Study on Desalination Characteristics of Nanofiltration Separation

2011 ◽  
Vol 305 ◽  
pp. 261-264
Author(s):  
Qing Yang ◽  
Xin Qiu ◽  
Xiang Shen
Keyword(s):  
Salt Concentration ◽  
Salt Solution ◽  
Ph Value ◽  
Influence Factors ◽  
Salt Rejection ◽  
Membrane Flux ◽  
Ionic Valence ◽  
Different Types ◽  
Monovalent Salt ◽  
Operation Pressure

The study discussed the desalination effect of influence factors (operation pressure, salt concentration, pH, ionic valence and etc.) for two different types nanofiltration (NF) (DK and NF90), based on desalination NF characteristics of membrane. The results showed the same desalination characteristics of the two kinds NF that desalination performance decrease directly with NF operation pressure and salt concentration increasing. When pH value was controlled in an acidic range of 4 to 7, it could obtain both high salt removal and membrane flux in salt solution. The salt rejection sequence of two NF was NaCl <MgCl2 <Na2SO4 <MgSO4 <Na3PO4 in different valence salt neuter solution. The different desalination characteristics of two kinds NF showed that monovalent salt rejection of DK (over 35%) was lower than that of NF90 (above 85%). The multivalent salt rejection of two NF showed higher removal efficiency, with DK over 96% and NF90 over 99%.

Synthesis and conformation of sequential basic polypeptides with branched and linear side chains

1985 ◽  
Vol 50 (12) ◽  
pp. 2925-2936 ◽  
Author(s):  
Štěpánka Štokrová ◽  
Jan Pospíšek ◽  
Jaroslav Šponar ◽  
Karel Bláha
Keyword(s):  
Amino Acid ◽  
Salt Concentration ◽  
Salt Solution ◽  
Theoretical Work ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Cd Spectra ◽  
Low Salt ◽  
Conformational Freedom ◽  
Basic Polypeptides

Polypeptides (Lys-X-Ala)n and (Lys-X-Gly)n in which X represents residues of isoleucine and norleucine, respectively, and polypeptide (Tle-Lys-Ala)n, were synthesized via polymerization of 1-hydroxysuccinimidyl esters of the appropriate tripeptides to complete previously studied series. Circular dichroism (CD) spectra of the respective polymers were measured as a function of pH and salt concentration of the medium. The results were correlated with those obtained previously with the same series containing different amino acid residues at the X-position. The helix forming ability of the polypeptides (Lys-X-Ala)n with linear X side chain was found to be independent of the length. In the series (Lys-X-Gly)n the unordered conformation was the most probable one except (Lys-Ile-Gly)n. This polymer assumed the β conformation even in low salt solution at neutral pH. An agreement with some theoretical work concerned with the restriction of conformational freedom of amino acid residue branching at Cβ atom with our experimental results is evident.

scholarly journals GERMINATION AND VIGOUR IN SEEDS OF THE COWPEA IN RESPONSE TO SALT AND HEAT STRESS

2019 ◽  
Vol 32 (1) ◽  
pp. 143-151 ◽  
Author(s):  
Luma Rayane de Lima Nunes ◽  
Paloma Rayane Pinheiro ◽  
Charles Lobo Pinheiro ◽  
Kelly Andressa Peres Lima ◽  
Alek Sandro Dutra
Keyword(s):  
Salt Stress ◽  
Heat Stress ◽  
High Temperature ◽  
Low Temperature ◽  
Vigna Unguiculata ◽  
Salt Concentration ◽  
Dry Weight ◽  
Germination Percentage ◽  
Different Types ◽  
Different Temperatures

ABSTRACT Salinity is prejudicial to plant development, causing different types of damage to species, or even between genotypes of the same species, with the effects being aggravated when combined with other types of stress, such as heat stress. The aim of this study was to evaluate the tolerance of cowpea genotypes (Vigna unguiculata L. Walp.) to salt stress at different temperatures. Seeds of the Pujante, Epace 10 and Marataoã genotypes were placed on paper rolls (Germitest®) moistened with different salt concentrations of 0.0 (control), 1.5, 3.0, 4.5 and 6.0 dS m-1, and placed in a germination chamber (BOD) at temperatures of 20, 25, 30 and 35°C. The experiment was conducted in a completely randomised design, in a 3 × 4 × 5 scheme of subdivided plots, with four replications per treatment. The variables under analysis were germination percentage, first germination count, shoot and root length, and total seedling dry weight. At temperatures of 30 and 35°C, increases in the salt concentration were more damaging to germination in the Epace 10 and Pujante genotypes, while for the Marataoã genotype, damage occurred at the temperature of 20°C. At 25°C, germination and vigour in the genotypes were higher, with the Pujante genotype proving to be more tolerant to salt stress, whereas Epace 10 and Marataoã were more tolerant to high temperatures. Germination in the cowpea genotypes was more sensitive to salt stress when subjected to heat stress caused by the low temperature of 20°C or high temperature of 35°C.

