Abstract: This paper describes a method for preparing metallic Cu nanoparticles in aqueous solution, and a metal-metal bonding technique using the Cu particles.Preparation of the Cu particle colloid solution was performed in water at room temperature in air using a copper source (0.01 M Cu(NO3)2), a reducing reagent (0.2 - 1.0 M hydrazine), and stabilizers (0.5×10-3 M citric acid and 5.0×10-3 M cetyltrimethylammonium bromide). The metallic Cu nanoparticles with sizes of ca. 60nm were prepared at all the hydrazine concentrations examined. A stage and a plate of metallic Cu were successfully bonded under annealing at 400oC and pressurizing at 1.2 MPa for 5min in H2 gas with help of the metallic Cu particles. A shear strength required for separating the bonded Cu substrates reached the maximum value at a hydrazine concentration of 0.8M, and it decreased beyond the concentration. Consequently, the largest shear strength of 22.9 MPa was achieved at the 0.8 M hydrazine concentration.
Abstract: Novel nitrogen removal technologies via nitrite
pathway attract increasing interest in recent years. In this study,
batch experiments were performed to investigate nitrite accumulation
characteristics and shifts in nitrifying community structure at
different growth environments including ammonia concentration, pH
and alkalinity. It was found that nitrite accumulation ratios were
maintained at around 95% at studied conditions, and the optimum pH
and Alk/N (ratio between alkalinity and nitrogen) for ammonium
oxidization were 8.5 and 8.33, respectively. Fluorescence in situ
hybridization analysis of nitrifying bacteria showed that high free
ammonia (from influent ammonium or caused by high pH)
significantly altered the structure of nitrifying community, leading to
abundance of ammonia-oxidizing bacteria (AOB), especially
Nitrososmonas, and inhibition of nitrite-oxidizing bacteria (NOB).
The results suggest that free ammonia plays more important role than
other studied conditions on nitrite accumulation.
Abstract: Among the technologies available to reduce methane
emitted from the pig industry, biofiltration seems to be an effective
and inexpensive solution. In methane (CH4) biofiltration, nitrogen is
an important macronutrient for the microorganisms growth. The
objective of this research project was to study the effect of
ammonium (NH4
+) on the performance, the biomass production and
the nitrogen conversion of a biofilter treating methane. For NH4
+
concentrations ranging from 0.05 to 0.5 gN-NH4
+/L, the CH4 removal
efficiency and the dioxide carbon production rate decreased linearly
from 68 to 11.8 % and from 7.1 to 0.5 g/(m3-h), respectively. The dry
biomass content varied from 4.1 to 5.8 kg/(m3 filter bed). For the
same range of concentrations, the ammonium conversion decreased
while the specific nitrate production rate increased. The specific
nitrate production rate presented negative values indicating
denitrification in the biofilter.
Abstract: In this article, we synthesize a novel chitosan -based
superabsorbent hydrogel via graft copolymerization of mixtures
acrylic acid (AA) and N-vinyl pyrollidon onto chitosan backbones.
The polymerization reaction was carried out in an aqueous medium
and in the presence of ammonium persulfate (APS) as an initiator and
N,N'-methylene bisacrylamide (MBA) as a crosslinker.The hydrogel
structures were confirmed by FTIR spectroscopy. The swelling
behavior of these absorbent polymers was also investigated in
various salt solutions. Results indicated that the swelling capacity
decreased with an increase in the ionic strength of the swelling
medium. Furthermore, the swelling of superabsorbing hydrogels was
examined in solutions with pH values ranging between 1.0 and 13.0.
It showed a reversible pH-responsive behavior at pHs 2.0 and 8.0.
This on-off switching behavior makes the synthesized hydrogels as
an excellent candidate for controlled delivery of bioactive agents.
Abstract: Ammonia nitrogen is one of the most hazardous
water pollutants, discharging into water receptors through industrial
effluents. Negative environmental impacts of such chemical species
in hydrosphere include accelerated eutrophication, water toxicity and
harming the aquatics. Natural zeolite clinoptilolite has very high
selectivity & capacity for ammonium cation sorption. It occurs in
high abundances and rich mines of this zeolite exist in different parts
of Iran and thus are available more cheaply and with different sizing.
