Pilot-scale study on an advanced Fe-Cu process for refractory wastewater pretreatment.

The extreme pH, high color, and poor biodegradability of refractory wastewater have severe impacts on its biological treatment. To address this issue, an advanced Fe-Cu process with redox reaction and spontaneous coagulation was investigated and applied for pilot-scale (wastewater flow rate of 2000 m3·day-1) pretreatment of separately discharged acidic chemicals and alkaline dyeing wastewater. The advanced Fe-Cu process had five functions: (1) increasing the pH of chemical wastewater to 5.0 and above, with an influent pH of approximately 2.0; (2) transforming refractory organics of chemical wastewater with 10.0% chemical oxygen demand (COD) and 30.8% color removal, thereby enhancing the ratio of biological oxygen demand after five days (BOD5) to COD (B/C) from 0.21 to 0.38; (3) neutralizing the pH of the pretreated chemical wastewater for coagulation application with alkaline dyeing wastewater to avoid adding alkaline chemical; (4) achieving average nascent Fe(II) concentrations of 925.6 mg∙L-1 using Fe-Cu internal electrolysis for mixed wastewater coagulation, resulting in an average of 70.3% color removal and 49.5% COD removal; (5) providing more efficient COD removal and B/C enhancement than FeSO4∙7 H2O coagulation while avoiding secondary pollution. The green process offers an effective, easy-implemented solution for the pretreatment of separately discharged acidic and alkaline refractory wastewater.

Ilexgenin A exerts anti-inflammation and anti-angiogenesis effects through inhibition of STAT3 and PI3K pathways and exhibits synergistic effects with Sorafenib on hepatoma growth.

Recently, we reported that Ilexgenin A exhibits anti-cancer activities and induces cell arrest. Here, we investigated the effect of Ilexgenin A on the inflammation, angiogenesis and tumor growth of hepatocellular carcinoma (HCC). Our current study revealed that Ilexgenin A significantly inhibited the inflammatory cytokines TNF-α and IL-6 levels and downregulated pro-angiogenic factor VEGF production and transcription in HepG2 cells. The underlying mechanism for Ilexgenin A effects appears to be through inhibiting STAT3 and PI3K pathways. Furthermore, we found that not only Ilexgenin A inhibited STAT3 and PI3K pathways in HepG2 cells but also blocked these signaling pathways in HUVECs. Most importantly, by employing two HCC xenografts models - HepG2 and H22, we showed that Ilexgenin A reduced tumor growth and exhibited synergy effect with Sorafenib. ELISA assay, histological analysis and immunohistochemistry examination revealed that the expression of VEGF and MVD was significantly decreased after the treatment with Ilexgenin A and the combination. Moreover, Ilexgenin A could enhance caspase-3/7 activity in vitro and transmission electron microscope indicated that the combination induced evident apoptosis of tumor cells and caused the structural changes of mitochondria in vivo. Although no apparent adverse effects occurred during the treatment period, Sorafenib monotherapy elicited hepatotoxicity for specific expression in the increased level of AST and the ratio of AST/ALT. However, the combination could remedy this adverse effect. In conclusion, the results described in the present study identifies Ilexgenin A as a promising therapeutic candidate that modulates inflammation, angiogenesis, and HCC growth.

Effects of operational parameters and common ions on the reduction of 2,4-dinitrotoluene by scrap copper-modified cast iron.