Experimental Research on Bonding Intensity of Iron Ores in the Sintering Process

2011 ◽  
Vol 391-392 ◽  
pp. 60-64
Author(s):  
Fang Yi Long ◽  
Sheng Li Wu ◽  
Juan Zhu ◽  
Yuan Du ◽  
Guo Liang Zhang
Keyword(s):  
South Africa ◽  
Liquid Phase ◽  
Experimental Research ◽  
Negative Correlation ◽  
Influence Factors ◽  
Iron Ores ◽  
Sintering Process ◽  
Different Types ◽  
Lower Porosity

The bonding intensity of four kinds of ores from Brazil, Australia and South Africa is researched in this study, and the influence factors are analyzed. The results show that, the ores of different types have apparently differences in bonding intensity, ores from Brazil and South Africa have high bonding intensity, while ores from Australia have low bonding intensity; The foundation of generation of effective liquid is adequate liquid phase fluidity and the lower porosity of core ore; The ratio of porosity of core ore and the index of liquid phase fluidity has negative correlation with the bonding intensity.

Study of the significance of the ph of the substrate of the biogas installation during treating it with a low-frequency electromagnetic field

2021 ◽  
pp. 106-114
Author(s):  
M.M. Zablodsky ◽  
◽  
P.B. Klendiy ◽  
O. P. Dudar ◽  
◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Electromagnetic Induction ◽  
Ph Value ◽  
Low Frequency ◽  
Decisive Role ◽  
Methane Fermentation ◽  
Different Types ◽  
Substrate Ph ◽  
Fermentation Substrate ◽  
Industrial Frequency

The article considers the issue of studying the value of pH, substrate in the process of methane fermentation in the mesophilic regime and the influence of the electromagnetic field of industrial frequency. The aim is to investigate the influence of electromagnetic fields on the pH value of the substrate during fermentation. Different types of microorganisms are involved in the process of methanogenesis, and the decisive role in it is played by methane-forming archaea, which are most sensitive to pH and should be in the range of 6.5 - 8. Therefore, it is necessary to check the effect of low frequency electromagnetic field on substrate pH. The study was performed for 25 days on two substrates, one of which was exposed to a low-frequency electromagnetic field with an electromagnetic induction of 3.5 mT. The research results show that the pH value of the substrate exposed to the electromagnetic field during the methane fermentation process was within acceptable limits, and the second substrate decreased, that is, it was acidified. Key words: methane fermentation, substrate, pH value, electromagnetic field

scholarly journals Molecular Dynamics Study on the Reverse Osmosis Using Multilayer Porous Graphene Membranes

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 805 ◽  
Author(s):  
Zhongqiang Zhang ◽  
Fujian Zhang ◽  
Zhen Liu ◽  
Guanggui Cheng ◽  
Xiaodong Wang ◽  
...  
Keyword(s):  
Salt Solution ◽  
Energy Barrier ◽  
Water Flux ◽  
Solution Concentration ◽  
Water Molecules ◽  
Porous Graphene ◽  
Salt Rejection ◽  
Layer Separation ◽  
Graphene Membrane ◽  
Graphene Membranes

In this study, the reverse osmosis (RO) of a salt solution was investigated using a molecular dynamics method to explore the performance of a multilayer porous graphene membrane. The effects of the salt solution concentration, pressure, layer separation and pore offset on the RO performance of the membrane were investigated and the influences of the number of layers and the gradient structure were determined. The results show that as the salt solution concentration increases, the energy barrier of the water molecules passing through the bilayer porous graphene membranes changes slightly, indicating that the effect of the water flux on the membrane can be ignored. The salt rejection performance of the membrane improves with an increase in the concentration of the salt solution. When the pressure is increased, the energy barrier decreases, the water flux increases and the salt rejection decreases. When the layer separation of the bilayer porous graphene membrane is the same as the equilibrium spacing of the graphene membrane, the energy barrier is the lowest and the membrane water flux is the largest. The energy barrier of the bilayer porous graphene membrane increases with increasing layer separation, resulting in a decrease in the water flux of the membrane. The salt rejection increases with increasing layer separation. The water flux of the membrane decreases as the energy barrier increases with increasing pore offset and the salt rejection increases. The energy barrier effect is more pronounced for a larger number of graphene layers and the water flux of the membrane decreases because it is more difficult for the water molecules to pass through the porous graphene membrane. However, the salt rejection performance improves with the increase in the number of layers. The gradient pore structure enhances the energy barrier effect of the water molecules permeating through the membrane and the water flux of the membrane decreases. The salt rejection performance is improved by the gradient pore structure. The research results provide theoretical guidance for research on the RO performance of porous graphene membranes and the design of porous graphene membranes.

