• Title/Summary/Keyword: capacitive deionization (CDI)

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Effect of surface modification of carbon felts on capacitive deionization for desalination

  • Lee, Jong-Ho;Ahn, Hong-Joo;Cho, Donghwan;Youn, Jeong-Il;Kim, Young-Jig;Oh, Han-Jun
    • Carbon letters
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    • v.16 no.2
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    • pp.93-100
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    • 2015
  • Surface modified carbon felts were utilized as an electrode for the removal of inorganic ions from seawater. The surfaces of the carbon felts were chemically modified by alkaline and acidic solutions, respectively. The potassium hydroxide (KOH) modified carbon felt exhibited high Brunauer-Emmett-Teller (BET) surface areas and large pore volume, and oxygen-containing functional groups were increased during KOH chemical modification. However, the BET surface area significantly decreased by nitric acid ($HNO_3$) chemical modification due to severe chemical dissolution of the pore structure. The capability of electrosorption by an electrical double-layer and the efficiency of capacitive deionization (CDI) thus showed the greatest enhancement by chemical KOH modification due to the appropriate increase of carboxyl and hydroxyl functional groups and the enlargement of the specific surface area.

Effects of N & P Treatment Based on Liquid Organic Materials for Capacitive Deionization(CDI) (축전식 탈염 공정의 액상 유기물에 따른 질소(N) 및 인(P) 처리 특성)

  • Lee, Bo-Ram;Jeong, In-Jo;Park, Soo-Gil
    • Journal of the Korean Electrochemical Society
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    • v.16 no.3
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    • pp.123-128
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    • 2013
  • Organic carbons such as methanol, ethanol, iso-propanol, methoxy ethanol, glucose are added(1, 2, 3%) in the 2000 ppm $NH_3$ and $H_3PO_4$. As vol.%. cyclic voltammetry measurement of the capacity with the addition of organic carbon, the results of $NH_3$ + 3 vol.% Methanol Addition, $H_3PO_4$ + 2 vol.% iso-propanol addition of the increase in capacity was observed. Applying to the CDI Module cell with an addiction of organic carbon is confirm that remove $NH_4$-N and $PO_4$-P in sewage. Namely, the removal efficiency of $NH_3$ was increase of 16.4% during adsorption, 30.4% during desorption and the removal efficiency of $H_3PO_4$ was increase of 63% during adsorption, 54.7% during desorption. Therefore, the result of this research is confirm that effect of the N, P removal and considered that reduction of the operating costs without removing the organic matter in the influent wastewater.

A Study on the Cell Structure for Capacitive Deionization System (축전식 탈염 시스템을 위한 셀 구조에 관한 연구)

  • Lee, Ju-Young;Seo, Seok-Jun;Park, Jung-Woo;Moon, Seung-Hyeon
    • Korean Chemical Engineering Research
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    • v.48 no.6
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    • pp.791-794
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    • 2010
  • This study presents channel design of a CDI stack to achieve high removal efficiency in a large scale by applying parallel flow structure with a concentrated stream. The flow pattern in the stack was simulated by COMSOL Multiphysics program. To prove the salt removal performance, a unit cell and 20 cell stacks were tested at a flow rate condition of 18 ml/min and 360 ml/min, respectively. The removal efficiencies of the unit cell and the 20 cell stacks were obtained as 70.8 % and 75.6 %, respectively, with 100 mg/L sodium chloride solution. During the operation of cell test, water pressures of unit cell and 20 cell pair stack maintained in the ranges of 1.1 psi and 1.3~1.5 psi, respectively. It was demonstrated that the parallel cell structure with two concentrated streams can be employed in a large scale CDI for salt removal.

Performance Study of Membrane Capacitive Deionization Process Applied by Perfluoropolymer and Aminated Poly(ether imide) Ion Exchange Membranes (불소화고분자와 아민화된 폴리이서이미드 이온교환막을 적용한 축전식 탈염공정의 성능 연구)

  • Kim, Ji Seon;Jeong, Joo Hwan;Rhim, Ji Won
    • Membrane Journal
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    • v.25 no.1
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    • pp.60-66
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    • 2015
  • To investigate the performance of the composite carbon electrodes which the ion exchange polymers were directly casted onto porous carbon electrode surfaces, the adsorption/desorption experiments were carried out by varying the feed concentration, feed flow rate, and desorption voltages for the NaCl solution. When the feed concentration was 100 mg/L, the increase of the adsorption time led to the increase of the salt removal due to the increase of the residence time inside the cell while the increase of the feed flow rate from 15 mL/min to 23 mL/min gave the decrease of the salt removal efficiency, 12% because of the short residence time. When the feed concentration was 200 mg/L, the salt removal was shown 10~15% low because of the incomplete desorption within the desorption intervals.

