Amine-substituent induced highly selective and rapid "turn-on" detection of carcinogenic 1,4-dioxane from purely aqueous and vapour phase with novel post-synthetically modified d10-MOFs.

Herein, an amine decorated Cd(II) metal-organic framework (MOF) with a uninodal 6-c topology was synthesized as a suitable platform for facile post-synthetic modification (PSM). The as-synthesized parent d10-MOF (1) with free -NH2 centers, when functionalized with two different carbonyl substituents (1-naphthaldehyde and benzophenone) of varying conjugation, produces two novel luminescent MOFs (LMOFs) viz.PSM-1 and PSM-2. The judicious incorporation of carbonyl substituents into the skeleton of 1 was rationalized via ESI-MS, 1H-NMR, FT-IR and PXRD analyses. Interestingly, both PSM-1 and PSM-2 show 'turn-on' luminescent behaviour in the presence of 1,4-dioxane with the limit of detection (LOD) as 1.079 ppm and 2.487 ppm, respectively, with prompt response time (∼55 s & ∼58 s, respectively). The inhibition of PET is comprehended to be the prime reason for luminescence enhancement upon interaction with the targeted analyte which was further validated from DFT calculations. In continuation, the PSM-MOFs were equally responsive towards 1,4-dioxane in several complex environmental matrices and cosmetic products. Additionally, vapor phase detection of 1,4-dioxane using PSM-MOFs has also been demonstrated as an additional advantage ensuring propagation of future research endeavour.

Concise total synthesis of (+)-Zeylenone with antitumor activity and the structure-activity relationship of its derivatives.

Natural products--polyoxygenated cyclohexenes exhibited potent anti-tumor activity, such as zeylenone, which is a natural product isolated from Uvaria grandiflora Roxb. This article will attempt to establish a gram-scale synthesis method of (+)-zeylenone and explain the structure-activity relationship of this kind of compound. Total synthesis of (+)-zeylenone was completed in 13 steps with quinic acid as the starting material in 9.8% overall yield. The highlight of the route was the control of the three carbon's chirality by single step dihydroxylation. In addition, different kinds of derivatives were designed and synthesized. Cell Counting Kit-8 (CCK8) assay was used for evaluating antitumor activity against three human cancer cell lines. The structure--activity relationship suggested that compounds with both absolute configurations exhibited tumor-suppressive effects. Moreover, hydroxyls at the C-1/C-2 position were crucial to the activity, and the esterification of large groups at C-1 hydroxyl eliminated the activity. Hydroxyl at the C-3 position was also important as proper ester substituent could increase the potency.

Solvent extraction and gas chromatography-mass spectrometric determination of probable carcinogen 1,4-dioxane in cosmetic products.

In the present work, a method based on solvent extraction and gas chromatography-mass spectrometry (GC-MS) has been validated for the determination of 1,4-dioxane in cosmetics. Various solvents including ethyl acetate, hexane, methanol, dichloromethane and acetone have been used for the extraction of 1,4-dioxane, among them the ethyl acetate was found to be the most efficient extracting solvent. This method has offered excellent quality parameters for instance linearity (R2 > 0.9991), limit of detection (LOD, 0.00065-0.00091 µg/mL), limit of quantification (LOQ, 0.00217-0.00304 µg/mL) and, precision intra-day (1.65-2.60%, n = 5) and inter-day (0.16-0.32%, n = 5) in terms of relative standard deviation (RSD%). A total of thirty-nine cosmetic samples of different brands and origin have been studied. Among them, the 1,4-dioxane was found in twenty-three samples (FB1-FB7, MC1-MC4, MC6-MC8, HS3, HS5, BL1-BL3, BL5 and PLD1-PLD3) at the levels between 0.15 µg/mL and 9.92 µg/mL, whereas in sixteen samples (MC5, HS1, HS2, SG1-SG5, BL4 and HP1- HP6) was found to be not detected. The recovery values were achieved between 93% and 99% in both low and high level of spiked samples. In comparison to the traditional analytical techniques, the proposed method was found to be very sensitive and cost-effective for the routine analysis of 1,4-dioxane at low concentration in cosmetics.

Resorcinarene Cavitand Polymers for the Remediation of Halomethanes and 1,4-Dioxane.