The aim of this study is to investigate ammonia nitrogen removal
over this natural sorbent from real samples of high polluted
wastewater discharging from a fertilizer producing plant. The
experimental results showed that this natural sorbent without even
any pre treatment system & with the same particle size available in
Iranian markets has still high capability & selectivity in ammonia
nitrogen removal both in batch and continuous tests.
Abstract: This study investigated possible ways to improve the
efficiency of the platinum precipitation process using ammonium
chloride by reducing the platinum content reporting to the effluent.
The ore treated consist of five platinum group metals namely,
ruthenium, rhodium, iridium, platinum, palladium and a precious
metal gold. Gold, ruthenium, rhodium and iridium were extracted
prior the platinum precipitation process. Temperature, reducing
agent, flow rate and potential difference were the variables controlled
to determine the operation conditions for optimum platinum
precipitation efficiency. Hydrogen peroxide was added as the
oxidizing agent at the temperature of 85-90oC and potential
difference of 700-850mV was the variable used to check the
oxidizing state of platinum. The platinum was further purified at
temperature between 60-65oC, potential difference above 700 mV,
ammonium chloride of 200 l, and at these conditions the platinum
content reporting to the effluent was reduced to less than 300ppm,
resulting in optimum platinum precipitation efficiency and purity of
99.9%.
Abstract: Nitrogen loss from irrigated cropland, particularly
sandy soils, significantly contributes to nitrate (NO3
-) levels in
surface and groundwaters. Thus, it is of great interest to use
inexpensive natural products that can increase the fertilizer efficiency
and decrease nitrate leaching. In this study, the ability of natural
Iranian zeolite clinoptilolite (Cp) and surfactant modified zeolite
clinoptilolite (SMZ) to remove NH4
+ and NO3
-, respectively, from
aqueous solutions was determined. The feasibility of using Cp and
SMZ as soil amendment to reduce nitrate leaching from soil using
lysimeters was also investigated. Zeolite showed 10.23% to 88.42%
NH4
+ removal efficiency over a wide range of initial NH4
+
concentrations. Nitrate removal efficiency by SMZ was 32.26% to
82.26%. Field study results showed that Cp and SMZ significantly (p
< 0.05) reduced leachate NO3-N concentration compared to control.
There was no significant difference between maximum and mean
leachate NO3-N concentration of SMZ lysimeters and those of Cp
lysimeters.
Abstract: In this study, communities of ammonia-oxidizing
archaea (AOA) and ammonia-oxidizing bacteria (AOB) in nitrifying
activated sludge (NAS) prepared by enriching sludge from a
municipal wastewater treatment plant in three continuous-flow
reactors receiving an inorganic medium containing different
ammonium concentrations of 2, 10, and 30 mM NH4
+-N (NAS2,
NAS10, and NAS30, respectively) were investigated using molecular
analysis. Results suggested that almost all AOA clones from NAS2,
NAS10, and NAS30 fell into the same AOA cluster and AOA
communities in NAS2 and NAS10 were more diverse than those of
NAS30. In contrast to AOA, AOB communities obviously shifted
from the seed sludge to enriched NASs and in each enriched NAS,
communities of AOB varied particularly. The seed sludge contained
members of N. communis cluster and N. oligotropha cluster. After it
was enriched under various ammonium loads, members of N.
communis cluster disappeared from all enriched NASs. AOB with
high affinity to ammonia presented in NAS 2, AOB with low affinity
to ammonia presented in NAS 30, and both types of AOB survived in
NAS 10. These demonstrated that ammonium load significantly
influenced AOB communities, but not AOA communities in enriched
NASs.
Abstract: Two commercial proteases from Bacillus
licheniformis (Alcalase 2.4 L FG and Alcalase 2.5 L, Type DX) were
screened for the production of Z-Ala-Phe-NH2 in batch reaction.
