Article ID Journal Published Year Pages File Type
640751 Separation and Purification Technology 2015 7 Pages PDF
Abstract

•MFEDI filled with strong-type resins was tested for high purity water production.•The critical current density was 75 A/m2 for this MFEDI system.•Both good purification and effective regeneration were achieved.•The conductivity of effluent was 0.060–0.062 μS/cm only.•Energy consumption and water recovery were 0.35–0.41 kW h/m3 water and 93.1%.

A promising membrane-free electrodeionization (MFEDI) process has been proposed for high purity water (HPW) production in our previous work. However, the employ of a large number of weak-acid resins in MFEDI limits this process for purifying the reverse osmosis (RO) permeate of tap water with a pH value below 6.0. In this work, a MFEDI system filled only with mixed strong-acid and strong-base resins was tested to desalinate the synthetic acidic RO permeate. Results demonstrated that the resins regeneration was achieved mainly by electrically enhancing water dissociation after a high current density was imposed to the resin layer. Both good purification and effective regeneration were achieved. The conductivity of effluent was 0.060–0.062 μS/cm only. The energy consumption fluctuated in the range of 0.35–0.41 kW h/m3 water and the water recovery reached 93.1%. The mixed concentrate collected during regeneration, with an average conductivity of 145 μS/cm and a pH value of 6.5, could be returned to a pretreatment unit for recovery. No chemical was needed and no wastewater was produced. Repetitive experimental results showed the MFEDI system could work stably.

Related Topics
Physical Sciences and Engineering Chemical Engineering Filtration and Separation
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