Biodegradable Ones Research Articles

On replacing single-use plastic with so-called biodegradable ones: The case with straws

Plastic pollution is a global environmental concern and several approaches have been implemented seeking to reduce and control releases of plastic waste, especially in marine environments. Recently, disclosure of data on occurrence of single-use plastic straws among the litter collected in beach cleaning campaigns unleashed a worldwide movement that resulted on banning of these items in several countries. The market then quickly began to offer sustainable solutions as the professed biodegradable plastic straws. However, cases of greenwashing added to current limitations related to the technical standards used to attest biodegradability of commercial plastic products may lead these measures to be largely ineffective. Herein, a case study assessing the composition of plastic straws marketed in Brazil and United States under false claims of biodegradability was used as background for discussion of this neglected issue, which goes far beyond plastics straws. Thus, although some local regulations have already banned single-use plastic products, additional actions in regional and global scales should be implemented, especially concerning proper labeling of the alleged biodegradable products. Therefore, from a multi-dimensional perspective and considering the resistance of the powerful plastic industry, multiple management strategies focused on educating people – in the matters of deciding purchases based on correct labeling and properly discarding the waste –, are possibly our best chance to drive a positive global environmental change. Additionally, we also suggest the inclusion of this relevant subject among the tasks proposed by the Basel Convention Partnership on Plastic Waste.

New stereocontrol on the block.

It is crucial to replace fossil fuel-based plastics with biodegradable ones that are made from renewable sources. Now, a new generation of bioplastics has been prepared through the stereoselective polymerization of diastereomeric monomers — a synthetic approach that allows tuning of the materials’ toughness, ductility and melting point.

Fungal degradation of reprocessed PP/PBAT/thermoplastic starch blends

It is well known that the inadequate disposal of polymeric materials causes significant environmental problems. Recycling and the use of biodegradable polymers are among the methods used to minimize these problems. However, the low mechanical performance of the majority of biodegradable polymers hinders the direct substitution of synthetic polymers, such as polyethylene (PE), polypropylene (PP) and polystyrene (PS), by biodegradable ones. Blending synthetic and biodegradable polymers is a way to develop recyclable biodegradable products with a good set of mechanical properties. Therefore, in this work we investigate the influence of extrusion cycles on the degradation of a polypropylene/poly (butylene adipate-co-terephthalate)/thermoplastic starch blend before and after inoculation with Aspergillus sp. and Penicillium sp. fungi degradaded for 30 days. The samples were exposed to the fungi and their mass loss, chemical structure, hydrophilicity, and morphology were observed as a function of inoculation time and processing cycles. Our results indicate that thermo-mechanical degradation favors the deposition of fungi in the samples and enables changes in film morphology and hydrophilicity.

Comparative analysis on the sorption kinetics and isotherms of fipronil on nondegradable and biodegradable microplastics

Biodegradable plastics have been introduced and widely used as a promising alternative to traditional nondegradable plastics. However, the differences in sorption behavior of pesticides on nondegradable and biodegradable microplastics has been insufficiently studied. Here, four types of nondegradable [polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polypropylene (PP)] and two types of biodegradable [polylactic acid (PLA), polybutylene succinate (PBS)] microplastics were selected to investigate the sorption mechanism of fipronil based on their sorption kinetics and isotherms. The results indicated that the sorption rates of PLA and PBS were much higher than those of PE, PP, PVC and PS and that the sorption capacities of fipronil on microplastics followed the order of PBS > PLA > PP > PE > PS > PVC. The sorption kinetics followed a pseudo-second-order kinetics model (R2 = 0.953–0.998) for all tested microplastics. External mass transport and intraparticle diffusion were the main rate controlling steps of the sorption of fipronil on microplastics. Furthermore, isotherm results indicated that a Langmuir model provided the best fit for fipronil sorption on PE, PS, PVC and PP (R2 = 0.997–0.999), while a Freundlich model was the most appropriate model for PLA and PBS (R2 = 0.998–0.999). The presence of surface O-containing functional groups and the spatial arrangement of rubbery domains are likely to affect the sorption process. The results from this work suggest that microplastics, especially biodegradable ones, may play an important role in the fate and transport of pesticides, and their effects on soil organisms (e.g., earthworms) require further investigation.

