Treatment of simulated Reactive Yellow 22 (azo) dye effluents using Spirogyra species

The potential of commonly available green algae belonging to Spirogyra species was investigated as viable biomaterials for biological treatment of simulated synthetic azo dye (Reactive Yellow 22) effluents. The results obtained from the batch experiments revealed the ability of the algal species in removing the dye colour and was dependent both on the dye concentration and algal biomass. Maximum dye colour removal was observed on the third day for all the system conditions. Monitoring of ORP values helped to understand the overlying biochemical mechanism of algal-dye system. Based upon the results, the dye-algal treatment mechanism was attributed to biosorption (sorption of dye molecules over the surface of algal cells), bioconversion (diffusion of dye molecules into the algal cells and subsequent conversion) and biocoagulation (coagulation of dye molecules present in the aqueous phase onto the biopolymers released as metabolic intermediates during metabolic conversion of dye and subsequent settlement).     

Is There a Generic Environmental Advantage for Starch–PVOH Biopolymers Over Petrochemical Polymers?

The current study was undertaken to address the general question of whether there is an environmental advantage for renewable, starch?Cpolyvinyl alcohol (PVOH) biopolymer blends over petrochemical polymers. This was addressed using life cycle assessment (LCA) over a set of multiple case studies based on a consistent set of parameters and methodological background. A group of starch?CPVOH blended biopolymers derived from different feedstocks (wheat, potato, maize) were compared with high density polyethylene (HDPE), low density polyethylene (LDPE) and expanded polystyrene (EPS) in a range of applications. The results suggest that a general environmental advantage does not exist for the starch?CPVOH blended biopolymers over their petrochemical counterparts in all applications and, instead, a case-by-case approach is necessary to evaluate environmental pros and cons, based on specific comparisons. Overall, starch?CPVOH biopolymers were found to offer environmentally superior options to LDPE in thermal packaging applications. However, this was not the case in other applications, where the outcome of comparisons between starch?CPVOH biopolymers and HDPE/EPS varied according to various factors, including the specific end-of-life scenarios and the recycled content of the petrochemical polymers. A hierarchy of critical parameters for LCA-based decision-making concerning starch?CPVOH biopolymers is suggested as a general outcome of this research.     

Construction, Characterization and Biological Activity of Chiral and Thermally Stable Nanostructured Poly(Ester-Imide)s as Tyrosine-Containing Pseudo-Poly(Amino Acid)s

In this paper we studied the synthesis of biodegradable optically active poly(ester-imide)s containing different amino acid residues in the main chain. These pseudo-poly(amino acid)s were synthesized by polycondensation of N,N′-(pyromellitoyl)-bis-l-tyrosine dimethyl ester as a diphenolic monomer and two chiral trimellitic anhydride-derived diacid monomers containing s-valine and l-methionine. The direct polycondensation reaction of these diacids with aromatic diol was carried out in a system of tosyl chloride (TsCl), pyridine (Py) and N,N′-dimethylformamide (DMF) as a condensing agent. The structures and morphology of these polymers were studied by FT-IR, ¹H-NMR, powder X-ray diffraction, field emission scanning electron microscopy (FE-SEM), specific rotation, elemental and thermogravimetric analysis (TGA) techniques. TGA profiles indicate that the resulting PEIs have a good thermal stability. Morphology probes showed these polymers were noncrystalline and nanostructured polymers. The monomers and prepared polymers were buried under the soil to study the sensitivity of the monomers and the obtained polymers to microbial degradation. The high microbial population and prominent dehydrogenase activity in the soil containing polymers showed that the synthesized polymers are biologically active and microbiologically biodegradable. Wheat seedling growth in the soil buried with synthetic polymers not only confirmed non-toxicity of polymers but also showed possibility of phyto-remediation in polymer-contaminated soils.     

