The banana pseudo-stem is not currently utilised in the food industry. The aim of this research was to investigate the chemical and pasting profile of banana pseudo-stem flour (BPF). Wheat flour were substituted with BPF (0, 5, 15 and 30%) and the pasting profile were determined. Results from mineral analysis showed that the levels of sodium (Na), potassium (K), calcium (Ca), magnesium (Mg) and phosphorus (P) were higher than those of iron (Fe), zinc (Zn) and manganese (Mn). The BPF had a 0.04% total titratable acidity (TTA) and a total soluble solid (TSS) of 1.30⁰ Brix with pH 5.41. BPF contained 28.26% total starch, 12.81% resistant starch and a total digestible starch value of 15.45%. An increased substitution level of BPF into wheat flour significantly (p
In this study, chitosan/polyvinyl alcohol (PVA)/zeolite nanofibrous composite membrane was fabricated via electrospinning. First, crude chitosan was hydrolyzed with NaOH for 24h. Afterward, hydrolyzed chitosan solution was blended with aqueous PVA solution in different weight ratios. Morphological analysis of chitosan/PVA electrospun nanofiber showed a defect-free nanofiber material with 50:50 weight ratio of chitosan/PVA. Subsequently, 1wt.% of zeolite was added to this blended solution of 50:50 chitosan/PVA. The resulting nanofiber was characterized with field emission scanning electron microscopy, X-Ray diffraction, Fourier transform infrared spectroscopy, swelling test, and adsorption test. Fine, bead-free nanofiber with homogeneous nanofiber was electrospun. The resulting membrane was stable in distilled water, acidic, and basic media in 20 days. Moreover, the adsorption ability of nanofibrous membrane was studied over Cr (VI), Fe (III), and Ni (II) ions using Langmuir isotherm. Kinetic parameters were estimated using the Lagergren first-order, pseudo-second-order, and intraparticle diffusion kinetic models. Kinetic study showed that adsorption rate was high. However, the resulting nanofiber membrane showed less adsorption capacity at high concentration. The adsorption capacity of nanofiber was unaltered after five recycling runs, which indicated the reusability of chitosan/PVA/zeolite nanofibrous membrane. Therefore, chitosan/PVA/zeolite nanofiber can be a useful material for water treatment at moderate concentration of heavy metals.
A radiotracer study was conducted to investigate the removal characteristics of cadmium (109Cd) from aqueous solution by polypyrrole/ sawdust composite. Several factors such as solution pH, sorbent dosage, initial concentration, contact time, temperature and interfering metal ions were found to have influence on the adsorption process. The kinetics of adsorption was relatively fast, reaching equilibrium within 3 hours. A lowering of the solution pH reduced the removal efficiency from 99.3 to ~ 46.7% and an ambient temperature of 25°C was found to be optimum for maximum adsorption. The presence of sodium and potassium ions inhibited 109Cd removal from its aqueous solution. The experimental data for 109Cd adsorption showed a very good agreement with the Langmuir isotherm and a pseudo-first order kinetic model. The surface condition of the adsorbent before and after cadmium loading was investigated using BET, FESEM and FTIR. Considering the low cost of the precursor's materials and the toxicity of 109Cd radioactive metal, polypyrrole synthesized on the sawdust of Dryobalanops aromatic could be used as an efficient adsorbent for the removal of 109Cd radioisotope from radionuclide-containing effluents.
The presence of Cs(I) ions in nuclear wastewater becomes an important issue for the reason of its high toxicity. The development of adsorbent embedded metal-based catalysts that has sufficient adsorption capacity is expected for the removal of Cs(I) ions from contaminated water. This study tested the use of maghemite, titania and combined maghemite-titania polyvinyl alcohol (PVA)-alginate beads as an adsorbent to remove Cs(I) ions from aqueous solution with the variables of pH and initial concentration using batch experiments under sunlight. The results showed that the use of combined maghemite-titania PVA-alginate beads can have an efficiency of 93.1% better than the use of either maghemite PVA-alginate beads with an efficiency of 91.8% or titania PVA-alginate beads with an efficiency of 90.1%. The experimental data for adsorption of Cs(I) ions from aqueous solution with the initial concentrations of 50, 100 and 200 mg L(-1) on the surface of combined maghemite-titania PVA-alginate beads were well fit by the pseudo-second-order and Langmuir models. The optimal adsorption of Cs(I) ions from aqueous solution by combined maghemite-titania PVA-alginate beads under sunlight occurs at pH 8 with an initial Cs(I) ion concentration of 50 mg L(-1). The combined maghemite-titania PVA-alginate beads can be recycled at least five times with a slight loss of their original properties.
