Abstract: The removal vanadium from aqueous solution using natural exchanger was investigated. The effects of pH, contact time and exchanger dose were studied at ambient temperature (25 0C ± 2 0C). The equilibrium process was described by the Langmuir isotherm model with adsorption capacity for vanadium. The natural exchanger i.e. tamarindus seeds powder was treated with formaldehyde and sulpuric acid to increase the adsorptivity of metals. The maximum exchange level was attained as 80.1% at pH 3 with exchanger dose 5 g and contact time 60 min. Method is applied for removal of vanadium from industrial effluents.
Abstract: Many of thermosetting resins have application only in filled state, reinforced with different mineral fillers. The co-filling of polymers with mineral filler and gases creates a possibility for production of polymer composites materials with low density. This processing leads to forming of new materials – gas-filled plastics (polymer foams). The properties of these materials are determined mainly by the shape and size of internal structural elements (pores). The interactions on the phase boundaries have influence on the materials properties too. In the present work, the gas-filled urea-formaldehyde resins were reinforced by waste phosphogypsum. The waste phosphogypsum (CaSO4.2H2O) is a solid by-product in wet phosphoric acid production processes. The values of the interactions polymer-filler were increased by using two modifying agents: polyvinyl acetate for polymer matrix and sodium metasilicate for filler. Technological methods for gas-filling and recipes of urea-formaldehyde based materials with apparent density 20-120 kg/m3 were developed. The heat conductivity of the samples is between 0.024 and 0.029 W/moK. Tensile analyses were carried out at 10 and 50% deformation and show values 0.01-0.14 MPa and 0.01-0.09 MPa, respectively. The apparent density of obtained materials is between 20 and 92 kg/m3. The changes in the tensile properties and density of these materials according to sodium metasilicate content were studied too. The mechanism of phosphogypsum adsorption modification was studied using methods of FT-IR spectroscopy. The structure of the gas-filled urea-formaldehyde resins was described by results of electron scanning microscopy at three different magnification ratios – x50, x150 and x 500. The aim of present work is to study the possibility of the usage of phosphogypsum as mineral filler for urea-formaldehyde resins and development of a technology for the production of gas-filled reinforced polymer composite materials. The structure and the properties of obtained composite materials are suitable for thermal and sound insulation applications.
Abstract: Reducing formaldehyde concentration in residential buildings is an important challenge, especially during the summer. In this study, a ceiling tile was used as a sorptive passive panel for formaldehyde removal. The performance of this passive panel was evaluated under different environmental conditions. The results demonstrated that the removal efficiency is comprised between 40% and 71%. Change in the level of relative humidity (30%, 50%, and 75%) had a slight positive effect on the sorption capacity. However, increase in temperature from 21 °C to 26 °C led to approximately 7% decrease in the average formaldehyde removal performance. GC/MS and HPLC analysis revealed the formation of different by-products at low concentrations under extreme environmental conditions. These findings suggest that the passive panel selected for this study holds the potential to be used for formaldehyde removal under various conditions.
Abstract: Polyoxymethylene dimethyl ethers (PODEn) as clean diesel additive can improve the combustion efficiency and quality of diesel fuel and alleviate the problem of atmospheric pollution. Considering synthetic routes, PODE production from methanol and formaldehyde is regarded as the most economical and promising synthetic route. However, methanol used for synthesizing PODE can produce water, which causes the loss of active center of catalyst and hydrolysis of PODEn in the production process. Macroporous strong acidic cation exchange resin catalyst was prepared, which has comparative advantages over other common solid acid catalysts in terms of stability and catalytic efficiency for synthesizing PODE. Catalytic reactions were carried out under 353 K, 1 MPa and 3mL·gcat-1·h-1 in a fixed bed reactor. Methanol conversion and PODE3-6 selectivity reached 49.91% and 23.43%, respectively. Catalyst lifetime evaluation showed that resin catalyst retained its catalytic activity for 20 days without significant changes and catalytic activity of completely deactivated resin catalyst can basically return to previous level by simple acid regeneration. The acid exchange capacities of original and deactivated catalyst were 2.5191 and 0.0979 mmol·g-1, respectively, while regenerated catalyst reached 2.0430 mmol·g-1, indicating that the main reason for resin catalyst deactivation is that Brønsted acid sites of original resin catalyst were temporarily replaced by non-hydrogen ion cations. A separation process consisting of extraction and distillation for PODE3-6 product was designed for separation of water and unreacted formaldehyde from reactive mixture and purification of PODE3-6, respectively. The concentration of PODE3-6 in final product can reach up to 97%. These results indicate that the scale-up production of PODE3-6 from methanol and formaldehyde solution is feasible.
