Baseer Haider | King Fahd University of Petroleum and Minerals (original) (raw)

Papers by Baseer Haider

Journal of Magnetism and Magnetic Materials

Environmental Science and Pollution Research

In this study, we report an effective degradation method for trace level beta-blockers (propranol... more In this study, we report an effective degradation method for trace level beta-blockers (propranolol and acebutolol) in hospital wastewater using a new droplet flow-assisted heterogeneous electro-Fenton reactor (DFEF) system. Biogenic iron–carbon nanocomposites (RHS/C-x% Fe) as eco-friendly and low-cost heterogeneous Fenton catalysts were synthesized from rice husk via hydrolytic sol–gel routes. Here, we demonstrate the use of natural air as a nebulizing agent for fast and continuous catholyte air saturation and Fenton catalyst transfer to the cathode electrode. The effects of key operational parameters were evaluated and optimized using central composite design. Results clearly indicated that enhanced beta-blocker degradation was mainly dependent on the interactive effects of electrolysis time, current density, and catalyst dosage. Fast degradation efficiencies (≥ 99.9%) was recorded at neutral pH conditions. The decay followed pseudo-first-order kinetics with degradation rates of up to 2.72 × 10−2 and 2.54 × 10−2 min−1 for acebutolol and propranolol, respectively. The synergistic contribution of •OHbulk attributable to DFEF process and •OHadsorbed for anodic oxidation (AO) at the anode electrode significantly enhanced the degradation process. Compared to AO, the conventional flow-assisted electro-Fenton (FEF), and the batch electro-Fenton (BEF), DFEF degradation efficiency followed a decreasing order: DFEF ˃ FEF ˃ BEF˃ AO. This trend in performance was mainly due to the fast and continuous cathodic electro-generation of H2O2 and Fe2+ regeneration. Additionally, in order to elucidate degradation mechanism, we used a combination of DFEF approach with liquid chromatography-tandem mass spectrometry analysis. This approach demonstrates a simple, cleaner, and highly efficient degradation approach for trace level recalcitrant pollutants in a complex aquatic matrix, without the need for external chemical addition and pH adjustment.

Recent Developments in Analytical Techniques for Corrosion Research

ZnO has attracted much attention due to its wide bandgap (3.2 eV) and high exciton binding energy... more ZnO has attracted much attention due to its wide bandgap (3.2 eV) and high exciton binding energy of 60 meV. These properties make ZnO a highly desirable material for high frequency devices that can work in harsh environment. We have grown ZnO thin films at different temperatures ranging from 100 ◦C to 500 ◦C. We have observed that surface roughness is first decreased with the increase in the growth temperature but then by further increasing the growth temperature beyond 300 ◦C, results in increased surface roughness of the grown samples, whereas grain size of the samples increases with the increase in the growth temperature. Crystalline quality of the films is also improved with the increase in the growth temperature but then degrades by further increase beyond 200 ◦C. We achieved the highest Hall mobility for the ZnO sample grown at 200 ◦C. The optimum growth condition of ZnO thin films on sapphire (0001) in our RF/DC magnetron-sputtering unit were achieved for the films grown at ...

Iron doped titanium nitride thin films were prepared by RF/DC magnetron sputtering of titanium an... more Iron doped titanium nitride thin films were prepared by RF/DC magnetron sputtering of titanium and iron targets in the presence of argon and nitrogen gasses. Iron concentration in the films was controlled by adjusting the DC power of the sputtering gun whereas the RF power for the titanium target was kept constant for all the films. Spectrophotometry of the grown films revealed a reduction in the bandgap with the increase in the iron concentration in the films. X-ray photoelectron spectroscopy of the films confirmed the presence of iron and the increase in its concentration with the increase in the DC sputtering power. The surface roughness of the films slightly increased with the increase in the iron concentration. All the grown films were n-type semiconductors and the carrier concentration increased with the increase in iron concentration. Positive magnetoresistance was observed in undoped or low-doped titanium nitride films, whereas negative magnetoresistance was observed in the ...

