Rania E. Morsi

Surface active properties of chitosan and its derivatives

This review discusses the definition of surface active agents and specifically natural polymeric surface active agents. Chitosan by itself was found to have weak surface activity since it has no hydrophobic segments. Chemical modifications of chitosan could improve such surface activity. This is achieved by introducing hydrophobic substituents in its glucosidic group. Several examples of chitosan derivatives with surfactant activity have been surveyed. The surface active polymers form micelles and aggregates which have enormous importance in the entrapment of water-insoluble drugs and consequently applications in the controlled drug delivery and many biomedical fields. Chitosan also interacts with several substrates by electrostatic and hydrophobic interactions with considerable biomedical applications.

Preparation and characterization of chitosan/silver nanoparticle/copper nanoparticle/carbon nanotube multifunctional nano-composite for water treatment: heavy metals removal; kinetics, isotherms and competitive studies

In this work, a multifunctional nanocomposite of chitosan, silver nanoparticles (Ag NPs), copper nanoparticles (Cu NPs) and carbon nanotubes (CNTs) has been successfully prepared. The structure has been confirmed using X-ray diffraction, scanning and transmittance electron microscopes. CNTs, Ag NPs and Cu NPs are distributed homogeneously inside the polymer matrix. The adsorption efficiency of chitosan for Cu(II), Cd(II) and Pb(II) reached 60% using 5 g L−1 adsorbent dose while for the multifunctional composite, it reached 100% adsorption efficiency with a reduction of the amount of adsorbent to 1 g L−1. For the multifunctional composite, 10 min is enough for almost complete removal of metal ions from the solution while for chitosan the efficiency is rather lower. The adsorption process fitted to the pseudo-second order kinetic model and Langmuir isotherm in the linear form in case of chitosan while in case of the multifunctional composite, it fitted to the pseudo-second order kinetic model and Langmuir and Freundlich models in the non-linear forms. The maximum amount adsorbed (Qmax) was found to be directly related to and fitted well with the electrode potential values of metal ions in case of chitosan while for the multifunctional composite, the ionic radius is the most dependent parameter. The multifunctional composite was found to be regenerated effectively using EDTA solution for up to five efficient cycles of adsorption/desorption processes.

Multifunctional nanocomposites of chitosan, silver nanoparticles, copper nanoparticles and carbon nanotubes for water treatment: Antimicrobial characteristics

Multifunctional nanocomposites of chitosan with silver nanoparticles, copper nanoparticles and carbon nanotubes either as bi- or multifunctional nanocomposites were prepared. Change in the overall morphology of the prepared nanocomposites was observed; carbon nanotubes, Ag NPs and Cu NPs are distributed homogeneously inside the polymer matrix individually in the case of the bi-nanocomposites while a combination of different dimensional shapes; spherical NPs and nanotubes was observed in the multifunctional nanocomposite. Multifunctional nanocomposites has a higher antimicrobial activity, in relative short contact times, against both Gram negative and Gram positive bacteria; E. coli, Staphylococcus aureus; respectively in addition to the fungal strain; Aspergillus flavus isolated from local wastewater sample. The nanocomposites are highly differentiable at the low contact time and low concentration; 1% concentration of the multifunctional nanocomposite is very effective against the tested microbes at contact time of only 10min.

Superabsorbent enhanced-catalytic core/shell nanocomposites hydrogels for efficient water decolorization

Spherical polyacrylamide (PAM) nanoparticles were prepared by inverse emulsion polymerization and were found to have an average particle size of 20 nm. In situ inverse emulsion polymerization of acrylamide in the presence of metal oxides nanoparticles (TiO2 and ZnO, either individually or in a mixture) was performed. Transmission electron microscope images clearly confirmed the formation of core/shell nanocomposite structures with inner metal oxide cores coated with a polyacrylamide shell. The composites were further cross-linked to prevent structural deformation in water. The water absorbencies of the prepared composites were 1660, 900, 1000 and 700% for PAM, TiO2/PAM, ZnO/PAM, and TiO2–ZnO/PAM core/shell nanocomposites, respectively. The water decontamination efficiency of the prepared composites was investigated using organic dyes as models of organic contaminants. The decolorization efficiency of the prepared composites was investigated in the dark and under illumination. The nanocomposites showed good ability for photodecolorization, especially the titania nanocomposite, which showed the best ability to photodecolorize Black T and Indigo dyes. A synergetic effect between the adsorption properties of the polymer and the photocatalytic activity of the metal oxides is proposed.

