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.     

Comparative Response of Indigenously Developed Bacterial Consortia on Progressive Degradation of Polyhydroxybutyrate Film Composites

The global demand of bioplastics has lead to an exponential increase in their production commercially. Hence, biodegradable nature needs to be evaluated in various ecosystems viz. air, water, soil and other environmental conditions to avoid the polymeric waste accumulation in the nature. In this paper, we investigated the progressive response of two indigenously developed bacterial consortia, i.e., consortium-I (C-I: Pseudomonas sp. strain Rb10, Pseudomonas sp. strain Rb11 and Bacillus sp. strain Rb18), and consortium-II (C-II: Lysinibacillus sp. strain Rb1, Pseudomonas sp. strain Rb13 and Pseudomonas sp. strain Rb19), against biodegradation behavior of polyhydroxybutyrate (PHB) film composites, under natural soil ecosystem (in net house). The biodegraded films recovered after 6 and 9 months of incubation were analyzed through Fourier transform infrared spectroscopy and scanning electron microscopy to determine the variations in chemical and morphological parameters (before and after incubation). Noticeable changes in the bond intensity, surface morphology and conductivity were found when PHB composites were treated with C-II. These changes were drastic in case of blends in comparison to copolymer. The potential isolates not only survived, but, also, there was a significant increase in bacterial diversity during whole period of incubation. To the best of our knowledge, it is the first report which described the biodegradation potential of Lysinibacillus sp. as a part of C-II with Pseudomonas sp. against PHB film composites.     

Potential of <Emphasis Type="Italic">pinhão</Emphasis> Coat as Constituents of Starch Based Films Using Modification Techniques

The potential of lignocellulosic fibers obtained by dry grinding of pinhão coat as fillers in starch filmogenic solutions for packaging applications was evaluated in this work. To improve the incorporation of this waste into the starch solutions different physical and chemical treatments were conducted. Thereafter, morphology, chemical structure, crystallinity and water absorption of the pinhão coat powders were determined. The composites were also characterized regarding their morphology, chemical structure, crystallinity, mechanical properties, water vapor permeability and hydrophilicity. Poor fiber/matrix adhesion and high water absorption of the fibers were evidenced. Consequently, water vapor permeability of composites was increased by incorporating the fibers. Moreover, mechanical properties were improved and the morphological results were used to support the water absorption differences among the powders. Regarding the food packaging applications, starch/pinhão coat composites appeared as promising materials to reach the requirements of respiring food products.     

Water Absorption Kinetics and Hygrothermal Aging of Poly(lactic acid) Containing Halloysite Nanoclay and Maleated Rubber

Poly(lactic acid)/halloysite nanoclay composites (PLA/HNC) containing maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH) were produced using melt compounding followed by compression molding. The effects of hygrothermal aging on the thermal properties and functional groups changes of the HNC reinforced PLA (with and without SEBS-g-MAH) at three different temperatures (i.e., 30, 40 and 50 °C) were analyzed using differential scanning calorimetry and Fourier transform infrared spectroscopy techniques. The diffusion coefficient (D) of PLA was decreased by the incorporation of HNC and SEBS-g-MAH. The activation energy of water diffusion (E _a ) of PLA/HNC/SEBS-g-MAH nanocomposites was higher than that of pure PLA. The glass transition temperature (T _g ), cold-crystallization temperature (T _cc ) and melting temperature (T _m ) of the PLA sample were shifted to lower temperature and the effect was more pronounced at 50 °C. The carbonyl index values of all PLA samples increased after immersed in 40 and 50 °C, which is due to the formation of higher amount of carboxyl groups during the hydrolysis process.     

