This page contains the analytical procedures of some of the unit one laboratory equipment for chemical analysis and various other lab testing including Fourier transform Infrared Spectrophotometer (FTIR), Scanning Electron Microscope (SEM), X-ray Fluorescent (XRF), X-Ray Diffraction (XRD) and more..

ANALYTICAL PROCEDURES – UNIT ONE LABORATORY EQUIPMENT

Fourier transform Infrared Spectrophotometer (FTIR)

FTIR – analytical procedures.

For functional unit determination, the Shimadzu Fourier transform Infrared Spectrophotometer (FTIR) 8400 S was used. Samples were weight-in at 0.01 g and homogenized with 0.01 g KBr anhydrous by mortar agate. The mixtures were pressed by vacuum hydraulic (Graseby Specac) at 1.2 psi to obtain transparency pellet. Scanned sample passed through infra red, where its continuing wave by detector that connected to computer and given described of tested sample spectrum. Samples for Fourier transform Infrared Spectrophotometer (FTIR) were usually scanned in the absorption area of 600 to 4000 cm-1. The results of analysis consisted of chemical structure, molecular binding form and certain functional groups of tested sample as basic of spectrum type.

Scanning Electron Microscope (SEM) Procedure

The Scanning Electron Microscope energy dispersive X–ray spectroscopy (SEM-EDS) Phenom Prox model, manufactured by phenomWorld Eindhoven, Netherlands was used to carry out the morphology analysis. Sample is placed on the Aluminium holder stub using sticky carbon tape. The sample was insulated using gold and then grounded electrically. The samples each are then labeled on their stub, then dried in the oven at 60^oC. Nitrogen line was opened at 50 psi and the vent button is pressed to fill the area with nitrogen for proper purging of the chamber. The sample holder stub was then placed in the sample chamber holes and the door was shut and the rotary pump picked and a vacuum of 5 x 10^-5 Pa was created. The filament light was switched on and the monitor too automatically switched on. At this stage, the accelerator voltage was 15kV and the filament burned out. The atoms on the surface are excited by the electron beam, emitting specific wavelengths of X-rays that are characteristic of the atomic structure of the elements. An energy dispersive detector (a solid–state device that discriminates among X-ray energies) can analyze these X-ray emissions. Appropriate elements are assigned, yielding the composition of the atoms on the specimen surface. The lowest scan mode of 10x is picked and the TV scan clicked. The magnification is then taking to 1000x at a slow scan, 2000, 3000 to 5,000. The Energy dispersion spectrum scan on the intensity of each of the element present and gives the  molar concentration in %, then Image was saved. This procedure is called The Scanning Electron Microscope Energy dispersive X–ray spectroscopy (SEM-EDS) and is useful for analyzing the composition of the surface of a specimen

UV Spectrophotometer Analytical Procedures

The T70 PG Instruments’ UV- Spectrophotometer was used to analyze the samples at different wavelength and absorption the Spectrophotometer was first switched on and allows to stabilize before the calibration was done using distilled water and a black body. After calibration the wavelength was set to 330nm and the corresponding absorption was displayed after pressing the key for absorption. This step was followed for other wavelength until it gets to 900 nm.

Gas Chromatography (GC-MS)

Samples (digested) were analyzed by gas chromatography/mass spectrometry (GC/MS), using

Agilent-Technologies (Little Falls, CA, USA) 6890N Network GC system, equipped with an Agilent Technologies 5975 inert XL Mass selective detector and Agilent- Technologies 7683B series auto injector. The separation was performed on Agilent Technologies capillary column

HP-5MS (30 m × 0.25 mm; film thickness 0.25 μm). Sample volume of 1.0 μL was injected into the column with split ratio 100:1. The carrier gas used was Helium at a flow rate of 1.2 mL min¹. The column temperature was programmed from 150^oC to 250 ^oC at a linear ramp rate of 4 ^oC min^-1, while the initial and final hold up time was 1 and 5 min, respectively. An electron ionization mode, with ionization energy of 70 eV, was used for GC/MS detection. Injector and MS transfer line temperature were set at 250 ^oC and 260 ^oC, respectively. The scanning mass range was selected from 30-550 m/z (mass-to-charge ratio).

The unknown samples were identified on the basis of matching of their relative retention times with those of standards (Sigma Chemical Co., St Louis, MO, USA). Samples were further identified and authenticated using their MS spectra compared to those from the NIST mass spectral library of the GC/MS system.