Structural and sorption properties of bio-nanocomposite films based on κ-carrageenan and cellulose nanocrystals

There is an increased interest on changing the synthetic based materials to biodegradable ones, especially with natural polymers, polysaccharides or proteins. In this research we prepared bio-nanocomposite formulations with different component concentrations and investigated their structural features, with focus on the interactions, sorption properties, and how the combination between them influences these properties. By infrared spectroscopy, principal component analysis (PCA) and two-dimensional correlation spectroscopy (2DCOS) was identified that in the blending process are involved the −SO4 and C(4)-O-S groups of β-d-galactose, CO groups, (O=S=O) of carrageenan and –OH and CO groups from CNCs.The water uptake and water sorption properties decrease with increasing the CNCs content in the formulations from about 15% for κ to 10% for κC15 and from about 128% for κ to 115% for κC15, respectively. The increase of the CNCs content induced an increase of the water contact angle from 47° for κ to 90° for κC15, indicating once again the involvement of the free hydroxyl groups in the hydrogen bonded interactions.

Long term stability of biodegradable polymers on building limestone

Synthetic polymers can be replaced by biodegradable ones as adhesives, water repellents and consolidants on the stone surfaces and facades of the historic buildings in their conservation to minimize future deterioration. In this study, the long-term stability of two biodegradable polymers, polyhydroxybutyrate (PHB) and poly-l-lactide (PLA), and an acrylic polymer (Paraloid B72) which is commonly used in conservation works of artefacts, were evaluated on limestone using a UV lamp-weathering chamber (up to 104 days) for future protection studies. Chemical and morphological changes induced by an accelerated weathering test were examined by Fourier Transform Infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) analyses. Protection efficiency of the polymers was determined by the changes in color, capillary water absorption, static contact angle on limestone. Paraloid B72, PHB, and PLA coatings significantly increased hydrophobicity while decreasing capillarity water absorption and caused negligible change in the color of the limestone. Protection efficiencies of PLA and PHB polymers were almost the same as that of Paraloid B72, a widely used acrylic polymer. However, PLA and PHB seemed to be favorable polymers as protective agents due to their reversibility and biodegradability, low chromatic changes, good hydrophobic behavior and good stability to weathering in reducing the effects of outdoor exposure on limestone surfaces.

Developments in Flame-Retardant Bio-composite Material Production

Abstract Flame-retardant composites have been researched for more than four decades, and demands are on the rise for this type of product in various applications. Since bio-composites have become popular these days, researchers have turned their attention to producing flame-retardant bio-composites. The main advantage of the bio-composite is its easy degradation process by naturally occurring bio-components. These types of composites can be partially biodegradable or fully biodegradable, and the rate of the degradability depends on the contents of the material. Partially biodegradable ones generally contain natural fiber as a reinforcement, along with a nonbiodegradable synthetic resin, while fully biodegradable ones contain either only biopolymers or a blend of natural fiber and biopolymer. Generally, flame-retardant bio-composites contain an additional flame-retardant filler material as well. This article will try to review the studies that have taken place on developing flame-retardant bio-composites and try to point out some key factors by which the properties of the end product may be controlled, so that the end products of the desired properties can be produced in further research.

Bioplastics and waste management

Pollution of the marine environment due to plastic materials is one of the most severe environmental problems humanity has to face in the 21st century. The strategy devised until now to address this issue is mainly based on two pillars: (1) increasing the interception of discarded plastic wastes by waste management systems; and (2) substituting the traditional “petro-based” polymers with biodegradable ones. Many issues on the overall sustainability of the second option by the waste management system must still be clarified.

Biodegradation of natural reinforcing fillers for polymer composites

Twelve different natural raw materials were selected as possible fillers for eco-friendly biocomposites. The target was to find the most biodegradable ones. Two mycological tests were held: in the aqueous and agar media. It was found that two tests showed different results. In aqueous media, the fillers with a high content of water-soluble and easy-hydrolysed compounds demostrated the most intensive biofouling. In agar media, the entire filler was exposed to biodigestion by fungi. Therefore, multi-compound fillers with a set of different macro- and microelements were more biodegradable than others.

Towards More Sustainable Material Formulations: A Comparative Assessment of PA11-SGW Flexural Performance versus Oil-Based Composites.

The replacement of commodity polyolefin, reinforced with glass fiber (GF), by greener alternatives has been a topic of research in recent years. Cellulose fibers have shown, under certain conditions, enough tensile capacities to replace GF, achieving competitive mechanical properties. However, if the objective is the production of environmentally friendlier composites, it is necessary to replace oil-derived polymer matrices by bio-based or biodegradable ones, depending on the application. Polyamide 11 (PA11) is a totally bio-based polyamide that can be reinforced with cellulosic fibers. Composites based on this polymer have demonstrated enough tensile strength, as well as stiffness, to replace GF-reinforced polypropylene (PP). However, flexural properties are of high interest for engineering applications. Due to the specific character of short-fiber-reinforced composites, significant differences are expected between the tensile and flexural properties. These differences encourage the study of the flexural properties of a material prior to the design or development of a new product. Despite the importance of the flexural strength, there are few works devoted to its study in the case of PA11-based composites. In this work, an in-depth study of the flexural strength of PA11 composites, reinforced with Stoneground wood (SGW) from softwood, is presented. Additionally, the results are compared with those of PP-based composites. The results showed that the SGW fibers had lower strengthening capacity reinforcing PA11 than PP. Moreover, the flexural strength of PA11-SGW composites was similar to that of PP-GF composites.

