Ask a question from expert

Ask now

Biodegradation of Bioplastics: Methods and Techniques

6 Pages1159 Words69 Views
   

Added on  2020-09-27

About This Document

This article discusses the different methodologies and techniques used for monitoring biodegradation processes of bioplastics materials using enzymes and microbes. It covers aerobic conditioning biodegradation, spectroscopy, mass loss, virtual analysis, and anaerobic hydrocarbon metabolism. The article also includes tables and graphs to illustrate the assessment standards of bioplastics under aerobic and anaerobic conditions.

Biodegradation of Bioplastics: Methods and Techniques

   Added on 2020-09-27

BookmarkShareRelated Documents
MethodologiesIn this section contains the significant procedures and illustrations used in monitoring biodegradationprocesses of bioplastics materials using enzymes and microbes. The procedures involve measuring anddetermining the percentage composition of organic carbon (IV) oxide and methane in the bioplastics.The commonly used methods are; aerobic conditioning biodegradation,Spectroscopy, mass loss,virtual analysis. and anaerobic hydrocarbon metabolism. Aerobic degradation process utilizes the microbes as a natural method for reducing pollutantshazardous wastes deposits. In the aerobic degradation organic chemicals (polymer) are broken downinto smaller compounds (monomers), and by products –water and carbon (IV) oxide using oxygen as theelectron acceptor. In anaerobic degradation conditioning the organic chemical wastes are decomposedby microbes in absence of oxygen. The bacteria utilizes chemical compounds such as nitrate,manganese, sulfate and carbon (IV) oxide in their reactions as electron acceptors to breakdown thepolymers into monomers and biomass (C plastic ––> CH4 + CO2 +H2O + C residual + biomass). Aerobic conditioning biodegradation; The microbes delay in moving the polymers through their outer cell membrane to reach the inner biochemical processing cells because the polymer molecules are large and insoluble in water. In order to reach the carbon and hydrocarbon compounds and apply the biochemical activities, the microbes evolve and initiate the excretion of extracellular enzymes the breakdown the polymers in a process known as depolymerization. The process involves two steps; (i)The microorganism attaches itself on the polymer surface (on hydrophilic polymers)(ii)The microorganism uses the polymer as a source of carbon for its growth hence degrading the polymer. While extracellular enzymes released inflict the primary chain and split it to low-molecular-weight monomers and dimers which are further used as source of electricity and carbon. Figure
Biodegradation of Bioplastics: Methods and Techniques_1
Biodegradation of bioplastics Bioplastics are biomaterials that is synthesized from different microorganisms under specialenvironmental and nutritional conditions for instance, polyesters (PLA, PHA, cellulose, PBS, PCL, andPBAT) are made from accumulating plant lipid and mixing it with microbes in containers and allow itgrow together. The number, weight and size of granules, monomers and macromolecular structure, andthe properties of polymer depend on the producer microbe. The table below shows the assessmentstandards of bioplastics under aerobic condition Table 1The CO2 produced during biodegradation is equated to a blank containing developed compost added topositive material, that is an assessed and biodegraded cellulose (Sakimoto et al., 2017). Themeasurement of methane and carbon (IV) oxide is based on the assumption that biodegradation ofcellulose used I the assessment is complete (Zhao et al., 2016). Moreover, the measurement andassessment of emission of CO2 gas from biodegradation process is done using different tools; which arethe gravimetric measurement respirometer (GMR) and cumulative measurement respirometer (CMR).The direct measurement respirometer (DMR) tool has non-dispersive infrared (NDIR) sensor or a gaschromatograph (GC) fixed to thermal conductivity detector (TCD) to analyze the transformed CO2quantity in the output gas. However, in anaerobic conditions biodegradation process is evaluated viameasuring production of biogas CH4 and CO2 as illustrated in ASTM D5526-94d (Yang et al., 2018).theother method used to assess and measure biodegradability under anaerobic condition is biochemicalmethane potential (BMP) (Zhang et al., 2018), it is grounded on the definite methane yield of the testmaterial. Table 5 (anaerobic)Figure 3 GraphSpectroscopy is another method used to assess and evaluate the process of biodegradation via changesin the bioplastic spectrum during the degradation process. The use of infrared spectroscopy (IR) tofacilitate IR radiation absorption in wavelength range of 4000-400 per centimeter. The IR band arecharacterized by magnitude and frequency whereby the frequency is represented on the values on thehorizontal axis which correspond to the wavenumbers absorbed in the IR while the magnitude is theamount of IR visible on the spectrum and is represented on the vertical axis of IR graph. Most commonlyused method of spectroscopic analysis is the Nuclear magnetic resonance (NMR). It expresses the seriesand sequence of active nuclei based on C, H, and O. Near infrared (NIR) and attenuated total reflectancespectroscopy (ATR-FTIR) are used to detect material spectra and in monitor the process ofbiodegradation in PCL plastic for 28 days at 370C temperatures under anaerobic and aerobic settings.Anaerobic hydrocarbon metabolism is another methodological approach used in anaerobicbiodegradation of various hydrocarbon compounds such as alkanes, polycyclic aromatic hydrocarbons(PAHs), and mono-aromatic hydrocarbons (Biochemistry of Anaerobic Degradation of Hydrocarbons;Meckenstock et al., 2016). The Anaerobic hydrocarbon metabolism process is regulated by principles
Biodegradation of Bioplastics: Methods and Techniques_2
developed deep study in greatly enhanced cultures or isolation of pure cultures from environments thatendure hydrocarbons while including bacteria reducing chemical such as nitrates and sulfates (Stagars etal. 2016). Well enhanced methanogenic principles coupled with syntrophic convert hydrocarbons tomethane as confirmed in the study of Jiménez et al. (2016) to evaluate conditioned bio-conversion ofhydrocarbons. For instance, activation of hydrocarbons under anoxic conditions case is the degradationof ethylbenzene with nitrate-reducing bacteria condition through either hydroxylation or carboxylationas the primary activation techniques for the irreplaceable aromatics like phenanthrene, naphthalene,and benzene (Meckenstock et al. 2016).
Biodegradation of Bioplastics: Methods and Techniques_3

End of preview

Want to access all the pages? Upload your documents or become a member.