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The electrode material with high electrosorption capacity and fast electrosorption rate is highly desired in capacitive deionization (CDI) process. To meet this demand, the nitrogen-doped cluster-like porous carbons (NCPCs) with hierarchical hollow nanoarchitecture were rationally prepared by carbonizing the polydopamine/nano-ZnO composite and employed as CDI electrodes. The resultant NCPCs possess an interconnected hierarchical structure with a hollow cavity, nitrogen-doping property, high specific surface, large pore volume and good wettability. All these merits can ensure a huge accessible electrosorption interface for the very quick diffusion of ions so that achieve an excellent CDI performance. Particularly, the sample carbonized at 900 °C (NCPC-900) with the optimal porous structure and chemistry composition exhibits the highest electrosorption capacity of 11.98 mg g− 1 in 100 mg L− 1 NaCl solution. Besides, the NCPC-900 electrode shows a good cycle stability over 20 electrosorption-desorption cycles. These results render that the NCPCs have the great potential as the electrode material for high performance CDI desalination.

To enhance the structure stability of conventional capacitive deionization (CDI) electrode, this work intends to provide a facile preparation of Titania nanotubes (TiO2-NTs) based electrode with carbon imbedded for capacitive deionization application. The TiO2-NTs array is obtained through anode oxidation method on the titanium substrate, then carbon precursors were induced into the nanochannels of TiO2-NTs carrier by the vacuum pressure and transferred to carbon capacitor through anaerobic pyrolysis process. Such structure possesses a unique combination with hollow carbon fibers as layer binders to fix the upper carbon spheres onto TiO2-NTs substrate. The as-prepared electrode revealed an excellent mechanical stability, electrosorption ability and electroconductibility as well as a favorable hydrophilicity especially after acid modification. This paper also investigates the influence of various operational parameters on the capacitive deionization process, including feed temperatures, flow rates and initial salt concentrations. The electrosorption kinetics is also analyzed within the deionization process, which shows the novel electrode presents a better sorption rate as well as a higher sorption capacity of 13.11 ± 0.58 mg/g at 1.2 V and 500 mg/L feed concentration. Furthermore, the removal principles of CDI electrode under multi-ion circumstance are compared and discussed depending on existing studies.

In this work, a novel tannic acid assisted interfacial polymerization (TAIP) method was developed for preparing loose nanofiltration membranes (LNMs). Piperazine (PIP) and tannic acid (TA), two kinds of common monomer for interfacial polymerization (IP), were employed to deposit on substrate for the TAIP process. The TAIP process resulted in enlarged pores in the skin layer due to the longer monomers, thus achieved considerable permselectivity in separating salts from dye/salt mixture solution. The optimal TAIP membrane (M4) exhibited high permeability (32.57 LMH·bar−1 to Congo Red solution), reasonable rejection to dyes (99.40% and 99.19% for Congo Red and Rose Bengal, respectively) and satisfactory transport to salts (90.59% to Na2SO4 and 97.75% to NaCl). Meanwhile, this membrane retained high performance in dye/salt separation (7.16 LMH·bar−1 of permeability, 97.47% of CR rejection and 2.55% of NaCl retention) under even as high as 6 wt% of salt concentration. Moreover, TAIP LNM showed high stability throughout a 30-hour-long running test to separate salts from dye/salt mixture solution. We anticipated the TAIP methodology, together with the consequential LNM, to provide a potential candidate for dye/salt separation application.

Desalination performance of hybrid capacitive deionization (HCDI) intensively depends on the electrode materials with redox activity and capacitance ability. Herein, Ag-doped hollow ZIFs-derived nanoporous carbon (Ag/ZCs) was employed as an anode material by the pyrolysis of Ag-doped hollow ZIFs precursor, which was fabricated by in situ tannic acid (TA) etching/reduction strategy. Provably, TA serves as not only an etchant for tailoring ZIFs structure, but also a reductant for Ag nanoparticles formation. The obtained Ag/ZCs possesses unique hollow cavities and high redox activity. As expected, the HCDI system with Ag/ZCs electrode exhibits excellent deionization capacity of 29.18 mg g−1 in 500 mg L−1 NaCl solution at 1.2 V, which is much higher than that of conventional carbon-based CDI system. Moreover, desirable regeneration stability of the Ag/ZCs HCDI was well maintained after 20 cycle experiments. The results demonstrate that Ag/ZCs is a potential anode material for HCDI applications.

