Polyvinyl alcohol as an immobilization matrix - a case of gold biosorption

2001 ◽  
Vol 43 (11) ◽  
pp. 17-23 ◽  
Author(s):  
K.-M. Khoo ◽  
Y.-P. Ting
Keyword(s):  
Polyvinyl Alcohol ◽  
Cell Immobilization ◽  
Chemical Properties ◽  
Isotherm Models ◽  
Transfer Resistance ◽  
Wide Ph Range ◽  
Freundlich Adsorption Isotherm ◽  
Alginate Gels ◽  
Freely Suspended ◽  
Time Required

The use of polyvinyl alcohol (PVA) as a matrix for cell immobilization has been extensively studied in various biological systems. However, its suitability has not been reported in biosorption studies where inactivated cells are used as biosorbents. In this work, PVA and alginate as immobilization matrices (for the biosorption of gold by a fungal biomass) were investigated by examining their physical and chemical properties. Compared to alginate gels, PVA gels were shown to be more resistant to mechanical abrasion, and more stable over a wide pH range. Although the PVA matrix did not affect the equilibrium uptake in gold biosorption studies, the time required to attain a removal of 80% of the initial metal concentration was 1.7 times that of the freely suspended biosorbent. This contrasts with the alginate immobilized biosorbent which required an increase of well over ten times the duration to attain the same removal efficiency. Results indicated that PVA gels conferred a lower mass transfer resistance than alginate gels. Gold biosorption by the PVA-immobilized fungi followed the commonly used Langmuir and Freundlich adsorption isotherm models although the former gave a better fit. The uptake of gold was dependent on the initial gold concentration and the biomass loading. Using a fungal biosorbent and gold ions as the model system, the results demonstrate the potential in the use of the PVA as a cell immobilisation matrix for biosorption studies.

Comparative study on polyvinyl alcohol and alginate for cell immobilization in biosorption

2000 ◽  
Vol 42 (5-6) ◽  
pp. 85-90 ◽  
Author(s):  
Y.P. Ting ◽  
G. Sun
Keyword(s):  
Polyvinyl Alcohol ◽  
Calcium Alginate ◽  
Dilute Hydrochloric Acid ◽  
Cell Immobilization ◽  
Chemical Properties ◽  
Yeast Cells ◽  
Lower Mass ◽  
Transfer Resistance ◽  
Alginate Matrix ◽  
And Chemical Properties

In this work, we compared the performance of a new method of cell immobilization in a novel matrix for biosorption. Yeast cells were entrapped in a polyvinyl alcohol (PVA) matrix, based on an adapted iterative freeze-thaw-freeze process. Spherical and uniform beads were produced, and SEM micrographs confirmed that the cells were uniformly dispersed within the PVA matrix. Further experiments revealed that the use of PVA as the immobilization matrix conferred better mechanical and chemical properties than the commonly used calcium alginate matrix. Experiments also showed that the PVA matrix gave rise to a lower mass transfer resistance than the alginate matrix. Finally, it was established that PVA-yeast biosorbent beads could be regenerated using dilute hydrochloric acid (10mM) and reused for at least five biosorption cycles with virtually no decrease in its bisorption capacity. Different metal/biosorbent in PVA-immobilized systems are currently being investigated.

Improvement of Ti/RuO2–IrO2 Anode Lifetime and Electrocatalytical Properties by Using an Eco-Friendly Thermal Decomposition Method Using Polyvinyl Alcohol as Solvent

2019 ◽  
Author(s):  
Charlys Bezerra ◽  
Géssica Santos ◽  
Marilia Pupo ◽  
Maria Gomes ◽  
Ronaldo Silva ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Polyvinyl Alcohol ◽  
High Efficiency ◽  
Electrochemical Impedance ◽  
Pechini Method ◽  
Low Cost ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Calcination Temperatures ◽  
Service Lifetime