A gene encoding a thermotolerant lipase with broad pH was isolated from an Antarctic Pseudomonas strain AMS3. The recombinant lipase AMS3 was purified by single-step purification using affinity chromatography, yielding a purification fold of approximately 1.52 and a recovery of 50%. The molecular weight was approximately ∼60 kDa including the strep and affinity tags. Interestingly, the purified Antarctic AMS3 lipase exhibited broad temperature profile from 10-70 °C and stable over a broad pH range from 5.0 to pH 10.0. Various mono and divalent metal ions increased the activity of the AMS3 lipase, but Ni(2+) decreased its activity. The purified lipase exhibited the highest activity in the presence of sunflower oil. In addition, the enzyme activity in 25% v/v solvents at 50 °C particularly to n-hexane, DMSO and methanol could be useful for catalysis reaction in organic solvent and at broad temperature.
In this present study, a series of polymer electrolyte thin films were synthesized by incorporating different ratios of lithium triflate (LiCF3SO3) in a low molecular weight polyvinyl chloride (PVC) matrix by the solution casting technique. The incorporation of LiCF3SO3 suppressed the high degree of crystallinity in PVC enabling the system to possess an appreciable ionic conductivity. The ionic conductivity of the samples, with different LiCF3SO3 content, was determined by the aid of ac impedance spectroscopy. The highest ionic conductivity of 4.04 10–9 S cm–1 was identified for the composition of PVC: LiCF3SO3 (75:25). Further understanding of the ionic conductivity mechanism was based on temperature-dependent conductivity data which obeyed Arrhenius theory, indicating that the ionic conductivity enhancement was thermally assisted. The possible dipole-dipole interaction between the chemical constituents was confirmed with changes in cage peak, analysed using Fourier transform infrared spectroscopy.
Polyaniline (PANI) and polyaniline composites with aluminium oxide (Al2O3) were prepared using the in situ polymerization method. The composites were then blended with acrylic paint and applied to carbon steel panels. The coated steel panels were evaluated for corrosion using the immersion test technique. The results revealed that the steel panels coated with polyaniline composites and with Al2O3 containing coatings had small corrosion as compared to the bare sample and the samples coated with polyaniline and paint alone. The samples were characterized by Fourier transform infrared (FTIR) and X-ray diffraction(XRD). In addition, the morphology of the finished samples was observed using the scanning electron microscopy (SEM). This novel composite was used as a paint pigment for enhancing the barrier properties and the paint protectable against aggressive ions. Meanwhile, corrosion was evaluated through visual monitoring using a digital camera after 60 days of fully immersion test in 5% NaCl. The weight loss method was also used to evaluate corrosion.
In this paper, we propose a metal-polydopamine (MPDA) framework with a specific molecular probe which appears to be the most promising approach to a strong fluorescence quencher. The MPDA framework quenching ability toward various organic fluorophore such as aminoethylcoumarin acetate, 6-carboxyfluorescein (FAM), carboxyteramethylrhodamine, and Cy5 are used to establish a fluorescent biosensor that can selectively recognize Hg2+ and Ag+ ions. The fluorescent quenching efficiency was sufficient to achieve more than 96%. The MPDA framework also exhibits different affinities with ssDNA and dsDNA. In addition, the FAM-labeled ssDNA was adsorbed onto the MPDA framework, based on their interaction with the complex formed between MPDA frameworks/ssDNA taken as a sensing platform. By taking advantage of this sensor, highly sensitive and selective determination of Hg2+ and Ag+ ions is achieved through exonuclease III signal amplification activity. The detection limits of Hg2+ and Ag+ achieved to be 1.3 and 34 pM, respectively, were compared to co-existing metal ions and graphene oxide-based sensors. Furthermore, the potential applications of this study establish the highly sensitive fluorescence detection targets in environmental and biological fields.
Transition metals are required constituent in bacterial metabolism to assist in some enzymatic reactions. However, intracellular accumulations of these metal ions are harmful to the bacteria as it can trigger unnecessary redox reactions. To overcome this condition, metalloregulatory proteins assist organisms to adapt to sudden elevated and deprived metal ion concentration in the environment via metal homeostasis. CsoR protein is a copper(I) [Cu(I)] sensing operon repressor that is found to be present in all major classes of eubacteria. This metalloregulatory protein binds to the operator region in its apo state under Cu(I) limiting condition and detaches off from the regulatory region when it binds to the excess cytosolic Cu(I) ion, thus derepressing the expression of genes involved in Cu(I) homeostasis. CsoR proteins exist in dimeric and tetrameric states and form certain coordination geometries upon attachment with Cu(I). Certain CsoR proteins have also been found to possess the ability to bind to other types of metals with various binding affinities in some Gram positive bacteria. The role of this metalloregulatory protein in host pathogen interaction and its relation to bacterial virulence are also discussed.
