Fatty Acid Composition of Vegetable Oils – Project topics materials

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Project Objective

The main objective of this project was to investigate the effect of selected synthetic antioxidants and their blends on the oxidation stability of sunflower oil-based biodiesel. Although the effect of antioxidants on the behaviour of edible plant oils has been widely investigated, less is known on the effectiveness and possible synergistic combinations of antioxidants on the stabilization of biodiesel.

Project Design

Initially the project included the investigation of oxidation stability for rapeseed (Canola) biodiesel, but after the first initial tests it was decided to focus on sunflower biodiesel due to its poor oxidation stability. The project was divided into three phases as shown schematically in Figure.

Preparation of biodiesel

Sunflower biodiesel was prepared by transesterification of sunflower oil with methanol using an alkali as catalyst. The biodiesel obtained was characterised using the EN 14214(BS EN 14214, 2012+A1:2014) and ASTM D 6751 (ASTM D6751-15ce1, 2016) specifications as a guideline for biodiesel quality as several batches was made.

Effect of antioxidant blends on oxidation stability

Oxidation stability was investigated by stabilising the sunflower biodiesel using three different types of antioxidants and their combinations at a fixed total dosage level of 0.15 wt.%. Three different types of antioxidants were used: A hindered phenolic antioxidant, tetrakis[methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)]methane (Anox 20), An amine-type antioxidant, poly(1,2-dihydro-2,2,4-trimethylquinoline) (Orox PK), A phosphite-type antioxidant tris(nonylphenyl) phosphite (Naugard P).

Chapter 1: Introduction
1.1 Project Objective
1.2 Rationale for Project
1.2.1 Biodiesel oxidation stability
1.2.2 Antioxidant effect
1.2.3 Biofuels industrial strategy of South Africa
1.3 Project Design
1.3.1 Phase 1: Preparation of biodiesel
1.3.2 Phase 2: Effect of antioxidant blends on oxidation stability
1.3.3 Phase 3: Results
Chapter 2: Literature
2.1 Introduction
2.2 History of Biodiesel
2.3 Biodiesel Specifications and Properties
2.3.1 Some important quality parameters specified for biodiesel
2.4 Biodiesel Production Technologies/Processes
2.4.1 Dilution/blending
2.4.2 Micro-emulsions
2.4.3 Thermal cracking (Pyrolysis)
2.4.4 Transesterification
2.5 Biodiesel Feed Stock
2.6 Fatty Acid Composition of Vegetable Oils
2.7 Sunflower Oil
2.7.1 Background
2.7.2 Sunflower oil composition
2.8 Transesterification
2.9 Transesterification Reaction Mechanisms
2.9.1 Parameters influencing transesterification
2.9.2 Monitoring transesterification reaction
2.10 Oxidation Stability of Biodiesel
2.10.1 Influence of fatty acid composition
2.10.2 Mechanism of oxidation
2.10.3 Autoxidation of linoleic acid
2.10.4 Mechanism of antioxidants
2.10.5 Antioxidants type
2.10.6 Effect of antioxidants on oxidative stability
2.10.7 Synergy.
2.11 Mixture Experiments
2.11.1 Mixture designs
2.11.2 Correlating the ternary IP mixture data with Scheffé K-polynomials
Chapter 3: Methodology
3.1 Background
3.2 Theory: Biodiesel Production
3.3 Experimental: Biodiesel production
3.3.1 Materials
3.3.2 Biodiesel preparation
3.3.3 Monitoring the mixing effect on the transesterification reaction
3.4 Biodiesel Characterisation Procedures
3.4.1 Gas Chromatography: GC-FID
3.4.2 Fourier Transform Infrared spectroscopy (FTIR)
3.4.3 H NMR spectroscopy.
3.4.4 Viscosity and density
3.4.5 Thin layer chromatography: TLC
3.4.6 Additional characterization methods
3.5 Oxidation Stability
3.5.1 Antioxidants
3.5.2 Antioxidant formulations with biodiesel
3.5.3 Rancimat oxidation test
3.6 Data reduction
Chapter 4: Results and Discussion
4.1 Effect of Reaction Time on Transesterification of Sunflower Biodiesel
4.1.1 GC-FID and H NMR
4.1.2 Viscosity measurements
4.1.3 Thin layer chromatography
4.1.4 FTIR analysis using HATR sample accessory
4.2 Biodiesel Characterisation
4.2.1 FTIR analysis using HATR sample accessory
4.3 Oxidative Induction Time
4.3.1 Oxidative induction periods from global Rancimat data analysis
4.3.2 Effect of antioxidant concentration on induction time
4.3.3 Effect of measurement temperature on induction time
4.3.4 Effect of antioxidant combinations on oxidative induction
4.3.5 Combinations of Orox PK with other phenolic-based compounds
Chapter 5: Conclusion