<p>Electrochemical oxidation processes are promising solutions for wastewater treatment due to their high efficiency, easy control and versatility. Mixed metal oxides (MMO) anodes are particularly attractive due to their low cost and specific catalytic properties. Here, we propose an innovative thermal decomposition methodology using <a>polyvinyl alcohol (PVA)</a> as a solvent to prepare Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes. Comparative anodes were prepared by conventional method employing a polymeric precursor solvent (Pechini method). The calcination temperatures studied were 300, 400 and 500 °C. The physical characterisation of all materials was performed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy, while electrochemical characterisation was done by cyclic voltammetry, accelerated service lifetime and electrochemical impedance spectroscopy. Both RuO<sub>2</sub> and IrO<sub>2</sub> have rutile-type structures for all anodes. Rougher and more compact surfaces are formed for the anodes prepared using PVA. Amongst temperatures studied, 300 °C using PVA as solvent is the most suitable one to produce anodes with expressive increase in voltammetric charge (250%) and accelerated service lifetime (4.3 times longer) besides reducing charge-transfer resistance (8 times lower). Moreover, the electrocatalytic activity of the anodes synthesised with PVA toward the Reactive Blue 21 dye removal in chloride medium (100 % in 30 min) is higher than that prepared by Pechini method (60 min). Additionally, the removal total organic carbon point out improved mineralisation potential of PVA anodes. Finally, this study reports a novel methodology using PVA as solvent to synthesise Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes with improved properties that can be further extended to synthesise other MMO compositions.</p>

Performance of Different Solid and Liquid Culture Media for the Improvement of Tuberculin Production

2020 ◽  
Keyword(s):  
Culture Media ◽  
Synthetic Medium ◽  
Chemical Properties ◽  
Economic Loss ◽  
Delayed Type Hypersensitivity ◽  
Basic Medium ◽  
Primary Methods ◽  
Lowenstein Jensen ◽  
Time Required ◽  
Modified Media

Tuberculosis (TB) is one of the most important zoonotic bacterial diseases. A huge economic loss which could be direct or indirect are associated with the disease. Currently, the primary methods used for detection of TB in humans and cattle include the measurement of a delayed type hypersensitivity to purified protein derivative (PPD). So, the need for preparation of purified PPD with adequate properties and increasing the final PPD yield with decreasing the time of tuberculin production has stimulated the interest in the development of its preparation. Our study was performed to compare between the standard and modified media for improving tuberculin production. Middle brook 7H10 agar medium was used as a modified basic medium for mycobacterial growth, followed by cultivation of mycobacteria on Middle brook 7H9 broth medium. For the production, strains were inoculated onto the culture medium (Dorest Henly synthetic medium). Other steps for tuberculin production was done according to standard Weighbridge protocol. The results demonstrated that the using of both Middle brook 7H10 agar and Middle brook 7H9 broth instead of Lowenstein-Jensen (LJ) and glycerin broth media which used in currently produced tuberculin, have better physical and chemical properties. In addition, reducing the time required for production by accelerating the time of microbial growth. Also, it was found that the tuberculin produced using modified media was slightly more potent or the same as currently tuberculin produced. So, both Middle brook 7H10 agar and Middle brook 7H9 broth media are recommended for production of tuberculin saving time and increasing potency of the product but more investigation was recommended for estimation types of protein present in both locally prepared and modified tuberculin.

Synthesis and Characterization of Chitosan templated Mesoporous Silica: Efficient use of Mesoporous Silica in the removal of Cu(II) from Aqueous Solutions

2016 ◽  
Vol 4 (2) ◽  
pp. 105-112
Author(s):  
Lalchhing puii ◽  
◽  
Seung-Mok Lee ◽  
Diwakar Tiwari ◽  
◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Aqueous Solutions ◽  
Background Electrolyte ◽  
Second Order ◽  
Order Kinetic ◽  
Sorption Data ◽  
Column Reactor ◽  
Wide Ph Range ◽  
Freundlich Adsorption Isotherm ◽  
Pseudo Second Order

A mesoporous silica was synthesized by annealing (3-Aminopropyl) triethoxysilane grafted chitosan at 800˚C. The mesoporous silica was characterized by the XRD (X-ray diffraction) analysis. The BET specific surface area and pore size of silica was found to be 178.42 m2/g and 4.13 nm. The mesoporous silica was then employed for the efficient remediation of aqueous solutions contaminated with Cu(II) under batch and column reactor operations. The mesoporous silica showed extremely high per cent removal of Cu(II) at wide pH range i.e., pH ~2.0 to 7.0. Relatively a fast uptake of Cu(II) was occurred and high percentage removal was obtained at initial concentrations studied from 1.0 to 15.0 mg/L. The equilibrium state sorption data were utilized for the Langmuir and Freundlich adsorption isotherm studies. Moreover, the effect of an increase in background electrolyte concentrations from 0.0001 to 0.1 mol/L NaNO3 was assessed for the uptake of Cu(II) by mesoporous silica. The equilibrium sorption was achieved within 240 min of contact and the kinetic data is best fitted to the pseudo-second-order and fractal like pseudo-second-order kinetic models. In addition, the mesoporous silica was used for dynamic studies under column reactor operations. The breakthrough curve was then used for the non-linear fitting of the Thomas equation and the loading capacity of the column for Cu(II) was estimated.

