Preparation of alumina-zirconia (Al-Zr) ceramic nanofiltration (NF) membrane for the removal of uranium in aquatic system

2018 ◽  
Vol 19 (3) ◽  
pp. 789-795 ◽  
Author(s):  
Youngkun Chung ◽  
Yeo-Myeong Yun ◽  
Yeo-Jin Kim ◽  
Yu Sik Hwang ◽  
Seoktae Kang
Keyword(s):  
Molecular Weight ◽  
Ceramic Membranes ◽  
Aquatic System ◽  
Membrane Performance ◽  
Water Treatment Process ◽  
Ph Conditions ◽  
Uf Membranes ◽  
Uranium Species ◽  
Aqueous Species ◽  
Positively Charged

Abstract In this research, ceramic nanofiltration (NF) membranes were prepared by depositing alumina-zirconia (Al-Zr) nanoparticles into the pores of ceramic ultrafiltration (UF) membranes for the removal of radioactive uranium in an aquatic system. The modified ceramic membranes showed NF membrane performance with around 1,000 Da molecular weight cut-off (MWCO) and 58% CaCl2 rejection. The removal efficiencies of uranium species by these successfully modified ceramic NF membranes exhibited differences depending on the pH conditions (pH 5.0, 7.4, and 10.0), and achieved the highest rejection of 91% at pH 7.4. This behavior is due to the dominant aqueous species of uranium in pH 7.4, (UO2)2CO3(OH3)−, which has the largest molecular weight among the conditions and the negatively charged species having electrostatic attraction to the positively charged ceramic NF membranes. The ceramic NF membrane prepared here is expected to be feasible in the advanced water treatment process to remove radioactive compounds.

Biodegradable Polymers Derived from Amino Acids for Biological Applications

2010 ◽  
Vol 76 ◽  
pp. 30-35 ◽  
Author(s):  
Naomi Cohen-Arazi ◽  
Ilanit Hagag ◽  
Michal Kolitz ◽  
Abraham J. Domb ◽  
Jeoshua Katzhendler
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Ring Opening ◽  
Building Blocks ◽  
Ring Opening Polymerization ◽  
Microwave Assisted Synthesis ◽  
Hydroxy Acids ◽  
Natural Amino Acids ◽  
Direct Condensation ◽  
Positively Charged

Optically active α-hydroxy acids derived from amino acids have been synthesized and polymerized into new biodegradable polyesters. The variety of functional side chains enables the design of positively charged, negatively charged, hydrophobic and hydrophilic chiral building blocks or any combination of these constituents. Hydroxy acids of 15 natural amino acids were prepared with retention of configuration using a straightforward and reliable method of diazotization of α-amino acids. Polyesters were synthesized from these hydroxy acids by a number of methods: direct condensation in bulk, microwave assisted synthesis and ring opening polymerization. The molecular weight of the prepared polymers ranges between 2000 to 5000Da for the direct condensation and the microwave methods, whereas the ring opening polymerization results in high molecular weight polymers (20000 to 30000Da). The polymers were analyzed for their optical activity (Circular Dichroism Spectroscopy), thermal properties (DSC), solubility, molecular weight and polydispersity (GPC), and aqueous degradation. These polymers were tested for their compatibility to neuronal cells growth and differentiation.

scholarly journals Performance Evaluation of Tight Ultrafiltration Membrane Systems at Pilot Scale for Agave Fructans Fractionation and Purification

Membranes ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 261
Author(s):  
Noe Luiz-Santos ◽  
Rogelio Prado-Ramírez ◽  
Enrique Arriola-Guevara ◽  
Rosa-María Camacho-Ruiz ◽  
Lorena Moreno-Vilet
Keyword(s):  
Molecular Weight ◽  
Ceramic Membranes ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Polymeric Membrane ◽  
Transmembrane Pressure ◽  
Hydraulic Permeability ◽  
Distribution Analysis ◽  
Permeate Flux ◽  
Membrane Systems

