Remarkable Biodegradability Research Articles

Ultra-high flame retardant starch/wood fiber composites based on the synergistic effect of ammonium polyphosphate and calcium carbonate

The development of bio-based composites and products from natural biomass offers a viable solution to the resource and environmental issues caused by non-renewable petrochemical feedstocks. Nevertheless, the high carbon content inherent in biomass renders bio-based materials highly flammable, thereby increasing their susceptibility to fire hazards and limiting their potential applications. In this study, flame retardant starch/wood fiber composites (SWA) were developed, utilizing starch as the matrix, wood fiber as the reinforcing phase, ammonium polyphosphate (APP) as the flame retardant, and calcium carbonate (CaCO3) as both an inorganic filler and a flame retardant synergist. The SWA composites incorporating 5 % (SWA-5) and 10 % (SWA-10) APP achieved UL-94 V-0 rating, with limiting oxygen index (LOI) of 41.5 % and 57.8 %, respectively. Compared to the control group, SWA-10 exhibited significantly reduced heat release and smoke emission rates, with total heat release (THR) and total smoke production (TSP) reduced by 50.4 % and 72 %, respectively. Additionally, SWA-5 exhibited excellent mechanical properties and outstanding thermal insulation, while SWA-10 showed remarkable biodegradability. Therefore, this work developed ultra-high flame retardant bio-based composites with excellent overall performance, making them suitable for thermal insulation and green building applications.

Soil Actinobacteria Exhibit Metabolic Capabilities for Degrading the Toxic and Persistent Herbicide Metribuzin.

Metribuzin, a widely used triazine herbicide, persists in agricultural soils and poses significant environmental pollution threats globally. The aim of this study was to investigate the biodegradation of metribuzin by actinobacterial strains in vitro at different environmental conditions. From an initial screen of 12 actinobacterial strains, four bacteria exhibited robust growth in the presence of the metribuzin as the sole carbon source at 50 mg/L concentration. The optimization of metribuzin biodegradation under different conditions (pH, temperature and inoculum size) using a spectrophotometric method revealed that maximum degradation of metribuzin occurred at a pH of 7.2, a temperature 30 °C, and at an inoculum volume of 4%. Subsequent GC-MS validation confirmed the remarkable biodegradation capabilities of the actinobacterial isolates, where the strain C1 showed the highest rate of metribuzin degradation of 83.12%. Detailed phylogenetic identified the active strains as Streptomyces toxytricini (CH), Streptomyces stelliscabiei (B2), and two Streptomyces heliomycini (C1, C3). Structural analysis by ATR-FTIR spectroscopy confirmed the extensive biotransformation of the herbicide molecule. Our findings highlight the immense untapped potential of soil actinobacteria, particularly the Streptomyces heliomycini C1 strain, as versatile bioremediation agents for removing persistent agrochemical pollutants.

Maximizing diclofenac bioremoval efficiency using Chlorella vulgaris strain H1 and Chlorella sorokiniana strain H2: Unveiling the impact of acetic acid on microalgae