Alcalase 2.4 L FG was the most efficient enzyme for the C-terminal
amidation of Z-Ala-Phe-OMe using ammonium carbamate as
ammonium source. Immobilization of protease has been achieved by
the sol-gel method, using dimethyldimethoxysilane (DMDMOS) and
tetramethoxysilane (TMOS) as precursors (unpublished results). In
batch production, about 95% of Z-Ala-Phe-NH2 was obtained at
30°C after 24 hours of incubation. Reproducibility of different
batches of commercial Alcalase 2.4 L FG preparations was also
investigated by evaluating the amidation activity and the entrapment
yields in the case of immobilization. A packed-bed reactor (0.68 cm
ID, 15.0 cm long) was operated successfully for the continuous
synthesis of peptide amides. The immobilized enzyme retained the
initial activity over 10 cycles of repeated use in continuous reactor at
ambient temperature. At 0.75 mL/min flow rate of the substrate
mixture, the total conversion of Z-Ala-Phe-OMe was achieved after 5
hours of substrate recycling. The product contained about 90%
peptide amide and 10% hydrolysis byproduct.
Abstract: The principal objective of this study is to be able to
extract niobium oxide from columbite-tantalite concentrate of Thayet
Kon Area in Nay Phi Taw. It is recovered from columbite-tantalite
concentrate which contains 19.29 % Nb2O5.The recovery of niobium
oxide from columbite-tantalite concentrate can be divided into three
main sections, namely, digestion of the concentrate, recovery from
the leached solution and precipitation and calcinations. The
concentrate was digested with hydrofluoric acid and sulfuric acid. Of
the various parameters that effect acidity and time were studied. In
the recovery section solvent extraction process using methyl isobutyl
ketone was investigated. Ammonium hydroxide was used as a
precipitating agent and the precipitate was later calcined. The
percentage of niobium oxide is 74%.
Abstract: The evolution of silica optical fiber strength aged in cetyltrimethylammonium chloride solution (CTAC) has been investigated. If the solution containing surfactants presents appreciable changes in physical and chemical properties at the critical micelle concentration (CMC), a non negligible mechanical behavior fiber change is observed for silica fiber aged in cationic surfactants as CTAC which can lead to optical fiber reliability questioning. The purpose of this work is to study the mechanical behavior of silica coated and naked optical fibers in contact with CTAC solution at different concentrations. Result analysis proves that the immersion in CTAC drastically decreases the fiber strength and specially near the CMC point. Beyond CMC point, a small increase of fiber strength is analyzed and commented.
Abstract: The acid rain causes change in pH level of soil it is
directly influence on root and leaf growth. Yield of the crop was
reduced if acidity of soil is more. Acid rain seeps into the earth and
poisons plants and trees by dissolving toxic substances in the soil,
such as aluminum, which get absorbed by the roots. In present
investigation, effect of acid rain on crop Vigna radiata was studied.
The effect of acid rain on change in soil fertility was detected in
which pH of control sample was 6.5 and pH of 1% H2SO4 and 1%
HNO3 were 3.5. Nitrogen nitrate in soil was high in 1% HNO3 treated
soil & Control sample. Ammonium nitrogen in soil was low in 1%
HNO3 & H2SO4 treated soil. Ammonium nitrogen was medium in
control and other samples. The effect of acid rain on seed
germination on 3rd day of germination control sample growth was
6.1cm with plumule 0.001% HNO3 & 0.001% H2SO4 was 5.5cm
with plumule and 8cm with plumule. On 10th day fungal growth was
observed in 1% and 0.1% H2SO4 concentrations when all plants were
dead. The effect of acid rain on crop productivity was investigated on
3rd day roots were developed in plants. On 12th day Vigna radiata
showed more growth in 0.1% HNO3 and 0.1% H2SO4 treated plants
as compare to control plants. On 20th day development of
discoloration of plant pigments were observed on acid treated plants
leaves. On 34th day Vigna radiata showed flower in 0.1% HNO3,
0.01% HNO3 and 0.01% H2SO4treated plants and no flowers were
observed on control plants. On 42th day 0.1% HNO3, 0.01% HNO
and 0.01% H2SO4 treated Vigna radiata variety and control plants
were showed seeds on plants. In Vigna radiate variety 0.1%, 0.01%
HNO3, 0.01% H2SO4treated plants were dead on 46th day and fungal
growth was observed. The toxicological study was carried out on
Vigna radiata plants exposed to 1% HNO3 cells were damaged more
than 1% H2SO4. Leaf sections exposed to 0.001% HNO3 & H2SO4
showed less damaged of cells and pigmentation observed in entire
slide when compare with control plant.