Fabrication and Electrochemical Characterization of Ion-selective Composite Carbon Electrode Coated with Sulfonated Poly(Ether Ether Ketone) (Sulfonated Poly(Ether Ether Ketone)을 코팅한 이온선택성 복합탄소전극의 제조 및 전기화학적 특성 분석)

  • Choi, Jae-Hwan;Park, Chan-Mi
    • Applied Chemistry for Engineering
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    • v.24 no.3
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    • pp.247-252
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    • 2013
  • Sulfonated poly(ether ether ketone) (SPEEK) with a certain degree of sulfonation were synthesized by reacting PEEK and sulfuric acid at different reaction time. Then ion-selective composite carbon electrodes (ISCCE) were fabricated by coating the prepared SPEEK on the surface of carbon electrodes. The specific capacitance and resistance of the ISCCE were analyzed by electrical impedance spectroscopy. The ion exchange capacities (IEC) of the SPEEKs were measured in the range of 1.60~2.57 meq/g depending on the sulfonation time. The SPEEK more than 2.5 meq/g of IEC was considered unsuitable for fabricating the ISCCE because it was dissolved in water. The specific capacitance of the prepared ISCCE increased with increasing the IEC of coated SPEEKs and the capacitance was improved up to about 20% compared to that of uncoated carbon electrode. In addition, the electrical resistance of coating layer decreased significantly with increasing the IEC of coated SPEEKs. It is expected that the desalination efficiency of conventional capacitive deionization process can be improved by using the prepared ISCCE coated with SPEEK.

Preparation of Carbon Electrodes Using Activated Carbon Fibers and Their Performance Characterization for Capacitive Deionization Process (활성탄소섬유를 이용한 탄소전극의 제조 및 축전식 탈염공정에서의 성능평가)

  • Park, Cheol Oh;Oh, Ju Seok;Rhim, Ji Won
    • Membrane Journal
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    • v.28 no.4
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    • pp.271-278
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    • 2018
  • In this study, the carbon electrodes using activated carbon fibers (ACFs) were prepared for the capacitive deionization process. The Polyvinylidene fluoride (PVDF) was used as the binder and the mixed ACFs with proper solvent was cast on the commercial graphite sheets to prepare the carbon electrodes. At this moment, the different particle sizes of ACFs were applied and the mixing ratio of solvent, PVDF and ACFs, 80 : 2 : 18 and 80 : 5 : 15, were used for the electrode preparation. Then their salt removal efficiencies were characterized under the various operating conditions, adsorption potential and time, desorption potential and time, concentration of feed NaCl solution and flow rate as well. Typically, the salt removal efficiency of 53.6% were obtained at the particle size below $32{\mu}m$, mixing ratio 80 : 2 : 18, adsorption 1.2 V and 3 min, desorption -0.1V and 1 min, and 15 mL/min flow rate of NaCl 100 mg/L.

Enhancement of Selective Removal of Nitrate Ions from a Mixture of Anions Using a Carbon Electrode Coated with Ion-exchange Resin Powder (이온교환수지 분말이 코팅된 탄소전극을 이용한 음이온 혼합용액에서 Nitrate 이온의 선택적 제거율 향상)

  • Yeo, Jin-Hee;Choi, Jae-Hwan
    • Applied Chemistry for Engineering
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    • v.24 no.1
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    • pp.49-54
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    • 2013
  • We fabricated a composite carbon electrode to remove nitrate ions selectively from a mixed solution of anions. The electrode was fabricated by coating the surface of a carbon electrode with the nitrate-selective anion exchange resin (BHP55, Bonlite Co.) powder. We performed capacitive deionization (CDI) experiments on a mixed solution containing chloride, nitrate, and sulfate ions using a BHP55 cell constructed with the fabricated electrode. The removal of nitrate ions in the BHP55 cell was compared to that of a membrane capacitive deionization (MCDI) cell constructed with ion exchange membranes. The total quantity of ions adsorbed in BHP55 cell was $38.3meq/m^2$, which is 31% greater than that of MCDI cell. In addition, the number of nitrate adsorption in the BHP55 cell was $15.9meq/m^2$ (42% of total adsorption), 2.1 times greater than the adsorption in the MCDI cell. The results showed that the fabricated composite carbon electrode is very effective in the selective removal of nitrate ions from a mixed solution of anions.

