https://repository.sustech.edu/handle/123456789/1304 2026-04-04T07:35:52Z 2026-04-04T07:35:52Z Abdalgader, Altaf Alsaid Mohamed Supervisor, -Abdelmoneim M. Awadelgied https://repository.sustech.edu/handle/123456789/28150 2023-02-23T08:08:37Z 2022-06-21T00:00:00Z

Detection of Heavy Metals Contents in Sudanese Cement Using Laser Induced Breakdown Spectroscopy Technique Abdalgader, Altaf Alsaid Mohamed; Supervisor, -Abdelmoneim M. Awadelgied In this work, Laser Induced Breakdown Spectroscopy (LIBS) was used to Investigate, and identify, the heavy metals in samples of cement collected from different local markets in Khartoum state. Four cement samples were used as study samples (Atbara, Barbar, Mas and Sakhr Al Sudan) cement. Optimal experimental conditions were evaluated using Nd: YAG laser in Q-switched mode with ability to deliver maximum pulse energy of one joule with a pulse width of 8 ns and operating at a 10 Hz was employed for production of plasma spark at the sample surface. A convex lens having focal length 30 mm was used to focus Nd-YAG laser pulse onto the surface of sample at 266 nm. With pulse energy 30 mj. The spectrometer used was Ocean Optics LIBS 2000+ system. Our LIBS 2000+ has four spectrometers modules to provide high resolution (FWHM 0.1 nm) in the (200 to 620) nm wavelength region. The detector has a gated CCD camera having 14,336 pixels. This makes it possible to measure a LIBS spectrum over broad spectral range (200 to 620) nm simultaneously with high spectral resolution (0.1 nm). The emission is observed at a 90° angle to the laser pulse. The recorded spectra of the samples were analyzed using NIST data. The analysis of the spectra showed considerable amounts of neutral atoms like (Ca, Fe, Si, Na, Ti, Cr, V, Sr, Zr, Kr, K and Cs) that were found in all samples. In addition to the ions: (Ca+1, Fe+, Si+1, Na+1, Ti+1, Cr+1, and K+1). The heavy metals like: metals (Cr, Fe, Ti, Mn, V, Xe, Y and Zn) were appeared in the four samples with nearly amounts, they are toxic metals harmful to human and environment. To identify the relationship between the laser pulsed energy and the intensity of the LIBS signal, the Mas cement sample was irradiated by different pulse laser V energies (10, 15, 20, 25, 30 and 32) mJ .respectively and 200 ns delay time. We observed when the laser pulse energy increase the line intensity was increase. LIBS were applied for the determination of plasma temperature and electron density of Cr in Mas cement sample. The plasma temperature and electron density were calculated at (10, 20, 25 and 30) mJ laser pulse energy using standard equations and well resolved spectral lines in the (428.97 ,430.117,435.17,and 435.96) nm region. These parameters were found to increase with increase in laser pulse energy. The Boltzmann distribution and experimentally measured line intensities support the assumption that the laser-induced plasma was in local thermal equilibrium. To identify the relationship between the laser delay time and the intensity of the LIBS signal, the Mas cement sample was irradiated by 32mj laser pulse energy and (200,300,400 ,500, 600, 700, 800, 1000, and 2000) ns delay times. We observed LIBS signal decreases with increase in laser delay times. The plasma temperature and electron density were calculated at (300,500, and 700) ns laser delay time at 32mj laser pulse energy using standard equations and well resolved spectral lines of Ca in the (422.67, 430.25and 430.774) nm region. It was observed that when the delay time increases the plasma temperature and electron density were decreased. Then the electron density increased with increased in plasma temperature. Thesis

2022-06-21T00:00:00Z Banaga, Mahasin Mohamed Daffalla Supervisor, - Abul Moneim. M. Awad elgied https://repository.sustech.edu/handle/123456789/27784 2023-02-23T08:05:33Z 2022-04-22T00:00:00Z