Abstract: The catalytic oxidation of CO and volatile organic compounds (VOCs) is considered as one of the most efficient ways to reduce harmful emissions from various chemical industries. The effectiveness of gold-based catalysts for many reactions of environmental significance was proven during the past three decades. The aim of this work was to combine the favorable features of Au and Cu-Ce mixed oxides in the design of new catalytic materials of improved efficiency and economic viability for removal of air pollutants in waste gases from formaldehyde production. Supported oxides of copper and cerium with Cu: Ce molar ratio 2:1 and 1:5 were prepared by wet impregnation of g-alumina. Gold (2 wt.%) catalysts were synthesized by a deposition-precipitation method. Catalysts characterization was carried out by texture measurements, powder X-ray diffraction, temperature programmed reduction and electron paramagnetic resonance spectroscopy. The catalytic activity in the oxidation of CO, CH3OH and (CH3)2O was measured using continuous flow equipment with fixed bed reactor. Both Cu-Ce/alumina samples demonstrated similar catalytic behavior. The addition of gold caused significant enhancement of CO and methanol oxidation activity (100 % degree of CO and CH3OH conversion at about 60 and 140 oC, respectively). The composition of Cu-Ce mixed oxides affected the performance of gold-based samples considerably. Gold catalyst on Cu-Ce/γ-Al2O3 1:5 exhibited higher activity for CO and CH3OH oxidation in comparison with Au on Cu-Ce/γ-Al2O3 2:1. The better performance of Au/Cu-Ce 1:5 was related to the availability of highly dispersed gold particles and copper oxide clusters in close contact with ceria.
Abstract: The development of value added composite products from bamboo with the application of gluing technology can play a vital role in economic development and also in forest resource conservation of any country. In this study, the gluability of Bambusa balcooa and Bambusa vulgaris, two locally grown bamboo species of Bangladesh was assessed. As the culm wall thickness of bamboos decreases from bottom to top, a culm portion of up to 5.4 m and 3.6 m were used from the base of B. balcooa and B. vulgaris, respectively, to get rectangular strips of uniform thickness. The color of the B. vulgaris strips was yellowish brown and that of B. balcooa was reddish brown. The strips were treated in borax-boric, bleaching and carbonization for extending the service life of the laminates. The preservative treatments changed the color of the strips. Borax–boric acid treated strips were reddish brown. When bleached with hydrogen peroxide, the color of the strips turned into whitish yellow. Carbonization produced dark brownish strips having coffee flavor. Chemical constituents for untreated and treated strips were determined. B. vulgaris was more acidic than B. balcooa. Then the treated strips were used to develop three-layered bamboo laminated panel. Urea formaldehyde (UF) and polyvinyl acetate (PVA) were used as binder. The shear strength and abrasive resistance of the panel were evaluated. It was found that the shear strength of the UF-panel was higher than the PVA-panel for all treatments. Between the species, gluability of B. vulgaris was better and in some cases better than hardwood species. The abrasive resistance of B. balcooa is slightly higher than B. vulgaris; however, the latter was preferred as it showed well gluability. The panels could be used as structural panel, floor tiles, flat pack furniture component, and wall panel etc. However, further research on durability and creep behavior of the product in service condition is warranted.
