Stability of colloidal silica (aerosil) hydrosols. II. Influence of the pH value and the adsorption of polyethylene glycols

AbstractFor the performance assessment of the radioactive waste repository, it is important to clarify the dynamic behavior of silica (silicic acid and hydrous or unhydrous silicon dioxides). The behavior of silica would be complicated when cement is used for the construction of the repository, since silica takes various forms due to polymerization, precipitation and dissolution with change of pH or temperature. In order to know the fundamental kinetic property of silica, this study has examined the dissolution rate of colloidal-silica.In the experiment, the concentration of silica in a soluble form was determined by the silicomolybdenum-yellow method. In this study, soluble-silica was defined as silica reacting with molybdate reagent and coloring yellow, and colloidal-silica was defined as silica in liquid phase except for soluble-silica. Colloidal-silica was obtained through the polymerization process, where the pH value of silica solution was brought down from over 10 by HNO3 solution. This study examined dissolution rate of colloidal-silica again by setting to 10 or 13 in pH-value and 288 K, 298 K or 313 K in temperature. In the experimental results, the dissolution reaction of colloidal-silica proceeded linearly with time, when the dissolution of colloidal silica was not restricted by the solubility of silica. To estimate the dissolution rate, we assumed df /dt = k*, where f is the soluble-silica fraction defined as the amount of soluble-silica divided by the silica amount introduced into the sample solution, t the time (s) and k* the rate constant (s-1). The activation energy for the dissolution of the colloidal-silica at pH 13 was estimated to be approximately 80 kJ·mol-1which was similar to that for amorphous silica (solid phase) at pH 13. This suggests the same reaction mechanism for the dissolution of colloidal-silica and amorphous silica in highly alkaline solution.

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Shear Thickening Polishing of Quartz Glass

Micromachines ◽

10.3390/mi12080956 ◽

2021 ◽

Vol 12 (8) ◽

pp. 956

Author(s):

Qi Shao ◽

Shixiang Duan ◽

Lin Fu ◽

Binghai Lyu ◽

Ping Zhao ◽

...

Keyword(s):

Surface Roughness ◽

Quartz Glass ◽

Glass Surface ◽

Material Removal ◽

Colloidal Silica ◽

High Efficiency ◽

Ph Value ◽

Shear Thickening ◽

Workpiece Surface ◽

Fine Quartz

Quartz glass is a typical optical material. In this research, colloidal silica (SiO2) and colloidal cerium oxide (CeO2) are used as abrasive grains to polish quartz glass in the shear thickening polishing (STP) process. The STP method employs the shear-thickening mechanism of non-Newtonian power-law fluid to achieve high-efficiency and high-quality polishing. The different performance in material removal and surface roughness between SiO2 and CeO2 slurries was analyzed. The influence of the main factors including polishing speed, abrasive concentration, and pH value on the MRR, workpiece surface roughness, and the surface topography was discussed. Two different slurries can both achieve fine quartz surface in shear thickening polishing with the polishing speed 100 rpm, and pH value 8. The quartz glass surface roughness Ra decreases from 120 ± 10 to 2.3 nm in 14 minutes’ polishing with 8 wt% 80 nm SiO2 slurry, and the MRR reaches 121.6 nm/min. The quartz glass surface roughness Ra decreases from 120 ± 10 to 2.1 nm in 12 minutes polishing by 6 wt% 100 nm CeO2 slurry and the MRR reaches 126.2 nm/min.

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Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

Nuklearmedizin ◽

10.1055/s-0037-1620603 ◽

1977 ◽

Vol 16 (01) ◽

pp. 30-35 ◽

Cited By ~ 1

Author(s):

N. Agha ◽

R. B. R. Persson

Keyword(s):

Complex Formation ◽

Significant Influence ◽

Room Temperature ◽

Ph Value ◽

Maximum Activity ◽

Reduction Step ◽

Labelling Yield ◽

Different Temperatures ◽

Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

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Rhenium-188 Labeled Hydroxyapatite and Rhenium-188 Sulfur Colloid

Nuklearmedizin ◽

10.1055/s-0038-1629737 ◽

1997 ◽

Vol 36 (02) ◽

pp. 71-75 ◽

Cited By ~ 6

Author(s):

S. Glatz ◽

S. N. Reske ◽

K. G. Grillenberger

Keyword(s):

