Photodecolorization of methylene blue over EGZrO2/EGZnO/EGFe2O3/HY photocatalyst: effect of radical scavenger

The photocatalytic activity of methylene blue (MB) was investigated in aqueous solutions under solar radiation using electrogenerated metals supported on HY zeolite (EGZrO2/EGZnO/EGFe2O3/HY) catalyst. The prepared catalysts were examined using X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunnauer-Emmett-Teller surface area analysis (BET). An amount of 0.375 g L-1 EGZrO2/EGZnO/EGFe2O3/HY was found to be the optimum dosage for 10 mg L-1 MB, which gave almost complete photodecolorization of MB (99.5%) after 1 h of contact time at pH 9. Next, the effect of inorganic salts such as NaCl, Na2CO3, Na2SO4, and KI was also studied. It was found that the presence of the Cl- and CO3-2 ions obstructed the photodecolorization, but the presence of SO42- accelerated the reaction. The presence of I- ions did not affect much on the decolorization rate. Furthermore, the addition of H2O2 significantly enhanced the photodecolorization for the 50 mg L-1 of MB solution under similar optimum conditions. It was also found that the radical scavenging agents such as dimethyl sulfoxide (DMSO) and methanol (MeOH) suppressed the decolorization, with DMSO being the most effective. The simple preparation of the photocatalyst and low amount of metal loading required exhibits the great potential of the system that could be applied in textile or other industries wastewater treatment

Tribological performance of raw and chemically modified RBD palm kernel

The objective of MITC2015 is for the scientists, scholars, engineers and students from universities, research institutions and industries all around the world to present findings of ongoing research activities, and hence foster research collaborations between the universities and the industries. The other objective is to introduce young tribologists in the scientific field of tribology through keynote lectures and presentations, to offer mentoring through senior scientists, and to foster the building of networks through the informal style of the event

Effect of surface modification of acetabular cup with embedded micro-pits on friction properties

This study describes an investigation of the effect on friction when an acetabular cup surface is embedded with micro-pits. The micro-pit is potentially a suitable structure to act as a lubricant reservoir, in order to reduce the level of friction present between the surfaces of a hip prosthesis. The experiments were carried out using a modified four-ball tribometer. Refined, Bleached and Deodorised (RBD) palm olein and additive-free paraffinic mineral oil were selected to provide lubrication. When the palm olein was applied to the acetabular surface, friction in the hip implant decreased. Severe damage on the acetabular surface resulted in lubricant-free test conditions. Meanwhile, the results of tests on the acetabular cup, with 10 to 40 embedded micro-pits on the surface, indicated that friction had decreased. Based on the experiments, surface modification of the acetabular cup with embedded micro-pits, could prolong the biomechanics of hip prostheses

Wear characterization of aluminum lubricated with palm olein at different normal load

The pin-on-disk tester is a method used for investigating wear. The sliding mechanism between the pin and the disc experimentally creates wear. In this paper, the wear characteristics of an aluminium pin sliding on an SKD11 disc lubricated with double fraction palm olein were investigated. The pin was made from pure aluminum A1100. The results were compared with those of tests in which the disc was lubricated with commercial hydraulic oil. In both sets of experimental conditions, the normal load varied from 4 to 10 kg. Rotational speed was set to 1200 rpm. From this study, it was found that different types of lubricant affect the wear progression and friction coefficient during a sliding movement. The wear progression and friction coefficient depend also on the load applied, surface roughness, pressure applied and contact surface area

The influence of normal load in wear resistance characteristic of palm fatty acid distillate

The aims of this study were to determine the friction coefficient and the wear behaviour of palm fatty acid distillate (PFAD) using a four-ball tribotester, following the ASTM D-4172. In this paper, the normal load applied on the ball bearings varied from 40 kg to 120 kg. Experimental temperature was held constant at 75°C, while rotational speed was fixed at 1200 rpm. The test duration was one hour. Tests that were carried out using palm fatty acid distillate were conducted in exactly the same way using commercial hydraulic oil (HO) as a reference lubricant. The analyses focused on the friction coefficient and worn scar characteristic. Wear scar diameter was measured and the worn surface condition was observed using a high resolution microscope. Results showed that PFAD has a lower coefficient of friction than commercial hydraulic oil

