Reductive decomposition of waste gypsum with SiO<Subscript>2</Subscript>, Al<Subscript>2</Subscript>O<Subscript>3</Subscript>, and Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> additives

From the point of view of a sustainable and environment-friendly society based on the recycling of material resources, it is preferable to utilize waste gypsum as a substitute for lime, which is currently produced by the calcination of limestone. In the present work, the reductive decomposition of CaSO₄ was investigated under an atmosphere of CO: 2 vol%, CO₂: 30 vol%, with N₂ as a carrier gas without and with the addition of SiO₂, Al₂O₃, or Fe₂O₃. It was found that the decomposition temperature of CaSO₄ was significantly reduced from 1673 K to 1223 K when only 5 wt% Fe₂O₃ was added to CaSO₄. In the case of the addition of SiO₂ or Al₂O₃ to CaSO₄, the decomposition temperature was reduced from 1673 K to 1623 K. This was due to the formation of composite oxides (calcium ferrite, calcium silicate, or calcium aluminate) during the reaction of CaSO₄ with the additives at a lower temperature. In addition, the formation of unfavorable product CaS was inhibited in the presence of 5 wt% Fe₂O₃, and this inhibition effect further increased as the addition of Fe₂O₃ was increased. In contrast, no significant effect on the inhibition of CaS formation was observed on the addition of SiO₂ or Al₂O₃.     

Purification and biochemical characterization of recombinant alcohol dehydrogenase from the psychrophilic bacterium <Emphasis Type="Italic">Pseudomonas</Emphasis><Emphasis Type="Italic">frederiksbergensis</Emphasis>

A gram-negative psychrophilic bacterium, with potential for biodegradation of long-chain n-alkanes was isolated from ice samples collected in Spitzbergen, Denmark. On the basis of results of biochemical and morphological tests and sequence analysis of 16S rRNA, the strain was identified as Pseudomonas frederiksbergensis. In this work, a short-chain NAD⁺-dependent alcohol dehydrogenase (alcDH) (Accession number: AAR13804) from the P. frederiksbergensis was cloned and transformed in E. coli BL21 (3DE) competent cells. The alcDH activity was highest in the crude extract of cells induced with 1.0 mM IPTG. The recombinant alcDH enzyme was purified to 93.4% homogeneity using three consecutive purification steps including ammonium sulphate, Q-Sepharose Fast Flow column and gel filtration chromatography employing Superdex 200 10/30 HR column. Enzyme enrichment and yield levels of 31.4 folds and 25.5%, respectively, were achieved. While the subunit molecular mass of the enzyme was determined on SDS-PAGE to be ~38 kDa, the aggregated native form of the enzyme had a molecular mass of ~238 kDa by gel filtration analysis. Reaction conditions optima for the recombinant alcDH were determined with propan-1-ol as the substrate. While the optimum pH was 9, the optimum temperature was 35 °C. The alcDH enzyme exhibited moderate thermal stability with half-lives of 150 min at 55 °C, 27 min at 65 °C and 8 min at 75 °C. Results for kinetic parameters indicated that the apparent K _m value for alcDH with propan-1-ol as the substrate was found to be 1.42 mM and the V _max value was 0.63 mmol mg⁻¹ min⁻¹. Experimental evidence revealed that the recombinant alcDH exhibited a wide range of substrate specificity, with higher levels of specific activity for aliphatic alcohols as compared to secondary alcohols. Taken together, the present study highlights the potential of alcDH as a member of cold-adapted enzymes in several key biotechnological applications including environmental bioremediation and biotransformations. It is envisaged that, with the ongoing screening of microorganisms and metagenomes, directed evolution approaches and the subsequent overexpression of recombinant proteins, more enzymes will be found that are suitable for bioremediation purposes.     

