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.     

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.     

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.     

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.     

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.     

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.     

Gene Cloning and Characterization of a Poly(<Emphasis Type="SmallCaps">l</Emphasis>-Lactic Acid) Depolymerase from <Emphasis Type="Italic">Pseudomonas</Emphasis> sp. Strain DS04-T

A gene encoding a poly(l-lactic acid) (PLA) depolymerase from Pseudomonas sp. strain DS04-T was cloned and overexpressed in Escherichia coli. The recombinant PLA depolymerase with a molecular weight of 19.2 kDa was purified to homogeneity. The optimum pH and temperature of the PLA depolymerase are 8.5 and 60 °C, respectively. K⁺, Ca²⁺ and Ni²⁺ enhance the enzyme activity, while Na⁺, Zn²⁺, Mg²⁺, Cu²⁺, Fe²⁺, Mn²⁺ and Co²⁺ inhibit it. The inhibition of different chemicals on the PLA depolymerase activity were examined, in which EDTA was found to have a significantly inhibitory effect. The main degradation product of the depolymerase is identified as lactic acid monomer by mass spectrometric analysis. Physicochemical properties, substrate specificity and sequence analysis indicated that PME is a new type of PLA depolymerase.     

Catalytic co-pyrolysis of <Emphasis Type="Italic">Pterospermum acerifolium</Emphasis> and plastic waste

The continuous increase in generation of solid wastes and gradual declining of fossil fuels necessities the development of sustainable conversion technologies. Recent studies have shown that the addition of biomass with hydrogen-rich co-reactants (plastics) altogether enhances the quality of bio-fuels using pyrolysis process. It was observed that red mud (which is produced as by-product in Bayer process) was used as a catalyst in few conversion process. In this study, pyrolysis of biomass (Pterospermum acerifolium) and waste plastic mixture with activated red-mud catalyst was investigated using thermo-gravimetric analysis. The kinetic parameters (activation energy and pre-exponential factor) of this process were determined using distributed activation energy model (DAEM). The DAEM was effectively applied to decide the activation energy (E) and pre-exponential factor (A) for each sample at various conversions during the catalytic co-pyrolysis. The biomass, plastic, biomass–plastic, and biomass–plastic–catalyst exhibited activation energies in the ranges of 78–268, 172–218, 67–307, and 202–292 kJ/mol, respectively.     

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.     

Biodegradation of Poly-ε-caprolactones and Poly-<Emphasis Type="SmallCaps">l</Emphasis>-lactides by Fungi

This work assessed biodegradation, by Aspergillus, Fusarium, Penicillium and Parengyodontium fungi, of four samples of poly-ε-caprolactone (PCL), three samples of poly-l-lactide (PLA) and one sample of poly-d,l-lactide (DL-PLA) produced by ring-opening polymerization initiated by aluminium complexes of corresponding lactones. Mesophilic fungal strains actively biodegrading PCL (F. solani) and PLA (Parengyodontium album and A. calidoustus) were selected. The rate of degradation by the selected fungi was found to depend on the physicochemical and mechanical properties of the polymers (molecular weight, polydispersity, crystallinity). The most degradable poly-ε-caprolactone sample was shown to have the lowest molecular weight; the most biodegradable polylactide DL-PLA had the lowest crystallinity. Mass spectral analysis of biodegraded polymer residues showed PCL to be degraded more intensively than PLA. It is established that in the case of Parengyodontium album the colonization of the films of polypropylene composites with DL-PLA is observed, which will undoubtedly contribute to their further destruction under the influence of abiotic factors in the environment.     

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.     

Online first publication of <Emphasis Type="Italic">Journal of material cycles and waste management</Emphasis>

Announcement

Online first publication of Journal of material cycles and waste management     

Mechanism and Characterization of Polyamide 4 Degradation by <Emphasis Type="Italic">Pseudomonas</Emphasis> sp.

We identified a biodegrading microorganism of polyamide (nylon) 4, a linear polymer of γ-aminobutyric acid (GABA). From activated sludge, the biodegrading bacteria strains of Pseudomonas sp. were isolated and identified by their taxonomic characteristics and nucleotide sequences of 16S rDNA. One strain, ND-11, was grown on a minimal medium containing polyamide 4 (PA4) as the sole carbon source. The strain produced GABA as a degradation intermediate, as identified by analyzing the NMR spectra of degraded products. The culture supernatant of strain ND-11 degraded the emulsified PA4 completely within one day. These results suggest that the ND-11 strain degraded PA4 using its extracellular enzymes to hydrolyze amide bonds.     

