As the environment preservation gradually becomes a matter of major social concern and more strict legislation is being imposed on effluent discharge, more effective processes are required to deal with non-readily biodegradable and toxic pollutants. Synthetic organic dyes in industrial effluents cannot be destroyed in conventional wastewater treatment and consequently, an urgent challenge is the development of new environmentally benign technologies able to mineralize completely these non-biodegradable compounds. This review aims to increase the knowledge on the electrochemical methods used at lab and pilot plant scale to decontaminate synthetic and real effluents containing dyes, considering the period from 2009 to 2013, as an update of our previous review up to 2008. Fundamentals and main applications of electrochemical advanced oxidation processes and the other electrochemical approaches are described. Typical methods such as electrocoagulation, electrochemical reduction, electrochemical oxidation and indirect electro-oxidation with active chlorine species are discussed. Recent advances on electrocatalysis related to the nature of anode material to generate strong heterogeneous OH as mediated oxidant of dyes in electrochemical oxidation are extensively examined. The fast destruction of dyestuffs mediated with electrogenerated active chlorine is analyzed. Electro-Fenton and photo-assisted electrochemical methods like photoelectrocatalysis and photoelectro-Fenton, which destroy dyes by heterogeneous OH and/or homogeneous OH produced in the solution bulk, are described. Current advantages of the exposition of effluents to sunlight in the emerging photo-assisted procedures of solar photoelectrocatalysis and solar photoelectro-Fenton are detailed. The characteristics of novel combined methods involving photocatalysis, adsorption, nanofiltration, microwaves and ultrasounds among others and the use of microbial fuel cells are finally discussed.

Decontamination of wastewaters containing synthetic organic dyes by electrochemical methods. An updated review

2.2. Fenton’s Chemistry 6575 2.2.1. Origins 6575 2.2.2. Fenton Process 6575 2.3. Photo-Fenton Process 6577 3. H2O2 Electrogeneration for Water Treatment 6577 3.1. Fundamentals 6578 3.2. Cathode Materials 6579 3.3. Divided Cells 6580 3.4. Undivided Cells 6583 4. Electro-Fenton (EF) Process 6585 4.1. Origins 6585 4.2. Fundamentals of EF for Water Remediation 6586 4.2.1. Cell Configuration 6586 4.2.2. Cathodic Fe2+ Regeneration 6586 4.2.3. Anodic Generation of Heterogeneous Hydroxyl Radical 6587

Electro-Fenton process and related electrochemical technologies based on Fenton's reaction chemistry

Adsorption of methylene blue on low-cost adsorbents: A review

The science of the total environment

Fouling in membrane bioreactors used in wastewater treatment

Using graphene oxide to enhance the activity of anammox bacteria for nitrogen removal.

Removal of aqueous Hg(II) and Cr(VI) using phytic acid doped polyaniline/cellulose acetate composite membrane.

Fouling reductions in a membrane bioreactor using an intermittent electric field and cathodic membrane modified by vapor phase polymerized pyrrole

Fe doped ZnIn 2 S 4 catalyst was prepared and tested for photocatalytic degradation of 2,4,6-tribromophenol (2,4,6-TBP), it was more efficient in debromination and total organic carbon (TOC) removal, compared with TiO 2 (P25) and ZnIn 2 S 4 . The preparation of Fe-ZnIn 2 S 4 involved a facile hydrothermal ZnIn 2 S 4 synthesis process at low temperature and without templates, followed by chemical reductive deposition of Fe. The catalysts were characterized using scanning electron microscopy (SEM) equipped with an X-ray energy dispersive spectroscopy (EDS), TEM and HRTEM, FT-IR spectra, X-ray diffraction (XRD) and UV–vis diffuse reflectance spectra. The band gaps of ZnIn 2 S 4 and Fe-ZnIn 2 S 4 calculated from the onset of the absorption edges were 2.12 eV and 2.05 eV, respectively. The calculated pseudo-first-order constants ( K r ) were in the order of TiO 2 (0.022 min −1 )  2 (0.0369 min −1 )  2 S 4 (0.362 min −1 )  2 S 4 (0.436 min −1 ). After 1 h reaction by Fe-ZnIn 2 S 4 , the released bromide concentration was 17.6mg l −1 , which was 1.11 and 2.69 times higher than ZnIn 2 S 4 and TiO 2 (P25), respectively. The increase in TOC removal was 7% and 33% compared to ZnIn 2 S 4 and TiO 2 (P25), respectively. The repeated tests proved that the synthesized Fe-ZnIn 2 S 4 was stable, reusable and durable in degradation of 2,4,6-TBP. The possible cycle of iron species and a tentative debromination pathway were proposed.

Fenglin Yang

Papers

Using graphene oxide to enhance the activity of anammox bacteria for nitrogen removal.

Removal of aqueous Hg(II) and Cr(VI) using phytic acid doped polyaniline/cellulose acetate composite membrane.

Fouling reductions in a membrane bioreactor using an intermittent electric field and cathodic membrane modified by vapor phase polymerized pyrrole

Photocatalytic degradation of 2,4,6-tribromophenol over Fe-doped ZnIn2S4: Stable activity and enhanced debromination

Integration of bio-electrochemical cell in membrane bioreactor for membrane cathode fouling reduction through electricity generation