X-ray Fluorescent (XRF)

The X-ray fluorescent (XRF) Nitron 3000 was powered on and Allowed to stabilized for 5 minutes after initialization. THE Cu-Zn method was chosen which normally detect large amount of elements and sesquioxides due to its intensity. Sample was placed on the sample holder while  the ray point was placed over it and the ray button was pressed to start taking the data. The data were collected in triplicates and this automatically takes the average.

This procedure was followed for all the X-ray fluorescent (XRF) samples to get the percentage chemical composition in oxide and elemental form.

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X-Ray Diffraction (XRD) Analytical Procedures

The X-Ray Diffraction (XRD) EMPYREAN MALVERN PANALYTICAL Diffractometer was powered and from  the panel, the voltage and current were set at 45kV and 40 mA. The temperature was set at 2123^oC. The computer system was switched on and the software of X-Ray Diffraction (XRD), TUMI was double clicked to run. The settings dialogue was clicked and all the required setting of power and temperature were checked to correspond to that of the XRD. Sample was poured into the sample holder and then placed in the sample chamber column. Then the door was shut and confirmed from the computer. The measurement setting were then set for scan axis as Gonio, start and end position were also set so is the angle and time of scan. The scan began and then stopped at the required time and the result was saved to a file.

The result obtained was then match with different library, such as the NIST and PubChem in order to get the chemical structure, name, and other physicochemical properties

HPLC Analytical Procedures

Separation of sample was performed by HPLC analysis, using a Thermo Scientific System equipped with a Star Solvent Delivery System 230, Injector Rheodyne 7125, Pro Star 330 (UV – Photo Diode Array Detector). Chromatographic separation was performed on a Zorbax ODS column (250 x 4.6 mm i.d. 5 μm) (Agilent, USA). The flow rate was set to 0.9 mL/min.

Operating conditions were as follows: column temperature, 20 °C, injection volume, 20 μL,

UVPDA detection at 278 nm. Before injection, extracts were filtered through 0.45 μL Nylon Membrane filter (Supelco, USA). Detection was performed with UV PDA detector by scanning from 278 to 360 nm.

The equipment RASI700 BIO Portable Gas Analyzer (2016 Eurotron Instruments (UK) an ISO9001:2008 company) was powered and allowed to initialize for 60 seconds.  After the initialization it was allowed to stabilize for five minutes. The rubber tube was then connected to the gas sample point (gas Bag or Gas outlet point from gas vessel) and the USB cord from the analyzer was connected to the computer. The gas was opened and allowed to flow into the sensor which then amplified the signal and then the reading was displayed for the whole gas present and sensed by the analyzer.

The save button was pressed and the data logged in the analyzer. The software was opened on the computer and the whole data was then printed on PDF. The system was switched off and the valve to the gas bag was closed. The analyser was allowed to be free of any gas and then purged with nitrogen before it was shut down.

PRINCIPLE OF MEASUREMENT FOR THERMAL CONDUCTIVITY

Diffusivity is the rate of diffusion measured as the rate at which heat is spread on a material. The Thermal conductivity of the materials each with the specific heat capacity which were constant was measured using radial heat conduction apparatus (Armfield equipment model HT12) with heat transfer service unit (Armfield equipment model HT10XC

The probe consists of single heater wire and thermocouple. When constant electric power (energy) is given to the heater, the temperature of the wire will rise in exponential progression. Temperature rising with time line increases if the sample has less thermal conductivity, and decreases if it has higher TC. Therefore, TC of a sample can be determined from the rising temperature using the equation below. 

Thermal Conductivity (TC)

where;

; Thermal conductivity of sample                                       [W/mK]

Q; generated heat per unit length of sample/time                      [W/m²]

Sample diameter = 0.0018  and length = 0.0043    [m]

X;  Thickness of sample                                                            [ m]

A; Area                                                                                    [m²]

T0 and T5; Temperature at t0 and t5                                   [K] t1 and t2;  measured time length                                               [second, s] Heat Transfer Coefficient U (W/m²•K)

The general definition of the heat transfer coefficient is:

Where;

Q: heat flux, W/m²;

U: heat transfer coefficient, W/(m²•K

∆T: difference in temperature between the solid surface and surrounding fluid area, K

Specific Heat Capacity, Cp (J/kg*^oC)

Specific heat capacity (Cp) =

∆

Unit of C is J/kg*^oC, M is the Mass (kg), Q is change in energy (J), and ∆T is Temperature change (^oC)

Thermal Diffusivity α (m²/s)

Thermal Diffusivity α (m²/s) =

; Thermal conductivity of sample                                       [W/mK]

Where ρ is the density of the material and

Cp is the specific heat capacity (J/gK).