Crystals

Titanium nitride thin films were grown on Si(001) and fused silica substrates by radio frequency ... more Titanium nitride thin films were grown on Si(001) and fused silica substrates by radio frequency reactive magnetron sputtering. Post-growth annealing of the films was performed at different temperatures from 300 °C to 700 °C in nitrogen ambient. Films annealed at temperatures above 300 °C exhibit higher surface roughness, smaller grain size and better crystallinity compared to the as-grown film. Bandgap of the films decreased with the increase in the annealing temperature. Hall effect measurements revealed that all the films exhibit n-type conductivity and had high carrier concentration, which also increased slightly with the increase in the annealing temperature. A detailed depth profile study of the chemical composition of the film was performed by x-ray photoelectron spectroscopy confirming the formation of Ti-N bond and revealing the presence of chemisorbed oxygen in the films. Annealing in nitrogen ambient results in increased nitrogen vacancies and non-stoichiometric TiN films.

Separation and Purification Technology

Abstract In this study, copper-boron-ferrite (Cu-B-Fe) composites were prepared and immobilized o... more Abstract In this study, copper-boron-ferrite (Cu-B-Fe) composites were prepared and immobilized on treated graphite electrodes via rice husk silica-based sol-gel approach. The effect of different bimetallic loading ratios was relatively evaluated for fast in-situ electrogeneration of reactive oxygen species (H2O2 and OH) via a new droplet flow-assisted heterogeneous electro-Fenton reactor system. The optimum loading ratios of 20 wt% Fe3+ and 10% wt. Cu2+ greatly improved the catalytic activities towards efficient pharmaceutical beta blockers (atenolol and propranolol) degradation in hospital wastewater. By using Central Composite Design optimization, high correlation coefficients (R2 and R2-(adj)) between the experimental and predicted data of 96.83% and 93.43% were realized. At optimized conditions, higher degradation efficiencies of ˃ 99.9% for both propranolol and atenolol in hospital wastewater were achieved. The critical contribution of OH radicals in the degradation process was assessed using radical scavengers. As a result, a surface mechanism at the integrated cathode electrode was proposed highlighting the contributions of iron and copper. It was confirmed that both copper and iron embedded in the porous graphite electrode surface catalyzed the efficient conversion of H2O2 to OH which in turn enhanced the degradation process. The fabricated cathode electrodes showed stable catalytic activities even after 20 experimental replicates at both neutral and acidic conditions.

Journal of chromatography. A, Jan 15, 2018

An environmentally friendly micro-solid phase extraction (μ-SPE) method utilizing a plant based n... more An environmentally friendly micro-solid phase extraction (μ-SPE) method utilizing a plant based nanocomposite as a sorbent for determination of trace level beta blockers (ß-blockers) in hospital wastewater prior to Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. μ-SPE extraction conditions were evaluated using a multivariate chemometric approach. Rice husk silica-carbon nanocomposite (5-20Wt.% Fe) in glycerol were synthesized via hydrolytic sol-gel method. The nanosorbent were fully characterized and then evaluated for μ-SPE of trace level ß-blockers in hospital wastewater. To establish the best extraction conditions at minimal experimental cost, multivariate techniques based on fractional factorial (FFD) and central composite designs (CCD) with desirability function (DF) were used to optimize the extraction conditions. Experimental results showed good agreement with predicted values and logical DF was realized at relatively low extraction time. Under optimized c...

Nanoscale Research Letters

Zinc nitride thin films were grown on fused silica substrates at 300°C by radio frequency magnetr... more Zinc nitride thin films were grown on fused silica substrates at 300°C by radio frequency magnetron sputtering. Films were grown at different N 2 /Ar flow rate ratios of 0.20, 0.40, 0.60, 0.80, and 1.0. All the samples have grain-like surface morphology with an average surface roughness ranging from 4 to 5 nm and an average grain size ranging from 13 to16 nm. Zn 3 N 2 samples grown at lower N 2 /Ar ratio are polycrystalline with secondary phases of ZnO present, whereas at higher N 2 /Ar ratio, no ZnO phases were found. Highly aligned films were achieved at N 2 /Ar ratio of 0.60. Hall effect measurements reveal that films are n-type semiconductors, and the highest carrier concentration and Hall mobility was achieved for the films grown at N 2 /Ar ratio of 0.60. X-ray photoelectron study was performed to confirm the formation of Zn-N bonds and to study the presence of different species in the film. Depth profile XPS analyses of the films reveal that there is less nitrogen in the bulk of the film compared to the nitrogen on the surface of the film whereas more oxygen is present in the bulk of the films possibly occupying the nitrogen vacancies.