Disinfection byproducts such as trihalomethanes are commonly found in drinking water. Trihalomethanes are formed upon chlorination of natural organic matter found in many drinking water sources. Inspired by molecular CHCl3⊂cavitand host-guest complexes, we designed porous polymers composed of resorcinarene receptors. These materials show higher affinity for halomethanes than a specialty activated carbon used for trihalomethane removal. The cavitand polymers show similar removal kinetics as activated carbon and have high capacity (49 mg g-1 of CHCl3). These materials maintain their performance in drinking water and can be thermally regenerated. Cavitand polymers also outperform commercial resins for 1,4-dioxane adsorption, which contaminates many water sources. These materials show promise for water treatment and demonstrate the value of using supramolecular receptors to design adsorbents for water purification.

Isoamericanoic Acid B from Acer tegmentosum as a Potential Phytoestrogen.

Phytoestrogens derived from plants have attracted the attention of the general public and the medical community due to their potentially beneficial role in relieving menopausal symptoms. The deciduous tree Acer tegmentosum Maxim (Aceraceae) has long been utilized in Korean folk medicine to alleviate many physiological disorders, including abscesses, surgical bleeding, and liver diseases. In order to explore structurally and/or biologically new constituents from Korean medicinal plants, a comprehensive phytochemical study was carried out on the bark of A. tegmentosum. One new phenolic compound with a 1,4-benzodioxane scaffold, isoamericanoic acid B (1), as well as with nine known phenolic compounds (2⁻10), were successfully isolated from the aqueous extracts of the bark of A. tegmentosum. A detailed analysis using 1D and 2D NMR spectroscopy, electronic circular dichroism (ECD) spectral data, and LC/MS afforded the unambiguous structural determination of all isolated compounds, including the new compound 1. In addition, compounds 2, 4, 5, and 9 were isolated and identified from the bark of A. tegmentosum for the first time. All isolated compounds were tested for their estrogenic activities using an MCF-7 BUS cell proliferation assay, which revealed that compounds 1, 2, and 10 showed moderate estrogenic activity. To study the mechanism of this estrogenic effect, a docking simulation of compound 1, which showed the best estrogenic activity, was conducted with estrogen receptor (ER) -α and ER-ß, which revealed that it interacts with the key residues of ER-α and ER-ß. In addition, compound 1 had slightly higher affinity for ER-ß than ER-α in the calculated Gibbs free energy for 1:ER-α and 1:ER-ß. Thus, the present experimental evidence demonstrated that active compound 1 from A. tegmentosum could be a promising phytoestrogen for the development of natural estrogen supplements.

Characterization of newly isolated Pseudonocardia sp. N23 with high 1,4-dioxane-degrading ability.

This study was conducted to elucidate the 1,4-dioxane degradation characteristics of a newly isolated 1,4-dioxane-degrading bacterial strain and evaluate the applicability of the strain to biological 1,4-dioxane removal from wastewater. A bacterial strain (designated strain N23) capable of degrading 1,4-dioxane as the sole carbon and energy source was isolated from an enrichment culture prepared from 1,4-dioxane-contaminated groundwater. Strain N23 was phylogenetically identified as belonging to the genus Pseudonocardia, based on 16S rRNA gene sequencing. 1,4-Dioxane degradation experiments revealed that strain N23 is capable of constitutive 1,4-dioxane degradation. Further, this strain exhibited the highest specific 1,4-dioxane degradation rate of 0.230 mg-1,4-dioxane (mg-protein)-1 h-1 among 1,4-dioxane-degrading bacteria with constitutively expressed degrading enzymes reported to date. In addition, strain N23 was shown to degrade up to 1100 mg L-1 of 1,4-dioxane without significant inhibition, and to maintain a high level of 1,4-dioxane degradation activity under a wide pH (pH 3.8-8.2) and temperature (20-35 °C) range. In particular, the specific 1,4-dioxane degradation rate, even at pH 3.8, was 83% of the highest rate at pH 7.0. In addition, strain N23 was capable of utilizing ethylene glycol and diethylene glycol, which are both considered to be present in 1,4-dioxane-containing industrial wastewater, as the sole carbon source. The present results indicate that strain N23 exhibits the potential for 1,4-dioxane removal from industrial wastewater.

Discovery of nicoyamycin A, an inhibitor of uropathogenic Escherichia coli growth in low iron environments.