Biodegradation of Natural Rubber and Natural Rubber Products by <Emphasis Type="Italic">Streptomyces</Emphasis> sp. Strain CFMR 7

The rubber degrading activity of Streptomyces sp. CFMR 7 whose whole genome sequence was recently determined was tested with non-vulcanized fresh latex and common vulcanized rubber products such as latex glove, latex condom and latex car tyre. The degradation activity was unequivocally demonstrated by scanning electron microscopy with respect to microbial colonization efficiency, disintegration of rubber material and biofilm formation after 3, 6 and 9 months of inoculation. Fourier transform infrared spectroscopy comprising the attenuated total reflectance analysis on these inoculated products revealed insights into the biodegradation mechanism of this strain whereby, a decrease in the number of cis -1,4 double bonds in the polyisoprene chain, the appearance of ketone and aldehyde groups formation indicating an oxidative attack at the double bond of rubber hydrocarbon. In the presence of strain Streptomyces sp. CFMR 7, gel permeation chromatography analysis revealed a significant shift of the molecular weight distribution to lower values. Clear decrease in the molecular weight was observed over 3, 6 and 9 months of cultivation on fresh latex samples compared to other vulcanized products. No shift in the molecular weight distribution was observed for non-inoculated control. These results clearly showed that Streptomyces sp. CFMR 7 was able to cleave the carbon backbone of poly (cis -1,4-isoprene). Although this strain was able to degrade both non-vulcanized and vulcanized rubber products, faster degradation was obtained with natural rubber and rubber products with low complexity.     

Preparation and Characterization of Polyaniline and Ag/ Polyaniline Composite Nanoporous Particles and Their Antimicrobial Activities

Polyaniline (PANI) and Ag/PANI nanoporous composite were prepared by an oxidative polymerization method. The oxidation process of PANI nanoparticles was occurred using (NH₄)₂S₂O₈ while the oxidation process of Ag/PANI nanoporous composite was occurred using AgNO₃ under the effect of artificial radiation. The structural, morphological, and optical properties of the PANI and Ag/PANI nanoporous structures were studied using different characterization tools. The results confirm the formation of polycrystalline nanoporous PANI and spherical nanoporous composite of Ag/PANI particles. Antibacterial activity tests against gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus, and gram-negative bacteria, Escherichia coli, and Salmonella species were carried out using different concentrations of PANI nanoparticles and Ag/PANI nanoporous composites. PANI has not antibacterial effect against all studied pathogens. In contrast, Ag/PANI nanoporous composites possessed antibacterial activity that is identified by the zone of inhibition. The inhibition zones of bacteria are in order; Salmonella species?>?S. aureus?>?B. subtilis?>?E. coli. The inhibition zones of all bacteria increased with increasing concentrations of Ag/PANI nanoporous composites from 200 to 400 ppm then decreased with further increasing of the dose concentrations to 600 ppm. Finally, a simplified mechanism based on the electrostatic attraction is presented to describe the antimicrobial activity of Ag/PANI nanoporous composite.     

Kinetic Analysis of the Temperature Effect on Polyhydroxyalkanoate Production by <Emphasis Type="Italic">Haloferax mediterranei</Emphasis> in Synthetic Molasses Wastewater

Haloferax mediterranei is an extremely halophilic archaeon that is able to synthesize polyhydroxyalkanoate (PHA) in high salt environment with low sterility demand. In this study, a mathematical model was validated and calibrated for describing the kinetic behavior of H. mediterranei at 15, 20, 25, and 35 °C in synthetic molasses wastewater. Results showed that the production of PHA by H. mediterranei, ranging from 390 to 620 mg h^?1 L^?1, was strongly dependent on the temperature. The specific growth rate (µ _max), specific substrate utilization rate (q _max), and specific decay rate (k _d) of H. mediterranei increased with temperature following Arrhenius equation prediction. The estimated activation energy was 58.31, 25.59, and 22.38 kJ mol^?1 for the process of cell growth, substrate utilization, and cell decay of H. mediterranei, respectively. The high temperature triggered the increased PHA storage even without nitrogen limitation. Thus, working at high temperatures seems a good strategy for improving the PHA productivity of H. mediterranei.     

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.     

Adsorption of Crystal Violet Dye from Aqueous Solution by Poly(Acrylamide-<Emphasis Type="Italic">co</Emphasis>-Maleic Acid)/Montmorillonite Nanocomposite

Poly(acrylamide-co-maleic acid)/montmorillonite nanocomposites, were synthesized via in situ polymerization with different maleic acid and MMT content. The capability of the hydrogel for adsorption of crystal violet (CV) was investigated in aqueous solutions at different pH values and temperatures. The pseudo-second-order kinetics model could fit successfully the adsorption kinetic data. The effects of maleic acid to acrylamide molar ratio (MA_R), weight percent of MMT (MMT%), the pH of medium and the solution temperature (T) on the CV adsorption capacity (q _e ) of adsorbents were studied by Taguchi experimental design approach. The results indicated that increasing the MMT% leads to a greater q _e . The q _e value of adsorbents increased also with increasing both MA_R and pH, while reduced when the temperature of medium increased. The relatively optimum conditions to achieve a maximum CV adsorption capacity for P(AAm/MA)/MMT adsorbents were found as: 0.06 for MA_R and 5 % of MMT%, medium pH = 7 and T = 20 °C.     