Preparation of crosslinked chitosan magnetic membrane for cations sorption from aqueous solution

2017 ◽  
Vol 75 (9) ◽  
pp. 2034-2046 ◽  
Author(s):  
Adnan Khan ◽  
Samina Begum ◽  
Nauman Ali ◽  
Sabir Khan ◽  
Sajjad Hussain ◽  
...  
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Adsorption Capacity ◽  
Magnetic Particles ◽  
Isotherm Models ◽  
Chitosan Membrane ◽  
Dilute Aqueous Solution ◽  
Chitosan Membranes ◽  
The Fourier Transform ◽  
Time Required

A chitosan magnetic membrane was prepared in order to confer magnetic properties to the membrane, which could be used for the removal of cations from aqueous solution. The crosslinked magnetic membrane was compared with pristine chitosan membrane in term of stability, morphology and cation adsorption capacity. The fabricated magnetic materials are thermally stable as shown by thermogravimetric curves. The membrane containing nickel magnetic particles (CHNiF-G) shows high thermal stability compared to the other membranes. The Fourier transform infrared spectroscopy showed successful preparation of chitosan magnetic membrane. Scanning electron microscopy micrographs showed the rough surface of the membrane with increased porosity. The prepared chitosan membranes were applied to cations of copper, nickel and lead in dilute aqueous solution. The chitosan membrane showed the following adsorption order for metallic cations: Cu2+ &gt; Ni2+ &gt; Pb2+, while CHNiF-G showed higher capacity, 3.51 mmol g−1 for copper, reflecting the improvement in adsorption capacity, since the amount of copper on pristine chitosan gave 1.40 mmol g−1. The time required for adsorption to reach to the equilibrium was 6 h for the selected cations using different chitosan membranes. The kinetic study showed that adsorption followed pseudo-second order kinetics. The most commonly used isotherm models, Freundlich, Langmuir and Temkin, were applied to experimental data using linear regression technique. However, The Temkin model fits better to experimental data.

scholarly journals Correlations between physico-chemical properties and nickel adsorption parameters in soils used in sanitary landfill liners

2020 ◽  
Vol 34 (3) ◽  
pp. 275-284
Author(s):  
Ricardo Antonio Ferreira da Silva ◽  
Danilo Brito da Costa ◽  
William de Paiva ◽  
Márcio Camargo de Melo ◽  
Veruschka Escarião Dessoles Monteiro
Keyword(s):  
Chemical Properties ◽  
Bentonite Clay ◽  
Exchange Capacity ◽  
Isotherm Models ◽  
Sanitary Landfill ◽  
Adsorption Parameters ◽  
Clayey Sand ◽  
Landfill Liners ◽  
Physico Chemical ◽  
Nickel Adsorption

The adsorption of heavy metals by sanitary landfill liners represents a measure of protection of surface and groundwaters against contamination by metals, mitigating risks to public health. Hence, this research aimed to identify, from correlations, the influence of physico-chemical properties of soils applied in landfill liners using nickel adsorption parameters. Batch equilibrium tests with initial nickel concentrations of 45 to 1440 mg.L-1 were performed in clayey sand and bentonite clay soil, as well as in mixtures. Nickel adsorption parameters from Freundlich and Langmuir isotherm models were obtained, exhibiting a better adjustment in the Freundlich model based on R² and RMSE criteria. Thus, the addition of bentonite clay improved the adsorption to nickel, and the cationic exchange capacity (CEC) was the property that considerably influenced the metal retention in the studied soils.

