Showing papers on "Distilled water published in 2012"

Fly Ash-based Geopolymer Lightweight Concrete Using Foaming Agent

Abstract: In this paper, we report the results of our investigation on the possibility of producing foam concrete by using a geopolymer system. Class C fly ash was mixed with an alkaline activator solution (a mixture of sodium silicate and NaOH), and foam was added to the geopolymeric mixture to produce lightweight concrete. The NaOH solution was prepared by dilute NaOH pellets with distilled water. The reactives were mixed to produce a homogeneous mixture, which was placed into a 50 mm mold and cured at two different curing temperatures (60 °C and room temperature), for 24 hours. After the curing process, the strengths of the samples were tested on days 1, 7, and 28. The water absorption, porosity, chemical composition, microstructure, XRD and FTIR analyses were studied. The results showed that the sample which was cured at 60 °C (LW2) produced the maximum compressive strength for all tests, (11.03 MPa, 17.59 MPa, and 18.19 MPa) for days 1, 7, and 28, respectively. Also, the water absorption and porosity of LW2 were reduced by 6.78% and 1.22% after 28 days, respectively. The SEM showed that the LW2 sample had a denser matrix than LW1. This was because LW2 was heat cured, which caused the geopolymerization rate to increase, producing a denser matrix. However for LW1, microcracks were present on the surface, which reduced the compressive strength and increased water absorption and porosity.

Effect of water absorption on pultruded jute/glass fiber-reinforced unsaturated polyester hybrid composites

Abstract: The use of natural fibers in polymer composites has given renewed interest to the development of green composites today. However, the moisture absorption of natural fibers gives serious concern, especially for their potential outdoor applications. This article reports the study results on the water absorption of pultruded jute/glass fiber-reinforced unsaturated polyester hybrid composites, which was subjected to various water conditions and their effects on its mechanical properties. Water absorption tests were performed by immersing composite specimens into three different water conditions, namely: distilled water, sea water, and acidic water, which were at room temperature, for a period of 3 weeks. The characteristic parameter of diffusion coefficient (D) and maximum moisture content (Mm) were determined from the obtained water absorption curves. The water absorption behavior of the glass/jute fiber-reinforced unsaturated polyester hybrid composite was found to follow a non-Fickian behavior. The effects...

Kapok Fiber Oriented Polyaniline for Removal of Sulfonated Dyes

Abstract: In the present work, kapok fiber oriented polyaniline (KF-O-PAN) was prepared via a facile polymerization of aniline on the surface of KF and optimized using response surface methodology based on a central composite design. Adsorption characteristics of KF-O-PAN were examined using three sulfonated dyes, that is, Congo Red (CR), Orange II (OG-II), and Orange G (OG-G), as the model adsorbates. The effects of contact time, pH, initial dye concentration, and poly(vinyl alcohol) sizing on the amount of dye adsorbed were investigated using a batch experiment. The amount of dye adsorbed in different water bodies including distilled water, tap water, well water, and lake water was compared to study further the influence of ionic strength. The results indicate that the adsorption equilibrium can be achieved within 4 h, and the monolayer adsorption capacity calculated from the Langmuir equation is 40.82, 188.7, and 192.3 mg/g for CR, OG-II, and OG-G, respectively. KF-O-PAN shows a higher amount of dye adsorbed despite the influences of ionic strength when pH ≤ 8 except for CR. The higher desorption efficiency using NaOH solution and multiple adsorption–desorption cycles suggests the potential of KF-O-PAN for efficient removal of sulfonated dyes from aqueous solution.

Effect of Chemical Treatment on Mechanical and Water-Sorption Properties Coconut Fiber-Unsaturated Polyester from Recycled PET

Abstract: Coconut fibers were used as reinforcement for unsaturated polyester resin from recycled PET that has been prepared using glycolysis and polyesterification reaction Various concentrations of alkali, silane, and silane on alkalized fiber were applied and the optimum concentration of treatments was determined Morphological and mechanical properties of the composite have also been investigated to study the effect of fiber surface treatment The influence of water uptake on the sorption characteristics of composites was studied via immersion in distilled water at room temperature Surface treatment of coconut fiber caused a significant increase in the tensile properties with the optimum treatment of 05% silane on the 5% alkalized coconut fiber/polyester composites For water absorption study, it was observed that the treated fiber composites showed lower water absorption properties in comparison to those of untreated fiber composites SEM investigation showed that the surface modification of fiber has better fiber-matrix interaction Thus, chemical treatments on the fiber improve fiber/matrix adhesion especially for silane on alkalized fiber treatment

Removal of Fluoride from Water by Adsorption onto Lanthanum Oxide

Abstract: Rare earth mineral based adsorbent viz. lanthanum oxide was investigated for potential application in defluoridation of drinking water for isolated and rural communities. Results of batch experiments indicated about 90% removal in 30 min from a 4 mg L−1 synthetic fluoride solution. The effects of various parameters like contact time, pH, initial concentration, and sorbent dose on sorption efficiency were investigated. Adsorption efficiency was dependent on initial fluoride concentration and the sorption process followed BET model. Variation of pH up to 9.5 has insignificant effect on sorption and beyond a pH of 9.5, the effect was drastic. Among anions investigated, carbonates exhibited high detrimental effect on fluoride adsorption while anions like bicarbonates, chlorides, and sulfates did not seriously affect the process. Adsorbent showed negligible desorption of fluoride in distilled water. Alum was more effective regenerant than HCl and NaOH. Results of cyclic regeneration with alum indicated that the sorbent could be regenerated for ten cycles without significant loss of sorption capacity. Studies with upflow fixed-bed continuous flow columns indicated the usefulness of sorbent for fluoride removal in continuous flow process.

