scholarly journals Fabrication of Eco-Friendly Superabsorbent Composites Based on Waste Semicoke

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2347
Author(s):  
Yongsheng Wang ◽  
Yongfeng Zhu ◽  
Yan Liu ◽  
Aiqin Wang
Keyword(s):  
Acrylic Acid ◽  
Ph Value ◽  
High Water ◽  
Sem Analysis ◽  
Water Absorbency ◽  
Ammonium Persulphate ◽  
Wide Ph Range ◽  
Maximum Water ◽  
Ph Range ◽  
Superabsorbent Composites

A series of novel superabsorbent composites of poly(acrylic acid)/semicoke were prepared by polymerization of acrylic acid using ammonium persulphate as initiator, N,N′-methylenebisacrylamide as crosslinker and semicoke which was the by-product of coal carbonizing as the inorganic components. FTIR and SEM analysis indicated that the superabsorbent composites had been successfully polymerized and the semicoke participated in construction of the 3D polymeric network. Meanwhile, the effects of initiator, crosslinker, semicoke, and neutralization degree, as well as the pH value, were investigated, and the results showed that superabsorbent composites containing 10% of semicoke possessed the maximum water absorbency of 584 g/g in distilled water and 75 g/g in 0.9% NaCl solution. The superabsorbent composites kept the high water absorbency within a wide pH range of 4–11, and still exhibited better re-swelling capability even after seven times. The superabsorbent composite with its excellent performance is a potential water-retaining agent used in agriculture.

scholarly journals Structure of bovine cytochromecoxidase in the ligand-free reduced state at neutral pH

2018 ◽  
Vol 74 (2) ◽  
pp. 92-98 ◽  
Author(s):  
Fangjia Luo ◽  
Kyoko Shinzawa-Itoh ◽  
Kaede Hagimoto ◽  
Atsuhiro Shimada ◽  
Satoru Shimada ◽  
...  
Keyword(s):  
Ph Value ◽  
Proton Pumping ◽  
Molecular Surface ◽  
Cellular Respiration ◽  
Inner Mitochondrial Membrane ◽  
Ph Change ◽  
Structural Alterations ◽  
Ligand Free ◽  
Wide Ph Range ◽  
Ph Range

Cytochromecoxidase (CcO), the terminal oxidase in cellular respiration, couples proton pumping to O2reduction. Mammalian CcO resides in the inner mitochondrial membrane. Previously, a model of H-pathway proton pumping was proposed based on various CcO crystal structures. However, all previously determined structures were solved using crystals obtained at pH 5.7, which differs from the environmental pH of CcO in the inner membrane. The structures of fully oxidized and ligand-free reduced CcO at pH 7.3 have now been determined. Structural comparison between the oxidized and reduced states revealed that the structural alterations that occurred upon redox change at pH 5.7 in Asp51, the magnesium-containing cluster, haem groups and helix X, which provide important structural evidence for the H-pathway proton-pumping proposal, also occur at pH 7.3. These structural alterations were restricted to a local region of CcO; no domain movement was detected, nor were significant structural alterations detected in peripheral regions at either pH value. These observations indicate that the small and precise structural alterations that occur over the course of the reaction cycle are not affected by pH change, and that isolated CcO precisely performs proton pumpingviathe H-pathway over a wide pH range. Because the pH is not uniform across the molecular surface of CcO, the fact that the overall structure of CcO is not affected by pH changes ensures the high enzymatic efficiency of this protein in the mitochondria.