Effect of the Pretreatment with UV and Gamma Radiations on the Modification of Plywood Surface by Photocuring with Epoxy Acrylate

In order to further improve the physical properties of plywood surface that was pretreated with UV and Gamma radiation at different radiation intensities before photocuring. After pretreatment with radiation the plywood surface was coated with different prepared formulations containing epoxyacrylate (EA-1020) as an oligomer, difunctional monomers such as tripropylene glycol diacrylate (TPGDA), 2-hexadioldiacrylate (HDDA), Ethylene Glycol dimethacrylate (EGDMA) and trifunctional monomer trimethyl propen triacrylate (TMPTA) with photoinitiator Darocur 1664. Thin polymer films were prepared on glass plate with these formulated solutions and cured under UV radiation. Pendulum hardness (PH) and gel content of the film were studied for selecting the formulations as top coat and as base coat. The polished plywood surface was coated with selected formulation and cured under UV radiation. Various rheological properties of UV cured plywood surface such as pendulum hardness, scratch hardness, microgloss, adhesion strength, percentage chipped off area and abrasion resistance were studied.     

Structural Differences Between Lignin Model Polymers Synthesized from Various Monomers

In a plant cell wall, lignin is synthesized from several monomeric precursors, combined in various ratios. The variation in monomer type and quantity enables multifunctional role of lignin in plants. Thus, it is important to know how different combinations of lignin monomers impact variability of bond types and local structural changes in the polymer. Lignin model polymers are a good model system for studies of relation between variations of the starting monomers and structural variations within the polymer. We synthesized lignin model polymers from three monomers, CF??based on coniferyl alcohol and ferulic acid in monomer proportions 5:1 and 10:1 (w/w), CP??based on coniferyl alcohol and p-coumaric acid in proportion 10:1 (w/w) and CA??based on pure coniferyl alcohol. We studied structural modifications in the obtained polymers, by combining fluorescence microscopy and spectroscopy, FT-IR and Raman spectroscopy, in parallel with determination of polymers?? molecular mass distribution. The differences in the low M _w region of the distribution curves of the 10:1 polymers in comparison with the CA polymer may be connected with the increased content of C=C bonds and decreased content of condensed structures, as observed in FT-IR spectra and indicated by the analysis of fluorescence spectra. The 5:1 CF polymer contains a different type of structure in comparison with the 10:1 CF polymers, reflected in its simpler M _w distribution, higher homogeneity of the fluorescence emitting structures and in the appearance of a new high-wavelength emission component. We propose that this component may originate from ??-conjugated chains, which are longer in this polymer. The results are a contribution to the understanding of the involvement of structural variations of lignin polymers in the cell wall structural plasticity.     

Water Aided Fabrication of Whey and Albumin Plastics

Development of polymeric materials that can reduce the reliance on petroleum derived synthetic polymers involves biopolymers such as proteins, starch, cellulose and lipids which can be obtained as agricultural co-products or by-products. Specifically, bioplastics from protein feedstock may have significant advantages over traditional plastics, especially in areas such as packaging, agriculture, horticulture and medical materials. This article focuses on fabricating plastics from whey and albumin proteins and describing properties of plastics made from them. These protein biomasses were plasticized using water and compression molded into plastic samples. Results indicated the importance of water on plasticization during fabrication and on mechanical performance later due to densification during drying.     

The Synthesis and FTIR, Kinetics and TG/DTG/DTA Study of Inter Penetrating Polymer Networks (IPNs) Derived from Polyurethanes of Glycerol Modified Castor Oil and Cardanol Based Dyes

Interpenetrating polymer networks from agricultural products such as glycerol modified castor oil polyurethanes and cardanol based dyes have not been extensively studied so far. Such polymers were synthesized using benzoyl peroxide as initiator and ethylene glycol dimethacrylate as cross-linker. Characterizations of these polymers were performed by Fourier Transform infra red spectra and thermal analysis techniques such as thermogravimetric analysis, derivative thermogravimetry and differential thermal analysis. The kinetic parameters such as activation energies and orders of reaction were estimated by using Freeman?CAnderson??s method. The effects of changes in polyurethane to dye monomer weight ratio and NCO/OH molar ratio of polyurethanes on the properties of such polymers were studied.     

Recent Advancement of Biopolymers and Their Potential Biomedical Applications

Journal of Polymers and the Environment - Recently, the advantages of biopolymers over conventional plastic polymers are unprecedented, provided that they are used in situations in which they raise...     