Water Retention Capacity of Polysaccharides from Prickly Pear Nopals of <Emphasis Type="Italic">Opuntia Ficus Indica</Emphasis> and <Emphasis Type="Italic">Opuntia Litoralis</Emphasis>: Physical–Chemical Approach

Polysaccharides were isolated from nopals mucilage pulp and peel of Opuntia Ficus Indica (OFI) and Opuntia litoralis (OL) by aqueous extraction and purified by ultrafiltration. Studying the glycosyl residue composition, these polysaccharides were assumed to be rhamnogalacturonan I (RG-I). The macromolecular features of these compounds have been characterized by SEC/MALLS and by low shear viscosimetry. In the present work, we have undertaken a comparative study about different polysaccharides resulting from OFI and OL growing in different area. This comparison is to see the influence of the geographical area in which these two plants push on the mechanism of retention of water by the different polysaccharides extract. The polysaccharides resulting from the nopal peels of the two plants are highly methylated (>70%), thus they are much more hydrophobic especially for peels of OFI growing in the desert area than those resulting from pulps. Consequently, they probably prevent the evaporation of water in nopals by increasing their water retention capacity. Prickly pear nopals of OFI and OL contain a significant amount of water (>80%), carbohydrates (75% compared to the soluble matter), proteins (8% compared to the soluble matter) and salt (17% compared to the soluble matter). Thus, they represent an important source of water and alimentation especially in the arid and semi-arid areas.     

Enzyme-Assisted Extraction and Pb<Superscript>2+</Superscript> Biosorption of Polysaccharide from <Emphasis Type="Italic">Cordyceps militaris</Emphasis>

The enzyme assisted extraction conditions of polysaccharide from Cordyceps militaris mycelia were firstly investigated by kinetics analysis and the optimal operating was found to be: extraction temperature 40 °C; solid-solvent ratio 1:20; extraction pH 4.0; cellulase concentration 2.0%. The polysaccharide extraction yield was 5.99% under these optimized conditions. Furthermore, a fundamental investigation of the biosorption of Pb²⁺ from aqueous solution by the C. militaris polysaccharide was performed under batch conditions. The suitable pH (5.0), polysaccharide concentration (0.20 g L^?1), initial Pb²⁺ concentration (300 mg L^?1) and contact time (40 min) were outlined to enhance Pb²⁺ biosorption from aqueous medium. The Langmuir isotherm model and pseudo first order kinetic model fitted well to the data of Pb²⁺ biosorption, suggesting the biosorption of Pb²⁺ onto C. militaris polysaccharide was monolayer biosorption and physical adsorption might be the rate-limiting step that controlled the adsorption process. FTIR analysis showed that the main functional groups of C. militaris polysaccharide involved in adsorption process were carbonyl, carboxyl, and hydroxyl groups.     

TCE plume remediation via ISCR‐enhanced bioremediation utilizing EHC® and KB‐1®

Groundwater below an operating manufacturing facility in Portland, Oregon, was impacted by chlorinated volatile organic compounds (CVOCs), with concentrations indicative of a dense, nonaqueous‐phase liquid (DNAPL) release. The downgradient plume stretched under the adjacent Willamette River, intersecting zones of legacy impacts from a former manufactured gas plant (MGP). An evaluation of source‐area and downgradient plume treatment remedies identified in situ bioremediation as most likely to be effective for the CVOC plume, while leaving the legacy impacts for other responsible parties. With multiple commercially available products to choose from, the team developed and implemented a bench test to identify the most appropriate technology, which was further evaluated in a field pilot study. The results of the testing demonstrated conclusively that bioremediation enhanced by in situ chemical reduction (ISCR) using EHC® and KB‐1® was most appropriate for this site, providing outstanding results. The following describes the implementation and results of the tests. © 2008 Wiley Periodicals, Inc.     