Abstract: This study investigated the removal efficiency of electrokinetic remediation of copper-contaminated soil at different combinations of enhancement reagents used as anolyte and catholyte. Sodium hydroxide (at 0.1, 0.5, and 1.0 M concentrations) and distilled water were used as anolyte, while lactic acid (at 0.01, 0.1, and 0.5 M concentrations), ammonium citrate (also at 0.01, 0.1, and 0.5 M concentrations) and distilled water were used as catholyte. A continuous voltage application (1.0 VDC/cm) was employed for 240 hours for each experiment. The copper content of the catholyte was determined at the end of the 240-hour period. Optimization was carried out with a Response Surface Methodology - Optimal Design, including F test, and multiple comparison method, to determine which pair of anolyte-catholyte was the most significant for the removal efficiency. "1.0 M NaOH" was found to be the most significant anolyte while it was established that lactic acid was the most significant type of catholyte to be used for the most successful electrokinetic experiments. Concentrations of lactic acid should be at the range of 0.1 M to 0.5 M to achieve maximum percent removal values.
Abstract: Sugarcane bagasses are one of the most extensively used agricultural residues. Using acid hydrolysis and fermentation, conversion of sugarcane bagasses to lactic acid was technically and economically feasible. This research was concerned with the solubility of lignin in ammonium hydroxide, acid hydrolysis and lactic acid fermentation by Lactococcus lactis, Lactobacillus delbrueckii, Lactobacillus plantarum, and Lactobacillus casei. The lignin extraction results for different ammonium hydroxide concentrations showed that 10 % (v/v) NH4OH was favorable to lignin dissolution. Acid hydrolysis can be enhanced with increasing acid concentration and reaction temperature. The optimum glucose and xylose concentrations occurred at 121 ○C for 1 hour hydrolysis time in 10% sulphuric acid solution were 32 and 11 g/l, respectively. In order to investigate the significance of medium composition on lactic acid production, experiments were undertaken whereby a culture of Lactococcus lactis was grown under various glucose, peptone, yeast extract and xylose concentrations. The optimum medium was composed of 5 g/l glucose, 2.5 g/l xylose, 10 g/l peptone and 5 g/l yeast extract. Lactococcus lactis represents the most efficient for lactic acid production amongst those considered. The lactic acid fermentation by Lactococcus lactis after 72 hours gave the highest yield of 1.4 (g lactic acid per g reducing sugar).
Abstract: The purpose of this study is to investigate the capacity
of natural Turkish zeolite for NH4-N removal from landfill leachate.
The effects of modification and initial concentration on the removal
of NH4-N from leachate were also investigated. The kinetics of
adsorption of NH4-N has been discussed using three kinetic models,
i.e., the pseudo-second order model, the Elovich equation, the
intraparticle diffuion model. Kinetic parameters and correlation
coefficients were determined. Equilibrium isotherms for the
adsorption of NH4-N were analyzed by Langmuir, Freundlich and
Tempkin isotherm models. Langmuir isotherm model was found to
best represent the data for NH4-N.
Abstract: An HPLC-UV analytical method was developed to
determine ethylenediaminetetraacetic acid (EDTA) in dairy
wastewater and surface water. The optimizing separation was achieved
by reversed–phase ion-pair liquid chromatography on a C18 column
using methanol as mobile phase solvent, tetrabutylammonium bromide
as the ion-pair reagent in pH 3.3 formate buffer solution at a flow rate
of 0.9 mL min-1 with a UV detector at 265 nm. No interference of Ca,
Mg or NO3
- was detected. Method performance was evaluated in terms
of linearity, repeatability and reproducibility. The method detection
limit was 5 μg L-1. The contents of EDTA in dairy effluents were 72 ~
261 μg L-1 at a large dairy site. A change of EDTA concentration was
observed downstream of the dairy effluent discharge, but this was well
under the predicted no effect concentration for aquatic ecosystem.