High-throughput screening and activity-guided purification identified nicoyamycin A, a natural product comprised of an uncommon 3-methyl-1,4-dioxane ring incorporated into a desferrioxamine-like backbone via a spiroaminal linkage. Nicoyamycin A potently inhibits uropathogenic Escherichia coli growth in low iron medium, a promising step toward developing novel antibiotics to treat recalcitrant bacterial infections.

Membrane electro-oxidizer: A new hybrid membrane system with electrochemical oxidation for enhanced organics and fouling control.

The synergistic combination of membrane filtration with advanced oxidation is of particular interest for next-generation wastewater treatment technologies. A membrane electro-oxidizer (MEO) hybridizing a submerged microfilter and an electrochemical cell was developed and investigated for tertiary treatment of secondary industrial (textile) wastewater effluent. Laboratory- and pilot-scale MEO systems were designed and evaluated for treatment efficiency and membrane fouling control. The MEO achieved substantial removal of color (50-90%), turbidity (>90%), and bacteria (>4 log) as well as chemical oxygen demand (13-31%) and 1,4-dioxane (∼25-53%). Fluorescence-based parallel factor analysis disclosed the degradation of humic-like organics with fluorophores. Size exclusion chromatograms with organic carbon detection confirmed the removal of specific organic molecules with ∼100 Da. While investigating the effects of oxidant quenching agents, reactive chlorine species and hydrogen peroxide were found to be most responsible for the anodic oxidation of secondary effluent organics. The efficacy of membrane fouling mitigation by the MEO was greater when higher electric current densities were applied, but was not dependent on the number of electrochemical cells installed. The MEO is a promising technology for enhanced organics removal with simultaneous fouling control due to its multifunctional active oxidants.

A phlorotannin constituent of Ecklonia cava alleviates postprandial hyperglycemia in diabetic mice.

CONTEXT: 2,7″-Phloroglucinol-6,6'-bieckol is a type of phlorotannin isolated from brown algae, Ecklonia cava Kjellman (Phaeophyceae; Laminareaceae). 2,7″-Phloroglucinol-6,6'-bieckol mediates antioxidant activities. However, there has been no research on improving postprandial hyperglycaemia using 2,7″-phloroglucinol-6,6'-bieckol. OBJECTIVE: This study investigated the inhibitory effects of 2,7″-phloroglucinol-6,6'-bieckol on activities of α-glucosidase and α-amylase as well as its alleviating effect on postprandial hyperglycaemia in streptozotocin-induced diabetic mice. MATERIALS AND METHODS: α-Glucosidase and α-amylase inhibitory assays were carried out. The effect of 2,7″-phloroglucinol-6,6'-bieckol on hyperglycaemia after a meal was measured by postprandial blood glucose in streptozotocin-induced diabetic and normal mice. The mice were treated orally with soluble starch (2 g/kg BW) alone (control) or with 2,7″-phloroglucinol-6,6'-bieckol (10 mg/kg bw) or acarbose (10 mg/kg BW) dissolved in 0.2 mL water. Blood samples were taken from tail veins at 0, 30, 60, and 120 min and blood glucose was measured by a glucometer. RESULTS: 2,7″-Phloroglucinol-6,6'-bieckol showed higher inhibitory activities than acarbose, a positive control against α-glucosidase and α-amylase. The IC50 values of 2,7″-phloroglucinol-6,6'-bieckol against α-glucosidase and α-amylase were 23.35 and 6.94 µM, respectively, which was found more effective than observed with acarbose (α-glucosidase IC50 of 130.04 µM; α-amylase IC50 of 165.12 µM). In normal mice, 2,7″-phloroglucinol-6,6'-bieckol significantly suppressed the postprandial hyperglycaemia caused by starch. The 2,7″-phloroglucinol-6,6'-bieckol administration group (2349.3 mmol·min/L) had a lower area under the curve (AUC) glucose response than the control group (2690.83 mmol·min/L) in diabetic mice. DISCUSSION AND CONCLUSION: 2,7″-Phloroglucinol-6,6'-bieckol might be used as an inhibitor of α-glucosidase and α-amylase as well as to delay absorption of dietary carbohydrates.

Three New Polyphenolic Acids from the Leaves of Eucalyptus citriodora with Antivirus Activity.