The development of nano-sized scaffolds with antibacterial properties that mimic the architecture of tissue is one of the challenges in tissue engineering. In this study, polycaprolactone (PCL) and PCL/gelatine (Ge) (70:30) nanofibrous scaffolds were fabricated using a less toxic and common solvent, formic acid and an electrospinning technique. Nanofibrous scaffolds were coated with silver (Ag) in different concentrations of silver nitrate (AgNO3) aqueous solution (1.25, 2.5, 5, and 10 %) by using dipping method, drying and followed by ultraviolet (UV) photoreduction. The PCL/Ge (70:30) nanofibrous scaffold had an average fibre diameter of 155.60 ± 41.13 nm. Characterization showed that Ag was physically entrapped in both the PCL and PCL/Ge (70:30) nanofibrous scaffolds. Ag(+) ions release study was performed and showed much lesser release amount than the maximum toxic concentration of Ag(+) ions in human cells. Both scaffolds were non-toxic to cells and demonstrated antibacterial effects towards Gram-positive Bacillus cereus (B. cereus) and Gram-negative Escherichia coli (E. coli). The Ag/PCL/Ge (70:30) nanofibrous scaffold has potential for tissue engineering as it can protect wounds from bacterial infection and promote tissue regeneration.
Enhanced red and orange fluorescence emissions of Sm3+ Rare earth (RE) ions were observed in sodium‑zinc tellurite glasses embedded with silver and gold nanoparticles (NPs). The fine distribution of NPs in the glass matrix with an average diameter ~ 11.09 nm and ~3.86 nm for Ag and Au NPs respectively were confirmed by using transmission electron microscope (TEM). The embedding of Ag and Au NPs into the glass structure caused an increasing in the transition emission intensity of Sm3+ ions, which is ascribed to the progress of the presence of the localized surface Plasmon resonance (LSPR) indicating from the characteristic absorption peaks. The luminescence and absorption spectra have been discussed using a standard hypothesis Judd-Ofelt theory for a certain absorption transitions 6P3/2, 4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2, 6F1/2 and emission transitions 6H5/2, H7/2, 6H9/2 and H11/2 under 409 nm excitation of the Sm3+ ions. The decay life time curve exhibited a non-exponential behavior of the studied glass samples and the results were compared with the similar reported glasses. An efficient red and orange fluorescence emission illustrate that the Sm3+-doped sodium‑zinc tellurite embedded with Ag and Au NPs are potential materials for the laser illumination.
Filamentous fungi such as Fusarium equiseti KR706303 and Penicillium citrinum KR706304
are capable of sequestering heavy metals from aqueous solutions. In the present study, the role
play by various functional groups present in the cell wall of F. equiseti KR706303 and P.
citrinum KR706304 during lead and copper ions biosorption was investigated. The fungal
biomass was chemically treated to modify the functional groups present in their cell wall. These
modifications were studied through biosorption experiments. It was found that an esterification
of the carboxyl and phosphate groups, methylation of the amine groups and extraction of lipids
significantly decrease the biosorption of both lead and copper ions studied. Therefore, the
carbonyl, hydroxyl and amide groups were recognized as important in the biosorption of metal
ions by the tested fungi. The study showed that there was no release of any metal ions from the
biomass after biosorption, indicating that ion exchange may not be a key mechanism in the
biosorption of lead and copper ions by these fungi but complexation of metal ions within the
fungal cell wall.
The formation of aqueous two-phase system (ATPS) with the environmentally friendly and recyclable ionic liquid has been gaining popularity in the field of protein separation. In this study, the ATPSs comprising N,N-dimethylammonium N',N'-dimethylcarbamate (DIMCARB) and thermo-responsive poly(propylene) glycol (PPG) were applied for the recovery of recombinant green fluorescent protein (GFP) derived from Escherichia coli. The partition behavior of GFP in the PPG + DIMCARB + water system was investigated systematically by varying the molecular weight of PPG and the total composition of ATPS. Overall, GFP was found to be preferentially partitioned to the hydrophilic DIMCARB-rich phase. An ATPS composed of 42% (w/w) PPG 1000 and 4.4% (w/w) DIMCARB gave the optimum performance in terms of GFP selectivity (1,237) and yield (98.8%). The optimal system was also successfully scaled up by 50 times without compromising the purification performance. The bottom phase containing GFP was subjected to rotary evaporation of DIMCARB. The stability of GFP was not affected by the distillation of DIMCARB, and the DIMCARB was successfully recycled in three successive rounds of GFP purification. The potential of PPG + DIMCARB + water system as a sustainable protein purification tool is promising.
