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This paper discusses the development of mixtures with silica fume as a stabilization/solidification agent and binder for industrial wastewater residue containing organic and heavy metal contaminants. The UCS (Unconfined Compressive Strength) gradually increased to 66.7% as the silica fume content increased to 15%. The leaching of TOC and chromium decreased as more OPC was substituted with silica fume. When the mix had 5% silica fume, it retained about 85% TOC, and chromium leached out 0.76 mg-Cr/g-Cr in acidic solution. Also, microstructural studies on the solidified wastes through the scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction analysis showed that the silica fume caused an inhibition to the ettringite formation which did not contribute to setting, but coated the cement particles and retarded the setting reactions. The results indicated that the incorporation of silica fume into the cement matrix minimized the detrimental effects of organic materials on the cement hydration reaction and contaminant leachability.
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PMID:Chemical characteristics and leachability of organically contaminated heavy metal sludge solidified by silica fume and cement. 1154 12

Alachlor photodegradation was performed using TiO(2), which was synthesized by a modified sol-gel method. The thickness of a TiO(2) film immobilised by a 5-time dip-coating was 174 nm and the average diameter of TiO(2) particles was about 10-15 nm in SEM images. The crystal structure of a TiO(2) film calcinated at 300 degrees C for 1 h was observed as a typical anatase type. The stability of a TiO(2) film by a modified sol-gel method was 4% better than TiO(2) by a typical sol-gel method. The removal rate of alachlor with both Fe(3+) and UV radiation in the absence of TiO(2) was 0.28 mg/l/h in 10 h and the removal rate of alachlor with Fe(3+)/UV in the presence of TiO(2) was 0.32 g/l/h, which was higher by 14% than that with Fe(3+)/UV system. TOC concentration during the alachlor degradation with both TiO(2) and UV radiation in the absence of added Fe(3+) decreased from 100%, through 81% and 51%, to 44% with time elapses of 4, 8, and 10 h, respectively, while TOC concentration with both added Fe(3+) and UV radiation in the absence of TiO(2) decreased from 100% to 70% in 10 h.
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PMID:Photodegradation of alachlor with the TiO(2) film immobilised on the glass tube in aqueous solution. 1312 16

A study of the characteristics of a novel photocatalyst indicated that it consisted of 17.3 nm nano size (average) TiO2 in the anatase phase and porous Fe2O3. SEM results revealed that nano size TiO2 was uniformly deposited onto the surface of Fe2O3 to form a bulk photocatalyst, as TiO2/Fe2O3. The porous TiO2/Fe2O3 catalyst had a BET surface area of 168 m2/g, which is three times higher than that of commercial TiO2. The experimental results indicated that the suspended TiO2/Fe2O3 photocatalyst in a photocatalytic oxidation (PCO) reactor was effective in removing TOC at 61.58% and color400 at 93.25% at 180 min illumination time, under 0.4 g/l catalyst loading and pH 7. Experimental results also revealed that pH at 7 and TiO2/Fe2O3 loading at 0.4 g/l was the optimum condition for removal of humic acids using a PCO reactor. Experimental results clearly indicated that the permeate flux rate of the ultrafiltration (UF) membrane was improved and the filtration membrane fouling phenomenon was reduced with the addition of TiO2/Fe2O3 photocatalysts to the UF membrane system. It was found that increasing the filtration time from 40 min to 185 min, the improvement to the permeate flux rate was from 57 to 83 L/hr x m2.
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PMID:Removal of natural organic matter from water using a nano-structured photocatalyst coupled with filtration membrane. 1497 44

