Characteristic of Co–Polyamide Nanofiltration Membrane: The Effect of Reaction Time

2012 ◽  
Author(s):  
A. L. Ahmad ◽  
B. S. Ooi ◽  
M. M. D. Zulkali ◽  
J. P. Choudhury
Keyword(s):  
Reaction Time ◽  
Pore Size ◽  
Flow Model ◽  
Effective Thickness ◽  
The Other ◽  
Nanofiltration Membrane ◽  
Polymerization Time ◽  
Nanofiltration Membranes ◽  
Crosslinking Process ◽  
Pore Flow

Membran penurasan nano yang diubahsuai daripada polipiperazinamida telah dihasilkan dalam masa tindakbalas yang berbeza. Membran berkenaan dicirikan terhadap liang saiz dan ketebalan berkesan/keporosan dengan menggunakan model DSPM. Liang membran menjadi kecil pada permulaan tindakbalas disebabkan proses pengaitan bersilang tetapi liang saiz akan bertambah untuk jangkamasa tindakbalas yang lebih lama kerana kelemahan dinding liang membran. Walau bagaimanapun, nilai ketebalan berkesan/keporosan bertambah dengan masa dan menjadi stabil selepas 60s. Kesan masa tindakbalas terhadap liang saiz adalah tidak ketara berbanding dengan kesannya terhadap ketebalan berkesan/keporosan. Selama 2 minit tindakbalas, nilai ketebalan berkesan/keporosan untuk lapisan penapis berubah sebanyak 150%. Kata kunci: Penurasan Nano, masa tindakbalas, saiz liang, ketebalan berkesan/keporosan Modified polypiperazinamide nanofiltration membranes were fabricated under different reaction time. The membranes were characterized for its pore size and effective thickness/porosity using Donnan Steric Pore Flow Model. The pore size was reduced initially due to the crosslinking process but becomes larger at longer reaction time because of the weaker pores wall. On the other hand, the effective thickness/porosity grows with polymerization time and becomes constant after 60s. The effect of reaction time on the pore size is not as significant as effective thickness/porosity. Within 2 minutes of polymerization time, the effective thickness of the barrier layer would vary about 150%. Key words: Nanofiltration, reaction time, pore size, effective thickness/porosity

EFFECT OF CURING TIME ON THE PORE SIZE AND EFFECTIVE THICKNESS/POROSITY OF POLYESTER THIN FILM COMPOSITE NANOFILTRATION MEMBRANES

2016 ◽  
Vol 78 (12) ◽  
Author(s):  
K. H. Mah ◽  
H. W. Yussof ◽  
M. N. Abu Seman ◽  
A. W. Mohammad
Keyword(s):  
Thin Film ◽  
Pore Size ◽  
Interfacial Polymerization ◽  
Effective Thickness ◽  
Membrane Properties ◽  
Curing Time ◽  
Nanofiltration Membranes ◽  
Film Composite ◽  
Thin Film Composite ◽  
Minute Point

Polyester thin film composite nanofiltration membranes were synthesized on the polyethersulfone (PES) support via the interfacial polymerization between triethanolamine (TEOA) and trimesoyl chloride (TMC). Here we report the effect of curing time in the interfacial polymerization process on membrane properties like pore size and effective thickness/porosity. The membrane properties were determined based on the uncharged solute permeation test and the hypothetical mechanistic structure (pore size, effective thickness/porosity) was determined using Donnan steric pore flow model (DSPM). This study also provides information on the effect of curing time on water permeability. From the 2 minute point to 10 minute point, the membranes pore sizes were reduced and negligible changes to effective thickness/porosity suggest the occurrence of additional cross-linking reaction between aqueous and organic monomers.

scholarly journals PROBING THE CONSTRUCT VALIDITY OF LLAMA_D AS A MEASURE OF IMPLICIT LEARNING APTITUDE

2021 ◽  
pp. 1-14
Author(s):  
Yuichi Suzuki
Keyword(s):  
Reaction Time ◽  
Construct Validity ◽  
Implicit Learning ◽  
Incidental Learning ◽  
The Other ◽  
Aptitude Test ◽  
Oral Fluency ◽  
The Relationship ◽  
Potential Test ◽  
Confidence Ratings

Abstract A subtest of the LLAMA test battery (LLAMA_D) has been proposed as a potential test of implicit learning aptitude. To improve its construct validity, in the present study, the original LLAMA_D (a) instructions for incidental learning were modified, and (b) confidence ratings of test responses and (c) reaction time (RT) measurements were added. This revised LLAMA_D was administered along with the other LLAMA subtests (LLAMA-B, -E, and -F). Unconscious knowledge that may (not) result from the exposure was assessed through the relationship between the accuracy/RT and confidence ratings. The results suggest that LLAMA_D accuracy largely reflects conscious retrieval of previously heard sound sequences. However, an index derived from the LLAMA_D RT measure (coefficient of variance) was associated with an aspect of oral fluency, which is presumably dependent on proceduralization. Several recommendations are proposed to redesign and extend LLAMA_D as a potential aptitude test for proceduralization.

