Electrospinning, the most favorable process of obtaining nanofibers, is capable of processing solution or melt polymers, ceramic materials or metals in many morphological variants, thus providing diverse functionalities. The chapter reviews the main ways in which nanofibers' characteristics can be influenced by solution parameters, process parameters and ambient conditions, afterwards focusing on the role of some of the most significant electrospinning parameters (applied voltage, flow rate, nozzle to collector distance) on the diameter of the nanofibers. Experimental studies to model the influence of process parameters in the case of electrospinning polyetherimide solutions are presented. Response surface methodology and MATLAB simulation software have been used to obtain the mathematical models that indicate the most favorable parameters.Electrospun nanofibers have many applications in filtration processes, bio-medicine (tissue engineering, drug delivery, scaffolds and wound healing), in energy devices and sensors, depending on their morphological characteristics. The morphology of the fibers obtained through electrospinning is governed by many factors. These factors are related to the polymer solution characteristics, process and ambient parameters. Main electrospinning parameters affecting nanofibers morphologyThe morphology of the nanofibers obtained through electrospinning is influenced by many factors. These factors can be grouped into three categories: polymer solution characteristics, process parameters and ambient parameters. Knowing the way these factors influence the electrospinning process, it becomes easier to obtain nanofibers with controlled structure and required functions [1, 2]. Polymer solution ViscositySome of the key parameters of the electrospinning process are the surface tension and the viscoelastic properties of the polymer solution [3][4][5]. The correct choice of the concentration of the polymer solution has a decisive effect on these processes, respectively, on the characteristics of the obtained nanofibers (diameter and morphology) [6,7].It is generally accepted that the viscosity of the polymer solution is the decisive parameter of the process, including the possibility of electrospinning and the characteristics of the nanofibers. In order to make electrospinning possible, the viscosity must be in a relatively narrow range. At very low viscosity values, the polymer filaments break and polymer droplets are produced, while at very high viscosity values, the polymer solution cannot pass through the nozzles and electrospinning does not take place. The area of optimum viscosity depends essentially on three parameters: the nature of the polymer, the nature of the solvent and the concentration of the polymer solution.There is a direct proportionality relationship between the concentration of the electrospun polymer solution and the diameter of the obtained nanofibers, but the value of the ratio of proportionality varies within relatively large limits.Electrospinning Method Used to Create F...

The objective of this work is to evaluate the feasibility of adsorption decolorization and recycling of polyamide acid dyeing baths in order to develop an in-plant decolorization system leading to water conservation and wastewater minimization. The color of the wastewater produced in the dyeing process of polyamide at two dye concentrations and in the rinsing phase has been removed by sorption. Two acid dyes from the same commercial range (Bezanyl) have been tested, both used without previous purification. Synthetic wastewater of known chemical composition has been used. The adsorbent that has been used is an acrylic weak base anion exchange resin with ethylenediamine functional groups, selected from several anion exchange resins. The color removal degree, expressed in percentage, was calculated from the relative decrease of absorbance. It was found that color removal is more efficient at 50 o C, especially for the green dye. The presence of the electrolyte favourizes the sorption, in what concerns both efficiency and duration of the process. Afterwards, bleached polyamide fabric was dyed with the two dyes, and the wastewater has been treated and recycled in scouring processes, as it is or mixed with fresh water (1:1). The color parameters, the color difference and the degree of whiteness of the polyamide samples scoured with recycled water were measured. The results of this study demonstrate that recycling of in-plant decolorized wastewaters from acid dyeing in new preparation stages is feasible, especially for low concentration dyeing, and has the potential to not only decrease wastewater volume and treatment cost, but also minimize water use as well as the discharge of textile pollutants such as salt and dyes.

Nanotechnology exerts a significant influence on materials science, providing new insights into the design of functional materials. One of the most studied areas of nanotechnologies is that of nanofibres, characterised by high specific volume, chemical activity and volume-dependent physical processes. The most promising method of producing nanofibres with various morphologies and functionalities from different materials is electrospinning, where high voltage is applied between the spinneret and the collector to the charged polymer solution (or melt) to draw polymer filaments. This chapter reviews the main electrospinning techniques for producing nanofibres from polymers, provides an overview on the influence of the spinning solution characteristics, the process parameters and the working environment on the process and highlights the many applications of electrospun nanofibres in the field of sensors. Latest advances in this field and the prospects for obtaining new electrospun nanofibre sensors are discussed.

There are many treatment methods used to remove color from textile wastewater, and Fenton oxidation, a well known Advanced Oxidation Process is one of the most efficient. Apart of Fe(II), other metal ions have been used as catalysts in Fenton's Reagent, and Cu(II) proved to be a good alternative. In this study the effect of the concentration of dye, catalyst and hydrogen peroxide were studied and optimized for the discoloration process of Reactive Black 5 using a Fenton-like process, H 2 O 2 /Cu(II) type. The experimental results were subjected to multiple linear regression analysis using MINITAB 16 software. The experimental data fitted to the second-order model, showing good regression prediction as the value of the coefficient of determination was high (R 2 = 0.9843). ANOVA showed that all three independent variables significantly affected the color removal. The significance of variables affecting the discoloration process and the possible relationships between them, whether antagonistic or synergistic, has been evaluated using the Response Surface Methodology (RSM). Optimum conditions indicated by the regression model for achieving maximum decolorization were found as: dye concentration 7.8 mg/L, catalyst concentration 1.52 mM and hydrogen peroxide concentration 14.68 mM. The maximum color removal was 92.278% at optimum conditions.