Ceramic and polymeric membrane systems were compared at the pilot scale for separating agave fructans into different molecular weight fractions that help to diversify them into more specific industrial applications. The effect of the transmembrane pressure of ultrafiltration performance was evaluated through hydraulic permeability, permeate flux and rejection coefficients, using the same operating conditions such as temperature, feed concentration and the molecular weight cut-off (MWCO) of membranes. The fouling phenomenon and the global yield of the process were evaluated in concentration mode. A size distribution analysis of agave fructans is presented and grouped by molecular weight in different fractions. Great differences were found between both systems, since rejection coefficients of 68.6% and 100% for fructans with degrees of polymerization (DP) > 10, 36.3% and 99.3% for fructooligosaccharides (FOS) and 21.4% and 34.2% for mono-disaccharides were obtained for ceramic and polymeric membrane systems, respectively. Thus, ceramic membranes are better for use in the fractionation process since they reached a purity of 42.2% of FOS with a yield of 40.1% in the permeate and 78.23% for fructans with DP > 10 and a yield of 70% in the retentate. Polymeric membranes make for an efficient fructan purification process, eliminating only mono-disaccharides, and reaching a 97.7% purity (considering both fructan fractions) with a yield of 64.3% in the retentate.

Characterization of Th Carbonate Solutions Using XAS and Implications for Thermodynamic Modeling

1996 ◽  
Vol 465 ◽  
Author(s):  
N. J. Hess ◽  
A. R. Felmy ◽  
D. Rai ◽  
S. D. Conradson
Keyword(s):  
Chemical Speciation ◽  
Chelating Agents ◽  
Chemical Species ◽  
Oxidation States ◽  
Carbonate Solutions ◽  
Ph Conditions ◽  
High Concentrations ◽  
Aqueous Complexes ◽  
Aqueous Species

ABSTRACTThe chemical behavior of actinide elements in tank solutions, in soil, and in groundwater is dependent upon the chemical species that form when aqueous solutions come in contact with the actinide compounds. In particular the chemical speciation of the reduced actinide oxidation states (III and IV) are important, for example, to DOE waste tank processing and, more generally, to nuclear waste disposal issues. Predicting the solubility of the actinides in these solutions requires identification of the strong aqueous complexes, such as carbonates and organic chelating agents, that can form in aqueous solution.Previous speciation work has often relied on indirect techniques such as potentiometric titrations or solubility measurements. Recent XAS experiments determine directly the speciation of the Th carbonato species of seven solutions under a range of carbonate concentrations and pH conditions. The presence of the pentacarbonato complex is confirmed and the complex's stability at low carbonate concentrations is determined. These experimental results support a proposed thermodynamic model that describes the solubility of Th(IV) hydrous oxide in the aqueous Na+-HCO3--CO32--OH--ClO4--H2O system extending to high concentrations at 25°C. This model is relatively simple in that only two aqueous species are included Th(OH)3CO3- and Th(CO3)56-.

scholarly journals Positively charged polyethylenimines enhance nasal absorption of the negatively charged drug, low molecular weight heparin

2006 ◽  
Vol 115 (3) ◽  
pp. 289-297 ◽  
Author(s):  
Tianzhi Yang ◽  
Alamdar Hussain ◽  
Shuhua Bai ◽  
Ikramy A. Khalil ◽  
Hideyoshi Harashima ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
Nasal Absorption ◽  
Positively Charged

scholarly journals In-line coagulation assessment for ultrafiltration fouling reduction to treat secondary effluent for water reuse

2020 ◽  
Author(s):  
Samia A. Aly ◽  
William B. Anderson ◽  
Peter M. Huck
Keyword(s):  
Membrane Fouling ◽  
Water Reuse ◽  
Hollow Fiber Membrane ◽  
Secondary Effluent ◽  
Membrane Performance ◽  
Coagulant Dosage ◽  
Pre Treatment ◽  
Uf Membranes ◽  
Fouling Reduction ◽  
The Impact

