Bentonite Interaction with Saline High-pH Solutions

2012 ◽  
Vol 1475 ◽  
Author(s):  
Heikola Tiina ◽  
Vuorinen Ulla
Keyword(s):  
Cementitious Materials ◽  
Buffering Capacity ◽  
Ongoing Research ◽  
High Ph ◽  
Ph Values ◽  
Safety Function ◽  
Bentonite Buffer ◽  
Different Temperatures ◽  
Leaching Solution ◽  
In The Beginning

ABSTRACTDegradation of cementitious materials produces leachates of high pH. Such an alkaline plume, if reaching the bentonite buffer, is likely to induce mineralogical and chemical changes in bentonite over long times and may jeopardise the set safety function of the buffer.The objective of this ongoing research is to study the possible alterations of two bentonites, MX-80 and Deponit CA-N, in alkaline leachates at two different temperatures. Also the buffering capacity of the bentonites against high pH will be evaluated.The ongoing batch experiments are carried out in an anaerobic glove-box (Ar atmosphere, low CO2) at two temperatures (25/60 °C) with three types of simulated cement waters (pH 9.7/9,3, 11.3/10.2 and 12.0/10.9) at 25/0 °C) and one saline groundwater simulate (pH 8.3/7.9) as reference. The solid to liquid ratio used is 1/10. For each set of experiments there are three parallels so that bentonite alteration can be analysed after three different time periods. In the experiment each bentonite sample is leached with several batches of leaching solution. For each renewal of the leaching solution the phases are separated by centrifugation, the reacted solution withdrawn and the chemical composition analysed.The high-pH experiments (11.3 and 12.0, at 25°C) have continuously shown an initial decrease in the pH-values after each leachate renewal, albeit less dramatic than in the beginning, indicating remaining buffering capacity of the bentonites. The other two experiments (pH 8.3 and 9.7 at 25°C) have shown rather unaltered pH-values. In general, slightly lower pH-values were observed in the Deponit CA-N samples than in those of MX-80. The main cations (Na and Ca) analysed in the leachates have shown a rather expected trends as a result of ion-exchange occurring in the bentonites. The analysed Si concentrations indicate possible dissolution of smectite. More conclusions are possible after the bentonites have been characterized. One experimental set of the 25 °C experiments has been finished and the bentonite phases are being characterized. Other experiment sets are still continued.

Impact of climate and bulking materials on characteristics of compost from ecological toilets

2012 ◽  
Vol 2 (2) ◽  
pp. 79-86 ◽  
Author(s):  
James W. McKinley ◽  
Rebecca E. Parzen ◽  
Álvaro Mercado Guzmán
Keyword(s):  
Low Carbon ◽  
Pathogen Inactivation ◽  
High Ph ◽  
Moisture Contents ◽  
Urine Diversion ◽  
Ph Values ◽  
Dominant Process ◽  
Nitrogen Ratio ◽  
Storage Times ◽  
Carbon Concentrations

Urine-diversion dehydration toilets (UDDT) are common throughout the developing world, and the toilet product is widely used as compost. There is no comprehensive research to date that characterizes the compost to determine its quality, extent of pathogen inactivation, and the effects of climate and bulking materials on the compost. Compost was collected from 45 UDDT in Bolivia and analyzed for physical, chemical, and biological parameters. Eighty percent and 56% of samples did not meet acceptable compost guidelines for moisture content and pH, respectively, indicating desiccation was the dominant process in UDDT. Bulking materials significantly impacted compost characteristics in terms of pH, carbon, carbon-to-nitrogen ratio, and carbon stability (P < 0.05). Composts with ash exhibited, on average, low carbon concentrations (4.9%) and high pH values (9.7), which can be harmful to plants and composting microorganisms. Composts with sawdust exhibited, on average, high carbon concentrations (40.0%) and carbon-to-nitrogen ratios (31.0). Climate had no significant impact on chemical characteristics, however composts from humid regions had significantly higher moisture contents (34.4%) than those from arid climates (24.8%) (P < 0.05). Viable Ascaris lumbricoides ova were identified in 31% of samples, including samples with high pH, low moisture contents, and long storage times.