Surface modification of titanium by hydrothermal treatment in Mg-containing solution and early osteoblast responses

Abstract: Surface modification on titanium was carried out in order to improve its bioactivity. Pure titanium was hydrothermally treated in distilled water and 0.1 M MgCl(2) solutions at 200°C for 24 h. Surface morphology, roughness, wettability and chemical composition were characterized before and after treatment. Bovine serum albumin was used as model to study protein adsorption. MC3T3-E1 cells were cultured and initial cell attachment, morphology, proliferation were evaluated. After hydrothermal treatment, nano-sized precipitations were observed and samples showed superhydrophilicity. Magnesium (Mg) was immobilized into titanium surface by hydrothermal treatment. Protein adsorption was significantly increased on Mg-containing samples. Cell attachment was improved and cell spreading was enhanced on Mg-containing samples compared with untreated or those treated in distilled water. Increased early cellular attachment on the MgTi surface resulted in subsequent increase of number of proliferated cells. Hydrothermal treatment in MgCl(2) solution was expected to be an effective method to fabricate titanium implant with good bioactivity.

Experimental studies on heat transfer and friction factor characteristics of CuO/water nanofluid under laminar flow in a helically dimpled tube

Abstract: An experimental investigation on the convective heat transfer and friction factor characteristics in the plain and dimpled tube under laminar flow with constant heat flux is carried out with distilled water and CuO/water nanofluids. For this, CuO nanoparticles with an average size of 15.3 nm were synthesized by sol–gel method. The nanoparticles are then dispersed in distilled water to form stable suspension of CuO/water nanofluid containing 0.1, 0.2 and 0.3% volume concentration of nanoparticles. It is found that the experimental Nusselt numbers for 0.1, 0.2 and 0.3% volume concentration of CuO nanoparticles are about 6, 9.9 and 12.6%, respectively higher than those obtained with distilled water in plain tube. However, the experimental Nusselt numbers for 0.1, 0.2 and 0.3% volume concentration of CuO nanoparticles are about 3.4, 6.8 and 12%, respectively higher than those obtained with distilled water in dimpled tube. The friction factor of CuO/water nanofluid is also increased due to the inclusion of nanoparticles and found to increase with nanoparticle volume concentration. The experimental results show that there exists a difference in the enhancement levels of Nusselt numbers obtained with nanofluids in plain tube and dimpled tube. Hence it is proposed that the mechanism of heat transfer enhancement obtained with nanofluids is due to particle migration from the core of fluid flow to tube wall.

Spectroscopic Studies on Indian Portland Cement Hydrated with Distilled Water and Sea Water

Abstract: The spectroscopicstudies have been carried out for Indian Portland cement hydrated with distilled and sea water in a water to cement ratio of 0.4. This study aims to analyze the effect of water on Portland cement. FTIR, DTA, XRD and EPR studies were used to characterize the hydration reaction of the cement pastes. Experimental results on setting time, compressive strength are also reported. The unreacted clinker phases and g-factors are calculated. The results indicate that sea water accelerates the cement hydration at early stage but retards in the latter stage of hydration.

Evaluation of human enamel surfaces treated with theobromine: a pilot study.

Abstract: Purpose The objectives of this in-vitro study were to investigate the effect of theobromine, which is the principle xanthine species in Theobroma cacao, at two concentrations on the surface hardness and topography of human enamel. Materials and methods Twenty-four freshly extracted human third molars were collected and stored in distilled water with 0.1% thymol solution at room temperature prior to the experiments. The enamel specimens were treated with one coat of theobromine at two concentrations (100 mg/l or 200 mg/l in distilled water) for 5 min. Enamel surfaces in the control group received no theobromine. They were then kept in distilled water for 1 week and subjected to SEM analysis. The specimens were demineralised by storing them in acidic hydroxyethylcellulose for three days. After baseline microhardness measurements, they were incubated either in 100 or 200 mg/l theobromine for 5 min. The control group was kept in distilled water. After washing the specimens under distilled water, they were kept in a remineralising solution for 18 h. Microhardness of the enamel surface was initially determined for each specimen before artificial demineralisation. After demineralisation, the experimental groups were incubated in 100 mg or 200 mg theobromine and control-group specimens were placed in remineralising solution. Results Enamel surfaces of the untreated control group presented a generally smooth and slightly hummocky surface with small lines of pits. Specimens treated with theobromine showed differences between the two concentrations. The group treated with 200 mg/l solution for 5 min showed a greater quantity of globules on enamel than did specimens treated with 100 mg/l solution. Conclusion As shown by the microhardness values, a consistent and remarkable protection of the enamel surface was found with the application of theobromine.