Decomposition reactions of epoxy resin and polyetheretherketone resin in sub- and supercritical water

Epoxy resin and polyetheretherketone (PEEK) resin were decomposed into their monomers such as phenol, cresols, and their analogues by thermal treatment in sub- and supercritical water in a 10-ml tubing bomb reactor. The addition of basic compounds such as Na₂CO₃ was effective in promoting the decomposition reaction of the resins. In the reaction of epoxy resin, the yield of identified products reached 10% for the reaction at 703K over 1h. In the reaction of PEEK resin, the total yield of phenol and dibenzofuran reached 88% for the reaction at 703K over 3h. Chemical participation of water in the decomposition reaction was confirmed by the reaction of dinaphthylether.     

Investigation of Biosurfactant Activity and Asphaltene Biodegradation by <Emphasis Type="Italic">Bacillus cereus</Emphasis>

In this research, a biosurfactant-producing bacterium with capability of asphaltene degradation was isolated from oil-contaminated soil samples, and identified as Bacillus cereus. This strain produced an effective biosurfactant in the presence of molasses and the surface tension was reduced to the level of 36.4 mN/m after 48 h under optimum conditions. The optimum values of carbon-to-nitrogen ratio (C:N), pH, and temperature for biosurfactant production were determined as 30:1, 7.3 and 29 °C, respectively, using response surface methodology. The maximum emulsification activity in the culture broth was 53 % after 48 h using kerosene at 25 °C. The goodness of fit of four growth kinetic models including Tessier, Contois, Logistic and Westerhoff was compared for the bacterial growth and molasses utilization of B. cereus in 5-L batch bioreactor during 120 h. Conducted kinetic study showed that biosurfactant production had a good fit with the Contois growth kinetic model (R² = 0.962) and the maximum specific growth rate (µ _max ), saturation constant (K _s ) and the yield of biomass per substrate (Y _x/s ) were determined to be 0.145 h^?1, 1.83 g/L and 0.428 g/g, respectively. The asphaltene biodegradation in flask was evaluated by FTIR analysis and quantified by a spectrophotometer. This bacterium was able to degrade up to 40 % of asphaltene as a sole carbon and energy source after 60 days at 28 °C. The resulting surface tension of 30.2 mN/m with the critical micelle concentration of 23.4 mg/L indicated good efficiency of the biosurfactant.     

Comparison of three ornamental plants for phytoextraction potential of chromium removal from tannery sludge

Based on pre-experimentation, three ornamental plants, Mirabilis jalapa, Impatiens Balsamin (I. Balsamin) and Tagetes erecta L., were selected as target plants to study the phytoextraction of chromium (Cr) in tannery sludge irrigated with four treatments according to Cr concentration gradient [Control (CK); 20.50 × 10³ mg kg^?1 (T1); 51.25 × 10³ mg kg^?1 (T2); 102.50 × 10³ mg kg^?1 (T3)]. Results of pot experiments showed that the biomass of Mirabilis jalapa and Tagetes erecta L. had no significant differences among the four treatments, while I. Balsamin showed a decline trend in the biomass with the increase of Cr concentration, probably due to some extent to the poisoning effect of Cr under treatment T2 or T3. Mirabilis jalapa accumulated Cr concentration, with 408.97, 124.97, 630.16 and 57.30 mg kg^?1 in its roots, stems, leaves and inflorescence, respectively. The translocation factor and the bioaccumulation coefficient of Mirabilis jalapa are each greater than 1, indicating that Mirabilis jalapa has the strong ability to tolerate and enrich Cr by biological processes. Comparing accumulation properties of the three ornamental plants, in the amount and allocation, Mirabilis jalapa showed the highest phytoextraction efficiency and could grow well at the high Cr concentration. Our experiments suggest that Mirabilis jalapa is the expected flower species for Cr removal from tannery sludge.     