Syntheses of Biodegradable Functional Polymers by Radical Ring-Opening Polymerization of 2-Methylene-1,3,6-trioxocane

2-Methylene-1,3,6-trioxocane (MTC) was polymerized via ring-opening in the presence of a radical initiator and the obtained polyester was biodegradable. MTC could also copolymerize with various vinyl monomers such as styrene, vinyl acetate, methyl vinyl ketone, N-vinyl-2-pyrrolidone, N-isopropyl acrylamide, and maleic anhydride. By copolymerizing MTC with these vinyl monomers in the presence of a radical initiator, we could obtain various biodegradable polymers with ester group introduced into the backbone. In addition the obtained copolymers exhibit certain functionalities such as photolysis, water-solubility, thermosensitivity, detergent builder, and water-absorbability.     

Pyrolysis and catalytic pyrolysis as a recycling method of waste CDs originating from polycarbonate and HIPS

Pyrolysis appears to be a promising recycling process since it could convert the disposed polymers to hydrocarbon based fuels or various useful chemicals. In the current study, two model polymers found in WEEEs, namely polycarbonate (PC) and high impact polystyrene (HIPS) and their counterparts found in waste commercial Compact Discs (CDs) were pyrolysed in a bench scale reactor. Both, thermal pyrolysis and pyrolysis in the presence of two catalytic materials (basic MgO and acidic ZSM-5 zeolite) was performed for all four types of polymers. Results have shown significant recovery of the monomers and valuable chemicals (phenols in the case of PC and aromatic hydrocarbons in the case of HIPS), while catalysts seem to decrease the selectivity towards the monomers and enhance the selectivity towards other desirable compounds.     

Landfill mining: a critical review of two decades of research

Landfills have historically been seen as the ultimate solution for storing waste at minimum cost. It is now a well-known fact that such deposits have related implications such as long-term methane emissions, local pollution concerns, settling issues and limitations on urban development. Landfill mining has been suggested as a strategy to address such problems, and in principle means the excavation, processing, treatment and/or recycling of deposited materials. This study involves a literature review on landfill mining covering a meta-analysis of the main trends, objectives, topics and findings in 39 research papers published during the period 1988-2008. The results show that, so far, landfill mining has primarily been seen as a way to solve traditional management issues related to landfills such as lack of landfill space and local pollution concerns. Although most initiatives have involved some recovery of deposited resources, mainly cover soil and in some cases waste fuel, recycling efforts have often been largely secondary. Typically, simple soil excavation and screening equipment have therefore been applied, often demonstrating moderate performance in obtaining marketable recyclables. Several worldwide changes and recent research findings indicate the emergence of a new perspective on landfills as reservoirs for resource extraction. Although the potential of this approach appears significant, it is argued that facilitating implementation involves a number of research challenges in terms of technology innovation, clarifying the conditions for realization and developing standardized frameworks for evaluating economic and environmental performance from a systems perspective. In order to address these challenges, a combination of applied and theoretical research is required.     

Synthesis and Characterization of Lactic Acid Oligomers: Evaluation of Performance as Poly(Lactic Acid) Plasticizers

The use of fully bio-based and biodegradable materials for massive applications, such as food packaging, is an emerging tendency in polymer research. But the formulations proposed in this way should preserve or even increase the functional properties of conventional polymers, such as transparency, homogeneity, mechanical properties and low migration of their components to foodstuff. This is not always trivial, in particular when brittle biopolymers, such as poly(lactic acid) (PLA), are considered. In this work the formulation of innovative materials based on PLA modified with highly compatible plasticizers, i.e. oligomers of lactic acid (OLAs) is proposed. Three different synthesis conditions for OLAs were tested and the resulting additives were further blended with commercial PLA obtaining transparent and ductile materials, able for films manufacturing. These materials were tested in their structural, thermal and tensile properties and the best formulation among the three materials was selected. OLA with molar mass (M_n) around 1,000 Da is proposed as an innovative and fully compatible and biodegradable plasticizer for PLA, able to replace conventional plasticizers (phthalates, adipates or citrates) currently used for films manufacturing in food packaging applications.     

