Jiatian Zhu,Yuqi Bao,Luxiong Lv,Fanyan Zeng,Dasong Du,Chen Liang,Jiayan Ge,Shuangfei Wang,Shuangquan Yao
The preparation of bio-oil through biomass pyrolysis is promoted by different demineralization processes to remove alkali and alkaline earth metal elements (AAEMs). In this study, the hydrothermal pretreatment demineralization was optimized by the response surface method. The pretreatment temperature, time and pH were the response elements, and the total dissolution rates of potassium, calcium and magnesium were the response values. The interactions of response factors for AAEMs removal were analyzed. The interaction between temperature and time was significant. The optimal AAEMs removal process was obtained with a reaction temperature of 172.98 °C, time of 59.77 min, and pH of 3.01. The optimal dissolution rate of AAEMs was 47.59%. The thermal stability of eucalyptus with and without pretreatment was analyzed by TGA. The hydrothermal pretreatment samples exhibit higher thermostability. The composition and distribution of pyrolysis products of different samples were analyzed by Py-GC/MS. The results showed that the content of sugars and high-quality bio-oil (C6, C7, C8 and C9) were 60.74% and 80.99%, respectively, by hydrothermal pretreatment. These results show that the removal of AAEMs through hydrothermal pretreatment not only improves the yield of bio-oil, but also improves the quality of bio-oil and promotes an upgrade in the quality of bio-oil.Keywords:eucalyptus;demineralization;hydrothermal pretreatment;thermostability;pyrolysis products
Jing Ru,Xiaochen Xu,Yuxuan Cheng,Nan Luo,Shuo Tan,Xi Chen,Feng Chen,Bing-Qiang Lu
Dental minerals are in an equilibrium state of demineralization and remineralization, which can be disrupted by pathogenic bacteria to cause dental caries. While the inorganic polymer polyphosphate (polyP) is ubiquitous in living organisms and is also widely involved in mineralization regulations, its specific influence on the mineralization balance of teeth remains unclear. As a concept-and-proof study, the effects of polyP on the demineralization and remineralization of teeth are investigated on dental enamel (the highly mineralized outer covering tissue of teeth) from the perspective of mineralization balance. We found that a high concentration (containing 1.0–20 mM P element, comparable to and higher than the free phosphate ions in body fluids) of polyP has the capability to demineralize enamel in the aqueous solution, yet this effect is absent in the simulated biological environments including simulated body fluid and MEM (α-minimum essential medium) solutions. More importantly, polyP with a very low concentration (containing ≥5.0 μM P) is able to inhibit enamel mineralization significantly. This suggests that polyP could impact the mineralization balance of enamel by preferentially inhibiting the remineralization process, thereby disrupting the equilibrium necessary for maintaining enamel health.
Jiayan Ge,Yuting Wu,Yushan Han,Chengrong Qin,Shuangxi Nie,Shijie Liu,Shuangfei Wang,Shuangquan Yao
Effective removal of alkali and alkaline earth metals (AAEM) is of great significance for promoting biomass pyrolysis. In this study, demineralization via hydrothermal pretreatment was performed, and the effect on the pyrolysis behavior was evaluated by thermogravimetric analysis (TGA) and thermal pyrolysis–gas chromatography-mass spectrometry (Py–GC/MS). The effects of reaction temperature, time, and pH on the dissolution rate of K + , Ca 2+ , and Mg 2+ were investigated. The optimal total dissolution rate of the metal elements was 42.10%. Compared with acid leaching, hydrothermal pretreatment allowed a higher crystallinity index. It significantly changed the pyrolysis behavior. The relative content of sugar in pyrolysis products was as high as 58%. The chemical compound distribution was concentrated in the range between C6 and C9, which was conducive for the refinement of gasoline by upgrading. This means that hydrothermal pretreatment has efficient demineralization, which promoted the thermal degradation behavior of biomass.
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