Faheemuddin Patel

A Comparative Study of Raw and Metal Oxide Impregnated Carbon Nanotubes for the Adsorption of Hexavalent Chromium from Aqueous Solution

The present study reports the use of raw, iron oxide, and aluminum oxide impregnated carbon nanotubes (CNTs) for the adsorption of hexavalent chromium (Cr(VI)) ions from aqueous solution. The raw CNTs were impregnated with 1% and 10% loadings (weight %) of iron oxide and aluminum oxide nanoparticles using wet impregnation technique. The synthesized materials were characterized using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Batch adsorption experiments were performed to assess the removal efficiency of Cr(VI) ions from water and the effects of pH, contact time, adsorbent dosage, and initial concentration of the Cr(VI) ions were investigated. Results of the study revealed that impregnated CNTs achieved significant increase in the removal efficiency of Cr(VI) ions compared to raw CNTs. In fact, both CNTs impregnated with 10% loading of iron and aluminum oxides were able to remove up to 100% of Cr(VI) ions from aqueous solution. Isotherm studies were carried out using Langmuir and Freundlich isotherm models. Adsorption kinetics of Cr(VI) ions from water was found to be well described by the pseudo-second-order model. The results suggest that metallic oxide impregnated CNTs have very good potential application in the removal of Cr(VI) ions from water resulting in better environmental protection.

Fog Collection by Mimicking Nature

Research on fog harvesting for drinking water is uncommon because it is not a continuous climatic phenomenon and concerns only arid and semi-arid regions abundant with fog. This paper proposes a new biomimetic-inspired method of harvesting fog by mimicking the skin of the Namib desert beetle. Stainless steel mesh panels are subjected to ultra shortening and annealing to create a hierarchical nano/micro hybrid surface, and an emulsion of PTFE, polyvinyl acetate and sodium benzene sulfonate is sprayed over the steel mesh. This produces hydrophilic nano/micro mounts and hydrophobic troughs. This method, although initially costly, offers a sustainable fog collecting system which can be adopted for arid and semi-arid regions of Pakistan and other similar regions.

Development of Novel Corrosion Techniques for a Green Environment

The synergistic effect of air pollution, brown clouds and greenhouse gasses is deleterious to human health and industrial products. The use of toxic inhibitors, chemicals in water treatment plants, and anti-fouling agents in desalination plants has contributed to the greenhouse effect. Conventional anti-corrosion techniques such as paints, coatings, inhibitor treatments, and cathodic protection paid no regard to greenhouse effect. Work on eco-friendly anti-corrosion techniques is scanty and largely proprietary. The use of nano-TiO2 particles introduced in alkyds and polyurethane-based coatings showed a higher corrosion resistance compared to conventional TiO2 coatings with significant photocatalytic activity to kill bacteria. The use of UV radiations for photo-inhibition of stainless steel in chloride solution can replace toxic inhibitors. Corrosion inhibition has also been achieved by using natural materials such as polymers instead of toxic chemical inhibitors, without adverse environmental impact. TiO2 films exposed to UV radiation have shown the capability to protect the steel without sacrificing the film. Self-healing materials with encapsulated nanoparticles in paints and coatings have shown to heal the defects caused by corrosion. These innovative techniques provide a direction to the corrosion scientists, engineers, and environmentalists who are concerned about the increasing contamination of the planet and maintaining a green environment.

Novel Aluminum Oxide-Impregnated Carbon Nanotube Membrane for the Removal of Cadmium from Aqueous Solution

An aluminum oxide-impregnated carbon nanotube (CNT-Al2O3) membrane was developed via a novel approach and used in the removal of toxic metal cadmium ions, Cd(II). The membrane did not require any binder to hold the carbon nanotubes (CNTs) together. Instead, the Al2O3 particles impregnated on the surface of the CNTs were sintered together during heating at 1400 °C. Impregnated CNTs were characterized using XRD, while the CNT-Al2O3 membrane was characterized using scanning electron microscopy (SEM). Water flux, contact angle, and porosity measurements were performed on the membrane prior to the Cd(II) ion removal experiment, which was conducted in a specially devised continuous filtration system. The results demonstrated the extreme hydrophilic behavior of the developed membrane, which yielded a high water flux through the membrane. The filtration system removed 84% of the Cd(II) ions at pH 7 using CNT membrane with 10% Al2O3 loading. A maximum adsorption capacity of 54 mg/g was predicted by the Langmuir isotherm model for the CNT membrane with 10% Al2O3 loading. This high adsorption capacity indicated that adsorption was the main mechanism involved in the removal of Cd(II) ions.

4 – Laser surface treatment of AISI 304 steel with the presence of B4C particles at the surface

Abstract AISI 304 steel surface is pre-prepared to form a thin carbon film containing 5% B 4 C particles prior to the laser-treatment process. The carbon film improved the absorption of the incident beam and accommodated B 4 C particles uniformly at the workpiece surface. The morphological and the metallurgical changes are examined in the treated layer by using optical and electron microscopes, energy dispersive spectroscopy, and X-ray diffraction. The microhardness and the residual stress formed at the treated surfaces are measured. It is found that the laser-treated surface is free from asperities and defect sites. The microhardness of the laser-treated surface increases significantly, which is attributed to the presence of B 4 C particles at the treated surface. In addition, the residual stress increases with the addition of B 4 C particles at the surface. The nitride phases are formed at the treated surface, which also contribute to the microhardness increase at the surface.