BackgroundDiclofenac (DFC) is a commonly detected pharmaceutical pollutant in wastewater, posing environmental risks. Microalgae have emerged as potential candidates for bioremediation due to their ability to degrade pollutants. This study focuses on investigating the biodegradation potential of two newly isolated microalgae strains, Chlorella vulgaris strain H1 and Chlorella sorokiniana strain H2, towards DFC removal. The optimization of pH is crucial for enhancing the efficiency of bioremediation processes. Therefore, in addition to assessing the biodegradation potential of microalgae, this study also investigates the impact of adjusting the pH of the culture medium using acetic acid as an additional carbon source on the biodegradation process. MethodsThrough genetic analysis using 18S rDNA sequencing, the microalgae strains were identified. Various parameters including growth dynamics, chlorophyll content, cell proliferation, photosynthetic activity, and DFC biodegradation efficiency were comprehensively assessed. Additionally, the impact of incorporating acetic acid as an additional carbon source in the culture medium on the biodegradation process was examined. Significant FindingsC. sorokiniana strain H2 demonstrated superior biodegradation rates compared to C. vulgaris strain H1 across varying DFC concentrations. Specifically, C. sorokiniana strain H2 exhibited remarkable biodegradation rates of 84 %, 83.72 %, and 29.57 % for DFC concentrations of 12.5 mg L−1, 25 mg L−1, and 100 mg L−1, respectively. In contrast, C. vulgaris strain H1 showed lower biodegradation rates of 66.64 %, 29.24 %, and 1.83 % for the corresponding DFC concentrations. The study highlights the potential of C. sorokiniana strain H2 as a promising candidate for the removal of pharmaceutical pollutants like DFC from wastewater. Furthermore, the use of acetic acid as a supplementary carbon source enhanced the biodegradation efficiency, suggesting a potential strategy for optimizing bioremediation processes.

Biodegradable and biocompatible nonisocyanate polyurethanes synthesized from bio-derived precursors

Despite the enormous use of polyurethanes (PUs) in multiple aspects of modern lifestyle, the industrial scale manufacturing of PUs uses toxic chemicals like isocyanates, phosgene till today. In addition, the non-biodegradability and non-biocompatibility of PUs and their debris are serious cause of concerns for the environment. To deal with these challenges, in the current work, a new approach is reported in which bio-derived non-isocyanate polyurethanes were synthesized by exploiting viable amino acid-based diamines and biscyclocarbonates from sebacoyl chloride and diglycerol derivatives in a readily doable process. The newly designed polyhydroxyurethanes (PHUs) exhibited remarkable biodegradability and biocompatibility (cell viability) in comparison with commercial diamine based PHUs. A series of PHUs were synthesized in bulk and solvent free green synthetic route by polycondensing library of amino acids (such as glycine, alanine, valine, and isoleucine etc.) based diamines consisting of varying alkyl chain lengths and biscyclocarbonates like sebacic biscyclocarbonate and diglycerol biscyclocarbonate etc. All the synthesized PHUs were thoroughly characterised by IR, NMR and HRMS spectroscopic techniques. The impact of chain length and molecular structure of the synthesized PHUs were also evaluated using DSC, TGA, SEC, water contact angle measurements and hydrolytic degradation studies. The molar masses of the PHUs obtained from the SEC analysis are in the range of ∼17,000–24,000 Da. The current study demonstrated that amino acids is one of the major degradation products and are biocompatible in in-vitro conditions. The PHUs and their degradable products showed excellent cell viability when studied in HEK293T cells that were carried out using microgram to milligram concentration of PHUs. The outcome of this work in comparison to conventional PHUs and polyurethanes clearly demonstrated good biocompatibility and hence drawing attention to potential applications in bio-adhesives, bio-implants, drug delivery, and green coatings etc. in the near future.

Low-Cost Production of Chitosan Biopolymer from Seafood Waste: Extraction and Physiochemical Characterization

Chitosan is an abundant natural biopolymer widely used in industrial and pharmaceutical applications. It stands out for its remarkable biodegradability, biocompatibility, and versatility. Herein, we tried to extract chitosan from mud crab (Scylla spp.), a seafood waste abundantly found in Bangladesh’s growing crab farming industry, via a simple low-cost production route. At first, chitin was extracted from crab shells through demineralization and deproteinization to eliminate minerals and proteins. The chitosan biopolymer was then obtained by deacetylation of purified chitin. To evaluate its physicochemical properties, the as-prepared chitosan was characterized by different analyses, such as water and fat binding capacity, solubility, viscosity, molecular weight, fourier transform-infrared, thermogravimetric, scanning electron microscopy, and ash content analysis. The results showed that the crab shell contains around 26.8% chitosan by dry weight, making it an excellent raw material for the massive production of the natural biopolymer chitosan. The prepared chitosan showed fat and water binding capacities of 200-300% and ~680.9%, respectively. Furthermore, it was highly soluble in 1% acetic acid and had an ash content of about 33.7%. Convincingly, the produced chitosan showed great physiochemical properties making it suitable for biomass efficiency, sustainable development, revenue generation, and biomedical applications. In addition, the recycling of seafood waste into a valued product is beneficial to help keep the environment clean, which is among the sustainability goals in Bangladesh and globally.

