A glassy carbon (GC) electrode modified with multi-walled carbon nanotubes (MWCNTs) and platinum nanoparticles (PtNPs), Pt/MWCNTs-GC, has been introduced for formic acid electro-oxidation (FAO). A similar loading of PtNPs has been conserved for a proper comparison between the Pt/MWCNTs-GC and the unmodified Pt/GC electrodes. The modification with MWCNTs could enhance the loading of PtNPs onto the GC electrode in a way that minimizes its agglomeration and increases its dispersion in the CNTs network. This not only increases the surface area exposed to the reaction but also interrupts the contiguity of the Pt active sites minimizing the adsorption of the poisoning CO. As a result, both of the / and / ratios were increased by 12.5 and 2.5 times. Several techniques will be combined to track the catalyst activity and to determine its morphology.
Background The use of hydrogel materials as adsorbents for heavy metal ions removal has grabbed the attention of several researchers due to its high removal capacity and generatability, thus providing both operational and economic efficiency. Aim The design phase of fabricating the hydrogel material is a very critical step. A full knowledge of the effect of different potential functional groups and their interactions together can surely save resources and time. Objective This study evaluates the removal capacity of different hydrogels whose functional groups remove via ion-exchange versus electrostatic interactions. Method The removal of Poly(2-Acrylamido-2-Methylpropane Sulphonic Acid) (PAMPS) was compared to that of sodium polyacrylate (NA-PA) hydrogels, which remove metals through electrostatic attraction and ion exchange respectively. Result It was found that the removal capacity of PAMPS, which has two anionic functional groups, is almost as good as one salt group available for ion exchange, reaching up to 92% and 87% respectively. A semi-interpenetrating network (IPN) based on both hydrogels showed slightly decreased removal capacity, almost to 80%, which was interpreted due to the loss of some active sites due to the inevitable attraction between PAMPS’s anionic functional groups and Na-PA’s salt group. Conclusion The obtained results encourage the use of hydrogel materials with salt groups employing ion-exchange mechanism.
Background Hydrogels are relatively newly developed materials that has piqued the curiosity of scientists in various fields, particularly for wastewater treatment applications. Heavy metal ions and dye removal hydrogels is becoming more popular due to its ease of use, low cost, increased effectiveness, biodegradability, and reusability. Objective Evaluate and study the adsorption behaviour of different hydrogel materials towards heavy metal ions and dyes. Methods The hydrogels investigated are Poly(2-Acrylamido-2-Methylpropane Sulphonic Acid) (PAMPS) hydrogels, commercial sodium polyacrylates (Na-PA), chitosan (CH), along with their binary and ternary mixtures. A semi-interpenetrating network (IPN) based on PAMPS and Na-PA was also investigated. The performance of each hydrogel towards six different heavy metals (Co+2, Cu+2, Ni+2, Cd+2, Zn+2, and Mn+2), cationic Methylene Blue (MB) dye, and anionic Methyl Orange (MO) dye, was studied and analysed. Results It was found that the Na-PA/CH hydrogel was the best performing hydrogel for heavy metal removal, removing more than 84% of all metals, followed by PAMPS/Na-PA which removed up to 70%. The best hydrogel mixture with both cationic and anionic dyes is PAMPS/CH, removing 90.1% and 85%, respectively. The proposed dye removal mechanism is electrostatic attraction between the dyes and the charged functional groups on the hydrogel’s surface. Conclusion It is concluded that the use of Na-PA with CH for heavy metal removal yields better results than when using each hydrogel separately. For dye removal, it was found that combining PAMPS with CH creates a very promising hydrogel suitable for removing both anionic and cationic dyes, which is critical for industrial applications.
Introduction: Hydrogels are hydrophilic polymers which are cross-linked to form three-dimensional structures, which can absorb, swell and retain huge amounts of water or aqueous fluids. Objective: This paper reports the preparation and characterisation of Poly(2-Acrylamido-2-Methylpropane Sulphonic Acid) (PAMPS) hydrogel with different crosslinking intensities. Methodology: 2-Acrylamido-2-methylpropane sulfonic acid (AMPS) monomer was purchased from Alfa Aesar Company as reagent grade. It was used as received (>98% purity) without any further purification. PAMPS hydrogel was prepared by free radical crosslinking solution polymerization of AMPS in water at room temperature under a nitrogen blanket in cylindrical glass tubes. The characteristics of the obtained PAMPS hydrogel were compared with those of commercial sodium polyacrylates hydrogel. Results: It was found that decreasing the crosslinker weight improved the absorbance capacity but to a limit. The suggested reasons were discussed. The mixture showed higher absorbance rate than PAMPS, and bigger absorbance capacity than sodium polyacrylates. Conclusion: This paper investigates the effect of crosslinker ratio on the swelling capacity of PAMPS. It was found that as the crosslinking ratio decreases, the porosity of the hydrogel increases, thus improving the swelling capacity.
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