In Vivo and In Vitro Degradation Studies for Poly(3-hydroxybutyrate-<Emphasis Type="Italic">co</Emphasis>-3-hydroxyhexanoate) Biopolymer

Studies have shown that the copolymer poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB-co-HHx)] possesses favorable mechanical properties for use in medical supplies and products (e.g., sutures, scaffolds, bone plates). One of the major under-addressed issues associated with the use of biodegradable, bio-based PHA polymers in resorbable medical products is the correlation between the mechanical properties and the in vivo material degradation over time. In this study, P(HB-co-17 mol% HHx) matrices were mechanically tested after either incubation in cultures of human embryonic kidney cells (HEK) for in vitro degradation studies for up to 4 weeks, or inserted into Danio rerio (zebrafish) tissues for in vivo degradation studies for up to 7 weeks. The mechanical properties and scanning electron microscopy (SEM) images of the degraded materials were examined and later correlated to understand the degradation phenomenon. Our results show that Young’s modulus of P(HB-co-17 mol%HHx) during in vitro studies decreased from 3.26 to 2.42 GPa within 4 weeks, and in vivo breakdown resulted in a significant decrease in Young’s modulus with a decrease from 3.26 to 0.51 GPa and a mass loss of 59 % within 7 weeks. SEM images showed the development of pores and cracks on the surface of the material over time. Plasticization and recrystallization were observed and likely play a role in the alteration of mechanical properties.     

Enhancement of biogas production potential from <Emphasis Type="Italic">Acacia</Emphasis> leaf waste using alkaline pre-treatment and co-digestion

The objective of this research was to evaluate possibility of utilizing Acacia leaves (A. mangium and A. auriculiformis), which is an agro-industrial waste from the pulp and paper industry. The effects of alkaline pre-treatment and co-digestion with Napier grass for the enhancement of biogas production from Acacia leaf waste (ALW) were investigated. Six continuous stirred tank reactors with a working volume of 5 L were carried out at the laboratory scale. The results showed that pre-treatment of Acacia leaf waste (pretreated ALW) by soaking in 3 % NaOH for 48 h increased the biogas and methane productivity to 0.200 and 0.117 m³/kgVS_added compared to 0.098 and 0.048 m³/kgVS_added of raw ALW digestion, respectively. Meanwhile, the co-digestion of Acacia leaves with different proportions of Napier grass at ratios of 1:1–1:3 in volatile solid basis also increased the production of biogas and its productivity. The maximum gas production yields of 0.424 and 0.268 m³/kgVS_added for biogas and methane were obtained at 1:3 ratio. This finding affirms the potential of ALW and its possibility to use as biogas feedstock in both single and co-substrate with Napier grass.     

Cure,Mechanical and Swelling Properties of Biocomposites from Chicken Feather Fibre and Acrylonitrile Butadiene Rubber

Biocomposites of acrylonitrile butadiene rubber (NBR) reinforced with chicken feather fibre (CF) were prepared using dicumyl peroxide (DCP) as vulcanizing agent. Composites with three series of chicken feather fibres were studied i.e., raw (RCF), sterilized (SCF) and alkali treated (ACF). The cure characteristics of composites were studied. The mechanical properties of NBR were found to be improved by the incorporation of chicken feather fibre in all forms. Surface modification of the fibre was done by alkaline treatment to improve the interfacial adhesion and it characterised by FTIR. Better properties are shown by the composites with ACF. The swelling behaviour of the composites in N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide and water were analyzed for the swelling coefficient values. The biodegradable characteristics of CF reinforced NBR composites were studied by soil burial test which indicated that it is an eco-friendly and acceptable material. Scanning electron microscopy studies support the results of mechanical properties. The outcome obtained from this study is believed to assist the development of environmentally–friendly composites especially for specific product applications like oil seals, hoses and automobile bushes etc.     