Abstract Low pressure membranes are attracting attention for their potential to improve secondary effluent quality, but membrane fouling can limit their widespread applicability. In this study, in-line coagulation as pre-treatment to ultrafiltration (UF) was investigated using a bench-scale hollow fiber membrane at a constant flux of 33 L/m2 h. Membrane fouling was monitored by observing change in trans-membrane pressure when the membrane was fed with secondary effluent and in-line coagulated secondary effluent over a 24-h period. The impact of four coagulants at different dosages on reversible and irreversible membrane fouling and permeate quality was studied. It was found that in-line coagulation improved UF performance to varying degrees depending on coagulant type and dosage. Generally, higher reduction of fouling was achieved by increasing coagulant dosage within the 0.5–5.0 mg/L range investigated. Ferric-based coagulants were better than aluminum-based coagulants with respect to improving membrane performance for the secondary effluent investigated, even at low dosages (0.5 mg/L). Further investigations are required to determine how in-line coagulation affects removal of organic compounds through UF membranes.

scholarly journals Characterization of dissolved organic matter at a water treatment plant with closed systems in different seasons

2020 ◽  
Vol 20 (5) ◽  
pp. 2013-2020
Author(s):  
Hudori Hudori ◽  
Toshiro Yamada ◽  
Yukitaka Suzuki ◽  
Maulana Yusup Rosadi ◽  
Hiroto Tamaoki ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Water Treatment ◽  
Dissolved Organic Matter ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Raw Water ◽  
Recycled Water ◽  
Water Treatment Process ◽  
Closed Systems

Abstract This research focuses on characterizing the dissolved organic matter found at water treatment plants with closed systems. Recycled water generated as a by-product of water treatment is added to raw water in those systems. The dissolved organic matter in the raw water was found to be higher in summer than in winter, but the water treatment process was able to produce purified water of the similar quality in both seasons. The recycled water contained mostly low molecular weight and protein-like substances, and this composition was different from that of the raw water, which mainly contained humic-like substances. The recycled water did not influence the concentration of humic-like substances or the molecular weight distribution in the influent water.

Charge-Affected Transperitoneal Movement of Amino Acids in Capd

1996 ◽  
Vol 16 (1_suppl) ◽  
pp. 88-90 ◽  
Author(s):  
Toshiyuki Nakao ◽  
Makoto Ogura ◽  
Hajime Takahashi ◽  
Tomonari Okada
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Dwell Time ◽  
Plasma Concentrations ◽  
University Hospital ◽  
Blood Samples ◽  
Significant Difference ◽  
Molecular Charge ◽  
Solute Movement ◽  
Positively Charged

Our objective was to investigate the influence of molecular charge on transperitoneal solute movement in continuous ambulatory peritoneal dialysis (CAPD). Tests of peritoneal equilibration were performed. Two liters of 2.27% or 2.5% glucose CAPD dialysate were infused and the dialysate samples were taken after 2 hr and 4 hr, and blood samples were obtained after 4-hr dwell time. Dialysate-to-plasma concentrations ratios (DIP) were calculated for creatinine (Cr) and three amino acids with almost the same molecular weight but quite different charges: glutamic acids (Glu: negatively charged), glutamine (Gin: near neutrally charged), and lysine (Lys: positively charged). The setting was a university hospital. There were 23 stable CAPD patients with a mean age of 56.5±9.5 years and a mean CAPD duration of 15.2±19.4 months. DIP ratio of Glu was much lower than those of Gin, Lys and Cr at both 2 hr and 4 hr (p < 0.01), and DIP of Lys was significantly lower than that of Gin (p < 0.01). There was no significant difference of DIP between Gin and Cr. The order of transperitoneal mobility among the three amino acids was Gin > Lys > Glu. Transperitoneal movement of solutes in CAPD is influenced by molecular charge, the movement of negatively charged solutes is most remarkably retarded in cases of amino acids.

Sign in / Sign up

Export Citation Format

Share Document