Screening and Evaluation of Biodegradation Potential of Bacterial Isolates Against Ethidium Bromide

Ethidium bromide (EtBr), an intercalating agent that is often employed in molecular biology procedures can bind to the DNA's minor groove, which can result in a variety of undesirable repercussions. EtBr is classified as one of the most lethal carcinogens, which makes its disposal extremely challenging and expensive. Reckless and irresponsible disposal of hazardous items can have severe impacts on the ecosystem and cause the environment's natural resources to wither away. Therefore, our study focuses on the isolation of bacterial isolates from different sources that have biodegradation potential against EtBr. Different bacterial isolates obtained from sewage water, tap water, and soil were grown in Luria Bertani (LB) broth and Nutrient agar (NA), followed by their screening and identification by performing various biochemical tests. All the isolates were grown in two different concentrations of EtBr (i.e., 30 g/ml and 60 g/ml) to determine their ability to degrade EtBr. For the current investigation, bacterial isolates obtained from the tap water (IS1, IS2, IS3, IS4, IS5, IS6) and sewage water (IS7, IS8, IS9, IS10, IS11, IS12, IS13) have shown degrading potential against EtBr at the concentration of 30µg/ml after 2 and 5 days, respectively, whereas, the bacterial isolates obtained from tap water (IS1, IS2, IS3, IS4, IS5, IS6) and sewage water (IS7, IS8, IS9, IS10, IS11, IS12, IS13) have shown degradation potential against EtBr at the concentration of 60µg/ml after 5 days and 8 days, respectively. All the isolates demonstrated EtBr bioaccumulation and were visible as vivid orange colonies under a UV transilluminator. None of the isolates obtained from the soil sample were able to degrade EtBr. The outcomes of the current investigation suggest that several bacterial isolates which were isolated from tap water and sewage water had remarkable biodegradation capacity against EtBr. The unique ability of bacterial isolates to biodegrade and accumulate EtBr can contribute to the improvement of the quality and safety of our environment. Further research into these isolates' potential for biodegrading various xenobiotics and dangerous substances could be very helpful in reducing the environment's rising toxicant concentrations.

Comparative Bioremediation of Tetradecane, Cyclohexanone and Cyclohexane by Filamentous Fungi from Polluted Habitats in Kazakhstan.

Studying the fates of oil components and their interactions with ecological systems is essential for developing comprehensive management strategies and enhancing restoration following oil spill incidents. The potential expansion of Kazakhstan's role in the global oil market necessitates the existence of land-specific studies that contribute to the field of bioremediation. In this study, a set of experiments was designed to assess the growth and biodegradation capacities of eight fungal strains sourced from Kazakhstan soil when exposed to the hydrocarbon substrates from which they were initially isolated. The strains were identified as Aspergillus sp. SBUG-M1743, Penicillium javanicum SBUG-M1744, SBUG-M1770, Trichoderma harzianum SBUG-M1750 and Fusarium oxysporum SBUG-1746, SBUG-M1748, SBUG-M1768 and SBUG-M1769 using the internal transcribed spacer (ITS) region. Furthermore, microscopic and macroscopic evaluations agreed with the sequence-based identification. Aspergillus sp. SBUG-M1743 and P. javanicum SBUG-M1744 displayed remarkable biodegradation capabilities in the presence of tetradecane with up to a 9-fold biomass increase in the static cultures. T. harzianum SBUG-M1750 exhibited poor growth, which was a consequence of its low efficiency of tetradecane degradation. Monocarboxylic acids were the main degradation products by SBUG-M1743, SBUG-M1744, SBUG-M1750, and SBUG-M1770 indicating the monoterminal degradation pathway through β-oxidation, while the additional detection of dicarboxylic acid in SBUG-M1768 and SBUG-M1769 cultures was indicative of the fungus' ability to undertake both monoterminal and diterminal degradation pathways. F. oxysporum SBUG-M1746 and SBUG-M1748 in the presence of cyclohexanone showed a doubling of the biomass with the ability to degrade the substrate almost completely in shake cultures. F. oxysporum SBUG-M1746 was also able to degrade cyclohexane completely and excreted all possible metabolites of the degradation pathway. Understanding the degradation potential of these fungal isolates to different hydrocarbon substrates will help in developing effective bioremediation strategies tailored to local conditions.