Nanofiltration membranes with narrowed pore size distribution via pore wall modification

2016 ◽  
Vol 52 (55) ◽  
pp. 8589-8592 ◽  
Author(s):  
Yong Du ◽  
Yan Lv ◽  
Wen-Ze Qiu ◽  
Jian Wu ◽  
Zhi-Kang Xu
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Pore Wall ◽  
Nanofiltration Membranes ◽  
Novel Method

A novel method has been proposed to modify the pore wall of nanofiltration membranes (NFMs) by filtrating molecules that are reactive to the NFMs, leading to narrowed pore size distribution.

Degradation of chlorpyriphos in water by advanced oxidation processes

2010 ◽  
Vol 10 (1) ◽  
pp. 1-6 ◽  
Author(s):  
R. Murillo ◽  
J. Sarasa ◽  
M. Lanao ◽  
J. L. Ovelleiro
Keyword(s):  
Reaction Time ◽  
Light Source ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
The Other ◽  
Molar Ratio ◽  
Optimum Conditions ◽  
Oxidation Processes ◽  
Other Hand ◽  
Initial Ph

The degradation of chlorpyriphos by different advanced oxidation processes such as photo-Fenton, TiO2, TiO2/H2O2, O3 and O3/H2O2 was investigated. The photo-Fenton and TiO2 processes were optimized using a solar chamber as light source. The optimum dosages of the photo-Fenton treatment were: [H2O2]=0.01 M; [Fe3 + ]=10 mg l−1; initial pH = 3.5. With these optimum conditions total degradation was observed after 15 minutes of reaction time. The application of sunlight was also efficient as total degradation was achieved after 60 minutes. The optimum dosage using only TiO2 as catalyst was 1,000 mg l−1, obtaining the maximum degradation at 20 minutes of reaction time. On the other hand, the addition of 0.02 M of H2O2 to a lower dosage of TiO2 (10 mg l−1) provides the same degradation. The ozonation treatment achieved complete degradation at 30 minutes of reaction time. On the other hand, it was observed that the degradation was faster by adding H2O2 (H2O2/O3 molar ratio = 0.5). In this case, total degradation was observed after 20 minutes.

scholarly journals DABCO Catalyzed Synthesis of Xanthene Derivatives in Aqueous Media

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Pradeep Paliwal ◽  
Srinivasa Rao Jetti ◽  
Anjna Bhatewara ◽  
Tanuja Kadre ◽  
Shubha Jain
Keyword(s):  
Reaction Time ◽  
Aqueous Media ◽  
Environmentally Friendly ◽  
The Other ◽  
Short Reaction Time ◽  
Xanthene Derivatives ◽  
Reaction Proceeds ◽  
Conventional Methods

The reaction of 5,5-dimethylcyclohexane-1,3-dione with various heteroarylaldehydes afforded the corresponding heteroaryl substituted xanthene derivatives 1(a–f). The reaction proceeds via the initial Knoevenagel, subsequent Michael, and final heterocyclization reactions using 1,4-diazabicyclo[2.2.2]octane (DABCO) as a catalyst in aqueous media. The synthesized heteroaryl substituted xanthenes 1(a–f) reacted with malononitrile to obtain different alkylidenes 2(a–f). Short reaction time, environmentally friendly procedure, avoiding of cumbersome apparatus, and excellent yields are the main advantages of this procedure which makes it more economic than the other conventional methods.

Preparation and Co (II) Removal of ZnO/Poly-Piperazineamide Nanofiltration Membranes

2017 ◽  
Author(s):  
Xiaoguang Zhang ◽  
Xuexing Chen ◽  
Qingchun Chen ◽  
Zhaolong Deng ◽  
Yan Liu ◽  
...  
Keyword(s):  
Reaction Time ◽  
Monomer Concentration ◽  
Attenuated Total Reflection ◽  
Radioactive Nuclide ◽  
Separation Performance ◽  
Separation Mechanism ◽  
Nanofiltration Membranes ◽  
Terephthaloyl Chloride ◽  
Nano Zno ◽  
Zno Particles

A series of nanofiltration membranes were prepared by interfacial polymerization of piperazine and terephthaloyl chloride on the surface of polyacrylonitrile (PAN) ultrafiltration membranes. ZnO nanoparticles were incorporated in the active separation layer to modify the performances of the membranes. The preparation conditions as the monomer concentration, dosage of nano-ZnO particles and the reaction time on removal of a simulated radioactive nuclide Co (II) were investigated. Fourier transform infrared in attenuated total reflection mode verified the formation of polyamide on the PAN ultrafiltration membrane. The scanning electron microscope images showed that the nano-ZnO particles can homogeneously fixed on the membrane surface. The retention of Co (II) increased with increasing the dosage of nano-ZnO in the range of 0∼0.03 g. Further adding more nano-ZnO, the rejection rate of Co (II) first decreased and then increased. The concentration of piperazine and terephthaloyl chloride showed similar effect on removal of Co (II) ion. 5 minutes polymerization time was sufficient to form an active separation layer on the substrate membrane which changed the separation mechanism from ultrafiltration to nanofiltration. The separation performance of NF3 prepared by the following conditions was optimum: 0.03g nano-ZnO, 0.6 wt% piperazine, 0.5 wt% terephthaloyl chloride, and the reaction time was 15 min. The rejection rates of 1000 mg/L Na2SO4 and Co2+ in CoCl2 solution were 90% and 75% respectively. The Co (II) removal rate can be increased to nearly 90% by using ethylenediaminetetraacetic acid disodium salt. Increasing the operation pressure or the feeding concentration of Co (II) can also improve the performances of the membranes in this experiment.

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