Influence of pH on the Absorption and Fluorescence Spectra of 6,7-Dihydroxycoumarin in Aqueous Solution

1982 ◽  
Vol 37 (3) ◽  
pp. 262-265 ◽  
Author(s):  
Jerzy Grzywacz ◽  
Stanisława Taszner
Keyword(s):  
Aqueous Solution ◽  
Fluorescence Spectra ◽  
Singlet State ◽  
Ph Value ◽  
Emission Spectra ◽  
Excited Singlet ◽  
Acid Base ◽  
Wide Ph Range ◽  
Ph Range ◽  
Influence Of Ph

Abstract Absorption and emission spectra of 6,7-dihydroxycoumarin [6,7-DHC] in aqueous solution over a wide pH range are reported. The absorption spectra proved to be strongly sensitive to the pH-value of the solution, whereas the emission spectra change in this range only insignificantly. An interpretation is attempted on the basis of the differences of the acid-base properties of the 6,7-DHC molecule in its ground and excited singlet state. For this purpose the pKa's and pKax's values have been calculated. It has been stated that in the excited state the phototautomer form is very unlikely.

Development of a waste-derived lignin-porphyrin bio-polymer with enhanced photoluminescence at high water fraction with wide pH range and heavy metal sensitivity investigations

2019 ◽  
Vol 21 (6) ◽  
pp. 1319-1329 ◽  
Author(s):  
Ho-Yin TSE ◽  
Shun-Cheung Cheng ◽  
Chi Shun Yeung ◽  
Chun-Yin Lau ◽  
Wing-Hei Wong ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
High Water ◽  
Water Fraction ◽  
Enhanced Photoluminescence ◽  
Metal Sensitivity ◽  
Wide Ph Range ◽  
Bio Imaging ◽  
Ph Range

A new lignin-porphyrin bio-polymer (AL-CTPP) for potential bio-imaging and heavy metals sensing.

Utilization of cross-linked chitosan/bentonite composite in the removal of methyl orange from aqueous solution

2014 ◽  
Vol 71 (2) ◽  
pp. 174-182 ◽  
Author(s):  
Ruihua Huang ◽  
Qian Liu ◽  
Lujie Zhang ◽  
Bingchao Yang
Keyword(s):  
Methyl Orange ◽  
Aqueous Solutions ◽  
Ph Value ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Wide Ph Range ◽  
Order Kinetic Model ◽  
Langmuir Isotherm Model ◽  
Ph Range ◽  
A Minor

A kind of biocomposite was prepared by the intercalation of chitosan in bentonite and the cross-linking reaction of chitosan with glutaraldehyde, which was referred to as cross-linked chitosan/bentonite (CCS/BT) composite. Adsorptive removal of methyl orange (MO) from aqueous solutions was investigated by batch method. The adsorption of MO onto CCS/BT composite was affected by the ratio of chitosan to BT and contact time. pH value had only a minor impact on MO adsorption in a wide pH range. Adsorption kinetics was mainly controlled by the pseudo-second-order kinetic model. The adsorption of MO onto CCS/BT composite followed the Langmuir isotherm model, and the maximum adsorption capacity of CCS/BT composite calculated by the Langmuir model was 224.8 mg/g. Experimental results indicated that this adsorbent had a potential for the removal of MO from aqueous solutions.

Deflocculation of Alumina Suspensions Using Polyelectrolyte Dispersants

2007 ◽  
Vol 352 ◽  
pp. 81-84
Author(s):  
Yang Qiao Liu ◽  
Lian Gao
Keyword(s):  
Acrylic Acid ◽  
Zeta Potential ◽  
Synergistic Effect ◽  
Surface Charge ◽  
Functional Groups ◽  
Ph Value ◽  
Rheological Measurements ◽  
Gel Casting ◽  
Ph Range ◽  
Poly Acrylic Acid

In this paper, the dispersing abilities of three polyelectrolytes, poly (acrylic acid), poly (acrylic acid-co-acrylate), and a four-member copolymer containing various anionic functional groups were tested for aqueous Al2O3 suspensions. The influence of the dispersants on the surface charge of the powder was evaluated by measuring the zeta potential in dilute Al2O3 suspensions. It was found that all the three dispersants shifted the isoelectric point to a lower pH value. Rheological measurements showed that the four-member dispersant decreased the viscosity in the widest pH range, which should be ascribed to the synergistic effect of different functional groups. The 58vol% concentrated Al2O3 slurry using the four-member dispersant was further consolidated using gel casting and was fully sintered at 1600oC.