3D Porous Graphene/Polyvinyl Alcohol Composites: The Effect of Modification on the Adsorption Properties

NANO ◽  
2016 ◽  
Vol 11 (11) ◽  
pp. 1650125 ◽  
Author(s):  
Shuang Sun ◽  
Xiaofei Ma
Keyword(s):  
Polyvinyl Alcohol ◽  
Graphene Nanosheets ◽  
Adsorption Properties ◽  
Isotherm Models ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Porous Structures ◽  
Edta Solution ◽  
Pseudo Second Order

Polyvinyl alcohol (PVA) was grafted on graphene nanosheets (GN) in the reduction of graphene oxide with hydrazine hydrate. The obtained GN-PVA (GP) suspension was treated with the freezing–thawing cycle to fabricate 3D porous monolithic GP materials, which were modified with carbon disulfide to introduce xanthan groups on the wall of porous materials, marked as GPCs. The characterization of GPCs confirmed that PVA was attached on the surface of GNs, and xanthan groups were effectively functionalized on the porous structures, which were composed of randomly oriented GNs. The Pb[Formula: see text] adsorption pattern for GPC materials was investigated. The kinetic adsorption and isotherm data fit the pseudo second-order kinetic and the Langmuir isotherm models, respectively. The maximum adsorption capacity of Pb[Formula: see text] reached 242.7[Formula: see text]mg/g. And GPCs for Pb[Formula: see text] adsorption could be regenerated with ethylenediamine tetracetic acid (EDTA) solution for repetitious adsorption.

scholarly journals Improved Electrochemical Performance of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 Cathode Material Synthesized by the Polyvinyl Alcohol Auxiliary Sol-Gel Process for Lithium-Ion Batteries

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
He Wang ◽  
Mingning Chang ◽  
Yonglei Zheng ◽  
Ningning Li ◽  
Siheng Chen ◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Cathode Material ◽  
Discharge Capacity ◽  
Electrochemical Impedance ◽  
Coulombic Efficiency ◽  
Sol Gel ◽  
Rate Capability ◽  
Lithium Ion ◽  
Transfer Resistance ◽  
Sol Gel Process

A lithium-rich manganese-based cathode material, Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2, was prepared using a polyvinyl alcohol (PVA)-auxiliary sol-gel process using MnO2 as a template. The effect of the PVA content (0.0–15.0 wt%) on the electrochemical properties and morphology of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 was investigated. Analysis of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 X-ray diffraction patterns by RIETAN-FP program confirmed the layered α-NaFeO2 structure. The discharge capacity and coulombic efficiency of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 in the first cycle were improved with increasing PVA content. In particular, the best material reached a first discharge capacity of 206.0 mAhg−1 and best rate capability (74.8 mAhg−1 at 5 C). Meanwhile, the highest capacity retention was 87.7% for 50 cycles. Finally, electrochemical impedance spectroscopy shows that as the PVA content increases, the charge-transfer resistance decreases.

scholarly journals 3D Printed Laminated CaCO3-Nanocellulose Films as Controlled-Release 5-Fluorouracil

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 986 ◽  
Author(s):  
Denesh Mohan ◽  
Nur Fatin Khairullah ◽  
Yan Ping How ◽  
Mohd Shaiful Sajab ◽  
Hatika Kaco
Keyword(s):  
Drug Delivery ◽  
Chemical Properties ◽  
Pharmaceutical Compounds ◽  
The Body ◽  
Therapeutic Effects ◽  
Layer By Layer ◽  
3D Printed ◽  
Time Required ◽  
Uptake And Release ◽  
And Chemical Properties

Drug delivery constitutes the formulations, technologies, and systems for the transport of pharmaceutical compounds to specific areas in the body to exert safe therapeutic effects. The main criteria for selecting the correct medium for drug delivery are the quantity of the drug being carried and the amount of time required to release the drug. Hence, this research aimed to improve the aforementioned criteria by synthesizing a medium based on calcium carbonate-nanocellulose composite and evaluating its efficiency as a medium for drug delivery. Specifically, the efficiency was assessed in terms of the rates of uptake and release of 5-fluorouracil. Through the evaluation of the morphological and chemical properties of the synthesized composite, the established 3D printing profiles of nanocellulose and CaCO3 took place following the layer-by-layer films. The 3D printed double laminated CaCO3-nanocellulose managed to release the 5-fluorouracil as an effective single composition and in a time-controlled manner.

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