MnGaN and CrGaN thin films were grown by molecular beam epitaxy on MOCVD GaN(0001)/sapphire(0001)... more MnGaN and CrGaN thin films were grown by molecular beam epitaxy on MOCVD GaN(0001)/sapphire(0001) and sapphire(0001) substrates respectively. Dependence of structural and magnetic properties of MnGaN and CrGaN samples on Ga/N flux ratios were investigated. Scanning tunneling microscopy studies of c-GaN(001) were performed to understand the surface reconstructions of this material, as Mn doped c-GaN has been predicted to have a Curie temperature about 6% higher compared to Mn-doped wurtzite GaN.[1] MnGaN samples were grown on MOCVD GaN(0001)/sapphire(0001) at substrate temperature of 550°C under different Ga/N flux ratios leading to 4 different growth regimes: N-rich, slight metal-rich, metal-rich, and Ga-rich. Mn incorporation and hence magnetic properties clearly depend on the growth conditions. The N-rich grown sample exhibits much larger magnetization compared to the other samples. Ga-rich magnetization is attributed to accumulates, but N-rich magnetization is attributed to carrier-mediated ferromagnetism and/or ferromagnetism due to clusters. Influence of the growth conditions on structural and magnetic properties of CrGaN on sapphire(0001) has been investigated. CrGaN samples are grown under different Ga/N flux ratio of 65% to 100% at substrate temperatures of 650 and 700°C by rf N-plasma molecular beam epitaxy. The Cr/Ga flux ratio is set to either 3% or 5%. These growth parameters allow to vary over a range of growth conditions from N-rich to Ga-rich. Surface conditions during growth influence the surface morphology and magnetic properties of CrGaN films. In particular, we show that N-rich and metal-rich growth conditions result in room temperature ferromagnetism. Scanning tunneling microscopy studies have been performed on c-GaN(001) grown by rf N-plasma molecular beam epitaxy. Scanning tunneling microscopy studies of c-GaN (001) reveal several surface reconstructions including 4x11, c(4x20), 4x9, c(4x16), 4x7, and c(4x12). These reconstructions depend on the surface Ga coverage with 4x11 having the highest Ga coverage and c(4x12) having the lowest Ga coverage per unit area. The reconstruction which is most commonly found on the surface is c(4x16). Scanning tunneling spectroscopy results suggest that c(4x16) reconstruction is in metallic state.

J Phys Chem a, 2007

Future nanoscale integrated circuits will require the realization of interconnections using molec... more Future nanoscale integrated circuits will require the realization of interconnections using molecular-scale nanostructures; a practical fabrication scheme would need to be largely self-assembling and operate on a large number of like structures in parallel. The self-directed growth of organic molecules on hydrogen-terminated silicon(100) [H-Si(100)] offers a simple method of realizing one-dimensional molecular lines. In this work, we introduce the ability to change the growth direction and form more complex, contiguous shapes. Numerous styrene and trimethylene sulfide L shapes were grown on a H-Si(100)-3x1 surface in parallel with no intermediate surface lithography steps, and similar shapes were also grown using allyl mercaptan and benzaldehyde on H-Si(100)-2x1. Registered scanning tunneling microscopy (STM) images and high-resolution electron energy loss spectroscopy (HREELS) were used to investigate the growth process.

It is discovered that the zero-dimensional character of the silicon atom dangling bond (DB) state... more It is discovered that the zero-dimensional character of the silicon atom dangling bond (DB) state allows controlled formation and occupation of a new form of quantum dot assemblies. Whereas on highly doped n-type substrates isolated DBs are negatively charged, it is found that Coulomb repulsion causes DBs separated by less than ~2 nm to experience reduced localized charge. The unoccupied

We study both experimentally and theoretically the electronic behavior of dangling bonds (DBs) at... more We study both experimentally and theoretically the electronic behavior of dangling bonds (DBs) at a hydrogen terminated Si(100)-2×1 surface. Dangling bonds behave as quantum dots and, depending on their separation, can be tunnel coupled with each other or completely isolated. On n-type highly doped silicon, the latter have a net charge of −1e, while coupled DBs exhibit altered but predictable filling behavior derived from an interplay between interdot tunneling and Coulomb repulsion. We found good correlation between many scanning tunneling micrographs of dangling bond structures and our theoretical results of a corresponding extended Hubbard model. We also demonstrated chemical methods to prevent tunnel coupling and isolate charge on a single dangling bond.