Soil Biodegradation Resistance of Cotton Fiber Doped with Interior and Exterior Silver Nanoparticles.

Engineering fibers with nanomaterials is an effective way to modify their properties and responses to external stimuli. In this study, we doped cotton fibers with silver nanoparticles, both on the surface (126 ± 17 nm) and throughout the fiber cross section (18 ± 4 nm), and examined the resistance to soil biodegradation. A reagent-free one-pot treatment of a raw cotton fabric, where noncellulosic constituents of the raw cotton fiber and starch sizing served as reducing agents, produced silver nanoparticles with a total concentration of 11 g/kg. In a soil burial study spanning 16 weeks, untreated cotton underwent a sequential degradation process-fibrillation, fractionation, and merging-corresponding to the length of the soil burial period, whereas treated cotton did not exhibit significant degradation. The remarkable biodegradation resistance of the treated cotton was attributed to the antimicrobial properties of silver nanoparticles, as demonstrated through a test involving the soil-borne fungus Aspergillus flavus. The nonlinear loss behavior of silver from the treated cotton suggests that nanoparticle depletion in the soil depends on their location, with interior nanoparticles proving durable against environmental exposure.

Copper-Cystine Biohybrid-Embedded Nanofiber Aerogels Show Antibacterial and Angiogenic Properties.

Copper-cystine-based high aspect ratio structures (CuHARS) possess exceptional physical and chemical properties and exhibit remarkable biodegradability in human physiological conditions. Extensive testing has confirmed the biocompatibility and biodegradability of CuHARS under diverse biological conditions, making them a viable source of essential Cu2+. These ions are vital for catalyzing the production of nitric oxide (NO) from the decomposition of S-nitrosothiols (RSNOs) found in human blood. The ability of CuHARS to act as a Cu2+ donor under specific concentrations has been demonstrated in this study, resulting in the generation of elevated levels of NO. Consequently, this dual function makes CuHARS effective as both a bactericidal agent and a promoter of angiogenesis. In vitro experiments have shown that CuHARS actively promotes the migration and formation of complete lumens by redirecting microvascular endothelial cells. To maximize the benefits of CuHARS, they have been incorporated into biomimetic electrospun poly(ε-caprolactone)/gelatin nanofiber aerogels. Through the regulated release of Cu2+ and NO production, these channeled aerogels not only provide antibacterial support but also promote angiogenesis. Taken together, the inclusion of CuHARS in biomimetic scaffolds could hold great promise in revolutionizing tissue regeneration and wound healing.