Abstract: A study was conducted at River Mayo Ranewo and River Lau, Taraba State Nigeria. The two rivers empty into the Upper Benue Basin. A survey of visual encounter was conducted within the two wetlands from June to August, 2014. The fish record was based entirely on landings of fishermen, number of canoes that land fish was counted, types of nets and baits used on each sampling day. Fishes were sorted into taxonomic groups, identified to family/ species level, counted and weighed in groups by species. Other aquatic organisms captured by the fishermen were scallops, turtles and frogs. The relative species abundance was determined by dividing the number of species from a site by the total number of species from all tributaries/sites. The fish were preserved in 2% formaldehyde solution and taken to the laboratory, were identified through keys of identification to African fishes and field guides. Shannon-Wieiner index of species diversity indicated that the diversity was highest at River Mayo Ranewo than River Lau. Results showed that at River Mayo Ranewo, the family Mochokidae recorded the highest (23.15%), followed by Mormyridae (22.64%) and the least was the family Lepidosirenidae (0.04%). While at River Lau, the family Mochokidae recorded the highest occurrence of (24.1%), followed by Bagridae (20.20%), and then Mormyridae, which also was the second highest in River Lau, with 18.46% occurrence. There was no occurrence of Malapteruridae and Osteoglossidae (0%) in River Lau, but the least occurrence was the family Gymnarchidae (0.04%). According to the result from the t-test, the fish composition was not significantly different (p≤0.05).
Abstract: Oxygen Reduction Reaction (ORR) performance of
iron and nitrogen co-doped porous carbon nanoparticles (Fe-NPC)
with various physical and (electro) chemical properties have been
investigated. Fe-NPC nanoparticles are synthesized via a facile
soft-templating procedure by using Iron (III) chloride hexa-hydrate as
iron precursor and aminophenol-formaldehyde resin as both carbon
and nitrogen precursor. Fe-NPC nanoparticles shows high surface area
(443.83 m2g-1), high pore volume (0.52 m3g-1), narrow mesopore size
distribution (ca. 3.8 nm), high conductivity (IG/ID=1.04), high kinetic
limiting current (11.71 mAcm-2) and more positive onset potential
(-0.106 V) compared to metal-free NPC nanoparticles (-0.295V)
which make it high efficient ORR metal-free catalysts in alkaline
solution. This study may pave the way of feasibly designing iron and
nitrogen containing carbon materials (Fe-N-C) for highly efficient
oxygen reduction electro-catalysis.
Abstract: Bio-composites derived from plant fiber and/or bioderived
polymer, are likely more ecofriendly and demonstrate
competitive performance with petroleum based composites. In this
research, the bio phenol-formaldehyde (bio-PF) was used as a matrix
and oil palm empty fruit bunch fiber (EFB) as reinforcement. The
matrix was synthesized via liquefaction and condensation to enhance
the combination of phenol and formaldehyde, during the process.
Then, the bio-PF was mixed with different percentage of EFB (5%,
10%, 15% and 20%) and molded at 180oC. The samples that viewed
under scanning electron microscopy (SEM) showed an excellent
wettability and interaction between EFB and matrix. Samples of 10%
EFB gave the optimum properties of impact and hardness meanwhile
sample 15% of EFB gave the highest reading of flexural modulus
(MOE) and flexural strength (MOR). For thermal stability analysis, it
was found that the weight loss and the activation energy (Ea) of the
bio-composites samples were decreased as the filler content
increased.
Abstract: In situ modified cyclohexanone-formaldehyde resins
were prepared by addition of alendronic acid during resin
preparation. Clay nanocomposites in ketonic resins were achieved by
adding clay into the flask at the beginning of the resin preparation.
The prepared resins were used for the synthesis of fire resistant
polyurethanes foam. Both phosphorous containing modifier
compound alendronic acid and nanoclay increases fire resistance of
the cyclohexanone-formaldehyde resin thus polyurethane produced
from these resins. The effect of the concentrations of alendronic acid
and clay on the fire resistance and physical properties of
polyurethanes was studied.
Abstract: The research work covered in this study includes the morphological structure and optical properties of TiO2-coated silk fibroin (SF) filters at 2.5% wt. TiO2/vol. PVA solution. SEM micrographs revealed the fibrous morphology of the TiO2-coated SF filters. An average diameter of the SF fiber was estimated to be approximately 10µm. Also, it was confirmed that TiO2 can be adhered more on SF filter surface at higher TiO2 dosages. The activity of semiconductor materials was studied by UV-VIS spectrophotometer method. The spectral data recorded shows the strong cut off at 390 nm. The calculated band-gap energy was about 3.19 eV. The photocatalytic activity of the filter was tested for gaseous formaldehyde removal in a modeling room with the total volume of 2.66 m3. The highest removal efficiency (54.72 ± 1.75%) was obtained at the initial formaldehyde concentration of about 5.00 ± 0.50ppm.
