Multivariate-Assisted Solid Phase Extraction Procedure for Simultaneous Preconcentration and Assessment of UV-Filters in Wastewater Prior to UV-Vis Spectrophotometric Determination

Determination of emerging pollutants such as UV-filters in environmental samples is very important because they have been proven to have harmful effects on human and aquatic life. In this study, a simple, fast and inexpensive method combining solid phase extraction (SPE) and UV spectrophotometry was developed for simultaneous preconcentration and determination of benzophenone and sulisobenzone in wastewater samples. The effect of factors affecting the preconcentration of UV-filters was optimized using univariate and multivariate approach. Under optimized conditions, the limits of detection (LOD), limits of quantification (LOQ) and preconcetration factors were in the range of 0.15–0.28 and 0.50–0.93 μg L−1, 50–55, respectively. The dynamic linear range was up to 250 μg L−1 for benzophenone and sulisobenzone. In addition, the intra- and inter-day precisions were 3.1–3.3 and 4.5–5.2%, respectively. The developed method was successfully applied to determine UV filters in wastewater samples attaining satisfactory recoveries over the range of 99.3–100.7%. The concentration of the target pollutants in wastewater samples ranged from 6.83 to 85.67 μg L−1

Ultrasound Assisted-Homogeneous Liquid-Liquid Phase Microextraction based on Deep Eutectic Solvents and Ethyl Acetate for Preconcentration of Selected Organochlorine Pesticides in Water Samples

Abstract: A novel and greener methodology for the simultaneous preconcentration of organochlorine pesticides in water samples based on ultrasound assisted-homogeneous liquid-liquid phase microextraction (UA-HLLME) has been developed. Gas chromatography-time of flight mass spectrometry was used for quantification of OCPS in water samples. In this method, choline-chloride-ethylene glycol deep eutectic solvent and ethyl acetate were used as the disperser solvent and extraction solvent, respectively. Univariate and multivariate approaches were used for optimization of the influential parameters that affect the extraction efficiency of the UA-HLLME method. Under the optimum conditions, enrichment factors ranging from 152 to 403 with acceptable recoveries of 85-100% were obtained. The dynamic linear ranges were obtained in the concentration range 0.015–1000 μg L−1 with correlation coefficients ranging 0.9952–0.9995. The limits of detection and quantification of the developed UA-HLLME method were in the range 1.9-8.6 ng L−1 and 5.9-26 ng L−1, respectively. The intra-day and inter-day precision expressed in terms of relative standard deviation (%RSD) ranged from 2.1-4.5% and 3.9-7.3%, respectively. The developed method was successfully applied for the preconcentration and determination of the selected OCPs from 3 different river water samples. The developed procedure displayed simplicity, environmental friendliness, relatively high extraction efficiency, short analysis time and relatively low detection limits

Near-Infrared Spectroscopy Combined with Multivariate Tools for Analysis of Trace Metals in Environmental Matrices

Environmental contamination by trace elements is becoming increasingly important problem worldwide. Trace metals such as cadmium, copper, lead, chromium, and mercury are major environmental pollutants that are predominantly found in areas with high anthropogenic activities. Therefore, there is a need for rapid and reliable tools to assess and monitor the concentration of heavy metal in environmental matrices. A nondestructive, cost-effective, and environmentally friendly procedure based on near-infrared reflectance spectroscopy (NIRS) and chemometric tools has been used as alternative technique for the simultaneous estimation of various heavy metal concentrations in environmental sample. The metal content is estimated by assigning the absorption features of metals associated with molecular vibrations of organic and inorganic functional groups in organic matter, silicates, carbonates, and water at 780–2500 nm in the near-infrared region. This chapter, reviewed the application of NIRS combined with chemometric tools such as multiple linear regression (MLR), principal component regression (PCR), and partial least squares (PLS) regression. The disadvantages and advantages of each chemometric tool are discussed briefly

