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Microbial Degradation of Polyester Based Biodegradable Plastics

Thesis Info

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Author

Satti, Sadia Mehmood

Program

PhD

Institute

Quaid-I-Azam University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2018

Thesis Completion Status

Completed

Subject

Microbiology

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/10945/1/Sadia%20Mehmood%20Satti_Microbio_2018_QAU_PRR.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726637930

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The present study was aimed to isolate and characterize microorganisms capable of degrading polyester-based biodegradable plastics under natural soil conditions. Two fungi, designated as strain SS2 and S45, were isolated from soil that could degrade various polyesters of natural as well as synthetic origin, both in emulsion as well as film form. Strain SS2 and S45 were identified through 18S rRNA gene sequencing and found closely similar to Penicillium sp. and Aspergillus sp., having 100 and 99% similarity with Penicillium oxalicum and Aspergillus fumigatus, respectively. P. oxalicum SS2 could efficiently degrade polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-valerate (PHBV) emulsion as well as films in liquid medium within 36-48 hrs. The fungus showed maximum growth and degradation at 30°C that represented its mesophilic nature. Furthermore, the role of P. oxalicum SS2 in degradation of polyester films in soil environment was evaluated by soil burial experiment in lab-built microcosms where the fungus degraded PHB and PHBV films in 7 days. Aspergillus fumigatus strain S45 showed degradation potential against poly(caprolactone) (PCL) and polyurethane (PU). Bio-augmentation of the fungus in soil accelerated biodegradation of PCL film. While measurement of weight loss and evolution of CO2 showed breakdown of PU film upon inoculation with S45. The biodegradation of polyesters was further confirmed through various qualitative assays such as scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and fourier transform infrared (FTIR) spectroscopy. Aspergillus fumigatus strain S45 was found to show esterase activity during biodegradation of PU. This study demonstrated soil as a reservoir for polyester-degrading microorganisms which could be utilized for the development of novel waste management strategies.
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جریبِ حیات

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ڈاکٹر مجاہد عباس ،لیکچرر، نمل یونیورسٹی اسلام آباد

جریب زمین کے لیے ہے یا حیات کے لیے،  زمین اور حیات دونوں ہی اس سے ناواقف رہتی ہیں۔ البتہ انسان جو زمین سے اگایا جاتا ہے اور پھر زمین میں ہی دبایا جاتا ہے جریبوں کی  پیمائش بن کے رہ جاتا ہے۔

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 اس  نے ٹیَلوں لگے فرش سے پلاسٹک کی میز اور کرسیاں اٹھا کر گھر کی پچھلی طرف لان میں رکھ دیں جہاں پھولوں کے احاطے میں سبزے کی بہار تھی۔  یہ لان اس کی زندگی میں افضال کی طرح  اہمیت رکھتا تھا۔ وہ جب بھی تھک جاتی تو وہاں آرام کرتی تھی، پودوں...

دینی مدارس اور مفکرین کی آراء

This article attempts to focus on Maddrassas education setting, its importance, introduction and correspondence with human resource development. The role of this development to create a sound and balanced environment in the society with moral and spiritual values. Firstly the paper addresses education and its functions in general then education from Islamic perspective like teaching especially spirituality and morality. Secondly the role of Madaris in Islamic cultural and traditional awareness through the righteous opinion oflearned scholars

Kinetic Study of Thermo-Catalytic Decomposition of Polypropylene under Isothermal and Non-Isothermal Conditions

Plastic based products are used worldwide for packing and other consumer goods. Their wider use and non-biodegradable nature make them a serious threat to the environment. In order to circumvent the problem, incineration and dumping them in soil are the common practices. However, these practices are now unacceptable in terms of recent legislation in the matter. Incineration leads to hazardous smoke, whereas frequent land filling contaminates the soil and underground water. Hence, recycling is the ultimate choice and this has two benefits. On one hand the plastics are disposed of and on the other hand some valuable products are also obtained which have substantial benefits for domestic and 22 commercial use. In the present research work thermal decomposition kinetics of polypropylene was investigated in the absence and presence of catalyst (molecular sieve LZ Y52, Zeolite mordenite ammonium, cobalt doped molecular sieve LZ-Y 52, Cu-Co/MS) in a thermobalance system, at isothermal and non isothermal heating conditions with heating rate of 5 oC/min, 10 oC/min, 15 oC/min and 20 oC/min in the temperature range of 30–600 oC under nitrogen atmosphere. The apparent activation energy (Ea) and Pre-exponential factor (A) were determined using Ozawa Flynn Wall, Tang Wanjun and Coats-Redfern (modified) methods. In the absence of catalyst, the apparent activation energy and pre-exponential factor were found in the range 61.3– 110.9 kJmol-1 and 2.1×107 - 3.3×1013 min-1 respectively. The activation energies and pre-exponential factor determined in the presence of molecular sieve LZ-Y52, Co/MS, Cu-Co/MS and zeolite mordenite ammonium catalysts were in the range of 58.38 – 74.50,47.59 – 54.75, 48.36 – 73.81 and 72.77 - 84.12 kJmol-1 and 2.4×107 - 9.05×108, 1.86×106 - 1.9×107, 3.2×106 - 9.9×108 and 2.7×108 - 3.6×109 min-1 respectively. Increasing the heating rate shifted the Tmax to a higher level. The lower activation energies observed indicates breakage of the bonds at weak links. Moreover, the values of kinetic parameters are significantly controlled by the heating rate, level of conversion and calculation technique. A comparison among the different techniques has been made on the basis of the apparent activation energy from the TG data. The activation energies determined by all the three methods are in good agreement with each other. Furthermore, the pyrolysis of model polypropylene was carried out over the temperature range 350-415°C in an indigenously manufactured furnace using Pyrex reaction vessel. The liquid and gaseous fractions produced were collected and monitored using gas chromatography/mass spectrometry. The conditions for thermal and catalytic degradation were optimized for maximum liquid oil production. 10% catalyst amount, temperature 395 oC, nitrogen flow rate 16 mL/min and reaction time 60 minutes were the optimum conditions used during experimental work.It was found that, in case of thermal degradation no condensable 23 products were observed while in case of catalytic degradation more than 70% condensable products were obtained at 395oC for 1 hour. In commercial catalysts molecular sieve LZ-Y52 while in modified catalysts the cobalt doped was found to be preeminent catalysts for the conversion of model polypropylene in to valuable products. The physical parameters of the oil obtained from the pyrolysis of PP in the presence of catalysts were determined so as to evaluate its potential application for fuel oil and compared with standard values of gasoline, diesel and kerosene oil. The values of physical parameters were found out to be in close agreements with the standard values of diesel and kerosene oil. Moreover, the study conducted on pure polypropylene on laboratory scale could successfully be applied to waste polypropylene on commercial scale.