Effect of pH on the Dispersion Stability of Aqueous Ferric Oxide Suspension

2007 ◽  
Vol 544-545 ◽  
pp. 717-720 ◽  
Author(s):  
C.H Lee ◽  
Eun Hee Lee
Keyword(s):  
Acrylic Acid ◽  
Zeta Potential ◽  
Ferric Oxide ◽  
Dispersion Stability ◽  
Effect Of Ph ◽  
Acidic Solutions ◽  
Aqueous Suspensions ◽  
Wide Ph Range ◽  
Ionization Behavior ◽  
Ph Range

We have studied the effect of pH on the dispersion stability of aqueous suspensions of Fe2O3 powders over a wide pH range in the presence of the poly (acrylic acid) (PAA). In order to investigate the ionization behavior of the PAA, pH of PAA solutions was measured. Sedimentation and zeta-potential measurements were conducted on aqueous Fe2O3 suspensions to characterize the dispersion stability of the suspensions. The PAA was ionized over a wide pH range and the quantity of ionization was abruptly increased at pH > 10. Thus, the dispersion of the Fe2O3 powders was observed even in acidic solutions and the dispersion stability of the suspensions increased as pH of the solutions increased. The magnitude of zeta-potential values increased with increasing pH.

scholarly journals Direct Synthesis of Hyperbranched Poly(acrylic acid-co-3-hydroxypropionate)

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Efkan Çatıker ◽  
Tahsin Filik
Keyword(s):  
Acrylic Acid ◽  
Hydrogen Transfer ◽  
Direct Synthesis ◽  
Bulk Polymerization ◽  
Swelling Behavior ◽  
Raw Material ◽  
Hyperbranched Poly ◽  
Wide Ph Range ◽  
Ph Range ◽  
Poly Acrylic Acid

Hyperbranched poly(acrylic acid-co-3-hydroxypropionate) (PAcHP) was synthesized by base-catalyzed hydrogen transfer polymerization of acrylic acid through one step. The copolymers obtained through solution and bulk polymerization were insoluble in water and all organic solvents tried. Structural and compositional characterizations of hyperbranched PAcHP were performed by using FTIR, solid13C-NMR, TGA, and titrimetric analysis. Acrylate fraction of the hyperbranched PAcHP obtained via bulk polymerization was determined as 60–65% by comparing TGA curves of hyperbranched PAcHP and pure poly(3-hydroxy propionate) (PHP). However, analytical titration of the same sample revealed that acrylic acid units were about 47.3%. The results obtained from TGA and analytical titration were used to evaluate the chemical structure of the copolymer. Hyperbranched PAcHP exhibited hydrogel properties. Swelling behavior of the copolymer was investigated at a wide pH range and ionic strength. The dynamic swelling profiles of hyperbranched PAcHP exhibited a fast swelling behavior in the first hour and achieved the equilibrium state within 12 h in PBS. Depending on the conditions, the copolymers exhibited swelling ratios up to 2100%. As the copolymer has easily biodegradable propionate and versatile functional acrylic acid units, it can be used as not only biodegradable material in medical applications but also raw material in personal care commodities.

scholarly journals Study on superabsorbent composites XVII. Preparation and characterization of poly(acrylic acid)/attapulgite/Namontmorillonite superabsorbent composites

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Junping Zhang ◽  
Kun Zhang ◽  
Aiqin Wang
Keyword(s):  
Acrylic Acid ◽  
Surface Morphology ◽  
Crystalline Structure ◽  
Great Influence ◽  
Clay Content ◽  
Ammonium Persulfate ◽  
Water Absorbency ◽  
Superabsorbent Composite ◽  
Superabsorbent Composites

AbstractA novel superabsorbent composite simultaneously incorporated with both attapulgite and Na-montmorillonite was prepared by aqueous polymerization using N,N’-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The effects of the clay content on swelling ability of the superabsorbent composite were investigated. The superabsorbent composite were characterized by IR, XRD and SEM. The results indicate that Na-montmorillonite was exfoliated in the composite, whereas, attapulgite kept its crystalline structure. The content of clay has great influence on surface morphology and water absorbency of the superabsorbent composite, and the collaborative effect of attapulgite and Namontmorillonite on swelling ability is superior to that of single one.