Natural organic matter (NOM) and scaling metal ions (e.g. Ca2 +) were confirmed important foulants in drinking water treatment especially in membrane filtration process. An electro-microfiltration (EMF) filtering module was constructed to separate humic substances (HSs) and calcium sulfate from tailwater by applying an electric field across the membrane. The operational parameters such as transmembrane pressure (TMP), cross-flow velocity, electric field intensity and their interactions on the EMF performance were studied thoroughly. A corresponding anti-fouling mechanism was proposed in the EMF process. Both NOM and metal ion removal rates increased to as high as 97.56% and 72.5% by EMF, respectively, compared to 50.74% and 0 in the blank control without electric field. A higher capacity of flux maintenance (increased by 2.86 times) and a better contamination resistance were gained at external voltage of 100 V. The ions' mass transfer was significantly affected by both electrostatic and TMP forces. Chelation bonds between HS and calcium ions were demonstrated broken under the electrostatic force, which prevented the membrane fouling to a certain degree. Final EMF permeate of tailwater revealed a low level of Ca2 + content of 4.893 mg/L, HS content of 0.037 (UV254) and conductivity of 46 μm/cm with a near natural pH of 7.56.

In current or next-generation reuse systems, the development of new classes of antifouling membranes is needed before viable membrane-based approaches for wastewater reclamation can be achieved. In this study, ZrO 2 /PES hybrid ultrafiltration membranes with uniform ZrO 2 nanoparticles were prepared by combining an ion-exchange process with a traditional immersion precipitation process. Hydrous ZrO 2 sol was synthesized by addition of anion-exchange resin in N , N -dimethylformamide solvent containing zirconyl chloride. Homogeneous ZrO 2 /PES casting solution was then obtained by dissolving PES polymer in the ZrO 2 sol. The existence and dispersion states of ZrO 2 nanoparticles in the resultant membrane matrix were examined by X-ray photoelectron spectrometer, thermogravimetric analysis, scanning electron microscope and transmission electron microscope. The results indicate that the ZrO 2 nanoparticles were well dispersed throughout the PES matrix and the diameter of the formed nanoparticles was about 5–10 nm. The hydrophilicity of the membranes was determined by measuring the contact angles. The antifouling property was determined by antifouling experiments and atomic force microscopy. The results confirm that the existence of ZrO 2 nanoparticles improves the hydrophilicity and reduces protein adsorption of membranes.

Membrane fouling remains one of the most problematic issues surrounding membrane use in water and wastewater treatment. Organic fouling and biological fouling contribute to irreversible fouling and flux decline in these processes. In this study, to obtain both organic antifouling and antibacterial properties, in situ formed Ag nanoparticles were immobilized in poly (vinylidene fluoride) (PVDF) ultrafiltration (UF) membranes, using N , N -dimethylformamide (DMF) as the reducing agent for Ag + and solvent for PVDF polymer simultaneously. The hydrophilicity of the membrane surface was improved by the integration of Ag nanoparticles, leading to a reduction in membrane contact angle (81 to 68°) and an increase in permeate flux (36.4 to 108.6 L/m 2 h). The organic antifouling and antibacterial performance of the Ag-loading membranes were evaluated by using bovine serum albumin (BSA) aqueous solution and Escherichia coli ( E. coli ) as model foulants, respectively. The experimental results confirm that the immobilization of Ag nanoparticles in PVDF UF membrane can mitigate the organic and biological fouling.

This study investigated the electrochemical degradation of isothiazolin-ones in aqueous solution on a Ti/SnO2–Sb/PbO2 electrode. 1-Nitro-2-crylic-acetone, acetic acid and formic acid were the main degradation intermediates identified by tandem mass spectrometry (MS/MS) and the pathway for electrochemical degradation of isothiazolin-ones was proposed. Kinetic analyses indicated that electrochemical degradation of isothiazolin-ones was a pseudo-first-order reaction. The influences of operating parameters, such as electrolysis time, initial concentration of isothiazolin-ones, current density, initial pH and electrolyte flow rate on electrochemical degradation of isothiazolin-ones were investigated. Electrochemical degradation of isothiazolin-ones as well as CODcr (chemical oxygen demand determined by potassium dichromate) was controlled by mass transport.