Mild desalination demo pilot: New normalization approach to effectively evaluate electrodialysis reversal technology

AbstractKey performance indicators for characterization of nanofiltration performance are well developed, similar key performance indicators for electrodialysis reversal are however underdeveloped. Under the E4Water project Dow Benelux BV and Evides Industriewater BV operate a pilot facility to compare both technologies for their application to mildly desalinate a variety of brackish water streams. Normalized pressure drop, normalized current efficiency and normalized membrane resistance proved to be a useful tool to interpret process performance and to initiate a cleaning procedure if required. The availability of these normalized key performance indicators enables optimization and process monitoring and control of electrodialysis reversal independent of the continuously changing conditions of the feed water

Decolorization and Mineralization of Reactive Dyes, by the H 2 O 2 /UV Process With Electrochemically Produced H 2 O 2

Abstract Decolorization of Reactive Red 238, Reactive Orange 16, Reactive Black 5 and Reactive Blue 4 was studied in the UV/H 2 O 2 process with H 2 O 2 being produced electrochemically. The experimental results show that decolorization increased considerably when switching on the electrochemical production of H 2 O 2 . Complete decolorization (>99%) was achieved for all dyes under the applied experimental conditions, partial mineralization (49-85%) was obtained, which depends on the type of dye. Reactive Red 238 was used to investigate operational parameters and it was found that decolorization was influenced by the applied electrical current of the electrochemical cell and flow rate. Decolorization and mineralization of Reactive Red 238 can be described by pseudo-first order kinetics. It was found that the initial concentration of Reactive Red 238 has a negative influence on the pseudo-first order reaction constant

Method for preparing maleic acid

The present invention pertains to a method for the preparation of maleic acid from 5-hydroxy-2(5H)-furanone or a tautomer thereof, said method comprising the step of subjecting 5-hydroxy-2(5H)-furanone or a tautomer thereof to an oxidation reaction selected from the group consisting of enzymatic oxidation, and electrochemical oxidation; wherein said oxidation reaction is carried out at a pH of at least 2, preferably at a pH of at least 3

Decolorization and mineralization of reactive dyes, by the H2O2H_2O_2/UV process with electrochemically produced H2O2H_2O_2

Decolorization of Reactive Red 238, Reactive Orange 16, Reactive Black 5 and Reactive Blue 4 was studied in the UV/$H_2O_2$ process with $H_2O_2$ being produced electrochemically. The experimental results show that decolorization increased considerably when switching on the electrochemical production of $H_2O_2$. Complete decolorization (>99%) was achieved for all dyes under the applied experimental conditions, partial mineralization (49-85%) was obtained, which depends on the type of dye. Reactive Red 238 was used to investigate operational parameters and it was found that decolorization was influenced by the applied electrical current of the electrochemical cell and flow rate. Decolorization and mineralization of Reactive Red 238 can be described by pseudo-first order kinetics. It was found that the initial concentration of Reactive Red 238 has a negative influence on the pseudo-firstorder reaction constant.Z uporabo UV/$H_2O_2$ postopka, kjer smo $H_2O_2$ proizvedli elektrokemijsko, smo preučevali razbarvanje reaktivnih barvil Reactive Red 238, Reactive Orange 16, Reactive Black 5 in Reactive Blue 4. Iz eksperimentalnih rezultatov je razvidno, da se razbarvanje znatno poveča, ko vključimo elektrokemijsko proizvodnjo $H_2O_2$. Popolno razbarvanje vseh barvil (>99 %) smo dosegli pod uporabljenimi eksperimentalnimi pogoji, delna razgradnja (49-85 %) pa je bila odvisna od vrste barvila. Za ugotavljanje delovnih parametrov smo uporabili reaktivno barvilo Reactive Red 238. Na razbarvanje vplivajo: uporabljen električni tok ter hitrost pretoka. Razbarvanje in razgradnjo reaktivnega barvila Reactive Red 238 lahko opišemo z reakcijo psevdo-prvega reda, kjer ima začetna koncentracija barvila negativen vpliv na konstanto reakcije

Selective Production of Maleic Acid from Furfural via a Cascade Approach Combining Photochemistry and Electro- or Biochemistry

Starting from furfural, maleic acid is efficiently synthesized in two steps under very mild conditions. In the first step, 5-hydroxy-2(5H)-furanone is synthesized via photochemical oxidation and proposed as a stable intermediate. Subsequent oxidation in the second step, by either an electrochemical or enzymatic process, results in maleic acid in high yield and selectivity

