Papers by Keyword: Pre-Treatment

Abstract: The textile industry in Indonesia is currently rapidly growing. However, this increase harms the environment because dyes from textile production are generally released into the environment without prior processing. Photocatalysis is one effort that can be used to overcome this problem. TiO₂ has been proven to be highly efficient in its work as a photocatalyst material. This study aims to investigate the effectiveness of methylene blue (MB) photodegradation using TiO₂ with steady pre-treatment optimizations. The pre-treatment was carried out by leaving the mixture of TiO₂ and methylene blue in various conditions under dark and room light conditions, resulting in ⁓37% and ⁓50% degradation efficiencies, respectively. Higher total percent MB degradation efficiencies (%Eff) were reached after visible light irradiation using mercury lamp in the post-treatment of more than 75%, concluding that the pre-treatment both in dark and room light storage optimized the MB degradation process. Therefore, these pre-treatment methods are potentially suitable for industrial wastewater treatment before the photocatalysis process to lower the waste management cost.

Abstract: In this work, the effect of peat clay particles (PCP) was investigated as pore former of polysulfone (PSf) hollow fiber membrane properties. Preparation of polysulfone membrane dope solution conducted by phase inversion technique using wet spinning method. A homogeneous dope solution is added with peat clay from four composition variations of 0-6 wt%. Followed by mixed dope until homogeneous for an hour at room temperature (~29 °C). The preparation of peat clay before used is by having it calcinated at 600 °C for 1 hour, then sifted to a size of 120 mesh. The hollow fiber membrane is casted using the wet spinning method with the dope solution flow rate set at 4 mL/min and the bore fluid flow rate at 4 mL/min. The hollow fiber membrane that has been formed is analyzed by FTIR, contact angle, water absorption, and porosity. The characteristics of the membrane show that the functional group in the addition of peat clay in the absorption of Si-OH and Si-O-Si. The specific spectrum of PSf-PEG/PC is indicated by peak wavenumbers 872 – 874 cm^-1. Polysulfone hollow fiber membrane mixed with peat clay shows the contact angle on the membrane surface shows hydrophobic characteristics without addiction of peat clay particles and become slightly hydrophilic with peat clay addiction of 71.28°. In addition, water absorption in each sample increases with the addition of peat clay from 0 to 4 wt%. The ability of water absorption increased to 32.51%, and membrane porosity increased from 23.66% to 38.87%. It is concluded that polysulfone hollow fiber membranes are enhanced by adding peat clay as a pore builder and hydrophilic additives and become less fouling in future application for water/wastewater treatment.Keywords: Peat clay, hollow fiber membrane, polysulfone, wet spinning, montmorillonite

Abstract: South Kalimantan-Indonesia is known to have extensive peatlands reaching 15% of a total peatland in Kalimantan. Due to that peat land water is mostly found and claim as abundant water sources. However, based on quality, peat land water has poor characteristic with high natural organic matter content. Therefore, peat water treatment is necessary to treat using effective method such as hybrid conventional filter and membrane using hollow fibre PVDF-TiO₂/SBE. This study aims to investigate the variation of media filter thickness and filtration pressure of hollow fibre (HF) PVDF-TiO₂/SBE membrane peat water treatment by filtration pre-treatment and HF membrane ultrafiltration. HF PVDF-TiO₂/SBE membrane was prepared by wet spinning method using spinneret set up. Hybrid process was divided into two steps: 1) conventional filter as pre-treatment and 2) HF ultrafiltration membrane under cross flow system. The filter media was used in this work is silica sand and activated carbon with varied thickness 30:10 and 10:30 cm. The HF membrane structure was analysed via scanning electron microscopy (SEM) to investigate the membrane morphology. The results show the fabricated HF membrane has a finger like-sponge sandwich structure morphology. In addition, 30:10 cm (silica sand: activated carbon) thickness exhibits TDS and turbidity removal of 92.18 and 61.37%, respectively as conventional filter pre-treatment. In other hand, HF membrane successfully removed TDS and turbidity of peat water up to 98.68% and 92.41% at 2 bar of filtration pressure. The highest permeate flux of HF membrane conducted of 13.055 Kg.m^-2.h^-1 at 3 bar. Conclusion of this work is the peat water treatment using activated carbon: silica filtration pre-treatment and HF membrane ultrafiltration can provide clean water with maximum turbidity and TDS removal.

Abstract: Rice straw and rice husk fibers (RS/RH) reinforced polymer-based composites have theability to conserve wood and petroleum resources. As natural filler, rice straw and rice husk offer asustainable material for the production of polymer-based composites. The application ofbiocomposite limits the burning of straw at the root and may further enhance the socioeconomicstatus of farmers and rural populations. This review mainly focuses on five different weightpercentage of reinforced RS and RH fiber content (5%, 10%, 15%, 20% and 25%) in polymercomposites. Nowadays, Epoxy, polyurethane, polyester, PVA, PLA and polyethylene are beingused as matrix material in polymer composites. This paper holds good with understanding themechanical properties, pretreatment methods and offer important insight into potential uses ofpolymer composites with biodegradable reinforce fiber.

