Enhancing Oil Removal from Water using Ferric Oxide Nanoparticles Doped Carbon Nanotubes Adsorbents

Oil contaminated water is one of the challenges in water resources management. It is crucial to remove the oil droplets from water in order to meet the discharge regulations set by the environmental authorities. Carbon nanotubes (CNTs) have generated a lot of attention as a new type of adsorbent due to their exceptionally high adsorption capacity for oil–water separation. The high hydrophobicity of CNTs makes them good candidates to enhance the de-oiling process from wastewater. In this study, we have reported the synthesis and evaluation of novel iron-oxide/CNTs nanocomposites for oil–water separation. The CNTs were doped with different loadings of iron oxide nanoparticles using a wet impregnation technique. The synthesized nanocomposite nanomaterials were characterized using field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (TEM), Brunauer, Emmett and Teller (BET) technique, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The effect of adsorption parameters, including, adsorbent dosage, contact time, and agitation speed on the oil removal efficiency were optimized using batch experiments. The sorption capacities of doped CNTs were found to be greater than 7 g/g for gasoline oil. The doped CNTs reached maximum sorption capacity after only 15 min providing one of the fastest minimum contact times reported of all oil sorbent materials. The loading of Fe2O3 nanoparticles on the negative surface of CNT decreases the negative sign and magnitude of the zeta potential by overcoming the repulsive effects of the electrical double layers to allow the finely sized oil droplets to form larger droplets through coalescence. Therefore increasing percentage of the Fe2O3 on the surface of CNT increased the removal of the emulsified oil from the water

Mechanical Behavior of a Novel Nanocomposite Polysulphone - Carbon Nanotubes Membrane for Water Treatment

Nowadays, global fresh water shortage is becoming the most serious problem affecting the economic and social development. Water treatment including seawater desalination and wastewater treatment is the main technology for producing fresh water. Membrane technology is favored over other approaches for water treatment due to its promising high efficiency, ease of operation, chemicals free, energy and space saving. Membrane filtration for water treatment has increased significantly in the past few decades with the enhanced membrane quality and decreased membrane costs. In addition to high permeate flux and high contaminant rejection, membranes for water treatment require good mechanical durability and good chemical and fouling resistances. Thus, investigation of the mechanical behavior of water treatment membranes with underlying deformation mechanisms is critical not only for membrane structure design but also for their reliability and lifetime prediction. Compared to ceramic and metallic membranes, polymer membranes with smaller pore size and higher efficiency for particle removal are widely used in seawater desalination with a high applied pressure. However, polymer membranes are mechanically weaker and have lower thermal and chemical stability compared to inorganic membranes. Blending of polymers with inorganic fillers is an effective method to introduce advanced properties to polymer based membranes to meet the requirements of many practical applications. The reinforced polymeric membranes with inorganic fillers can provide desirable mechanical strength as well as mechanical stability. Carbon nanotubes (CNTs) have received considerable attention from academic and industries over the last twenty years. In addition to their excellent electrical and thermal properties, CNTs exhibit outstanding mechanical characteristics due to its instinct mechanical strength and high aspect ratio. For the application of water treatment membranes, CNTs could be the excellent channels for water to go through and therefore, CNTs have proven to be excellent fillers in polymer membranes improving the permeability and rejection properties. In literature, it is reported that the mechanical strength of the polymer membranes was improved with the embedding of CNTs due to reinforcement effect of the more rigid CNTs. The mechanical responses of polymer_CNTs composites depended on the interfacial adhesion between the CNTs and the membrane-based polymer as well as the dispersion and distribution of the CNTs within the polymer matrix. In this study, a vertical chemical vapor deposition reactor was designed in order to synthesize CNTs of high aspect ratio using continues injection atomization. Bundles of high purity (99%) and high quality CNTs were produced by this system. The produced CNTs had diameters ranging from 20 to 50 nm and lengths ranging from 300 to 500 micron (corresponded aspect ratios ranging from 6000 to 25000). A novel polysulphone (PSF) based nanocomposite membrane incorporated with the produced high aspect ratio CNTs was then casted via phase inversion method, at a wide range of CNTs loading (0-5 wt. %), in polysulphone-dimethylformamide solutions using the Philos casting system. The poly(vinylpyrrolidone) was used as pore-forming additive. To demonstrate the effect of nanocomposite morphology on the mechanical behavior of the prepared membranes, a set of control samples consisted of PSF membranes embedded with commercial CNTs at the same CNTs loading, were casted at the same conditions. The commercial CNTs had a lengths of 1 ?m to 10 ?m and outer diameters of 10 nm to 20 nm (corresponded aspect ratios ranging from 50 to 1000), with purity >95% and BET surface area of 156 m2/g. The effects of CNTs content and aspect ratio on morphological, water transport and mechanical properties of the prepared PSF-based porous membranes were investigated. The surface and cross-section morphologies of PSF/CNTs porous membranes were examined using scanning electron microscopy (SEM). The orientation, dispersion and distribution of CNTs within polymer membranes were evaluated for the membrane samples with different CNTs content and CNTs aspect ratio. The average membrane pore size was evaluated by using SEM image analysis software. Uniaxial tensile behavior of the membranes was characterized by means of a universal material testing machine under different testing conditions. Wet specimens were carefully cut from the casted membranes by using a razor blade. Elastic, plastic and failure behaviors of the membranes are analyzed with the impacts of CNTs content and aspect ratio. The macroscopic mechanical behaviors of the membranes are correlated with their strain induced microstructure evolution by using SEM. In this, pore shape evolution, pore and CNTs orientations, neighboring pore interaction, interface between the CNTs and PSF matrix and the failure behavior of the deformed porous membranes were analyzed. The macroscopic stress-strain responses of the membranes were correlated with the microstructure of the studied nanocomposites membranes to provide a better understanding of materials' processing-microstructure-properties relationship.qscienc