TGA DTA

The TGA PerkinElmer TGA 4000 Made in Netherlands was used for the analysis. It was ensured that the nitrogen gas was on and that it is connected to the instrument in the “balance” port.  The “Pyris” manager Open up and the TGA button was selected at the top of the screen.  When the software was open there was were two dialogs within the application One is the instrument viewer and the other is the method editor. Using the tweezers of the TGA, a clean empty crucible with the wire basket (stirrup) was loaded onto the hang-down wire which is connected to the microbalance at the top of the instrument. After the crucible has been installed, <raise furnace> icon was selected.  The furnace then moved into position and raise up over the crucible.  When the furnace was in position the <zero balance> icon was selected and a few minutes was given in order to allow the crucible to stabilize and then the balance was zeroed repeatedly until it stabilizes.

When the balance as been satisfactorily zeroed, <cool furnace> icon was selected to move the furnace out of the way.  the sample stage was placed in position under the crucible and hang down wire then the crucible was carefully removed by lifting the wire basket from the hang down wire.  Sample was then placed on the crucible then the crucible and wire basket were carefully reinstalled on the hang-down wire.  the <raise furnace> icon was then selected, and the crucible was allowed to stabilize for 10 minutes.  While the sample stabilized the <measure sample> icon was then selected and the value automatically was recorded in the method editor. In Method Editor, the information about your sample was inputted for the: Maximum operating temperature and Maximum heat up rate. When your measurement was complete the furnace was switched off and placed in the cool position and the crucible was removed. 

Calorific value

Heating Value HHV (Calorific Value):

The HHV of the oil and its biodiesel was determined using the Bomb Calorimeter (Model 6100, Bomb Calorimeter, Parr Instrument Co., Moline, Illinois).  The bomb calorimeter was calibrated using the method described below by combusting a known mass, m, of standard benzoic acid which has a known heat of combustion of 26.453 kJ/g. The gross Heat of combustion was measured in an oxygen bomb calorimeter according to a standard procedure, ASTM D2382-88. A weighed sample of approximately 0.1 gram was placed inside the calibrated adiabatic bomb calorimeter with 1 millilitre of deionized water. A Chromel (chromium nickel alloy) wire was connected to the two electrodes in the pressure vessel (bomb) and placed in contact with the sample for ignition. The bomb was then assembled, sealed and purged twice by pressurizing to 0.5 MPa with pure (99.99%) oxygen after which it was vented. which later pressurized with pure oxygen to 2.0 MPa for the test and placed inside a bath containing 2 litres of water in an insulated jacket. A motorized stirrer was placed inside the water bath to circulate the water around the bomb creating a uniform temperature. The sample was then ignited by passing an electric current through the Chromel wire causing the sample to burn to completion in the high pressure oxygen. The bomb and the bucket were then held in a calorimeter jacket and serves as a thermal shield. The result was displayed in the display unit in (MJ/kg) or (Cal/g) depend on which unit the user selected. This procedure is repeated when there are other samples.

Hardness Test Procedure

The Brinell method was used for the testing of the material, since its Polymeric in nature. In the Brinell hardness test, an optical method, the size of indentation left by the indenter is measured. In contrast to the likewise optical Vickers method which involves a pyramid-shaped indenter being pressed into a specimen (sample), the Brinell method uses a spherical indenter to hit the sample for the test. The larger the indent left in the surface of a work piece (sample) by the Brinell indenter with a defined ball diameter and a defined test force, the softer the tested material. In order to determine the Brinell hardness (HB) according to ISO 6506, the spherical, hard metal (tungsten carbide) indenter is pressed into the sample with a defined test load (between 1 kgf and 3000 kgf). The Brinell hardness (HB) results from the quotient of the applied test force (F in newtons (N)) and the surface area of the residual indent on the specimen (the projection of the indent) after withdrawing the test force. The measurement is obtained by transforming the physical hit to an electric signal which is then detected by the amplifier and then displayed.