Blending Modification of PHBV/PCL and its Biodegradation by <Emphasis Type="Italic">Pseudomonas mendocina</Emphasis>

Poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) is a biodegradable polymer synthesized in microorganisms. The application of PHBV is limited by certain material disadvantages. Poly(ε-caprolactone) (PCL) possesses excellent thermodynamic and mechanical properties and was used to modify PHBV in the presence of triethyl citrate (TEC) and dicumyl peroxide (DCP), which was used as plasticizer and grafting agent, respectively. The effects of PCL and additive agents on the mechanical, thermal, amphipathic and degradability behaviors of the blends were investigated. The results showed that the mechanical properties of the PHBV blends improved by PCL incorporation and improved even further after TEC and DCP addition. The addition of DCP could not induce an increase in crystallization temperature but improved the crystallization degree of the blends. The presence of hydrophilic groups in TEC leads to an apparent increases in the hydrophilicity of the PHBV blends. A PHBV/PCL blend (40/60) with TEC (20 wt.%) and DCP (0.5 wt.%) was chosen for its good mechanical properties and hydrophilicity. The chosen ratio of the blends was also shown a preferable degradation activity by biodegradation assay using Pseudomonas mendocina. The addition of TEC and DCP has no conspicuous negative effect on the biodegradation.     

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.     

Mechanical Properties of Layered Laminated Woven Bamboo <Emphasis Type="Italic">Gigantochloa Scortechinii</Emphasis>/Epoxy Composites

This study investigated the application of bamboo as a natural composite, in which its potential as a composite material had been examined for 2–6 layers. In precise, the woven bamboo (BW) formed the culm fiber composite with an average of 0.5 mm thickness and 5.0 mm width strip. In addition, this study looked into a specific type of bamboo species known as Gigantochloa Scortechinii (Buluh Semantan), which can be found in Malaysia. This laminated plain BW, which had been reinforced with epoxy (EP), was developed by applying the hand lay-up technique. After that, the specimens were characterized via mechanical analyses, for instance, tensile, flexural, hardness, and impact tests. As a result, the 2-layer BW had displayed rather excellent results chiefly due to the incorporation of epoxy composite, although this is exceptional hardness value.     

Synthesis and Properties of <Emphasis Type="Italic">N</Emphasis>-Maleyl Chitosan-Cross-Linked Poly(Acrylic Acid-co-Acrylamide) Superabsorbents

A high-swelling superabsorbent was synthesized with biodegradable N-maleyl chitosan as cross-linker, acrylic acid (AA) and acrylamide (AM) as the monomers, ammonium peroxodisulfate–sodium bisulfite (NaHSO₃) as redox initiation system, by means of aqueous solution polymerization. The best reaction condition was based on the orthogonal experiment design. The optimal conditions on distilled water absorbency and on 0.9 wt% NaCl solution absorbency were monomer concentration 20 wt%, mole ratio of AA to (AA + AM) 60%, the neutralization degree of AA 40%, cross-linker concentration 2% and monomer concentration 25 wt%, mole ratio of AA to (AA + AM) 60%, neutralization degree of AA 50% and cross-linker concentration 1%, respectively. Factors influencing the water absorbency of superabsorbent also were investigated, by single factor experiment method. The absorbency of superabsorbents in distilled water and 0.9 wt% NaCl solution increased and then decreased with the increasing of monomer concentration, mole ratio of AA to (AA + AM) and degree of neutralization of AA. With the increasing of cross-linker concentration, the absorbency in distilled water increased and then decreased, but it decreased all the time in 0.9 wt% NaCl solution. In enzymatic degradation tests, the weight loss of superabsorbent was related to the content of cross-linker.     

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.     

Effect of <Emphasis Type="Italic">Moringa oleifera</Emphasis> Pod Husk Fibers on the Properties of Gelatin-Based Biocomposite

The objective of this work is to study the feasibility of reinforcing polymer composites by utilizing the biofibers from the agricultural residue of Moringa oleifera pod husks (MOPH). The chemical and physical properties of the fibers were comprehensively investigated to evaluate their potential as a filler in gelatin-based films. The effect of MOPH fiber concentrations of 0, 5, 10, and 15 wt% on the water vapor permeability (WVP), and mechanical and thermal properties of the gelatin-based films was studied. By incorporation of 10 wt% of the MOPH fibers in gelatin, the highest tensile strength and Young’s modulus, and the lowest WVP properties were obtained. Scanning electron microscopy (SEM) photographs indicated good interfacial adhesion between the fibers and the gelatin matrix. TGA of the biocomposites revealed an improvement of thermal stability. Moreover, under accelerated weathering, the gelatin-MOPH-10% biocomposite degraded more slowly than the gelatin control. These results indicate that the MOPH fibers are a good reinforcing filler and may be useful for biocomposite applications.