Scrap Cu-modified cast iron (CMCI) is a potent material for the reduction of 2,4-dinitrotoluene (2,4-DNT) by a surface-mediated reaction. However, the effects of operational parameters and common ions on its reduction and final rate are unknown. Results show that the 2,4-DNT reduction was significantly affected by Cu:Fe mass ratio and the optimum m(Cu:Fe) was 0.25%. The slight pH-dependent trend of 2,4-DNT reduction by CMCI was observed at pH 3 to 11, and the maximum end product, 2,4-diaminotoluene (2,4-DAT), was generated at pH 7. Dissolved oxygen (DO) in the water reduced the 2,4-DNT degradation and the formation of 2,4-DAT. CMCI effectively treated high concentrations of 2,4-DNT (60 to 150 mg L(-1)). In addition, varying the concentration of (NH4)2SO4 from 0.001 to 0.1 mol L(-1) improved the efficiency of the reduction process. The green rust-like corrosion products (GR-SO4 (2-)) were also effective for 2,4-DNT reduction, in which Na2CO3 (0.01 to 0.2 mol L(-1)) significantly inhibited this reduction. The repeated-use efficiency of CMCI was also inhibited. Moreover, 2,4-DNT and its products, such as 4A2NT, 2A4NT, and 2,4-DAT, produced mass imbalance (<35%). Hydrolysis of Fe(3+) and CO3 (2-) leading to the generation of Fe(OH)3 and conversion to FeOOH that precipitated on the surface and strongly adsorbed the products of reduction caused the inhibition of CO3 (2-). The 2,4-DNT reduction by CMCI could be described by pseudo-first-order kinetics. The operational conditions and common ions affected the 2,4-DNT reduction and its products by enhancing the corrosion of iron or accumulating a passive oxide film on the reactivity sites.

Simultaneously degradation of 2,4-dichlorophenol and EDTA in aqueous solution by the bimetallic Cu-Fe/O2 system.

Oxidative degradation of aqueous organic contaminants 2,4-dichlorophenol (2,4-DCP) using ethylenediaminetetraacetic acid (EDTA)-enhanced bimetallic Cu-Fe system in the presence of dissolved oxygen was investigated. The proposed process was applied for the pH range of 3~7 with the degradation efficiency of 2,4-DCP and EDTA varying within 10 %, and achieved at 100 % degradation of 40 mg L(-1) 2,4-DCP in 1 h, at the initial pH of 3, 25 g L(-1) of bimetallic Fe-Cu powder (WCu/WFe = 0.01289) and initial EDTA of 0.57 mM. However, the removal efficiency of 2,4-DCP in control tests were 7.52 % (Cu-Fe/O2 system) and 84.32 % (EDTA-enhanced Fe/O2 process), respectively, after 3 h, reaction. The proposed main mechanism, involves the in situ generation of H2O2 by the electron transfer from Fe(0) to O2 which was enhanced by ethylenediaminetetraacetic acid (EDTA), and the in situ generation of ·OH via advanced oxidation reaction. Accordingly, 2,4-DCP was attacked by ·OH to achieve complete dechlorination and low molecular weight organic acids, even mineralized. Systematic studies on the effects of initial EDTA and 2,4-DCP concentration, Cu-Fe dosing, Cu content, and pH revealed that these effects need to be optimized to avoid the excessive consumption of ·OH and new EDTA and heavy metal Cu pollution.

The pretreatment by the Fe-Cu process for enhancing biological degradability of the mixed wastewater.

The Fe-Cu process in combination with cyclic activated sludge system (CASS) was used to treat the mixed wastewater composed of industry wastewater and urban sewage in this work. The results showed that the pretreatment by the Fe-Cu process removed 20% of COD(cr) and 32% of total phosphorus (TP), which reduced the loading rate of the subsequent biological treatment. Mean while, biodegradability of the wastewater was enhanced, which created favorable condition for the subsequent biological treatment. The formation of heavy, lumpy or granular, absorbent, enriched with microorganisms bio-ferric activated sludge with good setting performance promoted degradation of various refractory organic contaminants. The increase by 10 times of nitrifying and denitrifying bacteria counts (total biofilm biomass increased by 59%) and 0.4 of pH value enhanced the biological nitrification and denitrification to ensure the final effluent NH(3)-N and TN to be 8 and 20mg/L, respectively. Agglomeration, passivation and clogging of iron were not observed in three months of continuous operation. Furthermore, the consumption of iron was low. All these led to an easy maintenance and low operating cost.

[Decolorization of the azo dye reactive red X-3B by an Al-Cu bimetallic system].

The decoloration mechanism and kinetics of the azo dye reactive red X-3B by an Al-Cu bimetallic system were investigated by measuring the dye removal, the TOC removal and the aniline concentration, and by adding EDTA as control experiments. The results showed the colority removal rate of X-3B reached 83% in the near neutral pH medium for 30 min and 96.4% for 120 min, in which, about 34% was due to the X-3B reduced to aniline, and about 20% and 30% was due to the flocculating of aluminum ions and surface adsorption of aluminum-fillings respectively. The decolorization of dyeing wastewater is a gradual reaction process, which first adsorbs a large number of dyeing ingredients and then carries out inner electrolysis reduction, improved effectively by the flocculating action of aluminum ions. The decolorization reaction appears to be a pseudo first-order reaction and increases with rising temperature.