Mechanical Integrity and In vitro Degradation Behavior of Mg–Zn–Ca Biodegradable Alloy Prepared by Different Casting Technologies

Mg–Zn–Ca alloys have been widely used as biodegradable orthopedic and cardiovascular scaffolds because of their non-cytotoxicity, remarkable biodegradability, good biocompatibility and excellent mechanical properties similar to human bone. However, degradation causes poor corrosion resistance and mechanical properties. In this study, Mg-6%Zn-0.6%Ca alloys were produced using three distinct methodologies: casting, casting via the ultrasonic vibration process (USV), and casting via the mechanical vibration process (MV). Surface characterization, mechanical characteristics and corrosion resistance of the as-cast (untreated) and treated species were studied. The morphology and microstructure showed that the grain size of the as-cast, MV and USV specimens all had average grain sizes of about 191, 93 and 82 µm, respectively. The ultrasonic vibration treated specimen has the greatest degree of grain refinement. Mechanical tests showed that microstructure refinement promotes the mechanical characteristics of Mg alloy, such as compression, ultimate tensile strength as well as elongation. It was observed that the USV-treated sample has exceptional mechanical properties (Compressive strength 360.64 MPa, ultimate tensile strength (UTS) 178.41 MPa and Elongation 3.45%). Corrosion tests revealed that the USV-treated specimen exhibited uniform corrosion and low corrosion rate due to uniform compact fine grains with higher oxide concentration of about 42.82 wt%. The results of electrochemical analyses revealed that the average corrosion rate obtained from Potentiodynamic polarization curves of the as-cast, MV and USV specimens was about 5.3144, 4.5311 and 4.1087 mm/year, respectively and the passive film resistance (Rf) that was obtained from the electrochemical impedance spectroscopy (EIS) model of the USV, MV-treated samples and as-cast sample was 457 Ω, 430 Ω and 204 Ω, respectively. The results of immersion tests revealed that the USV-treated sample lost less weight and exhibits a relatively low degradation rate than the as-cast and MV-treated samples. After two weeks the weight of the as-cast, MV and USV samples decreased by about 18.6%, 18.5%, 16.8%., and the degradation rates were 7.304, 7.097 and 6.78 mm/y, respectively, and then gradually declining over the course of the immersion period.

Peptide- and Metabolite-Based Hydrogels: Minimalistic Approach for the Identification and Characterization of Gelating Building Blocks.

Minimalistic peptide- and metabolite-based supramolecular hydrogels have great potential relative to traditional polymeric hydrogels in various biomedical and technological applications. Advantages such as remarkable biodegradability, high water content, favorable mechanical properties, biocompatibility, self-healing, synthetic feasibility, low cost, easy design, biological function, remarkable injectability, and multi-responsiveness to external stimuli make supramolecular hydrogels promising candidates for drug delivery, tissue engineering, tissue regeneration, and wound healing. Non-covalent interactions such as hydrogen bonding, hydrophobic interactions, electrostatic interactions, and π-π stacking interactions play key roles in the formation of peptide- and metabolite-containing low-molecular-weight hydrogels. Peptide- and metabolite-based hydrogels display shear-thinning and immediate recovery behavior due to the involvement of weak non-covalent interactions, making them supreme models for the delivery of drug molecules. In the areas of regenerative medicine, tissue engineering, pre-clinical evaluation, and numerous other biomedical applications, peptide- and metabolite-based hydrogelators with rationally designed architectures have intriguing uses. In this review, we summarize the recent advancements in the field of peptide- and metabolite-based hydrogels, including their modifications using a minimalistic building-blocks approach for various applications.

The Performance of Chitosan-based Activated Carbon for Supercapacitor Applications towards Sustainable Energy Technologies