scholarly journals A Comparative Study of Fe (II) Ion Adsorption onto Chemically Activated Banana Peel and Sawdust Bio-adsorbent

2018 ◽  
Vol 6 (2) ◽  
pp. 137-141
Author(s):  
Suman Lal Shrestha
Keyword(s):  
Ph Value ◽  
Banana Peel ◽  
Ion Adsorption ◽  
Ferrous Ions ◽  
Adsorption Models ◽  
Freundlich Isotherms ◽  
Adsorption Capacities ◽  
Time Period ◽  
Optimum Ph ◽  
Different Types

The adsorption capacity of ferrous ions onto bio-sorbents prepared from two different types of bio-waste of banana peel (CABP) and sawdust (CASD) treated with sulfuric acid was studied using Langmuir and Freundlich isotherms. Result shows that the optimum pH value for about 99 % Fe (II) adsorption onto the CABP and CASD was found to be 3 and 4, respectively, after 5 hours or more contact time period. Both the Langmuir and Freundlich adsorption models are fitted to remove the Fe (II) ions from aqueous solution by the bio-adsorbent of CABP and CASD. The maximum adsorption capacities for the CABP and CASD were found to be about 34 and 116 mg/g, respectively. These results showed that the CASD seems to be more effective bio-adsorbent than the CABP to remove the Fe (II) ions from drinking or/and wastewaters.Int. J. Appl. Sci. Biotechnol. Vol 6(2): 137-141 

scholarly journals Extraction of tetracycline using the ionic liquid-based aqueous two phase systems: Single-stage versus multi-stage

2018 ◽  
Vol 24 (4) ◽  
pp. 387-397 ◽  
Author(s):  
Yi Liu ◽  
Li Chen ◽  
Jun Zhou ◽  
Zongcheng Yan
Keyword(s):  
Extraction Efficiency ◽  
Ph Value ◽  
Influence Factors ◽  
Volume Ratio ◽  
Line Length ◽  
Single Stage ◽  
Two Phase ◽  
Extraction Behavior ◽  
Multi Stage ◽  
Tie Line

Ionic liquids-based aqueous two-phase extraction (ILs-ATPE) offers an alternative approach to the extraction of tetracycline (TC) through their partitioning between two phases. Single-stage and multi-stage strategies have been evaluated and compared for the purification of TC using ATPE composed of 1-butyl-3-methylimidazolium halide ([Bmim]X(X=Cl,Br)) and K2HPO4. The influence factors on single-stage extraction behavior of TC were optimized systematically, including the pH value, tie line length, and volume ratio. The optimal extraction efficiency of TC could reach above 95% when the volume ratio is higher than 1.5 and the tie line length is 30.52%. The multi-stage ATPE was also investigated by simulating a three-stage crosscurrent operation in test tubes. According to the TC isotherm curve and respective McCabe?Thiele diagrams, a predicted optimized scheme of the countercurrent multi-stage ATPE was determined. TC can be purified in the IL-rich top phase with a final extraction efficiency of 99% and a final TC concentration of 0.25 mg/mL, if a three- -stage [Bmim]Cl-K2HPO4 ATPE with volume ratio of 0.5 and tie line length of 30.52% was employed. Thus, the multi-stage extraction with small volume ratio is necessary to achieve a higher recovery yield, resulting in the reduction of the IL consumption.

scholarly journals Reclaiming land flooded with salt water.

1953 ◽  
Vol 1 (4) ◽  
pp. 225-244
Author(s):  
C.W.C. Beekom
Keyword(s):  
Salt Concentration ◽  
Sea Water ◽  
Salt Water ◽  
Soil Layer ◽  
Weather Conditions ◽  
Phleum Pratense ◽  
Active Growth ◽  
Warm Weather ◽  
Different Types ◽  
Spring Sowing