Abstract: Compatibility between sulfonated acetone- formalehyde superplasticizer (SAF) and copolymer-based grinding aids (GA) were studied by fluidity, Zeta potential, setting time of cement pasts, initial slump and slump flow of concrete and compressive strength of concrete. ESEM, MIP, and XRD were used to investigate the changing of microstructure of interior concrete. The results indicated that GA could noticeably enhance the dispersion ability of SAF. It was found that better fluidity and slump-keeping ability of cement paste were obtained in the case of GA. In addition, GA together with SAF had a certain retardation effect on hydration of cement paste. With increasing of the GA dosage, the dispersion ability and retardation effect of admixture increased. The compressive strength of the sample made with SAF and GA after 28 days was higher than that of the control sample made only with SAF. The initial slump and slump flow of concrete increased by 10.0% and 22.9%, respectively, while 0.09 wt.% GA was used. XRD examination indicated that new products were not found in the case of GA. In addition, more dense arrangement of hydrates and lower porosity of the specimen were observed by ESEM and MIP, which contributed to higher compressive strength.
Abstract: Homogeneous graft copolymerization of methyl methacrylate (MMA) onto cellulose was carried out in N, N – dimethyl acetamide/LiCl (DMAc/LiCl) and dimethyl sulfoxide/ paraformaldehyde (DMSO/PF) solvent system taking ceric ammonium nitrate (CAN), benzoyl peroxide (BPO) and tin (II)-2-ethyl hexanoate [Sn(Oct)2] as initiators. Different grafting parameters like graft yield (GY), grafting efficiency (GE) and total conversion of monomer to polymer (TC) were evaluated at different reaction conditions of temperature, time, and variation of the amount of monomer and initiator. The viscosity average molecular weight of grafted PMMA and number of grafts per cellulose chain were also calculated. The products were characterized by FT-IR and 1H-NMR analyses and possible reaction mechanisms were deduced. Thermal degradation of the grafted products was also studied by thermo-gravimetric analysis (TG) and differential thermo-gravimetry (DTG).
Abstract: Natural fibers are considered to have potential use as reinforcing agents in polymer composite materials because of their principal benefits: moderate strength and stiffness, low cost, and being an environmental friendly, degradable, and renewable material. A study has been carried out to evaluate impact properties of composites made by areca fibers reinforced urea formaldehyde, melamine urea formaldehyde and epoxy resins. The extracted areca fibers from the areca husk were alkali treated with potassium hydroxide (KOH) to obtain better interfacial bonding between fiber and matrix. Then composites were produced by means of compression molding technique with varying process parameters, such as fiber condition (untreated and alkali treated), and fiber loading percentages (50% and 60% by weight). The developed areca fiber reinforced composites were then characterized by impact test. The results show that, impact strength increase with increase in the loading percentage. It is observed that, treated areca fiber reinforcement increases impact strength when compared to untreated areca fiber reinforcement.
Abstract: The freezing point of milk is in important indicator of
the milk quality. The freezing point of milk is determined primarily
to prove milk adulteration with water and to determine the amount of
water in it. Chemical composition and properties of milk, thermal
treatment and presence of any substance can influence freezing point
of product. There are different substances, which can be added to
milk with main purpose to prolong shelf-life of raw milk. There are
detergent, preservatives, formaldehyde, hydrogen peroxide,
antibiotics, sodium carbonate, and hydrogen peroxide. Therefore the
aim of the present study was to determine freezing point of milk,
skimmed milk, pasteurized milk and milk with different substances
(formaldehyde, antibiotics, sodium carbonate, hydrogen peroxide,
disinfectant, and detergent) in different concentrations. The thermal
treatment and different undesirable substances presence in milk have
significant influence on freezing point of it.
