Biodegradable properties

Vegetable and seed oils as well as some synthetic base stocks present a new class of biodegradable base stocks. These fluids (10) have excellent biodegradation properties as measured by criteria developed by the Environmental Protection Agency (EPA) or Organization of Economic Cooperation and Development (OECD). OECD 301 and EPA 560/6-82-003 measure the biodegradation of lubricants. These tests were developed to measure the degradation of oil, especially two-cycle ok, on waterways. Aquatic toxicity criteria toward fish is also found to be acceptable for this class of fluids as measured by EPA 560/6-82-002 and OECD 203 1-12. 

Biodegradation. The biodegradation properties of various organics are shown in Table 13. The mechanism of aerobic degradation is shown in... 

The method consists of the retention by sorption of the porphyrins on poly (vinyl alcohol) (PVA) hydrogels. Poly (vinyl alcohol) (PVA) is selected as the polymer of choice for the purification of industrial and medical wastewaters due to its capacity to form physically crosslinked hydrogels with the advantages of non-toxic, non-carcinogenic and biodegradable properties. 

H. L. Zeng, C. Gao, D.Y. Yan, Poly(epsilon-caprolactone)-functionalized carbon nanotubes and their biodegradation properties, Advanced FunctionalMateriab, vol. 16, pp. 812-818, 2006. 

Polyhydroxyalkanoate (PHA) is a biodegradable and biocompatible thermoplastic that can be synthesized in many microoiganisms from almost all genera of the microbial kingdom. Many microoiganisms synthesize polyhydroxyalkanoates (PHAs) as intracellular carbon and energy reserve materials [1]. These microbial polyesters materials are thermoplastics with biodegradable properties [2]. PHAs are usually accumulated... 

Apart from the all-carbon backbone, poly(vinyl ester)s also exhibit a unique 1,3-diol structure (see Fig. 1). This structure is a common motif in many natural materials, e.g. carbohydrates. A number of oxidative or reductive electron transfer processes catalysed by natural redox systems are imaginable for this motif. The 1,3-diol structure is unique for a synthetic polymer and cannot be found in any other synthetic polymer class of significance. This explains the unusual biodegradation properties discussed below. 

Ingerslev, F. and B. HaUing-Sprensen (2000). Biodegradability properties of sulfonamides in activated sludge. Environmental Toxicology and Chemistry 19 2467-2473. 

Ortho ester linkages can also be used to improve biodegradation properties in long chain ethoxylates or block copolymers. It has been shown that a conventional PEG-PPG copolymer with a molecular weight of 2200 biodegrades to only 3% in 28 days. However, if an equivalent molecule is built up from PEG 350 and PPG 400, connected by ortho ester links, it will reach 62% biodegradation within 28 days and thus be classified as readily biodegradable [64]. 

Surfactants are used widely in industry, agriculture and medicine. The materials currently in use are produced primarily by chemical synthesis, or as by-products of industrial processes. For a microbial surfactant to penetrate the market, it must provide a clear advantage over the existing competing materials. The major considerations are (1) safety, i.e., low toxicity and biodegradability (2) cost (3) selectivity and (4) specific surface modifications. Biosurfactants exhibit low toxicity and good biodegradability, properties that are essential if the surfactant is to be released into the environment. 

Inulin can be modified to compounds that display good heavy metal complexing properties similar to ethylene diamine tetra-acetic acid (EDTA) but with better biodegradation properties (Bogaert et al., 1998). Inulin is first oxidized using sodium periodate to the dialdehyde, and then reduced to a polyol using Pt/C and hydrogen. The polyol can then be modified with carbon disulfide to form xanthate or with S03-pyridine to obtain an inulin sulfate. Alternatively, the dialdehyde can be animated with diaminoethane and sodium cyanoborohydride and the product reacted with monochloroacetic acid sodium salt to form carboxymethylamino inulin. Each of these compounds can be used to precipitate heavy metals. 

Among new applications [192,193] attention has been focused on the biocompatible, bioactive, and biodegradable properties. Dopamine and several enzymes, e.g., trypsine, have been covalently bound to polyphos-phazene chain. AJso anestisics, steroids, and antibacterial agents may be linked to polyphosphazene with promising pharmaceutical applications. 

Organic acids are also beneficial for use in perfume production, pharmaceuticals, medicine, and the production of other chemicals. For example, cinnamic acid is synthesized on a commercial scale from styrene and carbon tetrachloride (Roller, 1995). Due to biodegradable properties, there is a growing demand for organic acids for the production of polymeric materials (Bailly, 2002). 

Despite the efficiency of DR cationic surfactant solutions and several successful large-scale field tests, commercial use of these solutions has not been widespread largely because of their slow biodegradation properties. A new series of biodegradable mixed zwitterionic/anionic surfactant solutions, which can be disposed of by normal sewage treatment, has been developed by Akzo Nobel with excellent field test results in the primary system of the same district heating system in Herning, Denmark. 

Cost and biodegradabiUty have also been major concerns, and new families of ILs derived from renewable feedstock or from low-cost starting materials have beat described. These Bio-ILs are entirely composed of biomaterials [183]. An example to be cited is the development of the deep eutectic mixtures liquid systems based on choline chloride [ 184] for which the qualification of ILs is stiU the subject of controversies. Choline can be used as alternative cation in combination with suitable anion to generate ILs. The biodegradable properties of these ILs have been reported [185]. 

Detergents are amphipathic molecules which have enhanced solubility and biodegradability properties compared to soaps. Instead of having a sodium salt in the polar portion of the molecule, other ionic and polar groups are used giving rise to what are called "cationic", "anionic" and "nonionic" detergents. 

Solid base catalysts have gradually gained importance in the catalytic field due to their well-known advantages of non-corrosive and easier product separation[l]. However, in contrast to the extensive application of solid acid catalysts, the utilization of solid bases was limited for their rapid catalytic deactivation [2]. The deactivation problem was also foimd in the continuous synthesis of dimethyl carbonate (DMC). DMC has attracted more and more attention in recent years because of its low toxic and nicely biodegradable property [3,4]. Transesterification between methanol and propylene carbonate (PC) or ethylene carbonate (EC) is an attractive route for the synthesis of DMC. Both acid and base catalysts catalyze the reaction, and base catalyst was reported to be more effective [5]. Among bases, CaO showed unique catalytic activity for the transesterification reaction with high yield and selectivity [6]. Unfortunately, when CaO based catalyst was employed in the continuous synthesis of DMC, its activity gradually decayed with time-on-stream due to... 

The polypyrrole (Ppy)/dextrin nanocomposite is synthesised via in situ polymerisation and the preparation of this nanocomposite is shown in Figure 5.4. The backbone chain of this nanocomposite polymer contains hydrophobic side chains, which disrupt the microbial cell membrane leading to leakage of the cytoplasm in bacteria including Escherichia coli. Pseudomonas aeruginosa. Staphylococcus aureus and Bacillus subtilis. This material can be implemented in the fields of biomedicine, biosensors and food packaging due to the biodegradable property of dextrin as well as the antibacterial properties of the Ppy [79]. 

A variety of copolymers having high molar ratios of PDS compared to other monomers within the same linear aliphatic polyester family have been reported for the purpose of improving the mechanical and biodegradation properties [Shalaby, 1994]. For example, copolymer of PDS (80%) and PGA (up to 20%) has an absorption profile similar to Dexon and Vicryl sutures but it has compliance similar to PDS. Copolymer of PDS (85%) and PLLA (up to 15%) results in a more compliant (low modulus) suture than homopolymer PDS but with absorption profiles similar to PDS [Bezwada et al., 1990). 

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