In sustainable technologies, the application of supercapacitors (SC) for energy conversion and storage systems is rapidly increasing. Supercapacitors are widely employed in applications that require fast charge and discharge phases, such as in the automobile industry, where they are utilized in energy storage. Chitosan (CS) is a natural polymer material utilized in supercapacitor fabrication. Interest in supercapacitors is due to their high-energy capacity, storage for a shorter period, and longer lifetime. In this research, the fabrication of symmetric supercapacitors with activated carbon (AC) electrodes has been investigated in order to analyze their performance characteristics. AC is derived from CS biomass, which has remarkable biodegradability. It has been chemically activated using ZnCl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> as the activating agent. CS has been activated inside a furnace at 500, 600, and 700°C in an inert N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> atmosphere. A 1M aqueous potassium hydroxide (KOH) solution is used as the electrolyte. The test using electrolytes (KOH) revealed that the electrode's specific capacitance was 74.7 Fg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , the highest value discovered. However, using organic electrolytes would have produced better results that can be used as a guide for future advancements. The influence of activation temperature on the porous characteristics of prepared AC was investigated utilizing surface area and pore size analyses. The morphological characteristics of synthesized AC were analyzed through scanning electron microscopy (SEM) and Energy Dispersive X-Ray Analysis (EDX). Symmetric SC electrodes fabricated is analyzed in a two-electrode system applying standard electrochemical characterization methods using the potentiostat. Symmetric SC electrodes fabricated are analyzed in a two-electrode system applying standard electrochemical characterization methods using the potentiostat.

Towards biodegradable conducting polymers by incorporating seaweed cellulose for decomposable wearable heaters.

Thermotherapy shows significant potential for pain relief and enhanced blood circulation in wildlife rehabilitation, particularly for injured animals. However, the widespread adoption of this technology is hindered by the lack of biodegradable, wearable heating pads and concerns surrounding electronic waste (E-waste) in natural habitats. This study addresses this challenge by investigating an environmentally-friendly composite comprising poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), seaweed cellulose, and glycerol. Notably, this composite exhibits remarkable biodegradability, losing half of its weight within one week and displaying noticeable edge degradation by the third week when placed in soil. Moreover, it demonstrates impressive heating performance, reaching a temperature of 51 °C at a low voltage of 1.5 V, highlighting its strong potential for thermotherapy applications. The combination of substantial biodegradability and efficient heating performance offers a promising solution for sustainable electronic applications in wildlife rehabilitation and forest monitoring, effectively addressing the environmental challenges associated with E-waste.

Rapid synthesis and optimization of UV-photopolymerized cassava starch-based superabsorbent hydrogels as a biodegradable, low-cost, and effective adsorbent for MB removal

In this work, eco-friendly superabsorbent hydrogel (SAH) films based on cassava starch (CSt) and polyacrylic acid (PAA) were successfully fabricated and optimized via a one-pot synthesis and UV-photopolymerization under an air atmosphere to obtain the highest swelling ratio (Seq) and to be employed as an effective adsorbent for removing methylene blue (MB). The optimal CSt-g-PAA film exhibited uniform porous structures with a high specific surface area (24.99 m2/g), acceptable Young’s modulus (60.9 MPa), and a relatively high Seq value (35,645% or 356 g/g). It also revealed selective adsorption toward MB dye. The adsorption process of MB onto CSt-g-PAA SAH followed the pseudo-second-order and Langmuir isotherm models. The maximum adsorption capacity (qm), partition coefficient (PC), and removal efficiency for MB adsorption were evaluated to be 1,044 mg/g, 4.08 mg/g.µM−1, and 95%, respectively, making the CSt-g-PAA SAH film one of the most efficient starch-based adsorbents for MB removal. Thermodynamic studies indicated spontaneous and endothermic adsorption. The plausible adsorption mechanism was mainly described by electrostatic interaction and hydrogen bonding. Furthermore, the prepared CSt-g-PAA SAH film displayed excellent reusability, remarkable biodegradability, good biosafety, and low cost. Therefore, it may be a promising and sustainable adsorbent for removing dye pollutants and enhancing the ecosystem.

Immobilization of psychrophile Psychrobacter sp. ANT206 onto novel reusable magnetic nanoparticles and its application for nitro-aromatic compounds biodegradation under low temperature.