Abstract: The research study was based on an evaluation of the
ability of glued test samples to pass the criterion of sufficient
bondline adhesion under the exposure conditions defined in EN 302-
1. Additionally, an infrared spectroscopic analysis of the evaluated
adhesives (phenol-resorcinol-formaldehyde PRF and melamine-ureaformaldehyde
MUF) with different mix ratios was carried out to
evaluate the possible effects of a faulty technological process.
Abstract: Microbial contamination, most of which are fecal born in drinking water and food industry is a serious threat to humans. Escherichia coli is one of the most common and prevalent among them. We have developed a sensor for rapid and an early detection of contaminants, taking E.coli as a threat indicator organism. The sensor is based on co-polymerizations of aniline and formaldehyde in form of thin film over glass surface using the vacuum deposition technique. The particular doping combination of thin film with Fe-Al and Fe-Cu in different concentrations changes its non conducting properties to p- type semi conductor. This property is exploited to detect the different contaminants, believed to have the different surface charge. It was found through experiments that different microbes at same OD (0.600 at 600 nm) have different conductivity in solution. Also the doping concentration is found to be specific for attracting microbes on the basis of surface charge. This is a simple, cost effective and quick detection method which not only decreases the measurement time but also gives early warnings for highly contaminated samples.
Abstract: This research was to evaluate a technical feasibility of
making single-layer experimental particleboard panels from bamboo
waste (Dendrocalamus asper Backer) by converting bamboo into
strips, which are used to make laminated bamboo furniture. Variable
factors were density (600, 700 and 800 kg/m3) and temperature of
condition (25, 40 and 55 °C). The experimental panels were tested for
their physical and mechanical properties including modulus of
elasticity (MOE), modulus of rupture (MOR), internal bonding
strength (IB), screw holding strength (SH) and thickness swelling
values according to the procedures defined by Japanese Industrial
Standard (JIS). The test result of mechanical properties showed that
the MOR, MOE and IB values were not in the set criteria, except the
MOR values at the density of 700 kg/m3 at 25 °C and at the density
of 800 kg/m3 at 25 and 40 °C, the IB values at the density of 600
kg/m3, at 40 °C, and at the density of 800 kg/m3 at 55 °C. The SH
values had the test result according to the set standard, except with
the density of 600 kg/m3, at 40 and 55 °C. Conclusively, a valuable
renewable biomass, bamboo waste could be used to manufacture
boards.
Abstract: Formaldehyde is the illegal chemical substance used
for food preservation in fish and vegetable. It can promote
carcinogenesis. Superoxide dismutases are the important
antioxidative enzymes that catalyze the dismutation of superoxide
anion into oxygen and hydrogen peroxide. The resultant level of
oxidative stress in formaldehyde-treated lymphocytes was
investigated. The formaldehyde concentrations of 0, 20, 40, 60, 80
and 120μmol/L were treated in human lymphocytes for 12 hours.
After 12 treated hours, the superoxide dismutase activity change was
measured in formaldehyde-treated lymphocytes. The results showed
that the formaldehyde concentrations of 60, 80 and 120μmol/L
significantly decreased superoxide dismutase activities in
lymphocytes (P < 0.05). The change of superoxide dismutase
activity in formaldehyde-treated lymphocytes may be the biomarker
for detect cellular injury, such as damage to DNA, due to
formaldehyde exposure.
Abstract: The paper relates to a catalyst, comprising copperchromium
spinel, coated on carrier γ-Al2O3. The effect of preparation
conditions on the active component composition and activity
behavior of the catalysts is discussed. It was found that the activity of
carbon monoxide, DME, formaldehyde and methanol oxidation
reaches a maximum at an active component content of 20 – 30 wt. %.
Temperature calcination at 500oC seems to be optimal for the γ–
alumina supported CuO-Cr2O3 catalysts for CO, DME, formaldehyde
and methanol oxidation. A three months industrial experiment was
carried out to elucidate the changes in the catalyst composition
during industrial exploitation of the catalyst and the main reasons for
catalyst deactivation.
It was concluded that the CuO–Cr2O3/γ–alumina supported
catalysts have enhanced activity toward CO, DME, formaldehyde
and methanol oxidation and that these catalysts are suitable for
industrial application. The main reason for catalyst deactivation
seems to be the deposition of iron and molybdenum, coming from the
main reactor, on the active component surface.