Biomass Processing via Electrochemical Means

Traditional chemical transformations such as thermochemical and chemocatalytic conversions, fermentation, gasification, and pyrolysis are used for biomass processing. Alternative sustainable and green technologies such as electrochemical, photo-electrochemical, and bio-electrochemical conversions are currently being developed by the scientific community. Electrolysis offers many advantages for conversion of bio-based chemicals over alternative conversion routes.The development of economically feasible methods for producing industrially relevant chemicals with high purity and selectivity from sugars is gaining considerable attention in recent years. The electrochemical reduction of levulinic acid to valeric acid proceeds at low pH and high overpotential, whereas at low pH and low overpotential, γ- valerolactone is the main product. The electrochemical conversion of glycerol is primarily investigated for energy storage purposes, with foreseen applications in fuel cells, and for the production of hydrogen or formic acid. An integrated electrochemical process for lignin depolymerization with in situ downstream processing is often applied in order to prevent overoxidation

Electro-oxidative depolymerisation of soda and acid lignins catalysed by Ni/NiOOH electrode

The electrochemical depolymerization of lignin, especially if powered by renewable electricity, is a promising technology compared to conventional chemical oxidation because it can operate under mild, safe and eco-friendly reaction conditions, such as room temperature and atmospheric pressure. Among electrochemical approaches, the electro-oxidation of lignin at the anode is the most common one studied. During the electrochemical oxidation of lignin, the surface functionalisation (α-carbonylation) and the cleavage of C–C/C–O bonds are the two main competing reactions. This study aimed to define the operating conditions for the electro-oxidative depolymerisation of soda and acid lignins into valuable monomeric compounds. The performance of nickel oxide hydroxide (Ni/NiOOH) electrode was investigated by cyclic voltammetry (CV) adopting different reactions conditions. Moreover, in order to validate the catalytic performance of the selected electrode, the cyclic voltammetry study was also performed on guaiacol, considered as a model compound of a prominent lignin structural unit. The optimal reaction conditions among those tested were then adopted in the electrolysis of soda P1000 lignin into added-value aromatic compounds. pH 14, 20 g/L lignin and 0.4 V resulted the best reaction conditions among those tested for soda and acid lignins in the CV. Adopting these parameters, the main products of the constant potential electrolysis of soda lignin were sinapic acid, acetovanillone, vanillin and vanillic acid. Both the overall oxidation degree and monomers yield was 1%. The present research aids to future research involving elucidation of solutions aiming to avoid the electrode passivation and to increase the lignin oxidation in order to raise the aromatics yield

Electro-oxidative depolymerisation of technical lignin in water using platinum, nickel oxide hydroxide and graphite electrodes

In order to improve the lignin exploitation to added-value bioproducts, a mild chemical conversion route based on electrochemistry was investigated. For the first time, soda lignin Protobind™ 1000 (technical lignin from the pulp & paper industry) was studied by cyclic voltammetry to preliminarily investigate the effect of the main reaction parameters, such as the type of electrode material (platinum, nickel oxide hydroxide, graphite), the pH (12, 13, 14), the scan rate (10, 50, 100, 250 mV s-1), the substrate concentration (2, 20 g L-1) and the oxidation/reduction potential (from -0.8 to +0.8 V). Under the optimal reaction conditions among those tested (NiOOH electrode, pH 14, lignin 20 g L-1, 0.4 V), the electro-oxidative depolymerisation of lignin by electrolysis was performed in a divided cell. The reaction products were identified and quantified by ultra-pressure liquid chromatography coupled with mass spectrometry. The main products were sinapic acid, vanillin, vanillic acid, and acetovanillone. The obtained preliminary results demonstrated the potential feasibility of this innovative electrochemical route for lignin valorisation for the production of bio-aromatic chemicals. This journal i

Transport mechanisms in electrodialysis : The effect on selective ion transport in multi-ionic solutions

Water reuse is one of the possible solutions to prevent depletion of freshwater resources; however, it is often limited by the accumulation of specific ions in the recirculating water. Ion selective desalination technologies can increase the potential for water reuse. Electrodialysis is a water treatment technology that is able to selectively remove ions from water. In order to enhance and further develop the selectivity of the process, a fundamental understanding of the various mechanisms governing multi-ion transport in electrodialysis is essential. In the present study, a theoretical model for multi-ionic (Na+ and K+) mass transport in electrodialysis was developed including ion-water and ion-membrane frictions, and water transport. General properties and the selectivity of ion exchange membranes towards K+ over Na+ ions were experimentally determined and included in the model. The theory was successfully validated for ion flux through the membranes, ion concentrations in the solutions, and water transport by comparing theory with batch-mode electrodialysis experiments. Contributions of different ion transport mechanisms to the selective transport of Na+ and K+ ions were evaluated by model calculations. It was found that electromigration has the largest contribution to ion transport followed by convection, and that diffusion controls the selectivity of ion transport in electrodialysis under constant voltage operation