Synovial Fluid ◽

Ph Value ◽

Surgical Removal ◽

Radiation Synovectomy ◽

Sulfur Colloid ◽

Target Organs ◽

Aseptic Conditions ◽

In Vitro Stability ◽

Potential Use

Summary Aim: One therapeutic approach to rheumatoid arthritis and other inflammatory arthropathies besides surgical removal of inflamed synovium is radiation synovectomy using beta-emitting radionuclides to destroy the affected synovial tissue. Up to now the major problem associated with the use of labeled particles or colloids has been considerable leakage of radionuclides from the injected joint coupled with high radiation doses to liver and other non target organs. In this study we compared 188Re labeled hydroxyapatite particles and 188Re rhenium sulfur colloid for their potential use in radiation synovectomy. Methods: To this end we varied the labeling conditions (concentrations, pH-value, heating procedure) and analyzed the labeling yield, radiochemical purity, and in vitro stability of the resulting radiopharmaceutical. Results: After optimizing labeling conditions we achieved a labeling yield of more than 80% for 188Re hydroxyapatite and more than 90% for the rhenium sulfur colloid. Both of the radiopharmaceuticals can be prepared under aseptic conditions using an autoclav for heating without loss of activity. In vitro stability studies using various challenge solutions (water, normal saline, diluted synovial fluid) showed that 188Re labeled hydroxyapatite particles lost about 80% of their activity within 5 d in synovial fluid. Rhenium sulfur colloid on the other hand proved to be very stable with a remaining activity of more than 93% after 5 d in diluted synovial fluid. Conclusion: These in vitro results suggest that 188Re labeled rhenium sulfur colloid expects to be more suitable for therapeutic use in radiation synovectomy than the labeled hydroxyapatite particles.

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Influence of saliva pH-value on the ratio of amphetamine saliva to serum concentration

10.1055/s-0039-1679172 ◽

2019 ◽

Author(s):

C Wohkittel ◽

M Romanos ◽

A Diehl ◽

P Högger ◽

M Gerlach

Keyword(s):

Serum Concentration ◽

Ph Value

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DIP quality influenced by process water quality

TAPPI Journal ◽

10.32964/tj13.9.51 ◽

2014 ◽

Vol 13 (9) ◽

pp. 51-60

Author(s):

DENNIS VOSS ◽

HANS-JOACHIM PUTZ ◽

SAMUEL SCHABEL

Keyword(s):

Water Quality ◽

Surface Tension ◽

Ph Value ◽

Water Hardness ◽

Process Water ◽

Test Results ◽

Negative Effects ◽

Water Parameters ◽

Effects Of Ph ◽

Contamination Levels

The need for deinking mills to reduce their fresh water consumption has resulted in higher loads of various contaminants in the process water. Lower recovered paper quality also leads to higher contamination levels in the mills. This higher load has an influence on achievable target brightness. The objective of the work was to determine and explain the main reasons for relatively poor deinked pulp quality or poor deinking potential based on the influence of recovered paper composition and process water quality. The process water parameters significantly affect the deinking potential of recovered paper. The test results showed the negative effects of increased water hardness. For standard recovered paper mixtures, flotation selectivity is higher with increasing flotation pH-value. Good results were realized for standard recovered paper with low hardness, low surface tension, and high pH-value. The results for recovered paper containing flexo newsprint could be slightly improved with low hardness, low surface tension, and low pH-value. The results of the test program using design of experiments showed interacting effects of pH-value and surface tension on luminosity and flotation selectivity.

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Kualitas Fisik Daging Ayam Broiler yang Diberi Minyak Buah Merah dalam Pakan Komersial

Jurnal Ilmu dan Teknologi Peternakan Tropis ◽

10.33772/jitro.v6i1.5806 ◽

2019 ◽

Vol 6 (1) ◽

pp. 20

Author(s):

Abdul Rahman Ollong ◽

Rizki Arizona ◽

Rusli Badaruddin

Keyword(s):