Photochemical Kinetic Modeling of Degradation of Aqueous Polyvinyl Alcohol in a UV/H<Subscript>2</Subscript>O<Subscript>2</Subscript> Photoreactor

This study presents a photochemical kinetics model to describe the degradation of water-soluble PVA (Polyvinyl Alcohol) polymer in a UV/H₂O₂ batch reactor. Under the effect of UV light, the photolysis of hydrogen peroxide into hydroxyl radicals can generate a series of polymer scission reactions. For a better understanding and analysis of the UV/H₂O₂ process in the cracking of the PVA macromolecules, a chemical reaction mechanism of the degradation process and a relevant photochemical kinetics model are developed to describe the disintegration of the polymer chains. Taking into account the probabilistic fragmentation of the polymer, the statistical moment approach is used to model the molar population balance of live and dead polymer chains. The model predicts the PVA molecular weight reduction, the acidity of the solution, and hydrogen peroxide residual. In addition to previously published data collected in this laboratory, a new set of experiments were conducted using a 500 mg/L PVA aqueous for different hydrogen peroxide/PVA ratios for model validation. Measurements of average molecular weights of the polymer, hydrogen peroxide concentrations and pH of the PVA solution were determinant factors in constructing a reliable photochemical model of the UV/H₂O₂ process. Experimental data showed a decrease in the PVA molecular weight and a buildup of the solution acidity. The experimental data also served to determine the kinetics rate constants of the PVA photochemical degradation and validate the model whose predictions are in good agreement with data. The model can provide a comprehensive understanding of the impact of the design and operational variables.     

Successful ISCR‐enhanced bioremediation of a TCE DNAPL source utilizing EHC® and KB‐1®

Remediation of chlorinated solvent DNAPL sites often meets with mixed results. This can be attributed to the diametrically opposed nature of the impacts, where the disparate dissolved‐phase plume is more manageable than the localized, high‐concentration source area. A wide range of technologies are available for downgradient plume management, but the relative mass of contaminants in a DNAPL source area generally requires treatment for such technologies to be effective over the long term. In many cases, the characteristics of DNAPL source zones (e.g., depth, soil heterogeneity, structural limitations) limit the available options. The following describes the successful full‐scale implementation of in situ chemical reduction (ISCR) enhanced bioremediation of a TCE DNAPL source zone. In this demonstration, concentrations of TCE were rapidly reduced to below the maximum contaminant level (MCL) in less than six months following implementation. The results described herein suggest that ISCR‐enhanced bioremediation is a viable remedial alternative for chlorinated solvent source zones. © 2010 Wiley Periodicals, Inc.     

Green Synthesis of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/Cellulose/Polyvinyl Alcohol Hybride Aerogel and Its Application for Dye Removal

A novel Fe₃O₄/cellulose–polyvinyl alcohol (PVA) aerogel was successfully synthesized by an eco-friendly and facile method in this work. Cellulose/PVA matrix was prepared through an environmental friendly physical cross-linking process and further in-situ decorated with Fe₃O₄. Series of Fe₃O₄ decorated aerogels were prepared and the effects of Fe₃O₄ nanoparticles (NPs) on the aerogels were systematic investigated. As-prepared aerogels exhibited desirable properties including nanostructure, relatively high porosity, improved mechanical and superparamagnetism. The TEM results showed that Fe₃O₄ NPs were integrated in the three-dimensional matrix of cellulose/PVA with a diameter of 9–12 nm. Furthermore, the mechanical strength of the aerogels was significantly enhanced after the introduction of Fe₃O₄ NPs. Meanwhile, the obtained Fe₃O₄/cellulose/PVA aerogel exhibited excellent adsorption performance toward methyl blue dye, and can be reused through fenton-like catalysts oxidative degradation of organic dye in H₂O₂ solution. Therefore, they will have a great potential application as eco-friendly and economical adsorbents.     