Quantifying variability in removal efficiencies of chemicals in activated sludge wastewater treatment plants - a meta-analytical approach.

Large variations in removal efficiencies (REs) of chemicals have been reported for monitoring studies of activated sludge wastewater treatment plants (WWTPs). In this work, we conducted a meta-analysis on REs (1539 data points) for a set of 209 chemicals consisting of fragrances, surfactants, and pharmaceuticals in order to assess the drivers of the variability relating to inherent properties of the chemicals and operational parameters of activated sludge WWTPs. For a reduced dataset (n = 542), we developed a mixed-effect model (meta-regression) to explore the observed variability in REs for the chemicals using three chemical specific factors and four WWTP-related parameters. The overall removal efficiency of the set of chemicals was 82.1% (95% CI 75.2-87.1%, N = 1539). Our model accounted for 17% of the total variability in REs, while the process-based model SimpleTreat did not perform better than the average of the measured REs. We identified that, after accounting for other factors potentially influencing RE, readily biodegradable compounds were better removed than non-readily biodegradable ones. Further, we showed that REs increased with increasing sludge retention times (SRTs), especially for non-readily biodegradable compounds. Finally, our model highlighted a decrease in RE with increasing KOC. The counterintuitive relationship to KOC stresses the need for a better understanding of electrochemical interactions influencing the RE of ionisable chemicals. In addition, we highlighted the need to improve the modelling of chemicals that undergo deconjugation when predicting RE. Our meta-analysis represents a first step in better explaining the observed variability in measured REs of chemicals. It can be of particular help to prioritize the improvements required in existing process-based models to predict removal efficiencies of chemicals in WWTPs.

Physicochemical and Microbiological Properties and Humic Substances of Composts Produced with Food Residues

The consolidation of a wide and effective management system of solid residues, especially biodegradable ones, is one of the great challenges of current society. Composting was evaluated as an option of organic fertilization for soil enrichment, using raw food residues in substitution to bovine manure. The compost piles were built with 30% of biodegradable residues mixed with 70% of ground tree pruning material. The effects of different proportions of food residues (FR) and bovine manure (BM) as source of carbon were tested in 5 treatments (T1 = 15%BM + 15%FR, T2 = 20%BM + 10%FR, T3 = 10%BM + 20%FR, T4 = 30%BM and T5 = control, 30%FR), in randomized blocks, under open field conditions for 90 days. The pH, temperature and moisture content of the compost were measured weekly. The aged compost was evaluated for physicochemical and microbiological properties and carbon contents in the humic substances. The analyses of the results indicated that all studied composts reached the maturation stage with satisfactory contents of humic substances, macronutrients, and micronutrients, indicating that food residues can be used as a source of carbon in compost piles to produce organic fertilizers. The contents of the evaluated chemical contaminants were much lower than those established in the main legislation and current normative instructions and, in terms of contamination by pathogens, there was the absence of total coliforms, thermo tolerant coliforms, and Salmonellas.

The influence of additives on crystallization of blends based on polylactid acid

The sustainable development consists of the effort of replacing commonly used polymer materials for the biodegradable ones. They do not have sufficient physical and mechanical properties, therefore they have to be modified by producing various ratio mixtures or with the additives. Improving their processability and properties is an important challenge to be afforded before using these materials on the market. One way to improve the properties of these materials is to prepare their blends [1]. The most common way of the preparation of packaging materials is the injection moulding, where the crystallization of material is very important. That is the reason the crystallization has become one of the most studied characteristics of biodegradable blends based on PLA / PHB. The work is a contribution to works that deal with the description of the structure of PLA / PHB blends, which have been modified by the addition of various types of additives, mainly nucleating agents and plasticizers [2]. The films of these blends keep approximately unchanged mechanical properties after two weeks of storage. The presence of plasticizer (ATBC) and nucleating agent (BN) has no significant impact on the processing stability of PLA/PHB blends. The results show that the combination of the plasticizer and nucleating agent greatly affects the process of crystallization of PLA/PHB blends as well as the ratio of polymers and the heat treatment process.