Moisture Content ◽

Broiler Chickens ◽

Broiler Chicken ◽

Ph Value ◽

Cooking Loss ◽

Water Holding Capacity ◽

Broiler Meat ◽

Fruit Oil ◽

Water Holding ◽

Range Test

ABSTRAKPenelitian ini bertujuan untuk mengetahui pengaruh penambahan minyak buah merah (MBM) pada pakan terhadap kualitas fisik daging ayam broiler. Seratus ekor ayam broiler umur sehari (DOC) ditempatkan pada lima kelompok perlakuan pakan yang berbeda, yaitu: P1 (pakan kontrol/tanpa penambahan minyak), P2 (2% MBM), P3 (4% MBM), P4 (6% MBM) dan P5 (6% Minyak kelapa sawit). Setiap kelompok perlakuan terdiri dari empat ulangan masing-masing dengan lima ekor. Ayam broiler dipelihara selama 35 hari. Rancangan yang digunakan adalah Rancangan Acak Lengkap (RAL) dengan analisis variansi pola searah dan diuji lanjut dengan Duncan’s New Multiple Range Test (DMRT). Hasil penelitian menunjukkan bahwa semua variable yang diamati menunjukkan adanya pengaruh nyata (P<0,05) terhadap perlakuan yang diberikan. Dari hasil penelitian ini dapat disimpulkan bahwa penggunaan minyak buah merah (MBM) dalam pakan mampu memberikan pengaruh terhadap pH Daging, Daya Ikat Air (DIA), susut masak dan keempukan daging ayam broiler.Kata kunci : daging ayam broiler, daya ikat air, keempukan daging, pH daging, susut masakABSTRACT The experiment was conducted to study the effect of red fruit oil (RFO) onphysical quality of broiler chicken. One hundred day old chicken (DOC) were placed in four groups of different treatments, of from levels of RFO (P1 (diet without addition of RFO), P2 (2% RFO), P3 (4% RFO) and P4 (6% RFO) and P5 (6% Palm oil)). The treatment group consisted of fivereplications with five birds each. Broiler chickens were reared for 35 days. Statistical analysis used Completely Randomized Design (CRD) and followed by Duncan’s New Multiple Range Test (DMRT). The results showed that the pH value, moisture content, water holding capacity, and cooking loss was significant differences. It could be concluded that the addition of red fruit oil in the diet give effect of broiler chicken meat.Keywords: broiler meat, cooking loss, moisture content, pH value, water holding capacity

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BIOGAS PRODUCTION IN THE CONCENTRATED DISTILLERY WASTEWATER TREATMENT

Alternative Energy and Ecology (ISJAEE) ◽

10.15518/isjaee.2018.25-30.051-059 ◽

2018 ◽

pp. 51-59 ◽

Cited By ~ 1

Author(s):

N. Golub ◽

M. Potapova ◽

M. Shinkarchuk ◽

O. Kozlovets

Keyword(s):

Wastewater Treatment ◽

Dry Matter ◽

Ph Value ◽

Biogas Production ◽

Anaerobic Sludge ◽

Methane Formation ◽

Maximum Output ◽

Processing Technologies ◽

Spent Wash ◽

Distillery Spent Wash

The paper deals with the waste disposal problem of the alcohol industry caused by the widespread use of alcohol as biofuels. In the technology for the production of alcohol from cereal crops, a distillery spent wash (DSW) is formed (per 1 dm3 of alcohol – 10–20 dm3 DSW), which refers to highly concentrated wastewater, the COD value reaches 40 g O2/dm3. Since the existing physical and chemical methods of its processing are not cost-effective, the researchers develop the processing technologies for its utilization, for example, an anaerobic digestion. Apart from the purification of highly concentrated wastewater, the advantage of this method is the production of biogas and highquality fertilizer. The problems of biotechnology for biogas production from the distillery spent wash are its high acidity–pH 3.7–5.0 (the optimum pH value for the methanogenesis process is 6.8–7.4) and low nitrogen content, the lack of which inhibits the development of the association of microorganisms. In order to solve these problems, additional raw materials of various origins (chemical compounds, spent anaerobic sludge, waste from livestock farms, etc.) are used. The purpose of this work is to determine the appropriate ratio of the fermentable mixture components: cosubstrate, distillery spent wash and wastewater of the plant for co-fermentation to produce an energy carrier (biogas) and effective wastewater treatment of the distillery. In order to ensure the optimal pH for methanogenesis, poultry manure has been used as a co-substrate. The co-fermentation process of DSW with manure has been carried out at dry matter ratios of 1:1, 1:3, 1:5, 1:7 respectively. It is found that when the concentration of manure in the mixture is insufficient (DSW/manure – 1:1, 1:3), the pH value decreases during fermentation which negatively affects methane formation; when the concentration of manure in the mixture is increased (DSW/manure – 1:5, 1:7), the process is characterized by a high yield of biogas and methane content. The maximum output of biogas with a methane concentration of 70 ± 2% is observed at the ratio of components on a dry matter “wastewater: DSW: manure” – 0,2:1:7 respectively. The COD reduction reaches a 70% when using co-fermentation with the combination of components “wastewater: DSW: manure” (0,3:1:5) respectively.