Spectroscopic Variability and Optical Properties of Sudanese Edible Oils Using Spectroscopy Methods Banaga, Mahasin Mohamed Daffalla; Supervisor, - Abul Moneim. M. Awad elgied In this study, nondestructive test was applied on six types of edible oils (corn, extra virgin olive, sunflower, pressed sesame, factory sesame and peanuts) using spectroscopic methods. Raman spectroscopy and Fourier infrared spectroscopy were carried out to identify functional groups presence on oils while ultraviolet visible was used to study optical properties of edible oils. From Raman spectra of edible oils samples, the major bands can be found at (1084, 1266, 1303, 1441, 1657, 1749,) cm−1 . It is of particularly significance for edible oils that stretching of C=C bonds gave rise to strong Raman signals and C=O stretching bands were very weak; the contrary can be found in infrared spectra. FTIR spectrum of all samples in range from (400-4000) cm-1 . From comparison of IR and Raman spectra of edible oil samples, the frequencies of some characteristic peaks were identical, while the relative intensities differed markedly. On the contrary, Raman scattering signal at (560, 969) cm−1 was quite weak, but corresponding infrared absorption peak was obvious. The general appearance of the IR spectra of these vegetable oils was found to be very similar to a previously reported study. In the Raman spectrum, the spectrum of peanut and presses sesame differed from the previous studies. Thus, the combination of these two different methods has been very useful in the study of the oil which provides comprehensive information about the chemical compositions of edible oils. FTIR spectral data collected in MIR range 4000-400 cm-1 showed major peaks representing triglyceride functional groups which could be observed around 2925 cm-1 [C–H stretching (asymmetry)], 2854 cm-1 iv [C– H stretching (symmetry)], 1747 cm-1 [C=O stretching], 1463 cm-1 [C–H bending (scissoring)], 1238, 1163, 1118 and 1097 cm-1 [C–O stretching] and 722 cm-1 [C–H bending (rocking)]. A peak around 1653 cm-1 is attributed to C=C stretching (cis). A band shift at 3007 cm-1 ; assigned to C–H stretching vibration of cis- double bond (=C–H) characteristic to samples oils. The absorption spectrum of six important Sudanese oils can be divided into three main absorption regions the first region is from the beginning of the spectrum to 340 nm, the second region is (400 - 500) nm and the last region is from (600-800) nm. The shift in absorption peaks of these oils refer to different chemical group that oils contain. Absorption coefficient and refractive index of all oils under study were different because structure components of each oil were different and this confirm with Raman and FTIR results. High values of the absorption coefficient indicate the possibility of direct electronic transitions between the valence and conduction bands at these energies. Thesis

2022-04-22T00:00:00Z Mudawi, Alaa Ahmed Mohammed Supervisor, -Ali Abdel-Rahman SaeedMarouf https://repository.sustech.edu/handle/123456789/27700 2022-10-20T08:36:43Z 2022-01-12T00:00:00Z

Evaluation of the Quality Parameters for Some Laser-Irradiated Edible Oils Mudawi, Alaa Ahmed Mohammed; Supervisor, -Ali Abdel-Rahman SaeedMarouf This work focuses on the laser food irradiation; mainly on investigating of the influence of green laser (532nm) radiation on some physicochemical properties of sesame oil before and after storage period of 15 consecutive days, and the effect of heating and reheating on sunflower oil properties using carbon dioxide laser compared with the electrical heater was also studied. The samples of sesame oil were irradiated using diode laser beam with wavelength 532nm and 1 W output power, to duration times of 10, 20, 30, 40, 50 and 60 minutes, and kept for a storage period of 15 consecutive days along with an untreated control at ambient conditions. While two samples of sunflower oil were heated and twice heated with carbon dioxide laser beam up to 50c it takes 30 minutes; another two samples of sunflower oil were heated and twice heated up to 250c using electrical heater in two minutes, along with an unheated control sample at ambient conditions. Physicochemical properties like acid value, ester value, free fatty acids, peroxide value, density, refractive index, viscosity, and moisture of sesame oil and of sunflower oil samples were studied. Fourier transform infrared spectroscopy was used to evaluate the degree of oxidation after irradiation processes of sesame oil and sunflower to differentiate between the chemical changes in the oil samples. The properties of sesame oil were compared at the 1st and 15th day of storage. Color measurements of sunflower oil samples were studied too. Study reveals that green laser irradiation increases ester value, saponification value, acid value, free fatty acids, peroxide value, viscosity and moisture content of sesame oil; while, it slightly change refractive index and density. Study also indicates that the storage period of 15 days decreases the ester value, saponification value, and moisture content; while, it accelerate acid value, free fatty acid, peroxide value, density viscosity, and slightly increases the refractive index. Meanwhile, FTIR spectra of the stored samples revealed a notable difference due to the green laser irradiation and storage. The results also, demonstrated that when the same sunflower oil is reheated, the chemical reactions enhance foaming, darkening of oil color, increased viscosity, and off-flavor. Hence, repeated heating of the oil can lead to degradation of the cooking oil, both chemically and physically. These results suggest that exposing sesame oil to the green laser irradiation influences their oxidation stability and quality. It was also found that the long time of heating using laser rising temperature up to 50°c catalyzed chemical reactions that resulted in effects in the oil samples characteristics greater than the effects of the electrical heater in a few minutes with temperature 250°c. Thesis