Synthesis,Characterization and Application of Biodegradable Crosslinked Carboxymethyl Chitosan/Poly(Ethylene Glycol) Clay Nanocomposites

Crosslinked carboxymethyl chitosan (CMCh)/poly(ethylene glycol) (PEG) nanocomposites were synthesized using terephthaloyl diisothiocyanate as a crosslinking agent, in presence of montmorillonite (MMT), in different weight ratios of the two matrices. Characterization of nanocomposites was performed using different analyses. Swelling behavior was studied in different buffered solutions. It was found that formation of crosslinked CMCh/PEG nanocomposites increased the swell ability. Metal ions adsorption had also been investigated. The results indicated that crosslinked CMCh adsorbs various metal ions much more than non-crosslinked CMCh. Antimicrobial activity was examined against Gram-positive bacteria (S. aureus (RCMB 010027) and S. Pyogens (RCMB 010015), Gram-negative bacteria (E. coli (RCMB 010056), and also against fungi (A. fumigates (RCMBA 02564, G. candidum (RCMB 05096) and C. albicans (RCMB 05035). Data indicated that most of these nanocomposites exhibited good antimicrobial potency. Degradation studies were carried out in simulated body fluid for different time periods in order to find out the degradation index. Results showed that weight loss (%) of most of the nanocomposites increased as a function of incubation time.     

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.     

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.     

Selective Lead(II) Adsorption and Flocculation Characteristics of the Grafted Sodium Alginate: A Comparative Study

Synthesis of sodium alginate-g-poly(acrylamide-co-N-methylacrylamide) [S-III], sodium alginate-g-poly(N-methylacrylamide-co-N,N-dimethylacrylamide) [S-II], sodium alginate-g-poly(acrylamide-co-N,N-dimethylacrylamide) [S-I]. Sodium alginate-g-poly(N,N-dimethylacrylamide) [SAG-g-PDMA] and sodium alginate-g-poly(acrylamide) [SAG-g-PAM] were prepared by solution polymerization technique using potassium peroxydisulfate as the initiator at 70?°C in water medium. The graft copolymers were characterized by FTIR and NMR (¹H and ¹³C) spectroscopy, SEM and XRD studies. All the five graft copolymers were used to remove Pb(II) ions from the aqueous solution and also in flocculation studies of kaolin clay (1.0 wt%), silica (1.0 wt%) and iron ore slime (0.25 wt%) suspensions. A comparative studies of all the five graft copolymers were also made in both the two cases. The Pb(II) ion removal capacity of all the graft copolymers follows the order S-III?>?SAG-g-PAM?>?S-II?>?SAG-g-PDMA?>?S-I. But the flocculation performance of the graft copolymers follows the order S-II?>?S-I?>?S-III?>?SAG-g-PDMA?>?SAG-g-PAM. S-III was also used for the competitive metal ion removal with Hg(II), Cd(II), Cu(II) and Zn(II). Pb(II) adsorption of S-III (the best Pb(II) ion adsorber) follows pseudo second order rate equation and Langmuir adsorption isotherm.     

Accelerated Stability Testing of a Polyherbal Transdermal Patches Using Polyvinyl Alcohol and Hydroxypropyl Methylcellulose as a Controlling Polymer Layer

The present work was to evaluate the stability potential of (E)-4-(3,4-dimethoxyphenyl)but-3-en-l-ol (Compound D) in polyherbal transdermal patches. The polyherbal formulation composed of the rhizomes of Zingiber cassumunar and Curcuma longa, leaves and stems of Cymbopogon citratus, rind and leaves of Citrus hystrix fruit, and leaves of Acacia rugata and Tamarindus indica. Polyvinyl alcohol and hydroxypropyl methylcellulose were used as a matrix film, and glycerine was used as a plasticizer. Stability testing was established for 6 months under accelerated conditions as according to International Conference on Harmonisation guidelines. Mechanical properties, moisture uptake, swelling ratio, and in vitro studies were evaluated. New Zealand white rabbits were used as the animal model. Results obtained after 6 months showed that the polyherbal transdermal patches were stable, with a good mechanical properties and hydrophilicity. In vitro study kinetics for active Compound D fitted to the Higuchi model for both release and skin permeation. The transdermal patch containing polyherbal formulation was safe to apply on the skin without irritation. Thus, transdermal patches containing this polyherbal formulation had good stability potential, with no irritation on application.