Method for the fast determination of bromate, nitrate and nitrite by ultra performance liquid chromatography–mass spectrometry and their monitoring in Saudi Arabian drinking water with chemometric data treatment

A rapid, sensitive and precise method for the determination of bromate (BrO3(-)), nitrate (NO3(-)) and nitrite (NO2(-)) in drinking water was developed with Ultra performance Liquid Chromatography-Mass Spectrometry (UPLC-ESI/MS). The elution of BrO3(-), NO3(-) and NO2(-) was attained in less than two minutes in a reverse phase column. Quality parameters of the method were established; run-to-run and day-to-day precisions were <3% when analysing standards at 10µgL(-1). The limit of detection was 0.04µg NO2(-)L(-1) and 0.03µgL(-1) for both NO3(-)and BrO3(-). The developed UPLC-ESI/MS method was used to quantify these anions in metropolitan water from Saudi Arabia (Jeddah, Dammam and Riyadh areas) and commercial bottled water (from well or unknown source) after mere filtration steps. The quantified levels of NO3(-) were not found to pose a risk. In contrast, BrO3(-) was found above the maximum contaminant level established by the US Environmental Protection Agency in 25% and 33% of the bottled and metropolitan waters, respectively. NO2(-) was found at higher concentrations than the aforementioned limits in 70% and 92% of the bottled and metropolitan water samples, respectively. Therefore, remediation measures or improvements in the disinfection treatments are required. The concentrations of BrO3(-), NO3(-) and NO2(-) were mapped with Principal Component analysis (PCA), which differentiated metropolitan water from bottled water through the concentrations of BrO3(-) and NO3(-) mainly. Furthermore, it was possible to discriminate between well water; blend of well water and desalinated water; and desalinated water. The point or source (region) was found to not be distinctive

Silica based nanoscavengers for the determination of environmental pollutants using solid phase dispersion extraction

This thesis introduces newly developed nanoscavengers for the extraction and pre-concentration of harmful substances from water samples, using a new solid phase dispersion extraction technique (SPDE).  This technique is based on the dispersion of 250nm diameter, modified silica particles (nanoscavengers) in water samples, to extract the analytes. Uniform silica particles were synthesised by both a conventional sol-gel process and a new spray technique. Different types of nanoscavenger were synthesised by modification of the silica with a number of silane coupling agents, such as N-[3-(trimethoxysilyl)propyl]-ethylenediamine and its dithiocarbamate, 3-mercaptopropyltrimethoxysilane, octadecyltrichlorosilane and octadecyltrimethoxysilane.  The modification step was carried out by two different processes: the modification of pre-formed 250 nm silica particles and by a single-pot synthesis. The amino-nanoscavenger, when applied to the pre-concentration of copper from water gave a recovery of 98%.   A dithiocarbamate-nanoscavenger was applied to the pre-concentration of cadmium, copper, lead and nickel and recoveries were 99, 97, 91 and 92%, respectively.   Inorganic mercury and arsenic were pre-concentrated using a mercapto-nanoscavenger, and recoveries of 106 and 96% were obtained, respectively. The collection of organic species using the C18-nanoscavenger resulted in the recovery of 70% di-n-butyl phthalate.  Herbicides such as Atrazine, Ramrod, Diuran and Propazine were recovered with efficiencies of 66, 78, 82 and 59% respectively.  A dual-functionality-nanoscavenger was employed for the pre-concentration of 22 chlorinated pesticides, and recoveries varied from 70 to 100%.  Polynuclear aromatic hydrocarbons (PAHs) were also pre-concentrated from water samples using this dual-functionality-nanoscavenger, and recoveries of 13 PAHs varied from 70 to 100%. Nanoscavenger based solid phase dispersion extraction ‘SPDE’ offers many advantages over conventional approaches.  These include the minimization of reagents, transportability, field application and efficiency.</p

Spray synthesis of monodisperse sub-micron spherical silica particles

A novel spray approach has been developed for the synthesis of controlled size oxide microparticles and the technique is illustrated by the preparation of ca. 250 nm silica particles. Stöber-type spherical silica of uniform particle size is formed by spraying a tetraethoxysilane precursor solution onto the surface of a stirred ammoniacal hydrolysis medium. Particle size characteristics are determined through selection of reaction conditions, with solvent, temperature, reagent concentrations and mixing contributing to the particle size and dispersity. The silica products have been characterized by particle size distribution measurements, electron microscopy and nitrogen adsorption studies. The mechanism of particle formation under differing experimental conditions is discussed.<br/

Spectrofluorimetric determination of surface-bound thiol groups and its application to the analysis of thiol-modified silicas

A sensitive spectofluorimetric method has been developed for the quantitative measurement of surface-bound thiol groups. The procedure is based on the quantitative esterification of the thiol group with Rhodamine B and its subsequent release from the solid by base hydrolysis for spectrofluorimetric determination. Application of the method to the analysis of thiol-modified nanoparticulate silicas yielded results that compared favourably against alternative approaches based on measurements of mercury capacity and iodometric titration of the thiol groups. Non-specific Rhodamine uptake, assessed using unmodified silica and C-18-modified silica, did not significantly influence the analytical results. When applied to a typical 50 mg sample, the detection limit of the procedure was 1 nmole SH g(-1) silica

Nanoscavenger based dispersion preconcentration: sub-micron particulate extractants for analyte collection and enrichment

