IJCA - Volume I - Flipbook - Page 15
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The International Journal of Conformity Assessment
However, the disadvantages of traditional plastics
on human health and environment led to the design
of innovative plastic materials that can be recyclable
and degradable in environmental conditions without
any adverse impact [1,3].
All types of plastics undergo degradation, which
may be physicochemical, biological, or both.
Degradation occurs as a result of wind, waves, or
sunlight, which are examples of physicochemical
processes. Oxo-degradable or hydro-degradable
plastics are designed in such a way that they
undergo degradation via oxidation or hydrolysis.
Oxo-degradable plastics are the resultant products
of fossil-carbon-derived plastics mixed with some
additives such as antioxidants and prooxidants.
Photodegradable plastic is a subclass of oxodegradable plastic, where ultraviolet (UV) light
induces the oxidation process. Hydro-degradable
plastics are hybrid composites of petroleum-based
plastic and a natural polymer such as starch [4,6].
While the degradation of biodegradable plastics
is caused by microorganisms such as bacteria,
fungi, or enzymes, preferably, plastics degrade via
aerobic and anaerobic organisms resulting in carbon
dioxide, water, methane, and compost. The majority
of commercial biodegradable plastics are converted
into compost instead of gaseous products [2,7].
Besides food, most personal care, cosmetic,
and domestic products are packaged in plastic
containers. Unfortunately, the chemical stability
of these polymers—one of the main reasons of
its successful application—gives rise to serious
environmental and health problems due to the
huge amount of plastic waste released into the
environment each year. In principle, biodegradable
and compostable bioplastics would provide the
aforementioned societal benefits while affording,
respectively, a lack of harmful residues or valued
compost fertilizer. Polylactic acid (PLA), starch,
cellulose pulp, polyhydroxyalkanoates (PHAs) such
as polyhydroxybutyrate, and polyhydroxyoctanoate
are the main biopolymers used to produce today’s
single-use bioplastics items such as bags, dishes,
straws, coffee stirrers, glasses, horticulture pots,
mulching film, bin liners, dust sheets, bottles,
and packaging items. Today’s single-use plastic
packaging and lignocellulosic materials are
biodegradable and compostable when they meet the
requirements of European Union Standard EN 13432,
“Requirements for packaging recoverable through
composting and biodegradation – Test scheme
2022 | Volume 1, Issue 1
and evaluation criteria for the final acceptance of
packaging” [8-9].
The present study is a verification study for the
specification of EN 13432 and uses a cellophanebased biodegradable packaging material. The
sample exhibited was above 92% biodegradation
after 48 days of exposure. Moreover, the germination
rate of the sample compost demonstrated a more
than 93% germination rate. The biodegradability of
the test sample meets the criteria stipulated by EN
13432.
Materials and Methods
Test specimens of biodegradable plastics with a
particle size of 250 µm powder were used for the
study. AR-grade microcrystalline cellulose 98% was
used as the positive control. The compost inoculum
of four-month-old, well-aerated compost from the
organic fraction of municipal solid waste, sieved
on a screen of less than 10 mm, was used for the
study. The inoculum was characterized using a pH
meter (Eutech Instruments Ion 510 for determining
pH), a gas chromatography flame ionization
detector (GC-FID) (PerkinElmer gas chromatograph
Clarus 590 for determining volatile fatty acids), and
Kjeldahl distillation equipment (BUCHI distillation
unit K-350 for Kjeldahl nitrogen). The preliminary
characterization of the test sample was determined
by recording the spectrum using Fourier transform
infrared (FTIR) spectroscopy (PerkinElmer Spectrum
65). Aerobic and anaerobic degradability were
performed as per ISO 14855-1 and ASTM D5511,
respectively [10,11]. The toxic elemental analysis
of the compost so obtained after the aerobic
degradation study was recorded using inductively
coupled plasma atomic emission spectrometry
(Shimadzu, ICPE-9820). The ecotoxicity study of the
compost was based on OECD 208 guidelines [12],
which involved the evaluation of seedling emergence
and seedling growth of higher plants following
exposure to the test substance in the soil. Seeds of
Brassica juncea (mustard) and Vigna radiata (green
gram) were placed in contact with soil treated with
the test substance and evaluated for effects 21 days
after the 50% emergence of seedlings in the control
group.