Matched MeSH terms: Ions; Hydrophobic and Hydrophilic Interactions
The development of new adsorbent has rapidly increased in order to overcome the problem
of waste water treatment from heavy metal pollution. The ability of nickel (II)-ion imprinted
polymer (Ni-IIP) as an alternative adsorbent for the removal of nickel ion from aqueous has
been investigated. The Ni-IIP was prepared via bulk polymerization by using functional
monomers; methylacrylic acid (MAA) with picolinic acid as a co-monomer. Nickel ion was
used as template, AIBN as initiator and EGDMA as cross-linking agent. Non-imprinted control
polymer (NIP) was prepared in the same manner as Ni-IIP but in the absence of nickel
ion. The resultant of Ni-IIP and NIP were characterized by using Fourier Transform Infrared
(FTIR) spectroscopy and Scanning Electron Microscope (SEM). Result showed that, the adsorption
of nickel ion onto Ni-IIP increased as the adsorbent dosage increased and contact
time is prolonged. The adsorption isotherm model for Ni-IIP and NIP were fitted well with
Freundlich and Langmuir, respectively. Kinetic study for both Ni-IIP and NIP were followed
the pseudo-second order, indicates that the rate-limiting step is the surface adsorption that
involves chemisorption. Selectivity studies showed that the distribution coefficient of Ni2+
was higher compared to Zn2+, Mg2+ and Pb2+. The present work has successfully synthesized
Ni-IIP particles with good potential in recognition of Ni2+ ions in an aqueous medium.
Flocculants are foreign particles that aggregate suspended microalgae cells and due to cost factor and toxicity, harvesting of microalgae biomass has shifted towards the use of bioflocculants. In this study, mild acid-extracted bioflocculants from waste chicken's eggshell and clam shell were used to harvest Chlorella vulgaris that was cultivated using chicken compost as nutrient source. It was found that a maximum of 99% flocculation efficiency can be attained at pH medium of 9.8 using 60 mg/L of hydrochloric acid-extracted chicken's eggshell bioflocculant at 50 °C of reaction temperature. On the other hand, 80 mg/L of hydrochloric acid-extracted clam shell bioflocculant was sufficient to recover C. vulgaris biomass at pH 9.8 and optimum temperature of 40 °C. The bioflocculants and bioflocs were characterized using microscopic, zeta potential, XRD, AAS and FT-IR analysis. The result revealed that calcium ions in the bioflocculants are the main contributor towards the flocculation of C. vulgaris, employing charge neutralization and sweeping as possible flocculation mechanisms. The kinetic parameters were best fitted pseudo-second order which resulted in R2 of 0.99 under optimal flocculation temperature. The results herein, disclosed the applicability of shell waste-derived bioflocculants for up-scaled microalgae harvesting for biodiesel production.
Polymer electrolytes based on polyacrylonitrile (PAN) containing inorganic salts; lithium triflate (LiCF3SO3) and sodium triflate (NaCF3SO3) and ethylene carbonate (EC) as plasticizer were prepared using solvent casting technique. In this study, five systems of plasticized and unplasticized polymer electrolyte films i.e. PAN-EC, PAN-LiCF3SO3, PAN-NaCF3SO3 PAN-EC-LiCF3SO3 and PAN-EC-NaCF3SO3 systems have been prepared. The structural and morphological properties of the films were studied using infrared spectroscopy and scanning electron microscopy (SEM) while the conductivity study was done by using impedance spectroscopy. The infrared results revealed that interaction had taken place between the nitrogen atoms of PAN and Li+ and Na+ ions from the salts. SEM micrographs showed that the plasticized film, PAN-EC-NaCF3SO3 has bigger pores than PAN-EC-LiCF3SO3 film resulting in the film containing NaCF3SO3 salt being more conductive. On addition of salts and plasticizer, the conductivity of pure PAN increases to three orders of magnitude. The plasticized film containing NaCF3SO3 salt has a higher conductivity compared to that containing LiCF3SO3 salt. This result showed that the interaction between Li+-ion and the nitrogen atom of PAN was stronger than that of Na+-ion. The conductivity-temperature dependence of the highest conducting film from each system follows Arrhenius equation in the temperature range of 303 to 353 K. The conductivity-pressure study in the range of 0.01 - 0.09 MPa showed that the conductivity decreased when pressure was increased. This can be explained in term of free volume model.
