GRAFTING METHOD OF FLUORINATED COMPOUNDS TO CELLULOSE AND CELLULOSE ACETATE: CHARACTERIZATION AND BIODEGRADATION STUDY

Cellulose (Cell) and cellulose acetate (CA) are attractive durable materials; they can acquire various properties through modification in order to obtain valuable industrial products. First, a series of novel fluorinated cellulose carbamate and fluorinated CA carbamate have been synthesized. The introduction of fluoro-groups onto cellulose and CA chain backbone was achieved by the one-pot grafting method using diisocyanate as a coupling agent, which can be considered as a green procedure. The compounds prepared were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-ray diffractometry (XRD), thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) measurements. The results obtained from these analytical techniques confirm that modification occurs successfully. Second, the solubility behavior and biodegradation process of these new fluorinated materials have been studied. The results show that these new materials exhibit better solubility compared to cellulose, but this solubility decreases compared to that of CA. The phenomenon of biodegradation was studied using two methods, the rate of biodegradability was determined. The results of this part show that the biodegradation of fluorinated materials decreases compared to that of the starting materials. These novel materials are biodegradable, can substitute currently used industrial non-biodegradable products and be promising agents for several uses, such as bioplastics, drug carriers, etc. A sustainable development and an increased use of green chemistry principles are among the essential objectives of this work.

Multi-omics approach reveals new insights into the gut microbiome of Galleria mellonella (Lepidoptera:Pyralidae) exposed to polyethylene diet

The current plastic pollution throughout the world implies a crucial optimization of its (bio)degradation processes. In order to identify plastic degrading bacteria and associated enzymes, the gut microbiota of insects has raised interest. Some entomological models such as Tenebrio molitor (L. 1758), Plodia interpunctella (Hubner 1813) or Galleria mellonella (L. 1758) have the ability to ingest and degrade polyethylene. Then, it is promising to identify the composition and the role of the gut microbiota in this process. This study takes part in this issue by investigating G. mellonella as a biological model feeding with a polyethylene diet. Gut microbiome samples were processed by high throughput 16S rRNA sequencing, and Enterococcaceae and Oxalobacteraceae were found to be the major bacterial families. At low polyethylene dose, we detect no bacterial community change and no amplicon sequence variant associated with the polyethylene diet suggesting microbiome resilience. The functional analysis of insects gut content was promising for the identification of plastic degrading enzymes such as the phenylacetaldehyde dehydrogenase which participate in styrene degradation. This study allows a better characterization of the gut microbiota of G. mellonella and provides a basis for the further biodegradation study of polyethylene based on the microorganism valorization from insect guts.

Synthetic glass and jute fabric reinforced soy-based biocomposites: Development and characterization

In this work, both glass fabric and jute fabric reinforced nanoclay modified soy matrix-based composites were developed and characterized. Glass fabric (60 wt.%) reinforced composite showed maximum tensile strength of 70.2 MPa and thermal stability up to 202°C, which are 82.8% and 12.2% higher than those observed with corresponding jute composite. Water absorption and contact angle values of glass-soy specimens were tested, and found composites are water stable. Biodegradation study of composites under soil burial condition revealed that glass-soy composite with 40 wt.% glass fabric lost maximum 32.6% of its original weight after 60 days of degradation. The developed glass fabric-soy hybrid composites with reasonable mechanical, thermal, and hydrolytic stability can be used in different sectors as an alternative to the nondegradable thermoplastic reinforced glass fabric composites.

Characterization of Polycyclic Aromatic Hydrocarbons and Bioaugmentation Potential of Locally Isolated Beneficial Microorganisms Consortium for Treatment of Tar-Balls

Oil spills are one of the environmental pollutions that commonly occur along coastal areas. Tar-balls are one of the products that come from the oil spill pollution. In this study, tar-ball pollution was monitored at 10 points along the coastline of Marintaman Beach in Sipitang, Sabah, Malaysia. This research determined the physical characteristics, composition, and concentration of Polycyclic Aromatic Hydrocarbons (PAHs) in tar-balls. The total number of tar-balls collected was 227 (n=227). The tar-balls were observed in various shapes and the sizes were recorded in the range of 0.1 cm to 6.9 cm. The composition and concentration of Polycyclic Aromatic Hydrocarbons (PAHs) in the outer and inner layer of tar-balls were determined. The results showed that the main Polycyclic Aromatic Hydrocarbons (PAHs) compounds were found in inner layers of the tar-balls with benzo (g,h,i) perylene (72.26 mg/kg), flourene (59.87 mg/kg), dibenzo (a,h) anthracene (44.48 mg/kg), indeno (1,2,3-c,d) pyrene (78.18 mg/kg), and benzo (e) fluoranthene (45.70 mg/kg), respectively. Further research was done with the bioaugmentation study of locally isolated beneficial microorganisms (LIBeM) consortium for treatment of tar-balls in an Aerated Static Pile (ASP) bioreactor system. The results showed that, after 84 days of treatment, this consortium, consisting of C. tropicalis-RETL-Cr1, C. violaceum-MAB-Cr1, and P. aeruginosa-BAS-Cr1, was able to degrade total petroleum hydrocarbon (TPH) by 84% as compared to natural attenuation (19%). The microbial population of this consortium during the biodegradation study is also discussed in this paper.