Pilot scale testing composite swellable organosilica nanoscale zero‐valent iron—Iron‐Osorb®—for in situ remediation of trichloroethylene

Iron‐Osorb^® is a solid composite material of swellable organosilica with embedded nanoscale zero‐valent iron that was formulated to extract and dechlorinate solvents in groundwater. The unique feature of the highly porous organosilica is its strong affinity for chlorinated solvents, such as trichloroethylene (TCE), while being impervious to dissolved solids. The swellable matrix is able to release ethane after dechlorination and return to the initial state. Iron‐Osorb^® was determined to be highly effective in reducing TCE concentrations in bench‐scale experiments. The material was tested in a series of three pilot scale tests for in situ remediation of TCE in conjunction with the Ohio Environmental Protection Agency at a site in central Ohio. Results of these tests indicate that TCE levels were reduced for a period of time after injection, then leveled out or bounced back, presumably due to depletion of zero‐valent iron. Use of tracer materials and soil corings indicate that Iron‐Osorb^® traveled distances of at least 20 feet from the injection point during soil augmentation. The material appears to remain in place once the injection fluid is diluted into the surrounding groundwater. Overall, the technology is promising as a remediation method to treat dilute plumes or create diffuse permeable reactive barriers. Keys to future implementation include developing injection mechanisms that optimize soil distribution of the material and making the system long‐lasting to allow for continual treatment of contaminants emanating from the soil matrix. © 2011 Wiley Periodicals, Inc.     

Photochemical Degradation of Aqueous Polyvinyl Alcohol in a Continuous UV/H<Subscript>2</Subscript>O<Subscript>2</Subscript> Process: Experimental and Statistical Analysis

Polyvinyl alcohol (PVA), being a dominant contributor of total organic carbon (TOC) in textile wastewater, is not easily degradable by conventional methods of wastewater treatment. This study investigates the degradation of aqueous PVA in a continuous UV/H₂O₂ photoreactor since the feeding strategy of hydrogen peroxide proves to have considerable effects on the process performance. Response surface methodology involving the Box–Behnken method is adopted for the experimental design to study the effects of operating parameters on the process performance. Experimental analysis shows that the TOC removal varies from 16.11 to 42.70 % along with a reduction of the PVA molecular weights from 56.7 to 95.3 %. The TOC removal is significantly lower than the molecular weight reduction due to the generation of the intermediate products during oxidation. Operating the UV/H₂O₂ process in a continuous mode facilitates the degradation of highly concentrated polymeric solutions using a relatively small hydrogen peroxide concentration in the feed with a small residence time ranges from 6.13 to 18.4 min.     

Selective catalytic reduction of NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> using RDF char and municipal solid waste char based catalyst

Experiments were performed in order to investigate the possibility for the development of catalysts for low-temperature selective catalytic reduction (SCR) using municipal waste char and RDF byproduct. Physical and chemical activations, using water, and HCl and KOH, were employed to increase the catalytic activities. The characteristics of the activated catalysts were investigated using N₂ adsorption–desorption and FT-IR. The catalysts activated chemically using basic treatment showed higher NO _x removal efficiencies than those activated physically or chemically using acidic treatment. The de-NO _x performance of the activated catalysts was dependent on the chemical properties, such as oxygen functional groups as well as physical properties, such as specific surface area and pore volume. In order to investigate the effect of MnO _x , which has been reported to be efficient for the removal of NO _x in low-temperature SCR processes, the chemically activated catalyst was impregnated with manganese. The Mn-impregnated catalyst had the highest NO _x conversion at all of the temperatures tested in this study.     

MULTI INCREMENT® TCE vadose‐zone investigation

MULTI INCREMENT® and discrete sampling strategies were used to estimate the average concentration and the three‐dimensional distribution of TCE in a 3,300‐m³ zone composed of two decision units (e.g., area of concern, population, exposure unit). Authors of this article and a private contractor (Stanley Consultants Inc.), respectively, implemented these two sampling strategies independently. Compared to discrete sampling, the MULTI INCREMENT sampling strategy identified more locations where percent‐level concentrations of TCE have migrated, is more economical, and provided greater data quality. © 2008 Wiley Periodicals, Inc.     