A new modified low-energy emulsification method for preparation of water-in-diesel fuel nanoemulsion as alternative fuel

ABSTRACT In this research, 24 of water-in-diesel fuel nanoemulsions were prepared using mixed nonionic surfactants of sorbitan monooleate and polyoxyethylene sorbitan trioleate (MTS). The emulsions were formed using a new modified low-energy method at hydrophilic-lipophilic balance (HLB) value of 10 and a working temperature of 20°C. Five HLB values of 9.6, 9.8, 10, 10.2, and 10.4 were prepared to identify the optimum value that gives low water droplet size at working conditions as: 5 wt% of water contents, 10 wt% of mixed surfactant concentration, and a temperature of 20°C. The effect of mixed surfactant concentration and water content on the droplet size for 0, 15, 30, 60, and 90 days has been studied. Droplet size of the prepared nanoemulsions was determined by dynamic light scattering and the nanoemulsion stability was assessed by measuring the variation of the droplet size as a function of time. Results show that the mean droplet sizes were formed between 26.23 and 277.1 nm depending on the surfactant concentrations, water contents, and storage time. GRAPHICAL ABSTRACT

Petroleum Oil Dispersion Efficiency and Stability Using Eco-Friendly Chitosan-Based Surfactant and Nanoparticles

In this article, a new aspect of comparing oil dispersion efficiency and stability using eco-friendly surfactants and nanoparticles of the same natural origin was carried out. Nanoparticles effectively disperse oil in water as well as do surfactant but with different actions; surfactants act by reducing the interfacial tension between oil and water leading to the distribution of oil in water while nanoparticles give stable and uniform distribution of oil in water depending on oil trapping inside the polymer matrix. As a result, the dispersion stability of nanoparticles was found to be superior to that of surfactant.

Chapter 44 – Chitosan-Oregano Essential Oil Blends Use as Antimicrobial Packaging Material

Edible films have been in use for more than 100 years. It started with the application of wax coatings to fruit and vegetables and now includes active edible films with selectivity toward mass transfer, light barrier, and antimicrobial activity. The market for edible films and coatings has experienced remarkable growth over the last 5 years. Accompanying this growth is a vast amount of knowledge on edible films and coatings acquired through research and product development work as well as advances in material science and processing technology. Recently, increasing attention has been given to developing and testing films with antimicrobial properties to improve food safety and shelf life. Active biomolecules such as chitosan and its derivatives have a significant role in the food packaging area, as it is a biodegradable, biocompatible, nontoxic, and antimicrobial agent with excellent film properties. All this made it an active member in the food packaging industry. However, chitosan edible films still suffers from high water vapor permeation, which lowers its protective action. Therefore, the addition of oregano essential oil increases its hydrophobicity and improves its water vapor permeation. Oregano essential oil has high levels of carvacrol, thymol, γ-terpinene, and p-cymene and shows a high level of antimicrobial activity against different strains of Gram-positive and Gram-negative bacteria. This chapter traces chitosan oregano essential oil blends in recent research for the production of antimicrobial packaging.

Nanostructured mesoporous silica: influence of the preparation conditions on the physical-surface properties for efficient organic dye uptake

A series of ordered mesoporous silica such as MCM-41, SBA-3 and SBA-15, in addition to silica micro- (SM) and nano- (SN) mesoporous particles, were prepared. The preparation conditions were found to greatly influence the physical-surface properties including morphological structure, porosity, particle size, aggregate average size, surface area, pore size, pore volume and zeta potential of the prepared silica, while the chemical structure, predicted from FT-IR spectra, and the diffraction patterns, predicted from wide-angle X-ray diffraction spectra, were identical. Surface areas of approximately 1500, 1027, 600, 552 and 317 m2 g−1, pore volumes of 0.93, 0.56, 0.82, 0.72 and 0.5 cm3 g−1, radii of 2.48, 2.2, 5.66, 6.6 and 8.98 nm, average aggregate sizes of 56, 65.4, 220.9, 73, 61.1 and 261 nm and zeta potential values of −32.8, −46.1, −26.3, −31.4 and −25.9 mV were obtained for MCM-41, SBA-3, SBA-15, SN and SM, respectively. Methylene blue dye uptake capacity of the prepared silica types was investigated using the batch technique and, in addition, the most effective material was further studied by the column flow system. The kinetics and isotherms of the uptake process were studied. The morphological structure, surface area, pore radius and zeta potential values were the most correlated factors.

Aquatic environmental risk assessment of chitosan/silver, copper and carbon nanotube nanocomposites as antimicrobial agents

Despite the potential antimicrobial and water purification benefits of chitosan-based nanocomposites, there are growing concerns regarding the hazards of leached nanoparticles (NPs) to the in-contact circumference. The antibacterial performance of the nanocomposites of chitosan with silver and copper NPs and carbon nanotubes was assessed with an emphasis on their impact on fish health. The minimal inhibitory concentrations of each preparation and the growth curves of Aeromonas hydrophila exposed to different nanocomposites were measured. Five groups of Oreochromis niloticus were exposed to chitosan nanocomposites for three weeks. A combination of a low concentration of the NPs in the chitosan matrix improved their antimicrobial properties. However, aqueous exposure to these materials still had hazardous effects on fish health. Experimental groups of O. niloticus exposed to these nanocomposites exhibited oxidative stress, tissue DNA fragmentation and higher expression of pro-inflammatory and immune-related genes such as TNF-α and IL1β. Various pathological tissue alterations were observed in gills, liver, spleen and intestine. Exposure to some of the prepared nanocomposites led to significant DNA damage in hepatic cells with a marked increase in the apoptotic index.