Efficient biodegradation may offer a solution for the treatment of nitro-aromatic compounds (NACs) with toxicity, mutagenicity and persistence in the environment. In this study, dopamine (DA) functionalized magnetic nanoparticles with biocompatibility and hydrophilicity were synthesized and utilized for the immobilization of nitro-aromatic compounds degrading psychrophile Psychrobacter sp. ANT206 harboring the cold-adapted nitroreductase. The prepared nanocarriers were characterized using multiple methods. The highest immobilization yield of cells immobilized by Fe3O4@SiO2@DA was 90.67% under the optimized conditions of 10°C, pH 7.5, 2h and cell/support 1.2mg/mg, and the activity recovery was 89.41%. In addition, the obtained immobilized cells displayed excellent salinity stability and reusability. Moreover, immobilized P. sp. ANT206 strains showed remarkable biodegradation capability on nitrobenzene and p-nitrophenol. This study introduced those novel Fe3O4@SiO2@DA nanoparticles could be applied as ideal and low-cost nanocarriers for the immobilization of cells and large-scale bioremediation of hazardous NACs with perspective applications under low temperature.

Screening and metabolic potential of fungal strains isolated from contaminated soil and sediment in the polychlorinated biphenyl degradation

Polychlorinated biphenyls (PCBs) are widespread persistent pollutants deleterious for environment and very dangerous for human kind. As the bioremediation of PCB polluted sites by model white-rot fungi is still unsatisfactory, the use of efficient native strains which have the natural capacity to develop on polluted sites may constitute a relevant alternative strategy. In this study, we isolated 12 fungal strains from PCB contaminated soil and sediment, improved the screening method to obtain the most efficient ones in biodegradation and detoxification of PCBs and characterized potential underlying enzymatic activities. Four strains Penicillium chrysogenum, P. citreosulfuratum, P. canescens and Aspergillus jensenii, showed remarkable biodegradation capacities, greater than 70%. The remaining PCB-toxicity of their culture, including that of Trametes versicolor and Acremonium sclerotigenum, which present interesting ecological and metabolic properties, was studied. Only P. canescens was able to significantly reduce the toxicity related to PCBs and their metabolites. The enzymatic activities induced by PCBs were different according to the strains, namely laccases in T. versicolor and peroxidases in Ac. sclerotigenum. Our promising results show that the use of native fungal strains can constitute an effective strategy in the depollution of PCB polluted sites.

A soft tissue fabricated using a freeze-drying technique with carboxymethyl chitosan and nanoparticles for promoting effects on wound healing

Objective(s): Many people suffer from skin injuries due to various problems such as burns and accidents. Therefore, it is essential to shorten treatment time and providing strategies that can control the progression of the wound that would be effective in wound healing process and also reduce its economic costs.Methods: The present study aimed to prepare a nanocomposite dressing (NCD)composed of carboxymethyl chitosan (CMC), and Fe2O3 nanoparticles by a method called freeze-drying (FD) technique. The effect of different weight percentages of Fe2O3 (0, 2.5, 5, and 7.5 wt%) reinforcement on mechanical and biological properties such as tensile strength, biodegradability, and cell behavior was evaluated. Also, the X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used to characterize the soft porous membrane. The biological response in the physiological saline was performed to determine the rate of degradation of NCD in phosphate buffer saline (PBS) for a specific time.Results: The obtained results demonstrated that the wound dress was porousarchitecture with micron-size interconnections. In fact, according to the results, as the magnetite nanoparticles amount increases, the porosity increases too. On the other hand, the tensile strength was 0.32 and 0.85 MPa for the pure sample and the sample containing the highest percentage of magnetic nanoparticles, respectively.Besides, the cytotoxicity of this nanocomposite was determined by MTT assays for 7 days and showed no cytotoxicity toward the growth of fibroblasts cells and had proper in vitro biocompatibility. The obtained results revealed that NCD had remarkable biodegradability, biocompatibility, and mechanical properties. Therefore, NCD composed of CMC and Fe2O3 nanoparticles was introduced as a promising candidate for wound healing applications.Conclusions: According to the obtained results, the optimum NCD specimen with 5 wt% Fe2O3 has the best mechanical and biological properties.