Synthesis,Characterization and NH<Subscript>3</Subscript>/N<Subscript>2</Subscript> Gas Permeation Study of Nanocomposite Membranes

Carbon nanotubes have exceptional mechanical properties which make them very attractive for the development of composite membranes. In this research, NH₃/N₂ gas permeation behavior of flat sheet composite membranes was examined. The cellulose acetate-multiwalled carbon nanotubes composite membranes were synthesized using solution casting method. The morphology and dispersion of carbon nanotubes were observed through SEM. However, the composite membranes were also characterized using several analytical techniques such as X-ray diffraction analysis, tensile testing analysis, and thermal gravimetric analysis. Characterization of these membranes depicted that carboxylic group functionalized MWCNTs are extremely compatible with CA. The permeation experiments were performed with NH₃ and N₂ to explore the host–guest interaction of MWCNTs with chosen gases. The permeability of NH₃ was found pronounced compared to N₂. The NH₃/N₂ selectivity up to 90 was documented.     

Hydrolysis of <Emphasis Type="Italic">Sasa senanensis</Emphasis> culm with dilute sulfuric acid for production of a fermentable substrate

To prepare a substrate for microbial conversion of xylose into xylitol, the culm of Sasa senanensis was hydrolyzed with dilute sulfuric acid. When the reaction temperature was fixed at 121°C, an optimum yield of xylose was obtained by treatment with 2% sulfuric acid for 1 h. An increase in the sulfuric acid concentration or a prolonged reaction time resulted in a decrease in the xylose yield. A fermentable substrate with a relatively high xylose concentration (36.7 g l⁻¹) was obtained by hydrolysis with 2% sulfuric acid with a liquid-to-solid ratio of 5 g g⁻¹. During hydrolysis at elevated temperatures, certain undesired byproducts were also generated, such as degradation products of solubilized sugars and lignin, which are potential inhibitors of microbial metabolism. These compounds were, however, successfully removed from the hydrolysate by treatment with activated char.     

A Microscopic Study of Paper Decayed by <Emphasis Type="Italic">Trichoderma harzianum</Emphasis> and <Emphasis Type="Italic">Paecilomyces variotii</Emphasis>

The current study is interested in evaluating the decay of cotton, Whatman and chemical pulp caused by Trichoderma harzianum and Paecilomyces variotii. The structural changes of the paper were evaluated by Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). The SEM results show differences in hyphae colonization and paper decay patterns between studied species under the current study; P. variotii caused an eroded structure in the cotton (cavity forming), whereas the initial T. harzianum colonization produced rupture and erosion (soft-rot decay type II) for the three types of paper ,the gaps were elongated with sharp pointed ends, which consisted either of individual cavities or in chains. Moreover, FTIR results confirmed that there a relationship could be observed between fungal decay and crystalline cellulose content because the intensity of peaks at 1335 and 1111 cm^?1 significantly decreased due to the fungal decay. Furthermore, the intensity of O–H stretching absorption slightly decreased, and this may be attributed to hydrolysis of cellulose molecules.     

New Poly(aniline-<Emphasis Type="Italic">co</Emphasis>-<Emphasis Type="Italic">o</Emphasis>-phenylenediamine)/Kaolinite Microcomposites for Water Decontamination

Copolymers of aniline and o-phenylenediamine/kaolinite composites were synthesized by 5:1 molar ratios of the respective monomers with different percentages of nanoclay via modified in situ chemical co-polymerization. The results were verified by measuring the FT-IR and UV–vis absorption spectra for PANI-o-PDA/kaolinite composites. The thermal behaviour of the copolymer and composites was studied. PANI-o-PDA/kaolinite composites were thermally more stable than pure copolymer. Surface morphology of copolymer composites was recorded at different magnification power by SEM which revealed whitish micrometric beads distributed all over the field with particle size in the range of 0.122–0.233 μm. This work demonstrates that the PANI-o-PDA/kaolinite composites particles can be considered as potential adsorbents for hazardous and toxic metal ions of water from lake El-Manzala, Egypt. All of Cd(II), Cu(II), and Pb(II) posed dangerous health risk to the local population via fish consumption.     