PROXIMATE ANALYSIS

Percentage Moisture Content (PMC)

Moisture content of samples was determined based on mass loss after two hours at 105◦C under N₂ purge. Approximately 0.5 g of air-dried sample was weighed into a ceramic crucible.The samples were placed inside of a Lindberg muffle furnace, which was initially purged with N₂ gas for ≥20 min at a flow rate of 3 L min⁻¹, to ensure removal of all oxygen..After the 2 h heating, the furnace was turned off and samples were transferred immediately to a desiccator, left to cool for one hour and then weighed. 

Wc – Dc ∗ 100

MC       

????????

where, Wc is the Air dried weight of sample Dc is the Oven dried weight of sample at103 ℃  MC = Moisture content.

Volatile matter 

Volatile matter was determined by heating the oven dry samples under N₂ purge at 850◦C. During heating, the crucibles containing the sample were covered with ceramic lids, placed in a stainless steel box inside of a muffle furnace. A N₂ purge line and thermocouple were inserted through the top of the furnace and down into the stainless steel box through a small hole in the box cover. The box was purged with N₂gas for about 5 min at a flow rate of 5 L min⁻¹. After the initial purge, the N₂ flow rate was decreased to 3 L min−1, the furnace was set to the desired peak separation temperature, and turned on. The temperature inside of the stainless steel box was measured every 60 s during the heating treatments. Once the temperature inside of the stainless steel box reached 850◦C separation temperature, the furnace was switched off and furnace door opened. TheN₂ purge inside the stainless steel box was maintained (3 L min−1) during cool down (2–4 h), after which the crucibles were weighed.

Vm =  

where, B is the Air dried weight of sample

C is the Furnace calcined weight of sample at 900 ℃ 

Vm = Volatile matter

Ash content

Ash content of sample was determined by heating the same sample to 730◦C in an air atmosphere using the same muffle furnace. To ensure complete combustion, crucible lids were removed and a low flow of house air (1.5 L min⁻¹) was constantly flushed through the furnace. The furnace was heated to 730◦C and held at that temperature overnight (8–10 h). After ashing, the furnace was switched off and allowed to cool for one hour before the samples were transferred to a desiccator to cool. The crucibles were weighed and ash mass was determined by subtracting the empty crucible weight. All reported proximate analysis data were done in triplicate measurements.

???? ∗ 100

????????       

????

where, D is New weight of sample

B is the Initial of sample at 103 ℃ 

Ac = Ash content

Percentage Fixed Carbon (PFC) 

The percentage fixed carbon, PFC was calculated by subtracting the sum of percentage volatile matter (PVM) and percentage ash content (PAC) from 100. The carbon content is usually estimated as a “difference”, i.e., all the other constituents are deducted from 100 as percentages and the remainder is assumed to be the percentage of fixed carbon. This was determined using;

Fixed carbon (FC%)  = 100  – ( VM% +AC%)

Lignin, Cellulose, Hellocelluose

 Lignin content  

About 1 g (exactly weighed) of the sample was put in a 100 ml beaker and then treated with 20ml of 72% sulfuric acid, added to the sample drop by drop with constant stirring by a small glass rod. After complete disintegration, the reaction is allowed to stand and the beaker is covered with a watch glass and left over night at room temperature. It was then transferred quantitatively to a 1 liter round bottom flask, diluted with 3% sulfuric acid, and boiled for four hours under reflux. The lignin is filtered on an ashless filter paper and washed with hot distilled water till neutrality, then gravimetrically estimated and ignited at 850°C for 45 minutes. The weight of ash is subtracted to give the ash free lignin per cent.

Hemicellulose: 1 g of extracted dried sample was transferred into a 250 mL Erlenmeyer flask. 150 ml of 20 g/l NaOH was added. The mixture was boiled for 3.5 h with distilled water. It was filtered after cooling through vacuum filtration and washed until neutral pH. The residue was dried to a constant weight at 105 oC in a convection oven. The difference between the sample weight before and after this treatment is the hemicellulose content (%w/w) of dry biomass

Cellulose

This is calculated as:

Cellulose = 100% – (Hemicellulose + lignin)

Holocellulose estimation  

Holocellulose is the total carbohydrate fraction (cellulose and hemicellulose) of the raw material. 

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