Application of activated carbon to enhance biogas production rate of Flammulina velutipes residues with composting pretreatment

Activated carbon can not only alleviate toxicity of harmful substances to microorganisms but also enhance direct interspecies electron transfer (DIET) during anaerobic digestion. Therefore, this study aimed at investigating the effect of powder activated carbon (PAC) on anaerobic digestion of Flammulina velutipes residues which were pretreated by aerobic composting with production of alcohols and volatile fatty acids (VFAs). Results show the starting time of methane production peak period emerged at the 4th day for the PAC-treatment comparing with the 15th day for the control, implying PAC application enhanced methane production rate significantly by alleviating the inhibitory effect of isopropanol and propionic acid regarding remarkable biodegradation of alcohols and VFAs from composting. A Gompertz curve fitting also indicated that the PAC-treatment possessed the greatest rate constant of biogas (0.1847) and methane (0.1793) production. Fourier transform infrared spectra analysis indicated that PAC could facilitated to the decomposition of recalcitrant cellulose, protein, lipid and polysaccharides. Furthermore, addition of PAC could enrich more vadinBC27_wastewater-sludge_group with electrochemical activity and Methanosarcina with ability to accept electrons from carbon-based mediator, suggesting that vadinBC27_wastewater-sludge_group might participate in DIET with Methanosarcina and therefore PAC could promote syntrophic association between bacteria and methanogens via DIET.

Using scrap zero valent iron to replace dissolved iron in the Fenton process for textile wastewater treatment: Optimization and assessment of toxicity and biodegradability

A Fenton like advanced oxidation process (AOP) employing scrap zerovalent iron (SZVI) and hydrogen peroxide (H2O2) was studied for industrial textile wastewater treatment from a textile manufacturing plant located at Medellín, Colombia (South America). The wastewater effluent studied contains a mixture of organic compounds resistant to conventional treatments. The effect of initial pH and SZVI concentration and H2O2 concentration were studied by a response surface methodology (RSM) Box-Behnken design of experiment (BBD). The combined SZVI/H2O2 process led to reductions of 95% color, 76% of chemical oxygen demand (COD) and 71% of total organic carbon (TOC) at optimal operating conditions of pH = 3, SZVI = 2000 mg/L and [H2O2] = 24.5 mM. Molecular weight distribution measurement (MWD), ultraviolet–visible (UV–Vis) spectroscopy, HPLC, biodegradability and toxicity were used to characterize the pollutants after the treatment process finding that the resulting effluent was polluted mostly by low molecular weight carboxylic acids. A remarkable biodegradability enhancement of the effluent was evidenced by a BOD5/COD ratio increase from 0.22 to 0.4; also, the SZVI/H2O2 process successfully reduced the toxicity from 60% to 20% of dead A. Salina crustaceans.

2-Hydroxyethyl-1-ammonium 3-hydroxypropane-1-sulfonate: a biodegradable and recyclable ionic liquid for the one-pot synthesis of 2-amino-3-cyano-4H-pyrans

2-Hydroxyethyl-1-ammonium 3-hydroxypropane-1-sulfonate ‘HAHS’ was synthesized as a novel ionic liquid and characterized by various techniques. ‘HAHS’ ionic liquid was efficiently applied as a multifunctional promoter for the three-component synthesis of 2-amino-3-cyano-4H-pyrans. The 2-amino-3-cyano-4H-pyrans were produced not only in high to excellent yields but also no toxic solvent or catalyst was used. ‘HAHS’ ionic liquid was recovered and reused four times without the considerable decreasing in its activity. The effect of hydroxyl groups in the structure of ‘HAHS’ ionic liquid on its catalytic activity was studied. Moreover, the biodegradability potential of the ionic liquid was examined using the 5-day biological oxygen demand closed bottle test and the results showed that ‘HAHS’ has remarkable biodegradability potential.