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UV Curable Organic-Inorganic Hybrid Materials

MRS Proceedings ◽

10.1557/proc-628-cc6.14 ◽

2000 ◽

Vol 628 ◽

Cited By ~ 1

Author(s):

Guang-Way Jang ◽

Ren-Jye Wu ◽

Yuung-Ching Sheen ◽

Ya-Hui Lin ◽

Chi-Jung Chang

Keyword(s):

Hybrid Materials ◽

Colloidal Silica ◽

Sol Gel ◽

Solution Ph ◽

Uv Curable ◽

Inorganic Hybrid ◽

Degradation Temperature ◽

Sol Gel Process ◽

The Stability ◽

Thermal Degradation Temperature

This work successfully prepared an UV curable organic-inorganic hybrid material consisting of organic modified colloidal silica. Applications of UV curable organic-inorganic hybrid materials include abrasion resistant coatings, photo-patternable thin films and waveguides. Colloidal silica containing reactive functional groups were also prepared by reacting organic silane and tetraethyl orthosilicate (TEOS) using sol-gel process. In addition, the efficiency of grafting organic moiety onto silica nanoparticles was investigated by applying TGA and FTIR techniques. Experimental results indicated a strong interdependence between surface modification efficiency and solution pH. Acrylate-SiO2 hybrid formation could result in a shifting of thermal degradation temperature of organic component from about 200°C to near 400°C. In addition, the stability of organic modified colloidal silica in UV curable formula and the physical properties of resulting coatings were discussed. Furthermore, the morphology of organic modified colloidal silica was investigated by performing TEM and SEM studies‥

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Species Density and Lead (Pb) Pollution in Mangrove Ecosystem, South Kalimantan

Jurnal Biodjati ◽

10.15575/biodjati.v5i1.7411 ◽

2020 ◽

Vol 5 (1) ◽

pp. 70-81

Author(s):

Anang Kadarsah ◽

Dafiuddin Salim ◽

Sadang Husain ◽

Marta Dinata

Keyword(s):

Heavy Metal ◽

Oil Palm ◽

Ph Value ◽

Coal Mines ◽

Organic Matter Content ◽

Mangrove Ecosystem ◽

Organic Content ◽

Species Density ◽

Pb Pollution ◽

Mangrove Ecosystems

Its crucial to get information about lead (Pb) heavy metal pollution from mining and oil palm plantation on species density in mangrove ecosystem, to anticipate its impacts. This study aimed is to compare the types and densities of vegetation in mangrove ecosystems allegedly due to mining in Setarap village, Tanah Bumbu Regency and oil palm plantations in Kuala Tambangan Village, Tanah Laut Regency. We also analysis the condition of waters (TDS, pH and DO) and organic content in sediments to acquire data from the South Kalimantan mangrove ecosystems. The results showed there were four species of true mangroves (Avicennia alba, Acanthus ebracteatus, Nypa fruticans and Rhizophora apiculate) could live well in the environment affected by mining or oil palm plantations. The species density for trees was low (933 ind/ha) for mangroves affected by coal mines, while those affected by oil palm plantations had higher densities (1,067 ind/ha). pH value of waters in affected area by coal mining showed more acidic value (pH 5.76) especially at the back, while those by palm oil plantations are more acidic (pH 6) in the estuary. Organic matter content in sediments affected by coal mines was in the range of 0.61-6.59%, while those affected by oil palm plantations showed higher values (0.12-2.19%). Lead heavy metal content (Pb) in waters affected by coal mines was 0.031-0.056 mg/L, while the area affected by oil palm plantations was of higher value (0.110-0.128 mg/L). Lead (Pb) levels in sediments indicate higher values than waters, which reach 3.512-6.046 mg/Kg (affected by coal mines), and in areas affected by oil palm plantations reaching 6.658-6.66 mg/Kg. The general conclusion is that vegetation densities in areas affected by coal mines are lower than oil palm plantations. The level of lead (Pb) pollution in the sediments is higher than in the waters.

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