Six polyphenolic acids (1-6), including the three new compounds citriodolic acids A, B, and C (1-3), were isolated from the leaves of Eucalyptus citriodora. Their structures were elucidated by spectroscopic methods including one dimensional (1D)- and 2D-NMR, high-resolution electrospray ionization (HR-ESI)-MS, and circular dichroism (CD). The potential antivirus activity against respiratory syncytial virus (RSV) of all the isolated compounds was evaluated.

Biological wastewater treatment of 1,4-dioxane using polyethylene glycol gel carriers entrapping Afipia sp. D1.

A biological treatment system for 1,4-dioxane-containing wastewater was developed using the bacterium Afipia sp. D1, which can utilize 1,4-dioxane as the sole carbon source. Strain D1 was entrapped in a polyethylene glycol gel carrier to stably maintain it in a bioreactor, and continuous feeding tests were performed to treat model industrial wastewater containing 1,4-dioxane. 1,4-Dioxane removal activity rapidly increased soon after the start of feeding of influent with 400 mg/L 1,4-dioxane, and the volumetric removal rate reached 0.67 kg dioxane/m(3)/d on day 36 by a stepwise increase in loading. The start-up period of the 1,4-dioxane treatment reactor was approximately 1 month, and stable removal performance was subsequently achieved for more than 1 month. The average 1,4-dioxane effluent concentration and 1,4-dioxane removal efficiency were 3.6 mg/L and 99%, respectively, during stable operation. Further 1,4-dioxane degradation activity of the of the gel carrier was characterized in batch experiments with respect to temperature. The optimum temperature for 1,4-dioxane treatment was 31.7°C, and significant removal was observed at a temperature as low as 6.9°C. The apparent activation energy for 1,4-dioxane degradation was estimated to be 47.3 kJ/mol. This is the first report of the development of a 1,4-dioxane biological treatment system using gel entrapment technology.

Cytotoxic Plakortides from the Brazilian Marine Sponge Plakortis angulospiculatus.

Three new plakortides, 7,8-dihydroplakortide E (1), 2, and 10, along with known natural products 3, 4, spongosoritin A (5), 6-8, and plakortide P (9), were isolated from Brazilian specimens of Plakortis angulospiculatus. Compounds 2, 3, 5, and 7-9 displayed cytotoxic activities with IC50 values ranging from 0.2 to 10 µM. Compounds that contained a dihydrofuran ring were generally less active and displayed time dependence in their activity. The activities of compounds 2 and 7-9, carboxylic acids bearing a common six-membered endoperoxide, were higher overall than for compounds 3 and 5. The modes underlying the cytotoxic actions of plakortides 2, 3, 5, 7, and 9 were further investigated using HCT-116 cells. While dihydrofurans 3 and 5 induce a G0/G1 arrest, six-membered peroxides 2, 7, and 9 delivered a G2/M arrest and an accumulation of mitotic figures, indicating a distinctly different antimitotic response. Confocal analysis indicated that microtubules were not altered after treatment with 2, 7, or 9, therein suggesting that the mitotic arrest may be unrelated to cytoskeletal targets. Overall, we find that two related classes of natural products obtained from the same extract offer cytostatic activity, yet they do so through discrete pathways.

First evidence that Ecklonia cava-derived dieckol attenuates MCF-7 human breast carcinoma cell migration.

We investigated the effect of Ecklonia cava (E. cava)-derived dieckol on movement behavior and the expression of migration-related genes in MCF-7 human breast cancer cell. Phlorotannins (e.g., dieckol, 6,6'-biecko, and 2,7″-phloroglucinol-6,6'-bieckol) were purified from E. cava by using centrifugal partition chromatography. Among the phlorotannins, we found that dieckol inhibited breast cancer cell the most and was selected for further study. Radius™-well was used to assess cell migration, and dieckol (1-100 µM) was found to suppress breast cancer cell movement. Metastasis-related gene expressions were evaluated by RT-PCR and Western blot analysis. In addition, dieckol inhibited the expression of migration-related genes such as matrix metalloproteinase (MMP)-9 and vascular endothelial growth factor (VEGF). On the other hand, it stimulated the expression of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2. These results suggest that dieckol exerts anti-breast cancer activity via the regulation of the expressions of metastasis-related genes, and this is the first report on the anti-breast cancer effect of dieckol.

Structure elucidation of new acetylated saponins, Lessoniosides A, B, C, D, and E, and non-acetylated saponins, Lessoniosides F and G, from the viscera of the sea cucumber Holothuria lessoni.