The effect of sea floods on grassland is described and recommendations are made for the restoration of inundated grassland. Turf may be heavily damaged after +or- 4 weeks inundation with water containing more than 20 g. NaCl per 1. At lower salt concentrations Poa sp. and Trifolium repens are still badly damaged but other species, notably Lolium perenne, Agrostis stolonifera and Alopecurus sp., are capable of immediate regrowth after drainage. If grassland remains submerged during spring, rising temperatures promote active growth of the grasses followed by rapid decay caused by lack of oxygen. L. perenne is especially sensitive to submergence in warm weather. The dominant weed communities which appear on land on which the turf has been destroyed by sea-water are described. Reseeding is recommended as the quickest method of restoring badly damaged turf. The flooded land should first be thoroughly drained and then repeatedly harrowed to produce a shallow seed-bed on which herbage mixtures can be sown without the application of gypsum. Given average weather conditions, normal permanent grassland mixtures can be sown at salt concentrations, measured in spring, of up to 8-10 g. NaCl per 1. of moisture in the 5-20 cm. soil layer. At a salt concentration of about 10 g. per 1. measured in spring, L. perenne tends to dominate over other species while Poa sp. and T. repens suffer during the summer. At a salt concentration of 10-15 g. per 1. in spring, Poa sp. and T. repens should be omitted from seed mixtures, instead mixtures consisting of different types of L. perenne, Festuca pratensis and Phleum pratense should be sown. When the salt concentration of the soil moisture is higher that 15 g. per 1. in spring, sowing should be delayed and the weeds checked by mowing or grazing. Temporary rises of the salt concentration in dry symmers to 25 g. per 1. are tolerated by L. perenne, F. pratensis and Ph. pratense; similar rises up to 15-18 g. per 1. are tolerated by Poa sp. and T. repens.-W.J.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Parametric optimization of cyanobacterial coagulation at exponential and decline phases by combining polyaluminum chloride and cationic polyacrylamide

2021 ◽  
Author(s):  
Weijun Song ◽  
Yu Xie ◽  
Xi Li
Keyword(s):  
Chlorophyll A ◽  
Parametric Optimization ◽  
Ph Value ◽  
Cyanobacterial Bloom ◽  
Influence Factors ◽  
Exponential Phase ◽  
Polyaluminum Chloride ◽  
Cationic Polyacrylamide ◽  
Removal Ratio ◽  
Decline Phase

Abstract Microcystis spp. is the most common and problematic species during cyanobacterial bloom. This study employed Microcystis aeruginosa for coagulation experiments. Effects of polyaluminum chloride (PAC), cationic polyacrylamide (CPAM), and pH value on cyanobacterial removal at exponential and decline phases by coagulation were investigated by measuring chlorophyll a. A mathematical model between factors and response variables was established using response surface methodology (RSM). Results showed that factors of CPAM dosage, PAC dosage, and pH value could strongly affect the removal ratio of Microcystis at both exponential and decline phases. RSM revealed that the order of influence factors on the removal of chlorophyll a was CPAM &gt; PAC &gt; pH for Microcystis at the exponential phase, and these orders of CPAM &gt; PAC &gt; pH (PAC coagulation) and CPAM &gt; PAC &gt; pH (CPAM coagulation) were for Microcystis at the decline phase. It suggested that the growth phase of cyanobacteria was also quite important to optimize the coagulation process. Besides, a fitted model was developed, and it could well predict the removal ratio of chlorophyll a by coagulation with various treatments. The model recommended dosages of CPAM (3.72 mg/L) and PAC (10.23 mg/L) for Microcystis at the exponential phase with a pH value of 8.25, and dosages of CPAM (5.98 mg/L) and PAC (17.81 mg/L) were for Microcystis at the decline phase with a pH value of 8.21. Overall, these results would provide a technical guideline of combining PAC and CPAM to treat cyanobacteria at exponential and decline phases.

Chemo-Micro-Dilatation Modeling of Carbonation Shrinkage Phenomenon of the Porous Mortars

2011 ◽  
Vol 261-263 ◽  
pp. 680-684 ◽  
Author(s):  
T. X. Dinh ◽  
J. Jeong ◽  
H. Ramézani ◽  
Z. Q. Feng
Keyword(s):  
Cement Paste ◽  
Cement Mortar ◽  
Ph Value ◽  
Empirical Method ◽  
Micro Structure ◽  
Unknown Parameters ◽  
Scientific Goal ◽  
Different Types ◽  
Semi Empirical ◽  
Carbonation Shrinkage

In this paper, we investigate the CO2 carbonation on porous materials such as the cement paste mortar. Our scientific goal is to model the CO2 carbonation effect on the porous cement mortar by the micro-dilatation theory and to determine the chemo-mechanical stress development due to the chemical reactions. In fact, this phenomenon will modify not only the pH value of the cement paste but also the micro-structure due to collapsing pore-network. Based upon the micro-dilatation theory originally proposed by Cowin and Nunziato, four unknown parameters related to the micro-structure will be determined for the cement mortar using the semi-empirical method and numerical modeling. The experimental carbonation tests on two different types of cement paste (CEMI and CEMIII) have been realized to capture carbonated affected zones and to measure their shrinkage deformations.

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