Biodegradable plastic bags on the seafloor: A future threat for seagrass meadows?

Marine plastic litter is a global concern. Carrier bags manufactured from non-biodegradable polymers constitute a large component of this litter. Because of their adverse impact on marine life, non-biodegradable bags have recently been replaced by biodegradable ones. However, growing evidence shows that these latter are not readily degradable in marine sediments and can alter benthic assemblages. The potential impact of biodegradable bags on seagrasses inhabiting sandy bottoms, which are the most widespread and productive ecosystems of the coastal zones, has been ignored. Mesocosm experiments were conducted to assess the effect of a commercialized biodegradable bag on a common seagrass species of the Mediterranean, Cymodocea nodosa, both at the level of individual plant (clonal growth) and of plant community (plant-plant relationships), under three culture regimes (plant alone, in combination with a neighbour of the same species or of the co-existing seagrass Zostera noltei) simulating different natural conditions (bare substrate, monospecific meadows or mixed meadows). The bag behaviour in marine sediment and sediment physical/chemical variables were also examined. After six months of sediment exposure, the bag retained considerable mass (85% initial weight) and reduced sediment pore-water oxygen concentration and pH. In the presence of bag, C. nodosa root spread and vegetative recruitment increased compared to controls, both intra- and interspecific interactions shifted from neutral to competitive, and the growth form changed from guerrilla (loosely arranged group of widely spaced ramets) to phalanx form (compact structure of closed spaced ramets) but only with Z. noltei. These findings suggest that biodegradable bags altering sediment geochemistry could promote the spatial segregation of seagrass clones and influence species coexistence.

An innovative multistage treatment system for sanitary landfill leachate depuration: Studies at pilot-scale

In this work, an innovative methodology for the treatment of landfill leachates, after aerobic lagooning, is proposed and adjusted at pilot-scale. This methodology involves an aerobic activated sludge biological pre-oxidation (ASBO), a coagulation/sedimentation step (240mgFe3+/L, at pH4.2) and a photo-oxidation through a photo-Fenton (PF) reaction (60mg Fe2+, at pH2.8) combining solar and artificial light.The ASBO process applied to a leachate after aerobic lagooning, with high organic and nitrogen content (1.1–1.5gC/L; 0.8–3.0gN/L) and low biodegradability (BOD5/COD =0.07–0.13), is capable to oxidise 62–99% of the ammonium nitrogen, consuming only the affluent alkalinity (70–100%). The coagulation/sedimentation stage led to the humic acids precipitation, promoting a marked change in leachate colour, from dark-brown to yellowish-brown (related to fulvic acids), accompanied by a reduction of 60%, 58% and 88% on DOC, COD and TSS, respectively.The PF system promoted the degradation of the recalcitrant organic molecules into more easily biodegradable ones. According to Zahn-Wellens biodegradability test, a leachate with 419mg DOC/L after coagulation, would have to be photo-oxidized until DOC <256mg/L, consuming 117mM of H2O2 and 10.4kJ/L of accumulated UV energy, to achieve an effluent that can be biologically treated in compliance with the COD discharge limit (150mg O2/L) into water bodies. The biological process downstream from the photocatalytic system would promote a mineralization >60%. The PF step cost to treat 100m3/day of leachate was 6.41€/m3, combining 1339m2 of CPCs with 31 lamps.

Evaluation of wear and physical qualities of traditional and biodegradable polymeric films with Braille under vibrations

Physical parameters of Braille elements formed on polymeric films including biodegradable ones were tested in the investigation presented in this paper. A separate Braille element is analyzed. Plane strain and axisymmetric problems are investigated. At the places of maximum equivalent stresses deterioration of quality of material of a Braille element is expected. Equivalent stresses are used for determination of the number of cycles till the start of wear at the surfaces of the Braille element when the film performs vibrations according to the eigenmode. Graphical representations are obtained. The results of performed investigations are used in the process of interpretation of measurements of wear of vibrating Braille elements.

Investigation on drug solubility enhancement using deep eutectic solvents and their derivatives