We have performed Scanning tunneling microscopy study of hydrogen terminated Si (100). We will sh... more We have performed Scanning tunneling microscopy study of hydrogen terminated Si (100). We will show that single Si atoms in a solid state environment can be served as quantum dots. These negatively charged quantum dots can be tunnel coupled to the nearby Si quantum dots. We will demonstrate that this tunnel coupling can be controlled by adjusting the separation between the two Si atomic quantum dots. Moreover electron occupation in the tunnel coupled Si quantum dots can be controlled. We have used this tunnel coupling effect of Si atomic quantum dots to fabricate Quantum Cellular Automata Cells. Quantum Cellular Automata are used to transmit binary information through electrostatic interaction between adjacent cells without the transfer of charge from one cell to the next. Devices based on Quantum Cellular Automata will consume much less power compared to the conventional transistor based devices. Moreover, since there is no transfer of charge so power dissipation during its operati...

Besides the well-known rock-salt structure, ScN is expected to have a metastable wurtzite phase e... more Besides the well-known rock-salt structure, ScN is expected to have a metastable wurtzite phase exhibiting a band gap smaller than that of wurtzite GaN.^1 This indicates the possibility of wurtzite ScGaN alloys with varying band gap. Thus we have grown (Sc,Ga)N layers of varying Sc composition using rf MBE on GaN/sapphire(0001) substrates. Reflection high energy electron diffraction (RHEED) shows that the (Sc,Ga)N surface orientation follows that of the substrate, indicating epitaxial growth, and X-ray diffraction indicates single phase, (0001) orientated layers. Scanning electron microscopy and energy-dispersive x-ray spectrometry suggest no Sc precipitation, indicating the Sc is incorporated into the bulk. Based on XRD and RHEED measurements, negligible change in the lattice constants c or a, or of the ratio c/a are observed. This suggests a wurtzite structure for the ScGaN layer. Optical analyses are in progress. Work is supported by NSF. 1. N. Takeuchi, Phys. Rev B 65, 045204 (2...

The potential of (Ga,Mn)N for possible room-temperature spintronic applications requires the stud... more The potential of (Ga,Mn)N for possible room-temperature spintronic applications requires the study of the effects of growth parameters - like Ga/N flux ratio - on the Mn incorporation and possible MnGaN alloy formation. For rf molecular beam epitaxy, three regimes of growth - N-rich, metal-rich, and Ga-rich - are distinguished by the reflection high energy electron diffraction patterns and by Atomic Force Microscopy (AFM) images. We find that Mn incorporation is achieved for N-rich and metal-rich growth, but not for Ga-rich growth, based on energy dispersive x-ray spectroscopy and AFM images. Moreover, for N-rich growth, Rutherford Backscattering shows that Mn substitutes for Ga, based on comparison of random and aligned spectra. Yet no peak shift relative to the GaN peak position is observed in X-ray diffraction, indicating that Vegard's law does not hold for this system. Magnetic measurements will also be discussed.

Due to increasing interest in developing new magneto-optical and magneto-electronic devices, and ... more Due to increasing interest in developing new magneto-optical and magneto-electronic devices, and spin injection sources in spintronics applications, ferromagnetic (FM)MnxGay is an attractive candidate system to explore. Here we report that binary FM Mn3-deltaGa(1.14<delta<2.0) single crystalline thin films has been epitaxially grown on (w)-GaN(0001)surfaces using molecular beam epitaxy. The face-centered tetragonal structure of Mn3-deltaGa thin films with CuAu-L10 type ordering

MRS Proceedings, 2015

ABSTRACTThin film Ti doped ZnO (Ti-ZnO) film were grown on sapphire (0001) substrate by RF and DC... more ABSTRACTThin film Ti doped ZnO (Ti-ZnO) film were grown on sapphire (0001) substrate by RF and DC magnetron sputtering. Films were grown at a substrate temperature of 250 °C with different Ti/Zn concentration. Surface chemical study of the samples was performed by X-ray photoelectron spectroscopy to determine the stoichiometry and Ti/Zn ratio for all samples. Surface morphology of the samples were studied by atomic force microscopy. X-ray diffraction was carried out to determine the crystallinity of the film. No secondary phases of TixOywas observed. We observed a slight increase in the lattice constant with the increase in Ti concentration in ZnO. No ferromagnetic signal was observed for any of the samples. However, some samples showed super-paramagnetic phase.