We quantified the concentrations and distributions of metals (Cd, Cr, Cu, Ni, Pb, and Zn) in the sediments of Tuen Mun River, Hong Kong. The potential bioavailability of metals was assessed with a biomimetic extraction method using the sipunculan gut juices. The sediments were characterized by relatively high concentrations of trace metals. Field collected sediments were highly anoxic and the ratio of simultaneously extractable metal (sigmaSEM) to acid volatile sulfide (AVS) was much less than one in these sediments. The majority (>67%) of Cd, Pb, and Zn were bound to AVS, thus their concentrations in the sediment porewater were low. In contrast, Ni was little bound to AVS due to its lower ratios of SEM-Ni to total Ni concentrations. For Cu, relatively high concentrations in the sediment porewater was found, and total organic carbon, AVS and other resistant sulfide phase were the controlling factors for sedimentary Cu partitioning. Net metal adsorption from gut juices to anoxic sediments was observed in metal extraction experiments, suggesting that AVS determined the bioaccumulation and potential bioavailability of most metals in these sediments. Extraction of metals from the oxidized sediments by the gut juices was mainly attributed to metal redistribution from AVS to other geochemical phases. The gut juices were the most effective solvent or extractant than the simple electrolyte solution [I (NaNO(3)) = 0.01 M] and the natural overlying water. Cd was more easily extracted from the oxidized sediments than Zn that tended to have a stronger binding affinity with Fe-Mn oxide, clay and organic matter. The application of partial removal techniques in metal extraction experiments further demonstrated the differential controls of various sediment geochemical phases in affecting metal bioavailability, with the order of TOC > Fe-Mn oxides > carbonate.
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PMID:Metal partitioning in river sediments measured by sequential extraction and biomimetic approaches. 1548 75

This report presents an assessment of chemical variability in natural ecosystems of Wigierski National Park (NE Poland) derived from the calculation of geochemical baselines using a barbell cluster ANOVA design. This method enabled us to obtain statistically valid information with a minimum number of samples collected. Results of summary statistics are presented for elemental concentrations in the soil horizons-O (Ol + Ofh), -A and -B, 1- and 2-year old Pinus sylvestris L. (Scots pine) needles, pine bark and Hypogymnia physodes (L.) Nyl. (lichen) thalli, as well as pH and TOC. The scope of this study also encompassed S and C stable isotope determinations and SEM examinations on Scots pine needles. The variability for S and trace metals in soils and plant bioindicators is primarily governed by parent material lithology and to a lesser extent by anthropogenic factors. This fact enabled us to study concentrations that are close to regional background levels.
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PMID:The use of the barbell cluster ANOVA design for the assessment of environmental pollution: a case study, Wigierski National Park, NE Poland. 1551 52

Plasma treatment was evaluated as an alternative clean desizing technology in this work. As indicated by weight loss, O2 plasma treatment efficiently removed sizing agents such as polyvintyl alcohol (PVA), polyacrylic acid esters and their mixture (MIX) on polyethylene terephthalate (PET) fabrics. SEM pictures of the plasma treated samples directly proved the disappearance of the sizing agents. XPS analysis showed apparent changes in chemical composition and functional groups of the PET surface after O2 plasma treatment. Carbon content decreased due to the removal of sizing agents while oxygen content increased. O2 plasma treatment also increased hydrophilic functional groups of sizing agents, which is confirmed by C1s and O1s deconvolution analyses. After O2 plasma treatment, the PET fabric was subjected to conventional desizing process at different temperatures. Except for the PET fabric sized with PVA, plasma-treated fabrics showed more efficient desizing results when compared with untreated fabrics. Furthermore, the desizing effluent from the treated fabric gave lower TOC, COD and BOD values.
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PMID:Size removal on polyester fabrics by plasma source ion implantation device. 1632 34

