Environmentally-Friendly RF Plasma Treatment of Thai Silk Fabrics with Chitosan for Durable Antibacterial Property

A 13.56 MHz RF plasma discharge was successfully utilized to activate and coat Thai silk fabrics with chitosan for durable antibacterial property. Uncolored and untreated Thai silk fabrics were activated in Ar plasma for 5 minutes with an optimized RF power of 120 W under Ar pressure of 0.8 Torr. After plasma activation, specimens were submerged and stirred in a 1% (w/v) chitosan solution. FTIR analysis confirmed the presence of chitosan on the silk fabrics. From SEM analysis, chitosan was observed to coat silk fibers almost everywhere. RF plasma treated fabrics were able to absorb the chitosan solution substantially faster than those without the treatment. Another benefit of increased hydrophilicity is the ability of the treated fabrics to allow human perspiration to flow through more effectively, providing additional comfort when worn in tropical-zone countries. Antibacterial properties against E. coli and S. aureus reduced with increasing washing cycles dropping to approximately 95% after 5 rounds of washing. Extrapolation of linear trend lines revealed that for the case of E. coli, it will take approximately 16 washing cycles to reduce the antibacterial ability to 90%. For the case of S. aureus, it will take approximately 10 washing cycles to reduce the antibacterial ability to 90%. Fabrics without RF plasma treatment prior to chitosan solution submersion will have their antibacterial ability for E. coli and S. aureus reduced to 90% after only about 5 washing cycles. Thus, RF plasma treatment can effectively induce chitosan to provide a strong and durable coating for Thai silk fabrics, thus, offering a new, very environmentally-friendly coating technique for Thai silk with chitosan for potential use in the textile industry

Mechanical and Thermal Neutron Attenuation Properties of Concrete Reinforced with Low-Dose Gamma Irradiated PETE Fibers and Sodium Borate

This research investigated the mechanical and thermal neutron attenuation properties of concrete reinforced with low-dose gamma irradiated polyethylene terephthalate (PETE) fibers. Low dose (20 – 60 kGy) gamma irradiated PETE fibers of 1.3 and 25 denier size were uniformly mixed with concrete at 0.1%, 0.2%, and 0.3% volume fraction. The results showed that the fiber reinforced concrete (FRC) having 25 denier fibers provided higher compressive strength, flexural strength, and toughness than FRC with 1.3 denier fibers. Moreover, addition of PETE fibers in the concrete enhanced thermal neutron attenuation; however, both fibers exhibited no significant difference in thermal neutron attenuation ability. In addition, this study investigated the effects of adding sodium borate, a boron-containing compound, in concrete mixed with PETE at various proportions. It was found that when sodium borate powder was added, the compressive strength of the concrete decreased, whereas the thermal neutron attenuation ability significantly increased with respect to sodium borate content

Preparation of Microcrystalline Cellulose from Waste Cotton Fabrics Using Gamma Irradiation

Recycling process of waste cotton fabrics into value added products is still limited. Cotton fabrics are made of cotton fiber, which is a high cellulose source and it can be converted into microcrystalline cellulose (MCC). In this research, MCC was prepared by dissociation of waste cotton fabric using gamma irradiation with various radiation doses in dried phase and in wet phase by 35 % H2O2 solution. The properties of the prepared MCC were investigated and compared with standard Avicel PH101 MCC. The results from FTIR spectra and X-ray diffraction patterns show that the obtained MCC has typical similarity to commercial MCC. X-ray diffraction analysis showed that the crystallinity percentage (%Cr) was increased while crystallite size was decreased through gamma irradiation. At the same dose, degree of polymerization (DP) and solubility in water in dried phase, i.e. 135; 5.46 % were higher than wet phase irradiation i.e. 123; 4.38 %. Degree of polymerization and solubility in water decreases with increasing total irradiation dose. The investigated physicochemical properties of the obtained MCC conform to the European Pharmacopoeia requirements. The results indicated that waste cotton fabrics have a great potential as a low cost MCC raw material and can lead to many applications.Recycling process of waste cotton fabrics into value added products is still limited. Cotton fabrics are made of cotton fiber, which is a high cellulose source and it can be converted into microcrystalline cellulose (MCC). In this research, MCC was prepared by dissociation of waste cotton fabric using gamma irradiation with various radiation doses in dried phase and in wet phase by 35% H2O2 solution. The properties of the prepared MCC were investigated and compared with standard Avicel PH101 MCC. The results from FTIR spectra and X-ray diffraction patterns show that the obtained MCC has typical similarity to commercial MCC. X-ray diffraction analysis showed that the crystallinity percentage (%Cr) was increased while crystallite size was decreased through gamma irradiation. At the same dose, degree of polymerization (DP) and solubility in water in dried phase, i.e. 135; 5.46% were higher than wet phase irradiation i.e. 123; 4.38%. Degree of polymerization and solubility in water decreases with increasing total irradiation dose. The investigated physicochemical properties of the obtained MCC conform to the European Pharmacopoeia requirements. The results indicated that waste cotton fabrics have a great potential as a low cost MCC raw material and can lead to many applications

Review of Non-Thermal Plasma Technology for Hydrogenation of Vegetable Oils and Biodiesel