Influence of Biogenic Acid on Concrete Materials

Microbial sulphur cycle in sewers evocate the serious problem in the area concrete corrosion, health related aspects and odour.These problems are primarily related to the release of bacterially produced hydrogen sulphide from wastewater to the atmosphereduring sewage transports that dissolves in the condensate on the sewer crown. In the event sulphur-oxidizing bacteria oxidize thedissolved hydrogen sulphide and other sulphur compounds to sulphuric acid, which corrodes the concrete. The concrete graduallyexpands causing cracks and ruptures, loss of strength and overall decay of concrete.The paper is focused on the investigation of the concrete specimens surface biodegradation study. From the viewpoint of concretematerials biodeterioration, mainly the bacteria sulphur- and sulphide-oxidising bacteria and sulphate-reducing bacteria areimportant and interesting. The role of bacteria mentioned above has been linked to the generation of the biogenic sulphuric acidresulting in corrosion process by dissolution of calcium containing minerals from the concrete matrices. The penetration of thecorrosion was manifested by structural changes of concrete samples. The surface structure changes were by stereomicroscopy andatomic force microscopy (AFM) investigated.

Biodegradation Study of Potato Starch-based Bioplastic

Background: Plastics are indispensable for our society. The extensive use of petroleum-based plastic and dumping of the same in soil and water body greatly affects our environment and biodiversity. However, biodegradable plastics can reduce the volume of waste in packaging materials. Therefore, biomass-derived polymers are promising alternatives of the petroleum-based non-degradable polymer to address the environmental issues. Objective: A large number of reports on the synthesis and characterization of starch-based bioplastic are available in the literature. However, a detailed biodegradation study of the starch-based bioplastic is rarely reported. We have prepared potato starch-based bioplastic with the combination of various plasticizers (glycerol, sorbitol, and xylitol) through hydrogel formation and carried out their biodegradation study. Method: Present study investigated the biodegradation of potato starch-based bioplastic in the natural environment, in cultured bacteria, and with fungal α-amylase. Results: Starch-based plastic is completely degraded in the natural environment within two months. Bacteria culture in solid media resulted in various types of bacterial colonies. Among the various bacterial colonies, the white circular colony was the major bacteria that degrade starch-based plastic. Furthermore, we screened the starch-based plastic degrading bacteria and isolated the pure culture through the streak plate method. Conclusion: n presence of cultured bacteria and with fungal α-amylase, starch-based plastic is completely degraded within 96h and 48h respectively.

A double-layer dura mater based on poly(caprolactone-co-lactide) film and polyurethane sponge: preparation, characterization, and biodegradation study

A double-layer composite of the PCLA film and PU sponge with good biodegradability and biocompatibility was designed as a potential dural substitute.

Bioremediation of river sediment polluted with polychlorinated biphenyls: A laboratory study

Persistent organic pollutants (POPs) are lipophilic, persistent and bioaccumulative toxic compounds. In general, they are considered resistant to biological, photolytic, and chemical degradation and polychlorinated biphenyls (PCBs) belong to these chemicals. PCBs were never produced in Serbia, but they were imported and mainly used in electrical equipment, transformers, and capacitors. Our study aimed to analyse sequential multi-stage aerobic/anaerobic microbial biodegradation of PCBs present in the river sediment from an area known for long-term pollution with these chemicals. A study with an autochthonous natural microbial community (NMC model system) and NMC augmented with allochthonous hydrocarbon-degrading (AHD) microorganisms (isolated from location contaminated with petroleum products) (NMC-AHD model system) was performed in order to estimate the potential of these microorganisms for possible use in future bioremediation treatment of these sites. The laboratory biodegradation study lasted 70 days, after which an overall >33 % reduction in the concentration of total PCBs was observed. This study confirmed the strong potential of the NMC for the reduction of the level of PCBs in the river sediment under alternating multi-stage aerobic/anaerobic conditions.