Application of Capacitive Deionization in Water Treatment and Energy Recovery: A Review

Abstract

Water resources are the basis for human survival and development. However, human beings face severe challenges of water pollution and freshwater shortage. With the critical advantages of low energy consumption, high efficiency, low cost, green and pollution-free, and renewable electrodes, capacitive deionization (CDI) has become an up-and-coming water treatment technology. After decades of development, the application of CDI has expanded from seawater desalination to many fields. However, the existing literature still needs a comprehensive overview of the multi-functional application of CDI technology in water treatment. Therefore, our work critically reviewed the latest research progress of CDI in water treatment to meet the technical requirements of various application fields. This paper first summarizes the various applications of CDI in water treatment, focusing on CDI’s representative research results in heavy metal removal, organic contaminants removal, water softening, phosphate and nitrate removal, and water disinfection. In addition, we also discussed the latest research progress of energy recovery and energy consumption assessment for the CDI process. Finally, this paper discusses the challenges and future opportunities facing CDI technology.

Calcium‐activated geopolymer ceramics: Study of powder calcination and amorphous gel phases

“…EDS‐point analysis is associated with a mixture of crystalline and amorphous phases, which needs to be a reliable indicator of gel composition through certain constraints. Indeed, possibilities for coexisting phases in this region include Ca(OH) 2 , gels, and minerals 36,37 . Therefore, choosing point principle and idealized hypothesis (CPP and IH) are proposed, and the subsequent calculation and analysis are carried out under the above premise.…”

“…Indeed, possibilities for coexisting phases in this region include Ca(OH) 2 , gels, and minerals. 36,37 Therefore, choosing point principle and idealized hypothesis (CPP and IH) are proposed, and the subsequent calculation and analysis are carried out under the above premise.…”

Recycling of granite waste and burnt coal cinder for the preparation of sintered permeable bricks

“…The morphology of permeable bricks after sintering was observed by SEM (JSM‐IT300, JEOL, Japan), operated at 15.0 kV. Microstructure analysis of the samples was conducted by a mineral phase microscope (59XC‐PC, China) 23 . The mineral phases in the raw materials and the prepared permeable bricks were investigated using XRD (D/Max‐IIIA, JEOL, Japan) under the operating conditions of the voltage of 40 kV, current of 30 mA, with Cu Kα radiation, at the 2 θ angle range of 10–70°, and the step size of .02° with .2 s/step scanning rate 24 .…”

“…Microstructure analysis of the samples was conducted by a mineral phase microscope (59XC-PC, China). 23 The mineral phases in the raw materials and the prepared permeable bricks were investigated using XRD (D/Max-IIIA, JEOL, Japan) under the operating conditions of the voltage of 40 kV, current of 30 mA, with Cu Kα radiation, at the 2θ angle range of 10-70 • , and the step size of .02 • with .2 s/step scanning rate. 24 The infrared spectra of all samples in the 400-4000 cm −1 region were recorded using a Fourier transform infrared spectrometer (NEXUS, Thermo Nicolet, USA).…”

Stepwise recycling of valuable metals from spent lithium-ion batteries based on in situ thermal reduction and ultrasonic-assisted water leaching

“…The fine particle size (about 1-10 μm) is beneficial for promoting interfacial reactions during cathode regeneration, which is important for improving battery performance. 51,52 Overall, the ultrasonic-assisted water leaching method was found to be an effective and promising technique for producing high-purity Li 2 CO 3 for battery applications.…”