A new approach has been developed for the preconcentration of analytes from solution using nanoscavengers; monodisperse functionalised particles of sub-micron dimensions, that can be suspended as a quasi-stable sol in an aqueous solution, and quantitatively recovered with the analyte by conventional filtration. No external agitation of the sample is required as the particles move naturally through the sample by Brownian motion, convection and sedimentation. By careful choice and control of their particle size and surface chemistries, nanoscavengers can be designed to suit a number of different analytical problems. Surface modification of these nanometre-sized particles, through the grafting of complexing or partitioning functional groups, can produce nanoscavengers having affinities for specific analytes and operating through a wide range of mechanisms from covalent bonding to hydrophobic interaction. The approach is illustrated by the development of an extraction-based preconcentration of metals from solution that employs sub-micron Stober-type silica spheres, the surfaces of which have been modified using chelating diamine and dithiocarbamate groups. The concept has potentially widespread applicability as it is neither limited to metal extractions, nor to the use of silica-based nanoscavengers. Minimal involvement of organic solvents make nanoscavengers a potentially environmentally benign ("green") alternative to many conventional solvent extraction techniques

The Distribution and Accretion of Some Heavy Metals in Makkah Wells

The aim of this study is to determine the types of heavy metals frequently present in Makkah wells and the possible environmental causes of their distribution and accumulation. Makkah lies in a mountain range dominated by different types of rocks from the Precambrian and Lower Paleozoic eras, as well as subordinate sedimentary rocks and basaltic lava flow from the Tertiary and Qua-ternary periods. Natural contaminants in Makkah wells water can be attributed to the unique lo-cation. Many epidemiological studies have identified associations between the ingestion of wells water contaminated with heavy metals and increased risk of some illnesses. This study presents exclusive information on the levels and distribution of 9 heavy metals—arsenic, barium, cadmium, chromium, cobalt, copper, lead, mercury, and selenium—in the wells water in various rural and urban areas of Makkah city. These naturally occurring elements are considered significant mark-ers of water purity. More than 160 wells were involved in this three-year investigation. Water samples were collected during different seasons in order to assess any changes in the distribution and concentration of these heavy metals throughout the year. The collected water samples were filtered and digested before analysis using inductively coupled plasma mass spectrometr

Synthesis of Superior Visible-Light-Driven Nanophotocatalyst Using High Surface Area TiO2 Nanoparticles Decorated with CuxO Particles

This work provides an alternate unique simple methodology to design and synthesize chemically modified nanophotocatalyst based on high surface area TiO2 nanoparticles that can be used efficiently for the photodegradation of organic pollutants under normal visible light rather than complicated UV irradiation. In this study, dual visible light and UV-driven nanophotocatalysts were synthesized via wet chemistry procedures using high surface area TiO2 nanoparticles functionalized with (3-Aminopropyl) trimethoxysilane and attached chemically to the CuXO to improve the charge separation and maintain the non-charge recombination. The successful modification of the TiO2 nanoparticles and the formation of the TiO2-NH2-CuxO nanophotocatalyst were confirmed using different characterization techniques, and the results revealed the synthesis of high surface area TiO2 nanoparticles, and their chemical modification with an amino group and further decoration with copper to produce TiO2-NH2-CuxO nanophotocatalyst. The photocatalytic activity of TiO2 and TiO2-NH2-CuxO nanophotocatalyst were evaluated using methylene blue (MB) dye; as an example of organic pollutants. The resulting TiO2-NH2-CuxO nanophotocatalyst exhibited superior photocatalytic activity for the degradation of MB dye under visible light irradiation, due to the reduction in the energy bandgap. The degradation of the MB dye using the TiO2-NH2-CuxO nanophotocatalyst was investigated using LC-MS, and the results revealed that the hydroxyl free radical is mainly responsible for the cleavage and the degradation of the MB dye

Circular Carbon Economy (CCE): A Way to Invest CO2 and Protect the Environment, a Review

Increased levels of carbon dioxide have revolutionised the Earth; higher temperatures, melting icecaps, and flooding are now more prevalent. Fortunately, renewable energy mitigates this problem by making up 20% of human energy needs. However, from a “green environment” perspective, can carbon dioxide emissions in the atmosphere be reduced and eliminated? The carbon economic circle is an ideal solution to this problem, as it enables us to store, use, and remove carbon dioxide. This research introduces the circular carbon economy (CCE) and addresses its economic importance. Additionally, the paper discusses carbon capture and storage (CCS), and the utilisation of CO2. Furthermore, it explains current technologies and their future applications on environmental impact, CO2 capture, utilisation, and storage (CCUS). Various opinions on the best way to achieve zero carbon emissions and on CO2 applications and their economic impact are also discussed. The circular carbon economy can be achieved through a highly transparent global administration that is supportive of advanced technologies that contribute to the efficient utilisation of energy sources. This global administration must also provide facilities to modernise and develop factories and power stations, based on emission-reducing technologies. Monitoring emissions in countries through a global monitoring network system, based on actual field measurements, linked to a worldwide database allows all stakeholders to track the change in greenhouse gas emissions. The process of sequestering carbon dioxide in the ocean is affected by the support for technologies and industries that adopt the principle of carbon recycling in order to maintain the balance. This includes supporting initiatives that contribute to increasing vegetation cover and preserving oceans from pollutants, especially chemicals and radioactive pollutants, which will undoubtedly affect the process of sequestering carbon dioxide in the oceans, and this will contribute significantly to maintaining carbon dioxide at acceptable levels