Adsorption of malachite green on groundnut shell waste based powdered activated carbon

In the present technologically fast changing situation related to waste management practices, it is desirable that disposal of plant waste should be done in a scientific manner by keeping in view economic and pollution considerations. This is only possible when the plant waste has the potential to be used as raw material for some useful product. In the present study, groundnut shell, an agricultural waste, was used for the preparation of an adsorbent by chemical activation using ZnCl2 under optimized conditions and its comparative characterisation was conducted with commercially available powdered activated carbon (CPAC) for its physical, chemical and adsorption properties. The groundnut shell based powdered activated carbon (GSPAC) has a higher surface area, iodine and methylene blue number compared to CPAC. Both of the carbons were used for the removal of malachite green dye from aqueous solution and the effect of various operating variables, viz. adsorbent dose (0.1-1 g l(-1)), contact time (5-120 min) and adsorbate concentrations (100-200 mg l(-1)) on the removal of dye, has been studied. The experimental results indicate that at a dose of 0.5 g l(-1) and initial concentration of 100 mg l(-1), GSPAC showed 94.5% removal of the dye in 30 min equilibrium time, while CPAC removed 96% of the dye in 15 min. The experimental isotherm data were analyzed using the linearized forms of Freundlich, Langmuir and BET equations to determine maximum adsorptive capacities. The equilibrium data fit well to the Freundlich isotherm, although the BET isotherm also showed higher correlation for both of the carbons. The results of comparative adsorption capacity of both carbons indicate that groundnut shell can be used as a low-cost alternative to commercial powdered activated carbon in aqueous solution for dye removal.     

Graft Copolymerization of Methyl Acrylate onto Cellulosic Biofibers: Synthesis,Characterization and Applications

Graft copolymerization of cellulosic biopolymers with synthetic polymers is of enormous interest because of its application in biofiltration, biosorption, biomedical, biocomposites and various other eco-friendly materials. Synthesis of graft copolymers of methyl acrylate onto mercerized Grewia optiva biofibers using ferrous ammonium sulfate–potassium per sulfate as redox initiator in air was carried out. Different reaction parameters such as amount of solvent, monomer concentration, initiator molar ratio, reaction time and reaction temperature were optimized to get the maximum percentage of grafting. The graft copolymers thus formed were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis and differential thermogravimetric techniques. A plausible mechanism for explanation of the graft copolymerization reactions pattern shown is offered. The effect of grafting percentage on the physico–chemical properties of raw as well as grafted Grewia optiva biofibers has also been investigated. The graft copolymers have been found to be more moisture resistant and also showed better chemical and thermal resistance. Green polymer composites were also successfully prepared through compression molding technique by using grafted Grewia optiva biofibers as reinforcement.     

Novel Bioactive Chiral Poly(amide–imide)s Containing Different Amino Acids Linkages: Studies on Synthesis, Characterization and Biodegradability

In this paper chiral bioactive poly(amide–imide)s (PAI)s were synthesized from four different diacids containing chiral amino acids with 4,4′-methylene bis(3-chloro 2,6-diethylaniline) as a diamine via direct polycondensation reaction in a system of tetra-n-butylammonium bromide and triphenyl phosphite as a condensing agent. The structures of these polymers were confirmed by FT-IR, ¹H-NMR, specific rotation, elemental and thermogravimetric analysis (TGA) techniques. TGA showed that the 10 % weight loss temperature in a nitrogen atmosphere was more than 378 °C, which indicates that the resulting PAIs have a good thermal stability. The biodegradability of the monomers and prepared polymers was investigated in culture media and soil burial test for assessment of the susceptibility of these compounds to microbial degradation. The results showed that the synthesized monomers and theirs derived polymers are biologically active and nontoxic to microbial growth.     

Using biopolymers to remove heavy metals from soil and water

Chemical remediation of soil may involve the use of harsh chemicals that generate waste streams, which may adversely affect the soil's integrity and ability to support vegetation. This article reviews the potential use of benign reagents, such as biopolymers, to extract heavy metals. The biopolymers discussed are chitin and chitosan, modified starch, cellulose, and polymer-containing algae.     

Thermoplastic Starch (TPS)/Polylactic Acid (PLA) Blending Methodologies: A Review

Polylactic acid (PLA) and thermoplastic starch (TPS) are biodegradable polymers of biological origin, and the mixture of these polymers has been studied due to the desirable mechanical properties of PLA and the low processing cost of TPS. However, the TPS/PLA combination is thermodynamically immiscible due to the poor interfacial interaction between the hydrophilic starch granules and the hydrophobic PLA. To overcome these limitations, researchers studied the modification, processing, and properties of the mixtures as a strategy to increase the compatibility between phases. This review highlights recent developments, current results, and trends in the field of TPS/PLA-based compounds during the last two decades, with the main focus of improving the adhesion between the two components. The TPS/PLA blends were classified as plasticized, compatible, reinforced and with nanocomposites. This article presents, based on published research, TPS/PLA combinations, considering different methods with significant improvements in mechanical properties, with promising developments for applications in food packaging and biomedicine.