Microporous solid K3PW12O40 is prepared by precipitation of phosphotungstic acid and potassium ion, followed by calcination. Using this material as photocatalyst, a series of dye pollutants, such as rhodamine B, malachite green, rhodamine 6G, fuchsin basic, and methyl violet, were efficiently degraded in the presence of H202 under visible light irradiation (lambda > 420 nm). The photocatalyst was characterized via SEM, BET surface area, FT-IR, and XRD. The photocatalyst has relative large surface area, and the Keggin structure of phosphotungstic ions is intact during the precipitation and calcination. The degradation kinetics, TOC changes, degradation products, ESR detection of active oxygen species, and the effect of radical scavengers are also investigated to clarify the degradation process and the reaction pathway. The dyes can be facilely bleached and mineralized (ca. 40% of TOC removal for RhB), and the main degradation products of RhB detected, besides CO2, are the small organic acids. They are released from the surface of the catalyst to the bulk solution during the degradation of the dye, which avoids the poisoning of photocatalyst by the intermediates. The formation of active oxygen species such as the O2-*/ HO2* and *OH are detected during the degradation of dye, and they are proposed to be responsible for the degradation of dyes. The K3PW12040 catalyst is very stable and very easily separated from the reaction system for reuse.
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PMID:Photodegradation of dye pollutants catalyzed by porous K3PW12O40 under visible irradiation. 1683 May 69

In order to develop a catalyst with high activity for catalytic wet oxidation (CWO) process at room temperature and atmospheric pressure, Fe2O3-CeO2-TiO2/gamma-Al2O3 catalyst was prepared by consecutive impregnation method and the prepared parameters were optimized. The structure of the catalyst was characterized by BET, XRF, SEM and XPS technologies, and the actual wastewater was used to investigate the catalytic activity of Fe2O3-CeO2-TiO2/gamma-Al2O3 in CWO process. The experimental results showed that the prepared catalyst exhibited good catalytic activity when the doping amount of Ti was 1.0 wt%/o (the weight ratio of Ti to carriers), and the middle product, CeO2-TiO2/gamma-Al2O3, was calcined in 450'C for 2 h. The CWO experiment for treating actual dye wastewater indicated that the COD, color and TOC of actual wastewater were decreased by 62.23%, 50.12% and 41.26% in 3 h, respectively, and the ratio of BODs/COD was increased from 0.19 to 0.30.
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PMID:Preparation and characterization of Fe2O3-CeO2-TiO2/gamma-Al2O3 catalyst for degradation dye wastewater. 1729 63

Aeration in the inverse direction of effluent was applied as the measure of online backwashing to control membrane pollution in the dynamic membrane bio-reactor treating sewage wastewater. When the intensity of aeration was 5.6 m3/(m2 x h) and the aeration time was 5 min, it took 45 min for the dynamic membrane to recover filtration capacity. With the recovery of dynamic membrane filterability, effluent turbidity was below 5 NTU. The backwashing interval of the reactor could maintain about 15 h. SEM pictures showed that online aeration backwashing in the inverse direction of effluent could efficiently destroy part of dynamic membrane layer. After the dynamic membrane recovery, dynamic membrane could check more than 50% TOC of various molecule weights range > 3 x 10(4). Aeration in the inverse direction of effluent was an economical and effective means of online backwashing in the dynamic membrane bio-reactor.
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PMID:[Online aeration backwashing in the inverse direction of effluent applied in dynamic membrane bio-reactor]. 1767 29

The morphology and elemental composition of the corrosion products of copper teapot's inner-surface were characterized by the scanning electron microscopy and energy dispersive X-ray surface analysis (SEM/EDS), X-ray powder diffraction (XRD) and X-ray photon spectroscopy (XPS) analysis. It was revealed that Cu, Fe, Ca, P, Si and Al were the main elements of corrosion by-products, and the alpha-SiO(2), Cu(2)O and CaCO(3) as the main mineral components on the inner-surface of copper teapot. The effects of organic matters coming from Chinese tea on soluble copper release from copper teapots in tap water were also investigated. The results showed that the doses of organic matter (as TOC), temperate and stagnation time have significant effects on the concentration of soluble copper released from copper teapots in tap water.
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PMID:Effects of organic matters coming from Chinese tea on soluble copper release from copper teapot. 1790 99


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