Sea cucumbers produce numerous compounds with a wide range of chemical structural diversity. Among these, saponins are the most diverse and include sulfated, non-sulfated, acetylated and methylated congeners with different aglycone and sugar moieties. In this study, MALDI and ESI tandem mass spectrometry, in the positive ion mode, were used to elucidate the structure of new saponins extracted from the viscera of H. lessoni. Fragmentation of the aglycone provided structural information on the presence of the acetyl group. The presence of the O-acetyl group was confirmed by observing the mass transition of 60 u corresponding to the loss of a molecule of acetic acid. Ion fingerprints from the glycosidic cleavage provided information on the mass of the aglycone (core), and the sequence and type of monosaccharides that constitute the sugar moiety. The tandem mass spectra of the saponin precursor ions [M + Na]+ provided a wealth of detailed structural information on the glycosidic bond cleavages. As a result, and in conjunction with existing literature, we characterized the structure of five new acetylated saponins, Lessoniosides A-E, along with two non-acetylated saponins Lessoniosides F and G at m/z 1477.7, which are promising candidates for future drug development. The presented strategy allows a rapid, reliable and complete analysis of native saponins.

Isolation and structural characterization of the milled wood lignin, dioxane lignin, and cellulolytic lignin preparations from brewer's spent grain.

The structure of the lignin from brewer's spent grain (BSG) has been studied in detail. Three different lignin preparations, the so-called "milled-wood" lignin (MWL), dioxane lignin (DL), and cellulolytic lignin (CEL), were isolated from BSG and then thoroughly characterized by pyrolysis GC/MS, 2D-NMR, and derivatization followed by reductive cleavage (DFRC). The data indicated that BSG lignin presents a predominance of guaiacyl units (syringyl/guaiacyl ratio of 0.4-0.5) with significant amounts of associated p-coumarates and ferulates. The flavone tricin was also present in the lignin from BSG, as also occurred in other grasses. 2D-NMR (HSQC) revealed that the main substructures present are ß-O-4' alkyl-aryl ethers (77-79%) followed by ß-5' phenylcoumarans (11-13%) and lower amounts of ß-ß' resinols (5-6%) and 5-5' dibenzodioxocins (3-5%). The results from 2D-NMR (HMBC) and DFRC indicated that p-coumarates are acylating the γ-carbon of lignin side chains and are mostly involved in condensed structures. DFRC analyses also indicated a minor degree of γ-acylation with acetate groups, which takes place preferentially on S lignin (6% of S units are acetylated) over G lignin (only 1% of G units are acetylated).

3-deoxysilybin exerts anti-inflammatory effects by suppressing NF-κB activation in lipopolysaccharide-stimulated RAW264.7 macrophages.

3-deoxysilybin (3-DS), also known as (-)-isosilandrin A, is a natural flavonoid of Silybum marianum. This study was designed to investigate the anti-inflammatory effect and the underlying molecular mechanisms of 3-DS in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. 3-DS dose-dependently inhibited the production of NO and the expression of iNOS in LPS-stimulated RAW264.7 macrophages. 3-DS also inhibited the production of pro-inflammatory cytokines (MCP-1, TNF-α, IL-6, and IL-1ß) in LPS-stimulated RAW264.7 macrophages. Moreover, 3-DS decreased the NF-κB DNA binding activity in LPS-stimulated RAW264.7 macrophages. Furthermore, 3-DS suppressed NF-κB activation by inhibiting the degradation of IκBα and nuclear translocation of p65 subunit of NF-κB in LPS-stimulated RAW264.7 macrophages. Taken together, the present study suggests for the first time that 3-DS may exhibit an anti-inflammatory effect through the suppression of NF-κB transcriptional activation in LPS-stimulated RAW264.7 macrophages.

Endoperoxide polyketides from a Chinese Plakortis simplex: further evidence of the impact of stereochemistry on antimalarial activity of simple 1,2-dioxanes.