Sample Preparation
For pH measurement
The pH was monitored to treat the sample into
neutral in case the sample was in an acidic or basic
condition due its interfere with microorganism
activity [13]. The pH of the inoculum was maintained
between 7 and 8.5. For determining the pH sample,
one part of the sample was mixed with five parts of
distilled water. It was mixed by shaking and the pH
was measured immediately.
For GC-MS analysis
Acetic, propionic, butyric, isobutyric, valeric,
isovaleric, and hexanoic acids from the compost
material were analyzed using a gas chromatograph
equipped with flame ionization detection (splitless
injection) and a DB-WAX column (30 m x 0.25 mm x
0.25 µm). A DB-WAX column is a polar column used
for detecting volatile fatty acids; a polar column
is highly recommended due to its great resolution
and sensibility. The samples of raw compost
(approximately 200-250 g according to sample
moistures) were extracted using demineralized
water (in a 1:20 ratio representing the mass ratio
of solid-phase dry mass to aqueous phase) and
agitated for 24 hours in tightly closed brown bottles.
The aliquots of liquid phase were then centrifuged at
10,000 rpm, and the supernatants were acidified to
pH 2 with oxalic acid. After filtration through a 0.45
ml membrane filter directly into vials, the acidified
samples were analyzed using GC-FID to determine
the concentrations of individual acids. All samples
were extracted and analyzed in duplicate [14].
Results and Discussion
Characterization of Packaging Material Using FTIR
Spectroscopy
Each packaging material under investigation was
identified and characterized prior to testing for the
determination of the constituents of the packaging
materials. FTIR spectroscopy was employed for
the preliminary characterization. When compared
with sample spectra available in the library of the
equipment, it was found to have a 76.2% match with
cellophane. The band at 899.95 cm-1 is characteristic
of the glycosidic bond β-(1→ 4) cellulose [15]. The
range between 1200 cm-1 and 1100 cm-1 is in
the region of hemicellulose and cellulose, which
attained a maximum value around. A band around
1457 cm-1 corresponds to deformation -CH2 and
-CH3 groups and an intense peak at 1035 cm-1
corresponds to C-O stretching [16]. Moreover, a
band around 1735 cm-1 is characteristic of C-O
stretching while the peak at 2921 cm-1 is due to the
asymmetrical stretching of -CH2 and -CH, which
denote the characteristics of cellulose [17]. The
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broad peak between 3500 cm-1 and 3000 cm-1 is
attributed by the sum of the vibration of valence
bands of the hydrogen bond of the -OH group and
the bands of inframolecular and intermolecular
hydrogen bonds. The search spectrum is depicted in
Figure 1.
Figure 1: Overlay of FTIR spectra of the sample with the reference
sample from the software library
Aerobic Biodegradability
The ultimate aerobic biodegradability of the test
sample was conducted as per ISO 14855-1:2012.
Determination of the ultimate aerobic biodegradability
of plastic materials occurred under controlled
composting conditions (“Method by analysis of
evolved carbon dioxide — Part 1: General method”).
This test method determines the degree and rate of
the aerobic biodegradation of plastic materials on
exposure to a controlled-composting environment
under laboratory conditions.
The test substances were exposed to an inoculum
derived from compost from municipal solid waste.
This test method is designed to yield a percentage
of the conversion of carbon in the sample to carbon
dioxide and the rate of biodegradation. The inoculum
possessed an ash content of 60%, pH of 7.6, and
total dry solids of 52%. The inoculum should be as
free from larger inert materials as possible to make it
homogenous.
The samples were exposed to the inoculum in the
composting vessels that were incubated in the
dark with the temperature maintained at 58± 2°C.
A pressurized air system containing CO2-free, H2Osaturated air was provided to each of the composting
vessels at an accurate aeration rate. CO2 and O2