Abstract: Chitosan is an attractive polysaccharide obtained by
deacetylation of an abundant natural biopolymer called chitin. Chitin
and chitosan are excellent materials. To improve the potential of
chitin and chitosan modification is needed. In the present study,
grafting of maleic acid on to chitosan by cerium ammonium nitrate in
acetic acid solution was investigated with use of a microwave and
reflux system. The grafted chitosan was characterized by using a
Fourier-transform infrared spectrometry. The solubility and swelling
behavior of grafted chitosans were determined in acetate buffer (pH
3.6), citrophosphate buffer (pH 5.6 and pH 7.0), and boric buffer (pH
9.2) solutions. The sample obtained by microwave system with use of
a chitosan/maleic anhydride/ceric ammonium nitrate 0.2/3.922/0.99
gram of raw material within 30 minute showed the maximum
swelling ratio (13.6) in boric buffer solution.
Abstract: CTMA-bentonite and BTEA-Bentonite prepared by Na-bentonite cation exchanged with cetyltrimethylammonium(CTMA) and benzyltriethylammonium (BTEA). Products were characterized by XRD and IR techniques.The d001 spacing value of CTMA-bentonite and BTEA-bentonite are 7.54Å and 3.50Å larger than that of Na-bentonite at 100% cation exchange capacity, respectively. The IR spectrum showed that the intensities of OH stretching and bending vibrations of the two organoclays decreased greatly comparing to untreated Na-bentonite. Batch experiments were carried out at 303 K, 318 K and 333 K to obtain the sorption isotherms of Crystal violet onto the two organoclays. The results show that the sorption isothermal data could be well described by Freundlich model. The dynamical data for the two organoclays fit well with pseudo-second-order kinetic model. The adsorption capacity of CTMA-bentonite was found higher than that of BTEA-Bentonite. Thermodynamic parameters such as changes in the free energy (ΔG°), the enthalpy (ΔH°) and the entropy (ΔS°) were also evaluated. The overall adsorption process of Crystal violet onto the two organoclays were spontaneous, endothermic physisorption. The CTMA-bentonite and BTEA-Bentonite could be employed as low-cost alternatives to activated carbon in wastewater treatment for the removal of color which comes from textile dyes.
Abstract: In modern agriculture, polymeric hydrogels are
known as a component able to hold an amount of water due to their
3-dimensional network structure and their tendency to absorb water
in humid environments. In addition, these hydrogels are able to
controllably release the fertilisers and pesticides loaded in them.
Therefore, they deliver these materials to the plants' roots and help
them with growing. These hydrogels also reduce the pollution of
underground water sources by preventing the active components
from leaching. In this study, sIPN acrylamide based hydrogels are
synthesised by using acrylamide free radical, potassium acrylate, and
linear polyvinyl alcohol. Ammonium nitrate is loaded in the hydrogel
as the fertiliser. The effect of various amounts of monomers and
linear polymer, measured in molar ratio, on the swelling rate,
equilibrium swelling, and release of ammonium nitrate is studied.
Abstract: Hydroxymethylfurfural (HMF) is formed by thermally
treating products rich in carbohydrates. HMF and other furan
derivatives are toxic.
The aim of the research was to establish the content of HMF in
gingerbread biscuits with honey and sugar syrup additives by using
three leavening agents— ammonium carbonate (NH4HCO3 and
(NH4)2CO3), baking powder, and baking soda (NaHCO3).
The content of HMF is significantly affected by the leavening
agent used. The content of HMF with honey where ammonium
carbonate was used as additive range from 5.7 to 27.3mg 100g-1, but
when sugar syrup is used the content varies from 2.3 to 7.4mg 100g-1.
When baking powder and baking soda are used as leavening agents,
the content of HMF exceeds 4mg 100g-1 in the event honey had been
added and the baking time had been longer (10 minutes at 180°C or
9 minutes at 200°C).