Abstract: In this paper, the influence of the surface roughness of build plates as well as the process parameters laser power, scan speed and exposure curing time on the bonding of additively manufactured components made of TiAl₆V₄ to the build plates is analyzed. These analyses are carried out with build plates made of Titanium Grade 2 and AlMgSi0.5. The analyses show that higher surface roughness leads to lower bending strength and thus poorer bonding of components on the build plate. In addition, it is shown that the bending strength normalized to the bonding surface decreases at high laser power, especially at high scanning speeds. Furthermore, multiple exposure results in lower flexural strength.

Abstract: The natural oxide layer, which spontaneously covers the surface of aluminium and its alloys, is well adherent to the surface, but it does not show adequate corrosion resistance in many conditions. In order to improve the material anti-corrosion performance, it is necessary to replace the surface oxide by a conversion coating. The first step to do this is to prepare the alloy surface to subsequent treatments. The pre-treatment implemented before the conversion treatment is one of the main factors responsible for the performance of the conversion coating. It involves several phases, including desmutting that encompasses the part immersion in an acid or alkaline solution bath. In this work, the influence of hydrofluoric acid concentration in the desmutting bath's formulation was investigated. The samples surface were characterised by using electrochemical techniques, glow discharge optical emission spectrometry and contact angle measurements.

Abstract: Plasma technology is an effective way to modify the physicochemical properties of silk fabric. This study was a preliminary study to explore the dyeability of silk fabric with metal complex dyes after treated with plasma technology, which may improve the processability and broaden the application of silk fabric. This study investigated the optimal plasma treatment condition and evaluated treated silk fabric in terms of wettability, surface modification and dyeability. It was found that plasma treatment can enhance the wettability and dyeability of silk fabric via the formation of hydrophilic functional groups in the structure of silk fiber.

Abstract: The utilization of empty bunches (EFB) as biomass still limited. EFB is used as additional fuel in palm oil mills where the combustion process is directly used. This process has deficiencies due to the characteristics of empty bunches which tend to have high water content. To achieve good combustion results, EFB required pre-treatment technique. In this study, experimental studies of EFB pre-treatment is proposed by torrefaction to improve EFB energy quality. Torrefaction of EFB is performed in several temperature variations with a range between 150-300 °C (150,200,250,300) and a certain duration (15,20,25,30,45 minutes). An investigation is done by using a calorimetric bomb, proximate analysis to find the moisture and ash content and ultimate analysis, which determined the chemical properties of the pre-treatment process. The physical properties of EFB, which fibrous and tough makes EFB size reduction difficult to reach homogenous state. Mass yield of torrefied EFB decreased with increasing temperature as well as with increasing times of torrefaction. Fundamentally, the study has highlighted the effects of torrefaction on solid fuel properties of EFB and its potential as a solid fuel for future thermal applications.

Abstract: Aluminium alloys are covered spontaneously by a natural oxide layer, well adherent to the surface. For improving the material’s anticorrosion performance surface pre-treatments are needed in order to remove the superficial oxide and to prepare the alloy surface to subsequent treatments. The pre-treatment process involves several steps, including desmutting. The last requires the immersion of the part in an appropriate solution, typically composed of several chemicals, able to remove the oxide layer. In this work, the effect of the fluorides addition into a sulfuric acid-based solution, when used in a desmutting industrial process, was evaluated. Potentiodynamic curves, glow discharge optical emission spectrometry and contact angle techniques were used to characterize the surface of the aluminium alloy AA8006 after desmutting.

Abstract: 7475 aluminium alloy is widely used in aerospace industry and military field. There are many dispersoid former elements in 7475 aluminium alloy, such as Mn, Cr, Ti, Zr and Sc. And the dispersoid configuration has important effect on the performance of alloy wrought. The characteristic of dispersoids in the semi-continuous casting ingot of 7475 aluminum alloy and the evolution of their distribution during rolling have been investigated. The size, shape and distribution of dispersoids are controlled by pre-treatment before homogenization. The results show that there are many coarse triangular, irregular block and spindly rod-like dispersoids which contain some of Cr and Mg and a little of Cu and Zn in the 7475 aluminum alloy which subject to conventional one-step homogenization treatment. The size and the distribution of the Cr-containing dispersoids is not uniform. The width of the coarse dispersoids is close to 1 micron and the length of the spindly rod-like dispersoids is more than 4 microns. There is no dispersoids in the center of the dendritic grains, but the nonuniform distribution of dispersoids is eliminated when the hot rolling reduction exceed 80%. The dispersoids can be significantly refined and homogenously distributed by pre-treated before the conventional one-step homogenized. The pre-treatment can stimulate the nucleation of Cr-containing dispersoids, narrow down the dispersoids free zone. The size of the dispersoids is dramatically reduced by pre-treated before the conventional homogenization, and the width of the coarse dispersoids and length of the spindly rod-like ones are less than 300 nm and 1 micron.