Mohamad M. Ayad

Synthesis of silver-anchored polyaniline–chitosan magnetic nanocomposite: a smart system for catalysis

A simple route was employed for the fabrication of a polyaniline (PANI)–chitosan (CS)–magnetite (Fe3O4) nanocomposite (PANI–CS–Fe3O4) via the in situ polymerization of aniline in the presence of CS using anhydrous iron(III) chloride as an oxidizing agent. The magnetic character of the nanocomposite results from the presence of iron oxide nanoparticles, which were formed as side products during the synthesis of the PANI–CS nanocomposite. The synthesized PANI–CS–Fe3O4 nanocomposite was fully characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The reduction of silver nitrate by the synthesized nanocomposite enables the anchoring of silver (Ag) nanoparticles onto its surface. The catalytic properties of the Ag-decorated nanocomposite (Ag@PANI–CS–Fe3O4) toward the reduction of 4-nitrophenol was investigated using sodium borohydride as a reducing agent.

pH-Responsive sulphonated mesoporous silica: a comparative drug release study

Control of morphology and surface functionalization of mesoporous silica materials have enhanced the biocompatibility of these materials with high surface areas and total pore volumes. The functionalization of mesoporous silica materials with organic moieties exhibited controlled release and molecular recognition capabilities for drug delivery. Design of functional mesoporous silica with various mechanisms of controlled release and introduction of new characteristics is very interesting for the construction of highly selective drug carrier. Loading of procaine hydrochloride drug (PrHy) into functionalized KIT-6-SO3H and SBA-15-SO3H was investigated by a quartz crystal microbalance (QCM) technique and UV-visible spectroscopy. The release was carefully studied by systematically tuning the pH media at simulating gastric fluid without pepsin (SGF, pH 2) and simulating intestinal fluid without pancreatin (SIF, pH 7.4), as well.

Polypyrrole-coated cotton textile as adsorbent of methylene blue dye

Pollution caused by organic dyes is of serious environmental and health concern to the population. Dyes are widely used in textile coloring applications. In the present work, cotton textile was coated with a conducting polymer, polypyrrolexa0(PPy), in situ during the oxidative polymerization of pyrrole. The resulting materials were utilized as easily separated and recyclable adsorbent for the removal of methylene blue (MB)xa0as a modelxa0of cationic dyes in alkaline solutions. It showed also some affinity to remove Acid Green 25 as an anionic dye in acidic medium. The adsorption was assessed by monitoring the decrease in dye concentration by UV–Visiblexa0absorption spectroscopy. The influence of various parameters such as initial dye concentration, contact time, pH, temperature, and adsorbent dose on the adsorption process was studied. The pseudo-second-order kinetic model and Freundlich isotherm model were found to describe the adsorption process. The thermodynamic study revealed that the adsorption of MB by PPy was feasible, spontaneous, and exothermic process. Investigation of the substrate regeneration revealed that PPy deposited on cotton textile can be reused for dye adsorption several times with good efficiency and it allows for the recovery of MB for recycling purposes.

Cyclodextrin Functionalized Mesoporous Silica for Environmental Remediation of Methylene Blue Dye

Functionalization of mesoporous silica KIT-6 with β-cyclodextrin (β-CD) was successfully realized via post-grafting method as a new adsorbent for environmental remediation of methylene blue (MB) dye from aqueous solutions. The mesostructure properties were characterized by transmission electron microscope (TEM), low-angel X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and N₂ sorption isotherm. The remarkable adsorption of MB into β-CD-KIT-6 adsorbent was studied using UV-visible spectroscopy. The β-CD-KIT-6 exhibited higher adsorption capacity compared with unmodified-KIT-6. The adsorption behavior of MB into the β-CD-KIT-6 and unmodified-KIT-6 was carefully investigated using different kinetic and isotherm models. The adsorption process followed a pseudo-second order kinetic model and well-fitted to Langmuir isotherm. The thermodynamic parameters were evaluated and the adsorption of MB was found to be an exothermic and spontaneous process. The adsorption of MB into the β-CD-KIT-6 was highly dependent on the solution pH.

Acid green crystal-based in situ synthesis of polyaniline hollow nanotubes for the adsorption of anionic and cationic dyes

In this article, acid green (AG) dye played a dual pivotal role. The first role is as a structure-guiding agent and a soft template for the acid-free synthesis of polyaniline hollow nanotubes (PANI-HNTs) while the second role is as a target dye to be removed as a model of anionic dyes, alongside methylene blue (MB) as a model of cationic dyes. After characterization using X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), nitrogen adsorption–desorption isotherms (BET), and UV-visible absorption spectroscopy techniques, the prepared PANI-HNTs were exploited for the adsorption of basic MB dye and acidic AG dye from aqueous media. To optimize the adsorption process, the effects of different variables, such as adsorbent dose, contact time and pH, were studied. Due to the structural differences between the MB and AG dyes, the obtained data revealed that the best pH for the medium for optimal adsorption was 9.0 and 3.0, respectively. The rapid sorption dynamics were found to proceed in a second-order kinetic model and the equilibrium data for the adsorption of MB and AG dyes were fitted well to the Langmuir isotherm. The maximum monolayer capacity, qmax, for MB and AG was calculated from the Langmuir model and equalled 69.4 and 57.8 mg g−1, respectively. A thermodynamic study revealed that the adsorption of MB by PANI-HNTs was a feasible, spontaneous, and exothermic process. Investigation of the substrate regeneration revealed that PANI-HNTs can be reused for dye adsorption several times. Therefore, the synthesized PANI-NTs are highly efficient for the dual removal of basic and acidic dyes. TEM images showed that PANI-HNTs were formed with an external and internal diameter of 50–60 nm and 5–10 nm, respectively.

Polypyrrole-coated cotton fabric decorated with silver nanoparticles for the catalytic removal of p-nitrophenol from water

The development of new catalytic transformations with easy separation and recyclability is essential in chemical synthesis. An efficient heterogeneous catalytic system composed of a conducting polymer, polypyrrole (PPy), deposited on cotton fabric support, and decorated with silver nanoparticles is described. Such ternary composites can be used in environmental issues, such as water-pollution treatment. The model reduction of p-nitrophenol to p-aminophenol with sodium borohydride was investigated by means of UV–visible spectroscopy. The reaction was catalyzed even by PPy alone and the catalytic effect was strongly enhanced by silver nanoparticles. It obeys the first-order kinetics. The catalytic effect increases with the catalyst dose due to increased number of catalytic sites. This also applies to the increased content of silver. The elevated temperature as well as the reduced polarity of the reaction medium have negative effect on the catalyst performance. The catalysts can be reused several times while maintaining good efficiency. The ternary composites are thus good candidates for the catalytic reductive removal of toxic compounds from water.