Platinum-Based Carbon Nanodots Nanocatalysts for Direct Alcohol Fuel Cells

Platinum and its alloys are regarded as best nanocatalysts for the electro-oxidation of alcohol fuels especially in acidic conditions. The performance of nanocatalysts for alcohol fuel cells depends greatly on the support material. A good support material should have high surface area to obtain high metal dispersion. It should also bond and interact with the nanocatalysts to improve the activity of the overall electrode. Most importantly, the support material should offer great resistance to corrosion under the harsh fuel cell conditions. In this chapter, the use of carbon nanodots as support materials for Pt-Sn and Pt-TiO2 nanoparticles is discussed. The electrochemical activity of Pt/CNDs, Pt-Sn/CNDs and Pt/CNDs-TiO2 nanocatalysts was studied using cyclic voltammetry (CV) in acidic and alkaline conditions. Chronoamperometry (CA) was used to investigate the long-term stability of the nanocatalysts under the fuel cell environment. Electrochemical results demonstrated that binary Pt nanocatalysts are more active compared to monocatalysts. It was also observed that carbon nanodots are better support materials than carbon black. Blending carbon nanodots with titanium dioxide (a ceramic material) improves the corrosion resistance of the nanocatalyst. Cyclic voltammetry results also proved that alcohol electro-oxidation is enhanced in alkaline conditions

Wastewater Treatment Using Membrane Technology

Water contamination by heavy metals, cyanides and dyes is increasing globally and needs to be addressed as this will lead to water scarcity as well as water quality. Different techniques have been used to clean and renew water for human consumption and agricultural purposes but they each have limitations. Among those techniques, membrane technology is promising to solve the issues. Nanotechnology present a great potential in wastewater treatment to improve treatment efficiency of wastewater treatment plants. In addition, nanotechnology supplement water supply through safe use of modern water sources. This chapter reviews recent development in membrane technology for wastewater treatment. Different types of membrane technologies, their properties, mechanisms advantages, limitations and promising solutions have been discussed

Application of activated carbon-decorated polyacrylonitrile nanofibers as an adsorbent in dispersive solid-phase extraction of fluoroquinolones from wastewater

A cheap and simple sample preparation method, consisting of a dispersive solid-phase method and an adsorbent, activated carbon decorated PAN nanofibers, was employed and used for the extraction of antibiotics (ciprofloxacin, danofloxacin, and enrofloxacin) in wastewater. Electrospun PAN nanofibers that were decorated with activated carbon produced from waste tires were used as the solid phase and the antibiotics analyzed by using high-performance liquid chromatography. Parameters such as pH, mass of adsorbent (MA), extraction volume (EV), and extraction time (ET) were optimized owing to their potential effect on the extraction of antibiotics from water. The recovery of all antibiotics was satisfactory, in the range of 90%–99%. The limits of detection and quantification were 0.05, 0.11, 0.20, and 0.53, 1.21, 2.17 µg/L, respectively. The precision was determined from the repeatability and reproducibility and expressed as the intra-day (n = 20) and inter-day (n = 5) precision. The intra-day and inter-day precision was reported in terms of the percentage relative standard deviation, which was 3% and 4%, respectively. The adsorption capacity of the activated carbon-decorated PAN nanofibers was satisfactory, and the reusability of the adsorbent was impressive when reused ten times. The accuracy of the dispersive solid phase extraction (DSPE) was validated by spike recovery tests; the results proved the reliability and efficiency of adsorbing antibiotics from wastewater. Finally, the proposed method was applied to wastewater samples collected from a wastewater treatment plant, which included influent, secondary, and effluent wastewater. Keywords: Wastewater, Nanofibers, Activated carbon, Antibiotics, Polyacrylonitril

Nanocomposites for Electrochemical Sensors and Their Applications on the Detection of Trace Metals in Environmental Water Samples

The elevated concentrations of various trace metals beyond existing guideline recommendations in water bodies have promoted research on the development of various electrochemical nanosensors for the trace metals’ early detection. Inspired by the exciting physical and chemical properties of nanomaterials, advanced functional nanocomposites with improved sensitivity, sensitivity and stability, amongst other performance parameters, have been synthesized, characterized, and applied on the detection of various trace metals in water matrices. Nanocomposites have been perceived as a solution to address a critical challenge of distinct nanomaterials that are limited by agglomerations, structure stacking leading to aggregations, low conductivity, and limited porous structure for electrolyte access, amongst others. In the past few years, much effort has been dedicated to the development of various nanocomposites such as; electrochemical nanosensors for the detection of trace metals in water matrices. Herein, the recent progress on the development of nanocomposites classified according to their structure as carbon nanocomposites, metallic nanocomposites, and metal oxide/hydroxide nanocomposites is summarized, alongside their application as electrochemical nanosensors for trace metals detection in water matrices. Some perspectives on the development of smart electrochemical nanosensors are also introduced