Development of graphene oxide-based styrene/acrylic elastomeric disks from sugarcane bagasse as adsorbents of Nickel (II) ions

Microwave-assisted synthesis of amphoteric fluorescence carbon quantum dots and their chromium adsorption from aqueous solution

The chromium adsorption behavior from aqueous solution by the amphoteric Janus nitrogen-doped carbon quantum dots (AJ-N-CQDs) was investigated. The pseudo-first-order and the second-order adsorption kinetics models were employed to analyze the experimental data; the second-order adsorption kinetics model presented a better correlation to the experimental data, suggesting a chemisorptions process. The values obtained in the pseudo-first-order are still suitable for describing the Kinetics of Cr(VI) sorption. These values elucidate the surface processes involving chemisorption and physisorption in the adsorption of Cr(VI) by AJ-N-CQDs. The R² of the Boyd model gave a better fit to the adsorption data of AJ-N-CQDs (i.e., external diffusion), which means the surface processes involving external Cr(VI) adsorption by AJ-N-CQDs. The higher value of α may be due to the greater surface area of the AJ-N-CQDs for the immediate adsorption of Cr(VI) from the aqueous solution. AJ-N-CQDs have fluorescence spectra before and after Cr(VI) adsorption, indicating they are promising for chemical sensor applications.

Formulation and Characterization of Emulgel-Based Jelly Candy: A Preliminary Study on Nutraceutical Delivery

The development of consumer-friendly nutraceutical dosage forms is highly important for greater acceptance. In this work, such dosage forms were prepared based on structured emulsions (emulgels), where the olive oil phase was filled within the pectin-based jelly candy. The emulgel-based candies were designed as bi-modal carriers, where oil-soluble curcumin and water-soluble riboflavin were incorporated as the model nutraceuticals. Initially, emulsions were prepared by homogenizing varied concentrations (10% to 30% (w/w)) of olive oil in a 5% (w/w) pectin solution that contained sucrose and citric acid. Herein, pectin acted as a structuring agent-cum-stabilizer. Physico-chemical properties of the developed formulations were thoroughly analyzed. These studies revealed that olive oil interferes with the formation of polymer networks of pectin and the crystallization properties of sugar in candies. This was confirmed by performing FTIR spectroscopy and DSC studies. In vitro disintegration studies showed an insignificant difference in the disintegration behavior of candies, although olive oil concentration was varied. Riboflavin and curcumin were then incorporated into the jelly candy formulations to analyze whether the developed formulations could deliver both hydrophilic and hydrophobic nutraceutical agents. We found that the developed jelly candy formulations were capable of delivering both types of nutraceutical agents. The outcome of the present study may open new directions for designing and developing oral nutraceutical dosage forms.

Temperature- and pH-Responsive Super-Absorbent Hydrogel Based on Grafted Cellulose and Capable of Heavy Metal Removal from Aqueous Solutions

In this work, we prepared highly swelling, stimuli-responsive hydrogels capable of the highly efficient adsorption of inorganic pollutants. The hydrogels were based on hydroxypropyl methyl cellulose (HPMC) grafted with acrylamide (AM) and 3-sulfopropyl acrylate (SPA) and were synthesized via the growth (radical polymerization) of the grafted copolymer chains on HPMC, which was activated by radical oxidation. These grafted structures were crosslinked to an infinite network by a small amount of di-vinyl comonomer. HPMC was chosen as a cheap hydrophilic and naturally sourced polymer backbone, while AM and SPA were employed to preferentially bond coordinating and cationic inorganic pollutants, respectively. All the gels displayed a pronounced elastic character, as well as considerably high values of stress at break (several hundred %). The gel with the highest fraction of the ionic comonomer SPA (with an AM/SPA ratio = 0.5) displayed the highest equilibrium swelling ratio (12,100%), the highest volume response to temperature and pH, and the fastest swelling kinetics, but also the lowest modulus. The other gels (with AM/SPA = 1 and 2) displayed several times higher moduli but more modest pH responses and only very modest temperature sensitivity. Cr(VI) adsorption tests indicated that the prepared hydrogels removed this species from water very efficiently: between 90 and 96% in one step. The hydrogels with AM/SPA ratios of 0.5 and 1 appeared to be promising regenerable (via pH) materials for repeated Cr(VI) adsorption.

