates the practical significance of multistage treatment for the effective fractionation of biomass into its three components.
Lin Yingnan,Wang Chan,Yu Guofeng,Wang Haoya,Liang Rongning,Kong Fanyu,Song Dean
Utilizing renewable and green biomass to supply energy and chemicals has emerged as a fascinating research field due to its great potential to solve the problems of fossil resource shortage and ecological deterioration throughout the world. However, to date it has been an open challenge to achieve efficient biomass utilization for ultimately replacing the petrochemical industry. We report here a general and efficient strategy for complete utilization of biomass. Such strategy is accomplished by combination of hydrothermal extraction based on microwave heating and natural seawater extraction and further pyrolysis of residual solid. Bifunctional natural seawater not only functions as a solvent for carbohydrate conversion but also provides chloride element for promotion of pyrolysis of lignin in residual solid into high-value-added petrochemicals. Such strategy can achieve full biomass utilization with extremely high carbohydrate conversion efficiency of 91.5% and preferred production of aromatics such as 37.5% benzenes and 36.4% phenols in all identified pyrolytic compounds. This may pay the way for replacing fossil resources with biomass.
危险品化学品经营许可证（带存储）