Chemical investigation of the organic extract obtained from the sponge Plakortis simplex collected in the South China Sea afforded five new polyketide endoperoxides (2 and 4-7), along with two known analogues (1 and 3). The stereostructures of these metabolites have been deduced on the basis of spectroscopic analysis and chemical conversion. The isolated endoperoxide derivatives have been tested for their in vitro antimalarial activity against Plasmodium falciparum strains, showing IC50 values in the low micromolar range. The structure-activity relationships were analyzed by means of a detailed computational investigation and rationalized in the light of the mechanism of action proposed for this class of simple antimalarials. The relative orientation of the atoms involved in the putative radical generation and transfer reaction was demonstrated to have a great impact on the antimalarial activity. The resulting 3D pharmacophoric model can be a useful guide to design simple and effective antimalarial lead compounds belonging to the class of 1,2-dioxanes.

Optimization of the Fenton treatment of 1,4-dioxane and on-line FTIR monitoring of the reaction.

1,4-Dioxane is a non-biodegradable, toxic, hazardous, and priority pollutant widely used in the chemical industry as a solvent; as well as it is a resulting by-product of many industrial processes. The optimization of the Fenton treatment of 1,4-dioxane, and the on-line FTIR monitoring of its degradation route, including the assessment of the enhancement of the biodegradability of the solution along treatment are herein addressed. Besides the full removal of 1,4-dioxane, an 80% reduction of the chemical oxygen demand (COD) was achieved at the best tested treatment conditions. Whether the used concentration of H2O2 was expectedly addressed as the reaction factor most influencing the achieved COD removal at the end of the process; the performance of the treatment under acid pH conditions showed to have just a slight influence, thus supporting this process may suitably be performed at neutral pH value. On-line FTIR monitoring of the process novelly provided the degradation route of 1,4-dioxane along its oxidation treatment, as well as a comprehensive optimization of the Fenton process based on the increase of the biodegradability of the solution and the reduction of the consumption of reagents.

Anti-inflammatory activity of edible brown alga Eisenia bicyclis and its constituents fucosterol and phlorotannins in LPS-stimulated RAW264.7 macrophages.

Although individual phlorotannins contained in the edible brown algae have been reported to possess strong anti-inflammatory activity, the responsible components of Eisenia bicyclis have yet to be fully studied. Thus, we evaluated their anti-inflammatory activity via inhibition against production of lipopolysaccharide (LPS)-induced nitric oxide (NO) and tert-butylhydroperoxide (t-BHP)-induced reactive oxygen species (ROS), along with suppression against expression of inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), in RAW 264.7 cells. The anti-inflammatory activity potential of the methanolic extract and its fractions of E. bicyclis was in the order of dichloromethane>methanol>ethyl acetate>n-butanol. The strong anti-inflammatory dichloromethane fraction was further purified to yield fucosterol. From the ethyl acetate fraction, six known phlorotannins were isolated: phloroglucinol, eckol, dieckol, 7-phloroeckol, phlorofucofuroeckol A and dioxinodehydroeckol. We found that these compounds, at non-toxic concentrations, dose-dependently inhibited LPS-induced NO production. Fucosterol also inhibited t-BHP-induced ROS generation and suppressed the expression of iNOS and COX-2. These results indicate that E. bicyclis and its constituents exhibited anti-inflammatory activity which might attribute to inhibition of NO and ROS generation and suppression of the NF-κB pathway and can therefore be considered as a useful therapeutic and preventive approach to various inflammatory and oxidative stress-related diseases.

Reusability of iron sludge as an iron source for the electrochemical Fenton-type process using Fe²+/HOCl system.

This paper reports on the reusability and the optimal reuse of iron-rich sludge for an electrochemical Fenton-type process using sequencing batch mode and separation batch mode reuse models. In the sequencing batch mode, processes of electrochemical treatment, neutralization, sedimentation, and re-dissolution of iron sludge were all performed in the same reactor, whereas the neutralization and sedimentation of iron sludge in the separation batch mode was carried out in an iron recovery tank separated from the electrochemical reactor. The effects of iron speciation at different pH levels were discussed. It was found that ferric ions at a pH ≤2.5 were suitable for this electrochemical Fenton-type process where ferrous ions acted as hydroxyl radical scavengers, generating brownish deposits on the cathode at pH 3. When the sequencing batch mode was applied, the current efficiency in the Fenton-type process after the iron recovery declined due to the formation of insoluble deposits on the electrodes, which decreased at lower pH. The deposits were mainly formed during the neutralization and sedimentation steps after the electrochemical process. Fortunately, iron from the sludge could be reused for the electrochemical process when the separation batch mode was used, with 100% iron recovery and no decline in current efficiency.