Metal nanoparticles having interesting shapes can be prepared in aqueous solutions through simple reductions of metal ions with the presence of some additive reagents, such as cetyltrimethylammonium bromide and hexamethylenetetramine. In this review, some successful results for shape-controlled synthesis of metal nanoparticles in our group are summarized, which includes the synthesis of palladium nanocubes, palladium nanobricks, gold nanotripods. In addition, combining with indium tin oxide electrode surfaces, shape-controlled growth is shown to be possible to form gold nanoplates and copper oxide nanowires. Even in relatively mild synthetic conditions, interesting shape-controlled synthesis of metal nanoparticles is possible.
Highly ordered vertically grown zinc oxide nanorods (ZnO NRs) were synthesized on ZnO-coated SiO2/Si substrate using zinc acetylacetonate hydrate as a precursor via a simple hydrothermal method at 85 °C. We used 0.05 M of ZnO solution to facilitate the growth of ZnO NRs and the immersion time was varied from 0.5 to 4 h. The atomic force microscopy revealed the surface roughness of ZnO seed layer used to grow the ZnO NRs. The morphology of vertically grown ZnO NRs was observed by field emission scanning electron microscopy. X-ray diffraction examination and transmission electron microscopy confirmed that the structure of highly ordered ZnO NRs was crystalline with a strong (002) peak corresponded to ZnO hexagonal wurtzite structure. The growth of highly ordered ZnO NRs was favorable due to the continuous supply of Zn2+ ions and chelating agents properties obtained from the acetylacetonate-derived precursor during the synthesis. Two-point probe current-voltage measurement and UV-vis spectroscopy of the ZnO NRs indicated a resistivity and optical bandgap value of 0.44 Ω.cm and 3.35 eV, respectively. The photoluminescence spectrum showed a broad peak centered at 623 nm in the visible region corresponded to the oxygen vacancies from the ZnO NRs. This study demonstrates that acetylacetonate-derived precursors can be used for the production of ZnO NRs-based devices with a potential application in biosensors.
Polyurethane (PU) with three different functional groups: carboxyl, hydroxyl and sulphonyl group on its molecular structure were synthesised in this work. The synthesised material suppresses blood clotting and exhibits anticoagulant characteristics due to the presence of the important anionic groups. The synthesised PU was blended with polyethersulphone (PES) and fabricated into flat-sheet membrane to study the physico-chemical and biocompatibility properties of the PES membrane for blood purification application. PES-PU flat-sheet membranes were fabricated via the dry-wet phase separation technique. Different loading of PU (0, 1, 2, 3, 4, and 5%) blended with PES was studied and compared. Based on the in-vitro biocompatibility analysis of the membrane, it can be suggested that the membrane incorporated with PU has better anticoagulant properties compared to the pristine PES membrane. PU incorporation prolonged the clotting time, decreased the formation of thrombin, decreased soluble complement component 3a (C3a) generation and suppressed platelet adhesion and aggregation. The anionic groups on the membrane surface might bind to coagulation factors (antithrombin) and the calcium ions, Ca2+ and thus improve anticoagulant ability. Based on both physico-chemical and in-vitro studied, 4% loading of PU is the optimum loading for incorporation with PES membrane. These results suggested that the blended PES-PU membranes with good haemocompatibility allowed practical application in the field of blood purification.
The use of polymeric material in heavy metal removal from wastewater is trending. Heavy metal removal from wastewater of the industrial process is of utmost importance in green/sustainable manufacturing. Production of absorbent materials from a natural source for industrial wastewater has been on the increase. In this research, polyurethane foam (PUF), an adsorbent used by industries to adsorb heavy metal from wastewater, was prepared from a renewable source. Castor oil-based polyurethane foam (COPUF) was produced and modified for improved adsorption performance using fillers, analyzed with laser-induced breakdown spectroscopy (LIBS). The fillers (zeolite, bentonite, and activated carbon) were added to the COPUF matrix allowing the modification on its surface morphology and charge. The materials were characterized using Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), and thermal gravimetry analysis (TGA), while their adsorption performance was studied by comparing the LIBS spectra. The bentonite-modified COPUF (B/COPUF) gave the highest value of the normalized Pb I (405.7 nm) line intensity (2.3), followed by zeolite-modified COPUF (Z/COPUF) (1.9), and activated carbon-modified COPUF (AC/COPUF) (0.2), which indicates the adsorption performance of Pb2+ on the respective materials. The heavy metal ions' adsorption on the B/COPUF dominantly resulted from the electrostatic attraction. This study demonstrated the potential use of B/COPUF in adsorption and LIBS quantitative analysis of aqueous heavy metal ions.