Deep eutectic solvent (DES) is a room temperature liquid typically formed by mixing two solid compounds, such as a quaternary ammonium salt (QAS) (e.g. choline chloride) and a hydrogen bond donor (HBD) (e.g. urea or a carboxylic acid) at their eutectic composition. Very often, a range of room temperature liquids can also be obtained near the eutectic composition. Hence, it is more convenient to introduce a more general term deep eutectic solvent derivatives (DESDs) to describe a wide range of DES-like derivatives including those derived from ternary mixtures. The melting point of the mixture is lowered because the hydrogen bonding between DESD components reduces the lattice energy of components of the eutectic system. Based on the analysis of available data for 22 such choline chloride-based DES pairs, we found that the observed melting point depression can be statistically correlated with the difference between the hydrogen bonding contribution (δh) and the polar contribution (δp) to the solubility parameter of the hydrogen bond donor (HBD) component. The correlation was validated with a new DESD based on glycolic acid and choline chloride, which form DESDs at a molar ratio between 1:1 and 1:4 with DES-like properties. As a room temperature liquid, this DESD exhibits a wide range of solubility enhancement on several weakly basic poorly water-soluble drugs. For example, the solubility of itraconazole, piroxicam, lidocaine, and posaconazole has been observed to increase by 6700, 430, 28, and 6400-fold, respectively as compared to their aqueous solubility at room temperature. Furthermore, another new ternary DESD based on choline chloride, glycolic acid, and oxalic acid at a molar ratio of 1:1.6:0.4 is shown to further increase the solubility of itraconazole to a remarkable level of 5.36mg/mL (a 53,600-fold increase!). Because the components of such DESDs can include those biodegradable ones that had previously been used in formulated human products, the potential applicability of suitable DESDs to drug delivery, especially in enhancing drug solubility for topical formulations could be very attractive.

Biodegradability of Blended Polymers: A Comparison of Various Properties

Derived from natural gas, crude oil and petroleum, plastics create major problems due to instability of these petrochemicals. The disposal of plastics, especially those used in packaging, poses a serious challenge to waste management. Growing environmental awareness has imposed a paradigm shift from biostable materials to biodegradable ones that are compatible with the environment to ensure a safe eco-friendly atmosphere for packaging film and processes. The ever-increasing use of plastic film nowadays has resulted in biodegradability becoming an essential characteristic for plastics. An additional advantage of using biodegradable materials is that upon disintegration and composting, they may act as fertilizers and soil conditioners, enhancing crop yield while capitalizing natural resource conservation with an underpinning on environment friendly and safer atmosphere. This review article is thus an attempt to address this pressing problem by discussing a few biodegradable polymeric blends derived from renewable feedstocks with potential applications in our everyday lives.

Agronomic evaluation of green biodegradable mulch on melon

A two-year research was carried out in 2004-2005 in order to evaluate the effects of biodegradable green mulch on melon (Cucumis melo L. var. reticulatus Naud.) yield and quality. The loss of quality due to the presence of spot caused by the residues of biodegradable plastics was also investigated. The research was conducted over two years, in open field, at S. Piero a Grado, Pisa, Italy, (lat. 43.67498, long. 10.34737), from the beginning of May to the end of July of each year. The films tested in the first year experiment were two biodegradable ones with different colours (black and green) compared with a low-density polyethylene (LDPE) film, while in 2005 three biodegradable films, (two green and one black) were compared with a traditional LDPE film. The two green biodegradable films had different properties related to the biodegradation rate, faster in film Cv205, because of a different degree of Mater Bi polymer inside the film. In each year a randomized block design with four replications was followed. Green biodegradable films allowed obtaining a higher yield than LDPE films maybe because of the higher soil temperatures reached, and excellent fruit quality, especially for the soluble solids content and the ripening process. At the same time, the presence of residues on the fruit skin was rather low because of the degradation of films occurred at the ripening time. In the first year, the percentage of spotted fruits was low for every kind of film, while in the second one the green film showed a higher presence of residues on skin compared with the black one. The biodegradable materials covered the soil for the whole crop cycle with a good mulching effect, and the successive degradation allowed to avoid the removal and disposal of plastic film, with a certain economic advantage.

Analysis of the effect of perforation on the permeability of biodegradable non-barrier films

Perforated plastic films are used in Equilibrium Modified Atmosphere Packaging (EMAP) of fresh produce such as fruits and vegetables. The most common material used in such applications is the oriented polypropylene (OPP), which has low permeability with respect to relevant gases, namely water vapor (WV), CO2, and O2. Therefore, the synthesis of the in-package atmosphere is regulated only by the size and number of perforated holes. The replacement of the OPP films with biodegradable ones made of polylactic acid (PLA) or starch based polymers for environmental reasons results into difficulties with respect to designing the EMAP system, since these films are more permeable to the relevant gases and in particular to WV. As a result, the effect of micro-perforation is influenced by the permeability of the film. In the present work, the dependence of the gas flux through perforation on the permeability of the film for the same gas was investigated by experimental and numerical methods. It was shown that the effect of perforation decreases as the permeability of the film increases. The diffusive gas flux through perforation becomes independent of the film permeability, if it is about 100 times smaller than the diffusivity of the studied gas in air.