Preparation and performance of bionanocomposites based on grafted chitosan, GO and TiO2-NPs for removal of lead ions and basic-red 46

Wastewater rich in heavy metals and organic compounds represents one of the essential environmental pollutants. Therefore, a practical approach is to fabricate eco-friendly polymer-based systems with a high ability to absorb pollutants. Herein, bionanocomposites consisting of chitosan (Cs) grafted by various monomers, such as acrylamide (Am), acrylic acid (AA), and 4-styrene sulfonic acid (SSA), and hybrid nanoparticles of graphene oxide/titanium dioxide nanoparticles (GO@TiO₂-NPs) were fabricated. The prepared nanomaterials and bionanocomposites characterized via various tools. The data illustrated that the prepared GO had a thickness of 10 nm and TiO₂-NPs had a diameter of 25 nm. In addition, the grafted chitosan (gCs) using Am and SSA had the largest surface area (gCs2; 22.89 nm) and its bionanocomposite (NC5; 104.79 nm). In addition, the sorption ability of the 0.15 g of prepared bionanocomposites to the (100 mg/L) of lead ions (Pb²⁺) and (25 mg/L) of basic-red 46 (BR46) under various conditions has been studied. The results showed that gCs3 and NC5 had the highest adsorption of Pb²⁺ (79.54 %) and BR46 (79.98 %), respectively. The kinetic study results of the sorbents obeyed the Pseudo second-order model. In contrast, the isothermal study followed the Freundlich adsorption model for Pb²⁺ and the Langmuir adsorption model for BR46.

Eco-friendly Synthesis of Carbon Quantum Dots as an Effective Adsorbent

Fluorescent carbon quantum dots (CQDs) were prepared by an economical, green, and single-step procedure with the assistance of microwave heating of urea with bagasse (SCB), cellulose (C), or carboxymethyl cellulose (CMC). The prepared CQDs were characterized using a series of spectroscopic techniques, and they had petite size, intense absorption in the UV, and excitation wavelength-dependent fluorescence. The prepared CQDs were used for Pb(II) adsorption from an aqueous solution. The removal efficiency percentages (R %) were 99.16, 96.36, and 98.48% for QCMC, QC, and QSCB, respectively. The findings validated the efficiency of CQDs synthesized from CMC, cellulose, and SCB as excellent materials for further utilization in the environmental fields of wastewater pollution detection, adsorption, and chemical sensing applications. The kinetics and isotherms studied found that all CQDs isotherms fit well with the Langmuir model than Freundlich and Temkin models. According to R², the pseudo-second-order fits the adsorption of QCMC, while the first-order one fits with QC and QSCB.

Preparation of hydroxyethyl cellulose/ mangiferin edible films and their antimicrobial properties

In this study, we have used hydroxyethyl cellulose (HEC) to prepare antimicrobial films for multipurpose applications. Using HEC gives mangiferin powder (M) mechanical properties, while mangiferin powder gives HEC antimicrobial activities. Various concentrations of M (2.5, 5 and 10% wt/vol) were added to HEC to enhance the antimicrobial ability of HEC/M films. The results showed that 10% (wt/vol) was the optimum concentration to accomplish the antimicrobial activity. Various analyses were performed to study the prepared films' physical, chemical, mechanical, and antimicrobial properties.

Preparation of photoluminescent and anticorrosive epoxy paints immobilized with nanoscale graphene from sugarcane bagasse agricultural waste

Sugarcane bagasse agricultural waste has been one of the most common solid pollutants worldwide. Thus, introducing a simple method to convert sugarcane bagasse into value-added materials has been highly significant. Herein, we develop a simple and green strategy to reprocess sugarcane bagasse as a starting material for the preparation of graphene oxide nanosheets toward the preparation of novel photoluminescent, hydrophobic, and anticorrosive epoxy nanocomposite coatings integrated with lanthanide-doped aluminate nanoparticles. Environmentally friendly graphene oxide (GO) nanostructures were provided by a single-step preparation procedure from sugarcane bagasse (SCB) agricultural waste using ferrocene-based oxidation under muffled conditions. The oxidized SCB nanostructures were applied as a drier, anticorrosion, and crosslinking agent for epoxy coatings. Different concentrations of pigment phosphor were applied onto the epoxy coating. The generated epoxy-graphene-aluminate (EGA) paints were then coated onto mild steel. The hydrophobic properties and hardness as well as resistance to scratch of the EGA paints were examined. The transparency and colorimetric screening of the EGA nanocomposite paints were determined by the absorption spectral analysis and CIE Lab parameters. The luminescent translucent paints demonstrated a bright green emission at 520 nm when excited at 372 nm. The anticorrosion properties of the painted steel submerged in NaCl_(aq) were inspected by the electrochemical impedance spectral (EIS) method. The EGA paints with phosphor (11% w/w) exhibited the most distinct anti-corrosion properties and long-persistent luminescence. The produced paints displayed high durability and photostability.