Synthesis and Properties of Nonfluoro Aminated Poly(vinylbenzyl chloride-co-ethyl methacrylate-co-styrene) Anion Exchange Membranes for MCDI Process (막 축전식 탈염용 비불소계 아민화 Poly(vinylbenzyl chloride-co-ethyl methacrylate-co-styrene) 음이온교환막의 합성 및 특성)

  • Koo, Jin-Sun;Kwak, Noh-Seok;Hwang, Taek-Sung
    • Polymer(Korea)
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    • v.36 no.5
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    • pp.564-572
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    • 2012
  • A terpolymer of vinylbenzyl chloride-co-ethyl methacrylate-co-styrene (VBC-EMA-St) was prepared for membrane capacitive deionization (MCDI) by radical polymerization and amination reaction of various amination times. Nonfluoro aminated VBC-EMA-St anion-exchange membranes were characterized by Fourier transform infrared (FTIR) spectrometry. Molecular weight, polydispersity and thermal stability were obtained by gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). The basic properties such as water uptake, ion exchange capacity, electrical resistance and CDI charge-discharge current were measured. The optimal values of ion exchange capacity, water uptake, electrical resistance and molecular weight of synthesized anion-exchange membrane were 1.69 meq/g, 23.7%, 1.61 ${\Omega}{\cdot}cm$ and $3.4{\times}10^4$ g/mol, respectively. As compared with conventional membrane, the pattern of cyclic charge-discharge current of synthesized anion-exchange membrane indicated efficient electrosorption and desorption.

Confirmation of The Fouling Phenomena in CDI Process and The Establishment of Its Removal Process Conditions (CDI 전극 내 파울링 현상 확인 및 제거공정 조건의 확립)

  • Kim, Tae Yeong;Rhim, Ji Won
    • Membrane Journal
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    • v.29 no.5
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    • pp.276-283
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    • 2019
  • In this study, The experiments of the confirmation of the fouling phenomena in CDI process and the establishment of its removal process conditions were carried out. The foulant concentrations of humic acid sodium salt (HA) added to the feed solution were 5, 10, 15 mg/L, respectively. The occurrence of fouling under the certain adsorption/desorption conditions could be confirmed with an increase in adsorption and desorption concentration curve over time. Both the voltage and time in adsorption and desorption processes were changed to eliminate the fouled pollutants. Typically, the fouling removal condition was found at the adsorption condition 1.2 V/5 min and the desorption condition -3 V/2 min, respectively.

Bibliometric analysis of twenty-year research trend in desalination technologies during 2000-2020 (계량서지적 분석을 활용한 핵심 담수화 기술의 연구 동향)

  • Lee, Gyeonghun;Kim, Hye-Won;Boo, Chanhee;Beak, Youngbin;Kwak, Rhokyun;Kim, Choonsoo;Jeong, Seongpil
    • Journal of Korean Society of Water and Wastewater
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    • v.35 no.1
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    • pp.39-52
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    • 2021
  • The global water shortage is getting more attention by global climate change. And water demand rapidly increases due to industrialization and population growth. Desalination technology is being expected as an alternative water supply method. Desalination technology requires low energy or maintenance costs, making it a competible next generation technology, with examples such as forward osmosis (FO), membrane distillation (MD), capacitive deionization (CDI), and electrodialysis (ED) to compete with reverse osmosis (RO). In order to identify recent research trends in desalination technologies (FO, MD, RO, CDI, and ED) between 2000-2020, a bibliometric analysis was conducted in the current study. The number of published papers in desalination technology have increased in Desalination and Journal of Membrane Science mainly. Moreover, it was found that FO, MD, RO, CDI, and ED technologies have been applied in various research areas including electrochemical, food processing and carbon-based material synthesis. Recent research topics according to the desalination technologies were also identified.