Sonochemical synthesis and characterization of emulsion polymer for sorption of lanthanides

Synthesis of N-isopropyl acrylamide copolymerized acrylic acid caped with Dibenzo-18-crown-6 composite for selective separation of Co-60 radioisotope from radioactive liquid waste containing Cs-137

A new selective polymeric composite capped with crown ether was successfully synthesized using N-isopropyl acrylamide copolymerized acrylic acid paired with Dibenzo-18-crown-6, P(NIPAm-Co-AA-DB 18C-6), by Gamma irradiation and ultrasonic homogenizer polymerization. Scanner electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and dynamic light scattering were used to characterize the selected polymeric composite's chemical and physical constitution. SEM shows a rough irregular surface, and FTIR spectra confirmed the function groups of P(NIPAm-Co-AA-DB 18C-6). Moreover, a systematic study of monomer and crown ether concentration was investigated to enhance the composite's performance. The behavior of the synthetic composite toward the selective separation of Co-60 from Cs-137 in a binary system was evaluated. Effects of pH, contact time, and initial ion concentration were investigated in a batch mode and the maximum capacity reached 108.0 mg/g for Co-60 and 82.0 mg/g for Cs-137. Four Kinetic models were investigated (pseudo-first-order, pseudo-second-order, Elovich, and Intra-particle diffusion). Regarding the calculated parameters, pseudo-second-order and Elovich models are the most describing the sorption process, indicating the chemisorptions process. Six adsorption isotherms were examined, two-parameter models (Langmuir, and Freundlich) and three-parameter models (Redlich-Peterson, Khan, Sips, and Hills). The best-fitted isotherm was identified using three error methodological approaches: the correlation coefficient (R2), the chi-square test (χ2), and the root-mean-square error. Isotherm models fit the experimental values in the following sequence: Khan > Rdlish-Peterson > Hills > Sips. Finally, an application for column separation was conducted, and Co-60 was completely separated from Cs-137 by 0.1 M HNO3. These findings indicate promising applications in the successive separation of Co-60 from radioactive liquid waste containing Cs-137 from Egyptian reactors.

Graphical abstract

Ultrasonic/sonochemical synthesis and evaluation of nanostructured oil in water emulsions for topical delivery of protein drugs

Delivery of drugs and active agents to human skin by formulation containing nanosystems have shown remarkable advance in recent nanotechnology research. The aim of current investigation is to study protein drug, extracted from medicinal leech tissue and evaluate an isotropic and kinetically stable nanoemulsion formulation, with least surfactant and co-surfactant concentrations also with optimal solubility and stability, for topical delivery. It is a fact that physical properties of oil phase has an impact on nanoemulsion formation and stabilization. In this research, various factors, such as oil types (olive oil and sesame oil) and oil content for their effects on particle size and stability of protein nanoemulsion were first investigated. Secondly, optimized formulation of protein nanoemulsion was characterized by droplet size and zeta potential analysis, Transmission electron microscopy (TEM), viscosity, pH, and refractive index. Thirdly, stability studies were done to select the best formulation. The results of our experiments showed that an increase in the concentration of olive oil and sesame oil led to a nanoemulsion with smaller size of droplets and with higher stability, respectively. However; slight variations in droplet size were observed in case of nanoemulsion with olive oil. As a result of various experiments, a Nanoemulsion with 25% olive oil was selected as optimized formulation owing to its much smaller droplet size (143.1 nm), lower polydispersity index, higher zeta potential (-33.3 mV). No considerable changes in droplet size, viscosity and pH occurred during a 30-day storage period at 4 °C. This procedure also suggested that our selected nanoemulsion was physically stable. Additionally, TEM revealed that particles were morphologically spherical. In conclusion, our analyses of the experiments proved the fact that nanoemulsions are promising novel formulations for protein drugs and can greatly enhance stability of protein drugs.