Synthesis and Characterization of Novel Poly(N-vinylcaprolactam-co-itaconic Acid) Gels and Analysis of pH and Temperature Sensitivity

Abstract: Poly(N-vinylcaprolactam-co-itaconic acid), P(VC-co-IA), gels were synthesized in ethanol by using the free radical cross-linking polymerization method at 60 °C for 24 h in the presence of azobis(isobutyronitrile) (AIBN) and allyl methacrylate (AMA) as the initiator and the cross-linking agent, respectively. In order to determine the effect of the synthesis medium on the percentage of gelation (PG) and equilibrium swelling value (ESV), an ethanol/distilled water mixture (80:20, v/v) was also used as the synthesis medium for poly(N-vinylcaprolactam) (PVC) and P(VC-co-IA) gels. The swelling behaviors of the gels were investigated in distilled water at various temperatures and in different pH buffer solutions. Structural, morphologic, and thermal characterization studies of the gels were carried out using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA), respectively. The lowest PG and highest ESV were obtained for the gel including 5 m...

Tribological behaviour of polymeric materials in water lubricated contacts

Abstract: The present study aims at investigating the tribological behaviour of several unfilled polymer materials sliding against 316L stainless steel in distilled water. The tests were carried out in a uni ...

Determination of Oxygen Solubility in Liquid Media

Abstract: The present work aimed at determining the oxygen saturation in culture medium used in the production of pigments by Monascus ruber CCT 3802. This estimation allows the correction and the minimization of errors on the specific oxygen uptake rates determination because the conversion of oxygen partial pressure to oxygen concentration requires accurate information on oxygen solubility in experimental incubation media. By adding hydrogen peroxide and then transforming into water and oxygen using catalase, it was possible to determinate the saturation concentration of 7.677 and 6.772 mgO2L−1 in distilled water and in growth medium, respectively. The determination of these parameters makes possible the minimization of errors on the specific oxygen uptake rates determination, once many studies consider the saturation concentration in distilled water.

Isolation and characterisation of acaricidal and larvicidal novel compound (2S,5R,6R)-2-hydroxy-3,5,6-trimethyloctan-4-one from Streptomyces sp. against blood-sucking parasites

Abstract: The aim of the present study was to assess the acaricidal and larvicidal property of marine actinobacterial compound (2S,5R,6R)-2-hydroxy-3,5,6-trimethyloctan-4-one extracted and isolated from Streptomyces sp. VITDDK3 tested against the larvae of Rhipicephalus (Boophilus) microplus Canestrini (Acari: Ixodidae), Anopheles subpictus Grassi and Culex quinquefasciatus Say (Diptera: Culicidae). The isolate was taxonomically characterised, identified and designated as Streptomyces sp. VITDDK3. The crude compound was loaded on silica gel column and eluted with chloroform–methanol–water. The purity of the compound isolated was analysed by thin layer chromatography using chloroform and methanol as the solvent system and confirmed by high-performance liquid chromatography. The structure of the purified compound was established from infrared, ultraviolet, 1H-nuclear magnetic resonance (NMR), 13C-NMR and mass spectral data. The chemical shift assignments obtained for the aliphatic compound from 1H-NMR corresponding to the molecular formula C11H22O2. Bioassay-guided fractionation led to the isolation of compound, which was identified as (2S,5R,6R)-2-hydroxy-3,5,6-trimethyloctan-4-one. In the present study, Streptomyces sp. VITDDK3 crude extract and different fractions were tested against the larvae of parasites at a concentration of 1,000 ppm. Those fractions showing 100% mortality in 24 h alone was selected for further column chromatographic separation. The purified compound (2S,5R,6R)-2-hydroxy-3,5,6-trimethyloctan-4-one was tested in the concentrations of 250, 200, 150, 100 and 50 ppm and observed the per cent mortality of 100, 88, 62, 50 and 36 against R. microplus; 100, 100, 87, 62 and 39 against A. subpitcus; and 100, 94, 79, 51 and 33 against C. quinquefasciatus, respectively. The crude extract showed parasitic effects after 24 h of exposure at 1,000 ppm, and parasite mortality was observed against the larvae of R. microplus (LC50 = 88.74 ppm; r2 = 0.865) against the larvae of A. subpictus (LC50 = 162.59 ppm; r2 = 0.817) and against C. quinquefasciatus (LC50 = 120.15 ppm; r2 = 0.782), respectively. The maximum efficacy was observed in purified marine actinobacterial compound (2S,5R,6R)-2-hydroxy-3,5,6-trimethyloctan-4-one with LC50 and r2 values against the larvae of R. microplus (94.49 ppm; 0.982) and A. subpictus (69.65 ppm; 0.906) and against C. quinquefasciatus (82.82 ppm; 0.957), respectively. The control (distilled water) showed nil mortality in the concurrent assay.