     

Biodegradation of Agricultural Plastic Films: A Critical Review

The growing use of plastics in agriculture has enabled farmers to increase their crop production. One major drawback of most polymers used in agriculture is the problem with their disposal, following their useful life-time. Non-degradable polymers, being resistive to degradation (depending on the polymer, additives, conditions etc) tend to accumulate as plastic waste, creating a serious problem of plastic waste management. In cases such plastic waste ends-up in landfills or it is buried in soil, questions are raised about their possible effects on the environment, whether they biodegrade at all, and if they do, what is the rate of (bio?)degradation and what effect the products of (bio?)degradation have on the environment, including the effects of the additives used. Possible degradation of agricultural plastic waste should not result in contamination of the soil and pollution of the environment (including aesthetic pollution or problems with the agricultural products safety). Ideally, a degradable polymer should be fully biodegradable leaving no harmful substances in the environment. Most experts and acceptable standards define a fully biodegradable polymer as a polymer that is completely converted by microorganisms to carbon dioxide, water, mineral and biomass, with no negative environmental impact or ecotoxicity. However, part of the ongoing debate concerns the question of what is an acceptable period of time for the biodegradation to occur and how this is measured. Many polymers that are claimed to be ‘biodegradable’ are in fact ‘bioerodable’, ‘hydrobiodegradable’, ‘photodegradable’, controlled degradable or just partially biodegradable. This review paper attempts to delineate the definition of degradability of polymers used in agriculture. Emphasis is placed on the controversial issues regarding biodegradability of some of these polymers.     

Layer-by-Layer Deposition of Antibacterial Polyelectrolytes on Cotton Fibres

The introduction of molecules with biological properties on textile materials is essential for a number of biotechnological applications. With the purpose of testing new processes applied to textiles, in this study, we present the first results on the feasibility of using the Layer-by-Layer (LbL) deposition process in natural fibers such as cotton, with natural polyelectrolytes like chitosan (CH) and alginic acid sodium salt (ALG), the durability of CH/ALG multilayer on cotton were evaluated. The increase of negative charges to the substrate cotton was made with NaBr and TEMPO, to ensure the success of the process of LbL. Three characterization methods to assess electrostatic LbL deposition were performed: the contact angle between a liquid (water) and the sample surface, in order to characterize the wettability of the samples with the different layers of CH and ALG; dyeing of the CH/ALG assembled cotton fabric with cationic methylene blue that shows regular changes in terms of color depth (K/S value), which indicate that the surface were alternately deposited with CH and ALG layers and, finally, the analysis by infrared spectroscopy using Fourier Transform with Attenuated Total Reflection (ATR-FTIR), to assess the changes in the interaction between CH and ALG deposited on cotton samples.     

Biodegradable Polyesters and Polyamides From Difunctionalized Lauric and Coconut Fatty Acids

In this work, a major fatty acid from coconut oil was used as starting material in preparing biodegradable polymers. Thus, polyesters and polyamides from varying proportions of monomers, hydroxy- and amino- derivatives of lauric acid were synthesized. Initially, the derivatives were prepared by regioselective chlorination of lauric acid, in the presence of ferrous ions in strong acid medium. Subsequent hydroxylation and amination procedures yielded the hydroxy- and amino- derivatives of lauric acid. These monomers were polymerized in a reaction tube by simple polycondensation method at 220–230 °C for 6–8 h without catalyst. Molecular weight determination using –COOH by end group titration and gel permeation chromatography (GPC) gave an average molar mass of 3,000–5,000 g mol⁻¹ with n = 15–25 monomer units. Thermal properties such as glass transition (T_g) and decomposition (T_d) temperatures were obtained using differential scanning calorimetry (DSC). The same processes of synthesis and determinations above were applied to coconut fatty acids, derived from saponification of coconut oil, and resulted to very similar conclusions. A quick biodegradation assay against fungus Aspergillus niger UPCC 4219 showed that the polymers prepared are more biodegradable than conventional plastics such as polypropylene, poly(ethyleneterepthalate) and poly(tetrafluoroethylene) but not as biodegradable as cellulosic (newsprint) paper.