Synthesis and swelling behaviour of fast-swelling superabsorbent composites

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Fen Zhang ◽  
Mingzhu Liu ◽  
Xiaohua Qi ◽  
Zhenbin Chen
Keyword(s):  
High Water ◽  
Sodium Acrylate ◽  
Swelling Kinetics ◽  
Water Absorbency ◽  
High Porosity ◽  
Nacl Solution ◽  
Experimental Conditions ◽  
Swelling Equilibrium ◽  
Swelling Rate ◽  
Superabsorbent Composites

AbstractFast-swelling porous superabsorbent composites with high water absorbency in 0.9 wt% NaCl solution both at atmospheric pressure and under certain load (p ≈ 2×103 pa) were synthesized by a rapid solution polymerization of concentrated sodium acrylate, acrylamide and 2-hydroxypropyl acrylate. The porosity was induced through foaming conducted in the course of polymerization using acetone as porosity generator. The copolymerization and surface morphology of the porous copolymers were characterized by FTIR and SEM. To improve other properties of swollen hydrogel such as strength, resilience and dispersion, the copolymers were modified with inorganic salts after surfacecrosslinking by trihydroxymethyl propane glycidol ether. The influences of various experimental conditions, such as neutralization degree of acrylic acid, amount of initiator and crosslinker on the water absorbent capacity in 0.9 wt% NaCl solution were investigated. The resulting products under optimum conditions possessed the water absorbency of 65 g g-1 and 10 g g-1 in 0.9 wt% NaCl solution at atmosphere pressure and under load, respectively. The results of swelling kinetics measurement in 0.9 wt% NaCl solution showed that the composites had very fast swelling rate (they can reach swelling equilibrium in minutes). In addition, the effect of amount of acetone on swelling rate of the composites was examined in detail. It was shown that appropriate amount of acetone caused products with high porosity, which led to large swelling rate. Moreover, the swollen hydrogel exhibited excellent strength, better resilience and dispersion.

scholarly journals UV polymerization and property analysis of maleacylated methyl cellulose acrylic acid absorbent resin

2020 ◽  
Vol 22 (2) ◽  
pp. 34-41
Author(s):  
Ying Li ◽  
Amatjan Sawut ◽  
Gongbo Hou ◽  
Mingyu He ◽  
Mamatjan Yimit
Keyword(s):  
Acrylic Acid ◽  
Water Absorption ◽  
Water Retention ◽  
Methyl Cellulose ◽  
High Water ◽  
Optimal Conditions ◽  
Synthetic Resin ◽  
Reaction Conditions ◽  
High Water Absorption ◽  
Maximum Water

AbstractIn this paper, maleic anhydride (MA) was grafted onto methyl cellulose (MC) and then reacted with acrylic acid to synthesize a high gel strength and fast water absorption resin (AA-co-MC-g-MA) by UV polymerization. The reaction conditions of maleylated methylcellulose (MC-g-MA) were investigated, including the ratio of MC to MA, reaction time and catalyst amount. In addition, the reaction conditions for the synthesis of super absorbent resin were as follows: the amount of MC-g-MA, the degree of substitution of MC-g-MA, polymerization time, and the amount of initiator. Under optimal conditions, the maximum water absorption volume of synthetic resin was 2116 g/g, and the maximum salt absorption rate was 139 g/g. The water absorption resin prepared this time had high water absorption, water retention, excellent pH sensitivity, etc. It was hoped that it will have a good application prospect in the field of industrial production and agriculture in the future.

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