Characterization and Control of Erwinia spp. and Pluralibacter sp. in Tuna Salad Preparations

2019 ◽  
Vol 82 (6) ◽  
pp. 1071-1081
Author(s):  
KRISTIN BJORNSDOTTIR-BUTLER ◽  
SUSAN McCARTHY ◽  
RONALD A. BENNER
Keyword(s):  
Growth Conditions ◽  
Whole Genome ◽  
Processing Conditions ◽  
Optimum Growth ◽  
Significant Growth ◽  
Ph Values ◽  
Histamine Production ◽  
Different Temperatures ◽  
And Control ◽  
Erwinia Persicina

ABSTRACT Histamine-producing Erwinia and Pluralibacter spp. capable of producing toxic histamine levels were isolated from ingredients commonly used in tuna salad preparations. The characterization and control of these histamine-producing bacteria are necessary to prevent illness from tuna salad consumption. We confirmed the identity of two Erwinia spp. and one Pluralibacter sp. previously isolated from tuna salad ingredients through whole genome sequencing and phylogenic analysis and characterized them for growth and histamine production at different temperatures, pH values, and salt concentrations. In addition, we examined the effects of dried vinegar (DV) powder on growth and histamine production of these strains in inoculated tuna salad preparations. Optimum growth temperatures in tryptic soy broth (TSB) for the two Erwinia spp. and one Pluralibacter sp. were 30.1, 31.1, and 33.9°C, respectively, and growth in TSB was observed at 5°C for both genera. Optimum histamine production of Erwinia persicina, Erwinia spp., and Pluralibacter spp. in TSB with histidine occurred from 25 to 30°C, pH 4 to 6, and 0 to 4% NaCl. No significant growth or histamine production was observed in tuna salad preparations stored at 4°C. Growth and histamine production by Erwinia or Pluralibacter spp. was inhibited in tuna salad containing celery and onion and 2% DV, whereas significant growth and histamine production occurred in tuna salad without DV. Understanding optimum growth conditions and histamine production can provide guidance to tuna salad manufacturers in formulating products and adjusting processing conditions that minimize hazards from these histamine-producing bacteria. Addition of 2% DV to tuna salad preparations may prevent histamine production in the event of temperature abuse. HIGHLIGHTS

scholarly journals Thermodynamic Investigations on the Inclusion Complexation of Piroxicam with Cyclodextrin Derivatives

2005 ◽  
Vol 73 (3) ◽  
pp. 147-161 ◽  
Author(s):  
Charumanee S. ◽  
Weiss-Greiler P. ◽  
Wolschann P. ◽  
Viernstein H. ◽  
Titwan A. ◽  
...  
Keyword(s):  
Ph Value ◽  
Equilibrium Constants ◽  
Inclusion Complexation ◽  
Solubility Diagram ◽  
Phase Solubility ◽  
Cyclodextrin Derivatives ◽  
Ph Values ◽  
Solubility Behavior ◽  
Solubility Method ◽  
Different Temperatures

Thermodynamic studies of piroxicam in aqueous solution complexed with β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD) and two β-cyclodextrin derivatives, hydroxypropyl-β-cyclodextrin (HP-P-CD) and methyl-β-cyclodextrin (Me-β-CD) were performed at different temperatures and pH values using the phase solubility method. The phase solubility diagrams of β-CD, γ-CD and HP-β-CD is of AL-type behavior, indicating the formation of 1:l complexes. The related stability constants range from β-CD > γ-CD > Me-β-CD > HP-β-CD, respectively. An Ap-type solubility diagram is observed for Me-β-CD, indicating the formation of 1:2 complexes at higher CD concentrations. From the temperature dependence of the equilibrium constants the reaction enthalpies and entropies have been determined. The contributions of the reaction entropies are small and no enthalpy-entropy-compensation is observed, except for γ-CD, where a very small negative reaction entropy could be estimated. Moreover, the influence of the pH value is rather high because the differently charged forms of piroxicam show different solubility behavior in water.

scholarly journals Correlation between pH, buffering capacity, calcium and dental caries in schoolchildren

2018 ◽  
Vol 63 (01) ◽  
pp. 63-68
Author(s):  
Efka Zabokova Bilbilova ◽  
Ana Sotirovska Ivkovska ◽  
Olivera Sarakinova ◽  
Olga Kokoceva Ivanovska ◽  
Natasha Stavreva
Keyword(s):  
Dental Caries ◽  
Free Group ◽  
Buffer Capacity ◽  
Saliva Sample ◽  
Buffering Capacity ◽  
Active Group ◽  
Ph Buffering ◽  
Ph Values ◽  
Salivary Ph ◽  
Ph Buffering Capacity