Laser treatment of high strength low alloy steel and electrochemical response of the surface

Purpose – The purpose of the present study is to report the results of the laser treatment of high-strength low-alloy (HSLA) steel surface and corrosion response of the treated surface that was carried out. Metallurgical and morphological changes in the laser-treated layer are also examined. Laser treatment of the alloy surface improves the surface properties; however, development of high thermal stress field in the treated layer can exceed the yielding limit of the alloy lowers, particularly, the corrosion resistance of the resulting surface. Design/methodology/approach – Pre-prepared workpiece surfaces are laser-treated and electrochemically tested in an electrolytic solution. Corrosion rate of the resulting surface is analyzed and pit sites are examined. Findings – It is found that the presence of nitride compounds and fine grains acts like as a self-protective layer at the laser-treated surface while lowering the corrosion resistance. Consequently, laser gas-assisted treatment provides a positive effe...

Development and Processing of SiAlON Nano-Ceramics by Spark Plasma Sintering

The development of SiAlON-based ceramics has shown great impact in the field of cutting/drilling tool industry and other engineering applications. It is highly desirable to cut-down the cost of the cutting tools by increasing their service lifetime. Potential ways to improve tool life is by preparing these SiAlON-based ceramics adopting non-conventional synthesis routes and by using different precursors. The present study reports the results of synthesis of SiAlON-based nano-ceramics via spark plasma sintering (SPS) technique. Generally, metal nitride and metal oxide precursors are used for synthesizing self-reinforced SiAlON ceramics. In this work, nano-sized metallic precursors including amorphous-Si3N4 and crystalline β-Si3N4, SiO2, AlN and Al2O3 were used, which could be a novel way to synthesize SiAlONs at low temperatures with enhanced performance. The properties of these SiAlONs are tailored by optimizing the synthesis parameters. The synthesized samples were characterized by X-ray diffraction and field emission scanning electron microscopy to study the effect of processing parameters on microstructure, density and hardness.

Cadmium Removal from Contaminated Water Using Polyelectrolyte-Coated Industrial Waste Fly Ash

Fly ash (FA) is a major industrial waste generated from power stations that add extra cost for proper disposal. Recent research efforts have consequently focused on developing ways to make use of FA in environmentally sound applications. This study, therefore, investigates the potential ability of raw fly ash (RFA) and polyelectrolyte-coated fly ash (PEFA) to remove cadmium (Cd) from polluted water. Using layer-by-layer approach, functionalized fly ash was coated with 20 layers from 0.03% (v/v) of cationic poly(diallyldimethylammonium chloride) (PDADMAC) and anionic polystyrene sulfonate (PSS) solutions. Both surface morphology and chemical composition of the adsorbent (PEFA) were characterized using Field-Emission Scanning Electron Microscope (FE-SEM), X-Ray Diffraction (XRD), Fourier-Transform Infrared (FTIR), and X-Ray Fluorescence (XRF) techniques. The effects of pH, adsorbent dosage, contact time, initial contaminant concentration, and mixing rate of the adsorption of Cd were also studied in batch mode experiments. Results of the study revealed that a 4.0 g/L dosage of PEFA removed around 99% of 2.0 mg/L of Cd in 15 min at 150 rpm compared to only 27% Cd removal achieved by RFA under the same conditions. Results also showed that adsorption by PEFA followed both Langmuir and Freundlich models with correlation coefficients of 98% and 99%, respectively.

Effect of copper nano particles on high temperature tensile behavior of Mg-Y2O3 nanocomposite

Magnesium reinforced with 0.7 volume percentage of yttria is considered to be one of the most promising light weight structural nanocomposite materials, whose performance was further enhanced with incorporation of 0.3 volume percentage of nano copper particles. Elongation-to-fracture tensile test revealed that the nano copper particle effectively maintained strengthening effect on magnesium-yttria nanocomposite at up to 100 °C and gradually diminished with further increase in test temperature used in this study. Nano copper particle induced impressive enhancement in magnesium-yttria nanocomposite and led to their potential near net shape fabrication in to intricate shaped objects at a substantially low temperature.

Manufacture of microporous ceramic layer by suspension–sedimentation for filtration applications

Microporous layers of 0.3 µm α-alumina powder were deposited on the surface of porous zirconia substrates (average pore size of about 1 µm) using suspension–sedimentation method. The characteristics of the deposited alumina microporous layer was evaluated using different types of dispersants, namely, citric acid, sodium dodecyl sulfate and Triton X-100. The effect of these dispersants on the stability and settling characteristics of alumina suspension was evaluated by sedimentation tests. Scanning electron microscopy analysis of the microporous layers (prior to sintering) revealed that sodium dodecyl sulfate dispersant produced uniform layers with least agglomeration of alumina particles, whereas citric acid showed more agglomeration of alumina particles and the use of Triton X-100 developed holes on the surface of alumina layer. The layers deposited using sodium dodecyl sulfate dispersant were then sintered at 1400 °C in air. Scanning electron microscopy observations revealed that a uniform porous alumina layer with average pore size in the range of 0.5–1.0 µm was produced with this method. The results of sedimentation tests indicated that alumina powder suspension prepared with sodium dodecyl sulfate dispersant yielded very good stability with lowest particle settling rate, whereas citric acid exhibited the highest particle settling rate.