2022-01-12T00:00:00Z Baba, Mohamed Ahmed Mahgoub Mohamed Salih Supervisor, -Abdelmoneim Mohamed Awadelgied https://repository.sustech.edu/handle/123456789/25615 2020-12-31T11:19:42Z 2020-10-15T00:00:00Z

Characteristics of Lanthanum Titanium Oxide Thin Films Deposited by Pulsed Laser Deposition under Different Annealing Temperatures Baba, Mohamed Ahmed Mahgoub Mohamed Salih; Supervisor, -Abdelmoneim Mohamed Awadelgied In this work, the influence of annealing temperature and the variation of the thermal stability during the deposition were investigated. Pulsed laser deposition system was capable of manufacturing two groups of La2Ti2O7 thin films on Si (100) substrate at different annealing temperatures based on the pulse rate frequency 3 and 4 Hz for 85 and 64 minutes, respectively. Both groups of samples were deposited with a KrF excimer laser with fixed parameters at different annealing temperatures 25, 400, 450, 500, 600, 650, and 700 0C, separately. In order to study the effect of temperature on the microstructure, optical properties of La2Ti2O7 films, the fabricated films were investigated using x-ray diffractometer (XRD), scanning electron microscope (SEM) associated with energy dispersive x-ray spectrometer (EDS), atomic force microscopy (AFM), and the ellipsometry. The XRD patterns of the LTO target and films were analyzed into monoclinic structural and an amorphous nature, respectively. While the EDS spectra confirmed that, the film's chemical composition was of lanthanum, oxygen, titanium with the disappearance of any impurities. The SEM images illustrated that the average thicknesses of the LTO thin films were found to be decreased linearly with the increasing of annealing temperatures for the thin films that were deposited in 3 and 4 HZ together. The AFM reported that all the LTO film were smooth, dense, and uniform. At room temperature, the highest roughness was recorded for the two groups of thin films then become smoother when the temperature increased up to 500 0C, and they were slightly rougher with the increase of temperature up to 700 0C for both groups of films were deposited with 3 and 4 Hz. The obtained results from the ellipsometry pointed out that the refractive indices of the first group of LTO films in the wavelength range of (400– V 1000) nm is within (2.42 – 2.12) changing with the annealing temperatures with the variation of 0.09, particularly at 1000 nm. While it was found within (2.38 to 2.11) changing with the annealing temperatures as well with a small variation of 0.12 specifically at the 1000 nm for the second group of LTO films. As such as the refractive indices of both groups reduced with the increasing of wavelengths following a normal dispersion. On the other hand, the extinction coefficient of the two groups was invariable rose as the temperature rises up to 700 °C together. Further, the real part of the dielectric constant of LTO films in the wavelength range 400–1000 nm is within (4.43 – 5.90) and (4.47 – 5.67) adjusting with the different annealing temperatures for the first and the second group, respectively. While the imaginary part of the dielectric constant of the two groups gradually increases (with peaks shift) during the temperature rises from 25 to 700 °C. Furthermore, the maximum depolarization at 450 nm was found (65%) and (28%) when the thin films deposited with 600 0C and 450 0C for the first and the second group, respectively. While the minimums depolarization were (3%) for the both groups at the same wavelength. Based on the achieved results from the XRD, SEM, AFM, EDX, and ellipsometry, it can be concluded that the annealing temperature controls the characteristics of the LTO thin films. Thesis

2020-10-15T00:00:00Z