Evaluation of the current state and perspective of wastewater treatment and reuse in Qatar

In Qatar, many freshwater resources have already been depleted due to the overconsumption as a result of the population and economic growth. Moreover, due to the lack of sufficient sewage treatment infrastructure, Qatar is facing a daily problem in treating the wastewater. Dumping untreated sewage effluents (SE) contaminates groundwater resources and worsens the current water status in the country. On the other hand, treated SE (TSE), which is estimated at about 0.75 million m3/d, could be one of the main sources of fresh water which can be used in agriculture and industry and even as a source of drinking water in Qatar. Qatar uses only about 27% of TSE in growing fodder (25 million m3/y) and landscape irrigation (1 million m3/y) while about 73% of the total TSE is discharged to septic lagoons to dry or percolate into groundwater (70 million m3/y) and runoff (0.5 million m3/y). Qatar can better utilize its TSE in several applications by further treating the produced TSE. In this paper, a review on the current state and a perspective into the wastewater treatment and reuse in Qatar is presented. Moreover, the main aspects, which should be considered while making a decision on reusing the treated SE in Qatar, are also addressed.Scopu

Exposure to heavy metals and neurocognitive function in adults: a systematic review

Abstract Exposure of individuals to heavy metals (HMs) is a growing concern with far-reaching implications for human health. HMs encompass a diverse range of elements that, when present in excess or in particular chemical forms, have the potential to elicit adverse effects on the central nervous system and cognitive function. This systematic review aims to comprehensively investigate the relationship between exposure to HMs and neurocognitive function in adults. The methodological framework for this review adheres rigorously to the Meta-analyses Of Observational Studies in Epidemiology (MOOSE) guidelines. A meticulous and extensive search strategy was executed within PubMed and Web of Science, specifically targeting articles published in the English language until the cutoff date of December 5, 2023. The evaluation of the retrieved studies was systematically conducted by employing the assessment approach outlined by (Gascon et al. in Environ Int 86 60 67, 2016). The initial search yielded a substantial pool of 1573 articles, culminating in a refined selection comprising eight pertinent studies, collectively enrolling a participant cohort totalling n = 1,828,126. Notably, the studies under review predominantly manifested a cross-sectional or cohort design and were geographically situated within the continents of North America and Asia. Furthermore, it is imperative to underscore that a predominant and recurring observation emanating from the majority of the scrutinized investigations underscores a significant correlation between exposure to cadmium (Cd) and mercury (Hg) and deleterious neurocognitive outcomes in the adult population. In summary, our systematic review postulates that exposure to HMs through various routes of exposure harbors the potential for adverse effects on adult neurocognitive function; however, it is incumbent upon future research endeavors to validate and corroborate these findings through further empirical exploration