Demonstrating the In Situ Biodegradation Potential of Phenol Using Bio‐Sep® Bio‐Traps® and Stable Isotope Probing

The effect of phenol concentration on phenol biodegradation at an industrial site in the south of Wales, United Kingdom, was investigated using standard Bio‐Sep^® Bio‐Traps^® and Bio‐Traps^® coupled with stable isotope probing (SIP). Unlike many ¹³C‐amendments used in SIP studies (such as hydrocarbons) that physically and reversibly adsorb to the activated carbon component of the Bio‐Sep^® beads, phenol is known to irreversibly chemisorb to activated carbon. Bio‐Traps^® were deployed for 32 days in nine site groundwater monitoring wells representing a wide range of phenol concentrations. Bio‐Traps^® amended with ¹³C‐phenol were deployed together with non‐amended Bio‐Traps® in three wells. Quantitative polymerase chain reaction (qPCR) analysis of Bio‐Traps^® post‐deployment indicated an inhibitory effect of increasing phenol concentration on both total eubacteria and aerobic phenol‐utilizing bacteria as represented by the concentration of phenol hydroxylase gene. Despite the chemisorption of phenol to the Bio‐Sep^® beads, activated carbon stable isotope analysis showed incorporation of ¹³C into biomass and dissolved inorganic carbon (DIC) in each SIP Bio‐Trap^® indicating that chemisorbed amendments are bioavailable. However, there was a clear effect of phenol concentration on ¹³C incorporation in both biomass and DIC confirming phenol inhibition. These results suggest that physical reductions of the phenol concentrations in some areas of the plume will be required before biodegradation of phenol can proceed at a reasonable rate. © 2013 Wiley Periodicals, Inc.     

<Emphasis Type="Italic">Mesua ferrea</Emphasis> L. Seed Oil Based Highly Branched Environment Friendly Polyester Resin/Clay Nanocomposites

To develop a high performance environment friendly material, highly branched polyester/clay nanocomposites have been prepared from Mesua ferrea Linn seed oil-based polyester resin and hydrophilic bentonite nanoclay. The prepared nanocomposites were characterized by Fourier transform infra-red spectroscopy, X-ray diffractometer, scanning electron microscope, transmission electron microscope and rheological studies. Partial exfoliation of clay layers by the polymer chains with good interfacial interactions was observed in the nanocomposites. The formation of delaminated nanocomposites was manifested through the enhancement of tensile strength, scratch hardness, chemical resistance, impact resistance, thermostability, etc. The results show enhancement of three times in tensile strength and 18 °C in thermostability by inclusion of 5 wt% nanoclay as compared to the pristine polymer. By the influence of 5 wt% nanoclay four times enhancement in elongation at break as compared to the pristine polymer was noticed. Thus these nanocomposites have the potential to be used in many advanced applications.     

Preparation of MgCr<Subscript>2</Subscript>O<Subscript>4</Subscript> from waste tannery solution and effect of sulfate,chloride, and calcium on leachability of chromium

This paper presents a study regarding the preparation of MgCr₂O₄ from waste tannery solution, and chromium leaching behavior is also investigated with varying amounts of sulfate, chloride and calcium. The phase transformation, crystallinity index and crystallite diameter were characterized using XRD, FT-IR and thermal analysis. A well-crystallized MgCr₂O₄ was successfully prepared at 1400 °C. The sintering temperature had a major impact on the formation of MgCr₂O₄ compared with sintering time. The MgCr₂O₄ phase was observed initially at 400 °C and its crystallite diameter increased with increasing temperature. The concentration of total chromium leached and Cr(VI) decreased gradually with increasing temperature. The considerable amount of Cr(VI) was found in the leachate at 300–500 °C caused by Cr(VI) intermediary products. Sulfate and chlorine could impact the transformation efficiency of chromium adversely, and chlorine has a more significant effect than sulfate. The presence of calcium disturbed the formation of MgCr₂O₄ and new chromium species (CaCrO₄) appeared, which resulted in a sharp increase in the concentration of leached Cr(VI). Incorporating Cr(III) into the MgCr₂O₄ spinel for reusable products reduced its mobility significantly. This was demonstrated to be a promising strategy for the disposal of chromium containing waste resource.