A new approach using palm olein, palm kernel oil, and palm fatty acid distillate as alternative biolubricants: improving tribology in metal-on-metal contact

Metal-on-metal (MoM) hip replacements are commonly used hip implants. However, one of the issues under debate is the interference of friction and wear. The purpose of this feasibility study is to elucidate the performance of palm lubrication between the femoral head and the acetabular cup. In the tribology of hip implants, the use of palm olein, palm kernel oil, and palm fatty acid distillate as synthetic lubricants for human joints has shown tremendous potential. A modified pin-on-disc as hip screening has been used to evaluate the friction and wear on an acetabular cup with an inner diameter of 28 mm. The wear debris was then observed with microscopy image analysis. This study revealed that the physical and unique chemical properties in palm oil can optimize the rate of friction and wear on the metal acetabular cup and thus allow for a stable implant of MoM

Low-temperature stabilization of electrosynthesized tetragonal zirconia, its photoactivity toward methylene blue decolorization

Zirconia nanoparticles (ZrO2) were prepared by a simple electrochemical method and characterized using X-ray diffraction, transmission electron microscopy, Brunnauer–Emmett–Teller surface area analysis, and ultraviolet-visible diffuse reflectance spectroscopy. In this study, tetragonal ZrO2 (t-ZrO2) particles were stabilized at a lower calcination temperature without the addition of a dopant in the preparation step. It was suggested that the use of tetraethylammonium perchlorate as the supporting electrolyte was responsible for the stabilization of t-ZrO2 by preventing the agglomeration of metal clusters with undesired powders in the electrolysis system, resulting in a decrease in ZrO2 crystal size. The photoactivity of the catalyst was optimized using central composite design with response surface methodology and the optimum values of the parameters were a solution pH of 11, contact time of 4 h, catalyst dosage of 1.0 g L-1, and calcination temperature of 523 K. This resulted in 84.9% decolorization of methylene blue (MB) obtained from the predicted model, which fitted well with the laboratory results of 83.6%. The kinetics study demonstrates that the reaction followed pseudo first-order kinetics, and the rate constants KR = 0.09 mg L-1 h-1 and KLH = 0.43 L mg-1 were determined using the Langmuir–Hinshelwood model. The mineralization of MB was measured by chemical oxygen demand removal, BOD5/COD, and TOC/TOC0 ratio analyses with values of 78.5%, 1.48, and 0.21, respectively, after 4 h of contact time. The regeneration study shows that the catalyst could be maintained with a slight decrease in decolorization (<10%) after five cycling runs. Furthermore, t-ZrO2 facilitated good photoactivity towards MB decolorization under UV light in a batch reactor compared with commercial t-ZrO2 (58.7%) and Degussa P25 TiO2 (64.5%)

A facile preparation of nanosized Zno and its use in photocatalytic decolorization of methyl orange

Nanoparticles zinc metal was prepared by a simple electrochemical method of a N,N-dimethylformamide solution containing 0.1M tetraethylammonium perchlorate in the presence of naphthalene as a mediator in a one-compartment cell fitted with a platinum plate cathode and a zinc plate anode at 60 mA/cm2 of constant current under a nitrogen atmosphere. The prepared zinc oxide (ZnOelec) was characterized by FE-SEM, TEM, XRD, nitrogen-sorption and DRUV spectrophotometer, which confirmed that the particles of ZnOelec are composed of pure nanosized ZnO with a large surface area and majority of particle size was less than 20 nm. The particles size of the ZnOelec affected its photoactivity, which clearly observed when it was tested on a decolorization of methyl orange under UV illumination. By using ZnOelec, 50% of higher removal percentage of MO was achieved compared to commercial zinc, which only gave 30% after 30 min of contact time. These result shows that ZnOelec has a great potential to be used as a catalyst for the photocatalytic decolorization of industrial dyes wastewater

Machining pits on the curvature surface cup using spark process

In this study, investigations have been conducted using electrical discharge process (die-sinker) to obtain new surface in metal hip implant, which place pit on the surface of curvature cup. A circular array of pit in circle shape was successfully created on the surface of acetabular. There are 8 pits that have been embedded on the surface area of the acetabular by each diameter machine and the depths are 1.1 mm and 0.5 mm respectively. This new surface improvement will prolong the life span of the implant due to lubrication activities in hip tribology