[Catalytic reduction of CCl4 in water by Fe0 and amended Fe0].

Various bimetallic reductants of Cu/Fe, Ag/Fe, Pd/Fe and Ni/Fe were prepared by plating Cu, Ag, Pd and Ni on the surface of Fe0. Reductive dechlorination of toxic pollutants of CCl4 in water with Fe0 and amended Fe0 by batch experiments was investigated. Results show that CCl4 in water can be rapidly dechlorinated by above five catalytic reductants, and the presence of Cu, Ag, Pd can enhance the dechlorination rate dramatically. The reaction of CCl4 with various reductants was followed the pseudo first order kinetics, and the dechlorination rate constant of CCl4 in water by Fe0, Cu/Fe, Ag/Fe, Pd/Fe and Ni/Fe was 0.0393, 0.0925, 0.158, 0.0496 and 0.0533 min(-1) respectively. The byproducts and pathway of dechlorination of CCl4 by Fe0 and amended Fe0 was identified by GC/MS. Results indicate that the products and dechlorination rate of CCl4 by various bimetallic reductants are varied. The main products are chloroform and dichloromethane in Cu/Fe and Ag/Fe system, and that is methane in Pd/Fe system. Hydrogenolysis is the dominant reaction pathway of CCl4 by Fe0 and amended Fe0.

[Electrochemical reduction characteristics of nitro-benzene compounds at the copper electrode and the influence of pH on reduction].

The electrochemical reduction characteristics of nitro-benzene compounds were investigated using cyclic voltammetry technique. The reductive reactivity of the nitro-benzene compounds at the copper electrode was evaluated, the reduction mechanisms of the nitrobenzene compounds at the copper electrode and the influences of pH on them were also discussed in this paper. The experimental results show that nitro-benzene compounds is capable of reducing directly at the copper electrode, and the reduction peaks were at - 0.58V and - 1.32V or so (vs. SCE). Both acidity and basicity favor reduction of nitro-group at the copper electrode: the elimination reaction is easy to occur in the alkaline medium with the formation of nitroso-group; in the acid medium the probability of the reaction between the obtained electrons nitro group and hydrogen ions raises, which causes magnification of the current through the solution; in addition, the growth of hydrogen atoms in number favors the occurring of the addition and substitution reactions at the electrode. pH strongly influenced the electrochemical reduction characteristics of the nitrobenzene compounds at the copper electrode, and it mainly depends on the properties of the substituents on the benzene ring, their configurations and numbers, and their location versus nitro group on the benzene ring. The results provide a theoretical and experimental basis for investigating the reduction mechanisms by the catalyzed iron inner electrolysis process.

Reduction of nitrobenzene by the catalyzed Fe-Cu process.

The electrochemical reduction characteristics of nitrobenzene were investigated using cyclic voltammetry. In addition, the difference in reduction mechanisms between Master Builders' iron and the catalyzed Fe-Cu process was discussed in this paper. The results showed that nitrobenzene was reduced directly on the surface of copper rather than by the hydrogen evolved at cathode in the catalyzed Fe-Cu process. The reduction was realized largely by the hydrogen evolved at cathode in Master Builders' iron. Both acidity and basicity favored the direct reduction at the copper electrode. The catalyzed Fe-Cu process was superior to Master Builders' iron in treating nitrobenzene-containing water, withal. This advantage was particular noticeable under alkaline conditions. The reduction was investigated in the cathode and anode compartments, respectively, and the experimental results showed that the direct pathway had a large role in the reduction by the catalyzed Fe-Cu process. To reduce nitrobenzene directly at the copper electrode is easier than to reduce it by the hydrogen evolved at cathode, copper could be regarded as the electrocatalyst in this case. The influence of copper usage on the treatment efficiency by the catalyzed Fe-Cu process was also studied. The results indicated copper increased the reduction rate. The catalyzed Fe-Cu process is of practical value.