The hydrogenation of lipid derivative compounds has received much attention as it is one of the key chemical reactions of industrial processes to improve the physical and chemical properties of those compounds such as thermal resistance, cold flow properties, oxidative stability, etc. The principle of hydrogenation of vegetable oil for margarine production relies on the addition of hydrogen to the carbon double bond positions of fatty acid molecules to become a single bond, increasing the saturated fatty acids until the texture becomes semi-solid. The partial addition of hydrogen to biodiesel improves its oxidation resistance. At present, industrial-scale using catalytic hydrogenation of lipid derivative compounds operates under high temperature and high-pressure environments, leading to a high trans-fat content in the products and requiring catalyst separation from the product. Non-thermal plasma (NTP) technology as a green process can be deployed to substitute conventional hydrogenation, on a laboratory scale for the time being, because no catalyst is required and the process can occur at near ambient temperature and low or atmospheric pressure. Moreover, trans-fat formation is several times lower than that of catalytic hydrogenation. The present review article provides more insight into the various types of NTP technology for lipid derivative compounds hydrogenation, including discussions on different experimental setup configurations, parameters affecting plasma hydrogenation, properties of synthesized products, as well as the advantages and drawbacks of environmentally-friendly plasma hydrogenation compared to conventional catalytic hydrogenation

Exploring Qualitative and Quantitative Decoration on Amine-Modified Mesoporous Silica for Enhance Adsorption Performances

Using the triblock copolymer Pluronic F127 as a surfactant, tetraethyl orthosilicate (TEOS) as a silica source, and hydroxylamine hydrochloride as an amine source, a group of amines-modified mesoporous silica Santa Barbara Amorph-16 (SBA-16) materials with different template withdrawal methods and amine loading concentrations were prepared through sol-gel conditions. The investigation will provide qualitative and quantitative information on amine-modified SBA-16 decoration with a brief overview of the non-destructive analysis methods for advanced materials as adsorbent candidates. Highly ordered mesostructured amine-modified SBA-16 materials were prepared using high-temperature (or calcination) and solvent extraction de-templating methods. Mesostructured amine-modified SBA-16 has been successfully examined using a Synchrotron Radiation Low-Angle X-ray Diffraction (SR-LXRD) instrument for phase identification, Small-Angle Synchrotron X-rays Scattering (SAXS) for identifying structural changes in a porous material, Fourier Transform Infrared (FTIR) for identifying functional groups, Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) elemental analyzer for determining the number of silica, oxygen, and nitrogen elements, and a Specific Surface Area (SSA) analyzer for measuring the specific surface areas. The SR-LXRD and SAXS results demonstrated that the synthesized novel materials were defined unambiguously as a bi-continuous cubic body center Im3m mesostructured. FTIR and SEM-EDS analyses verified that the amine groups were uniformly deposited on the SBA-16 surface. The SSA analyzer results also clarified that the novel materials exhibited ordered and meso-framework amine-modified SBA-16 with a large surface area. Novel materials can be considered high-potential uranium adsorbent candidates. Preliminary adsorption investigations have shown that the amine-modified SBA-16 materials can adsorb uranium in natural seawater showing an uptake capacity of as much as 24.48 mg-U/g-adsorbent

Enhancement of Stability in Alkali Solution of Polyethylene Terephthalate Fibers using Low-Dose Gamma Irradiation for Fiber-Reinforced Neutron Shielding Concrete

Polyethylene terephthalate (PETE) fibers are used as a reinforcing agent to enhance concrete strength as well as to shield against thermal neutrons. This study increased the stability of PETE fibers in a strong alkali solution characteristic of concrete (pH = 12) using low-dose gamma radiation to induce crosslinking of the polymer chains. Results indicated that gamma ray dose of only 30 kGy resulted in the highest molecular weight, tensile strength and degree of crystallinity of PETE fibers with size 1.3 D. The surface topology using SEM micrography were also evaluated. An accelerated age testing revealed that these radiation-treated fibers will maintain their mechanical strength in concrete for up to at least 60 months. Thermal neutron attenuation test of fiber-reinforced concrete (FRC) indicated that the degree of thermal neutron shielding increased with increasing PETE fiber content, and that at 0.3% fiber content, FRC exhibited the highest thermal neutron attenuation of about 60% compared to unreinforced concrete. Therefore, these FRCs can readily be utilized as an effective neutron shielding material for nuclear and radiation applications to enhance radiation safety

Process and Energy Intensification of Glycerol Carbonate Production from Glycerol and Dimethyl Carbonate in the Presence of Eggshell-Derived CaO Heterogeneous Catalyst

The process and energy intensifications for the synthesis of glycerol carbonate (GC) from glycerol and dimethyl carbonate (DMC) using an eggshell-derived CaO heterogeneous catalyst were investigated. The transesterification reaction between glycerol and DMC was typically limited by mass transfer because of the immiscible nature of the reactants. By varying the stirring speed, it was observed that the mass transfer limitation could be neglected at 800 rpm. The presence of the CaO solid catalyst made the mass transport-limited reaction process more prominent. Mass transfer intensification using a simple kitchen countertop blender as an alternative to overcome the external mass transfer limitation of a typical magnetic stirrer was demonstrated. A lower amount of the catalyst and a shorter reaction time were required to achieve 93% glycerol conversion or 91% GC yield, and the turnover frequency (TOF) increased almost 5 times from 1.5 to 7.2 min−1 when using a conventional magnetic stirrer and countertop blender, respectively. In addition, using a simple kitchen countertop blender with 7200 rpm, the reaction temperature of 60 °C could be reached within approximately 3 min without the need of a heating unit. This was the result of the self-frictional heat generated by the high-shear blender. This was considered to be heat transfer intensification, as heat was generated locally (in situ), offering a higher homogeneity distribution. Meanwhile, the trend toward energy intensification was promising as the yield efficiency increased from 0.064 to 2.391 g/kJ. A comparison among other process intensification techniques, e.g., microwave reactor, ultrasonic reactor, and reactive distillation was also rationalized