RSC Advances
·
2019
·Vol. 9
·期 46
·26676-26684
·
IF 3.049
Qinghao Wu,Dawei Liang,Xiumei Ma,Shanfu Lu,Yan Xiang
Capacitive deionization (CDI) is a novel low-energy green desalination technology that has attracted much attention in recent years, especially for the desalination of low salinity water. One of the key issues in CDI is the electrode materials, and many efforts have been devoted to developing materials with high specific surface areas, appropriate pore distributions, and good electronic conductivity, in order to obtain a high salt adsorption capacity. In this study, chitosan was selected as a precursor for the preparation of high-performance chitosan-based activated carbon (CTS-AC) for use in CDI electrodes via pyrolysis and KOH activation. The results show that CTS-AC800 (activated at 800 °C) has the largest BET specific surface area (2727 m2 g−1), and exhibits an appropriate pore size distribution (<10 nm), nitrogen doping (2.0%) and good electronic conductivity (2.09 S cm−1). The CDI performance results show that the CTS-AC800 electrode has a saturated salt adsorption capacity of 14.12 mg g−1 in a 500 mg L−1 NaCl solution and retains 95% capacity after 150 adsorption–desorption cycles. Thus, chitosan is a promising, sustainable precursor for CDI electrode materials.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED ENERGY
·
2022
·
IF 11.446
Rukuan Chai,Yuetian Liu,Liang Xue,Zhenhua Rui,Ruicheng Zhao,Jingru Wang
Water reinjection was widely implemented in the geothermal development for not only disposing tailwater but also maintaining reservoir pressure. Accompanying this was the formation damage, especially in the injection of decreased salinity water which was synthesized by adding surface water and condensed water into produced water for inhibiting the process equipment corrosion, treating the cooling tower condensate, and etc. Fine migration is the prevailing mechanism; however, it is insufficient in some scenarios. Multiple experiments were conducted to investigate the characteristics and mechanisms of formation damage of sandstone geothermal reservoirs during the decreased salinity water injection. First, coreflooding (CF), nuclear magnetic resonance (NMR), and contact angle (CA) experiments were conducted to analyze the characteristics of the formation damage. Subsequently, scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), and nanoindentation experiments were implemented to study the corresponding mechanisms. Finally, the damage mode of sandstone geothermal reservoirs in decreased salinity water injection was proposed. The CF, NMR, and CA experimental results indicated that the decreased salinity water injection resulted in severe formation damage, as manifested by the reduction of permeability, shrinkage of the pore-throat, and enhancement of the water-wettability of core samples. That is, formation damage not only indicates that the fluid is more difficult to be injected but also that it is more difficult for the injected fluid to flow. As the salinity decreases, these trends gradually enhance. The SEM results illustrated that fine migration is noticeable in decreased salinity water injection, meanwhile mineral dissolution which causes secondary pores and microfracture is also apparent. Both reactions are enhanced as the salinity decreases. The same conclusion was validated by the XRD and ICP-OES results, as manifested by the decrease in the concentrations of clay, K-feldspar, and plagioclase, and the increase in quartz, as well as the emergence of Si 4+ , Mg 2+ , Ca 2+ , and K + in the effluents produced during the decreased salinity water injection. The nanoindentation results explicated that mineral dissolution weakened the mechanical strength of the minerals, which might effectively facilitate compaction. The elastic modulus and hardness of the quartz, K-feldspar, and plagioclase decreased from 107.5&93.7&72.3GPa and 13.7&10.1&7.4GPa of the original sandstone to 108.1&86.0&69.5GPa and 13.6&10.3&6.4GPa of the deionized water flushed one, respectively. In conclusion, formation damage was synergistically dominated by the external cause of compaction and the internal causes of fine migration and mineral dissolution. These factors compressed the pore-throat, decreased the connectivity of the porous media, enhanced the water-wettability of the sandstone surface, and consequently impeded water flow.
研究领域:
地质学
·
石油工程
·
地热能开发
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）