The aim of this study was to determine salivary pH, buffering capacity and calcium levels in caries-free and caries-active children. We examined 80 children of both genders, 15 years of age. Subjects were divided into four groups as follows: caries-free females, caries-active females, caries-free males, caries-active males; each group consisted of 20 subjects. The unstimulated saliva sample was collected by the spitting method and then pH, buffering capacity and calcium in saliva was measured. The results showed that mean level of buffering capacity of saliva was decreased significantly in the caries-active group as compared to caries-free group. The obtained data showed that the mean levels of pH and calcium were decreased in the caries-active group as compared to the caries-free group, but the difference was not statistically significant. The saliva with its constituents plays an important role in maintaining oral and especially dental health. Salivary pH values were found to be higher in the caries-free group. In our study, there was no significant correlation of pH values and caries activity with gender. Buffer capacity values were significantly lower in the caries-active group than in the caries-free group. There were significant differences when the groups were compared in the caries-active group where buffer capacity values were higher in boys than in girls. Calcium content of saliva was higher in the caries-free group. The results obtained in this study related to the values of the pH, buffering capacity and calcium in saliva, may serve as parameters for determining the caries risk patients, and accordingly to plan and carry appropriate caries preventive measures. Keywords: saliva, dental caries, pH, buffer capacity, calcium

Resistance of Spirulina platensis to Ammonia at High pH Values

1991 ◽  
Vol 32 (7) ◽  
pp. 953-958 ◽  
Author(s):  
Shimshon Belkin ◽  
Sammy Boussiba
Keyword(s):  
Spirulina Platensis ◽  
High Ph ◽  
Ph Values

Chemisorption of methylene blue by kaolinite

Clay Minerals ◽  
1967 ◽  
Vol 7 (1) ◽  
pp. 19-31 ◽  
Author(s):  
F. A. Faruqi ◽  
Susumu Okuda ◽  
W. O. Williamson
Keyword(s):  
Methylene Blue ◽  
Special Reference ◽  
Cation Exchange ◽  
High Ph ◽  
Inorganic Cations ◽  
Ph Values ◽  
Aqueous Suspensions ◽  
Exchange Site

AbstractThe chemisorption of methylene blue by kaolinite crystals increased as the aqueous suspensions changed from acid to alkaline because, at high pH values, not only the basal pinacoids but the edge-faces were negatively charged. The inability to calculate acceptable specific surfaces or cation exchange capacities from the chemisorption data is discussed, with special reference to the orientation of adsorbed dye cations, the covering of more than one exchange site by a monomer or polymer, the different concentrations of exchange sites on the basal pinacoids and edge-faces respectively, the possibility that such sites occur on the tetrahedral rather than on the octahedral basal pinacoid, and the incomplete replacement of inorganic cations.

Survival of Salmonella in Cheddar Cheese

1976 ◽  
Vol 39 (5) ◽  
pp. 328-331 ◽  
Author(s):  
CHARLES H. WHITE ◽  
EDWARD W. CUSTER
Keyword(s):  
New Brunswick ◽  
Cheddar Cheese ◽  
Survival Times ◽  
High Ph ◽  
Salmonella Newport ◽  
Large Numbers ◽  
Different Temperatures

Salmonella newport, S. new-brunswick, and S. infantis were singly added to Cheddar cheese milk to evaluate the behavior of Salmonella in Cheddar cheese made from the milk and to obtain survival times when cheese was stored at different temperatures. Of a total of 48 lots of cheese inoculated with Salmonella, detectable numbers of these pathogens appeared in 16 samples aged at 4.5 C for 9 months and from six samples stored at 10 C. The information obtained under the conditions of this study indicates that these enteropathogenic microorganisms when initially present in large numbers in milk can survive for extended storage periods in Cheddar cheese of high pH made from the milk.

Preliminary Study on the Removal of Hexavalent Chromium in Wastewater with Reduction of Sulfur Dioxide

2013 ◽  
Vol 864-867 ◽  
pp. 1699-1703
Author(s):  
Ji Ming Wu ◽  
Sheng Gao Cheng
Keyword(s):  
Reaction Time ◽  
Sulfur Dioxide ◽  
Hexavalent Chromium ◽  
Reduction Reaction ◽  
High Concentration ◽  
Reaction Conditions ◽  
Ph Values ◽  
Different Temperatures ◽  
Preliminary Study ◽  
High Concentrations

The paper focused on a self-developed methodology through using sulfur dioxide to deal with high concentration of chromium-containing wastewater. It studied the effects of different pH values, different reaction time, different temperatures and different amounts of sulfur with sulfur dioxide reduction reaction on the chromium-containing wastewater. The results showed that: when the reaction conditions were controlled as follows: the pH values ranged from 2 to 4, the reaction temperature was controlled 40~60°C, the amount of sulfur in theoretical was 1.2 times and the reaction time was 40 min, the hexavalent chromium in the high concentrations of chromium-containing wastewater could be effectively removed.

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