Efficient Copper Removal from an Aqueous Anvironment using a Novel and Hybrid Nanoadsorbent Based on Derived-Polyethyleneimine Linked to Silica Magnetic Nanocomposites

Novel magnetic iron oxide-dextran sulphate nanocomposites as potential anticoagulants: Investigating interactions with blood components and assessing cytotoxicity

Examining the critical role of anticoagulants in medical practice, particularly their central function in preventing abnormal blood clotting, is of the utmost importance. However, the study of interactions between blood proteins and alternative anticoagulant nano-surfaces is still understood poorly. In this study, novel approach involving direct functionalisation of magnetic iron oxide nanoparticles (MNPs) as carriers with sulphated dextran (s-dext) is presented, with the aim of evaluating the potential of magnetically-responsive MNPs@s-dext as anticoagulants. The physicochemical characterisation of the synthesised MNPs@s-dext includes crystal structure analysis, morphology study, surface and electrokinetic properties, thermogravimetric analysis and magnetic properties` evaluation, which confirms the successful preparation of the nanocomposite with sulfonate groups. The anticoagulant potential of MNPs@s-dext was investigated using a standardised activated partial thromboplastin time (APTT) test and a modified APTT test with a quartz crystal microbalance with dissipation (QCM-D) which confirmed the anticoagulant effect. Time-resolved solid-liquid interactions between the MNPs@s-dext and model blood proteins bovine serum albumin and fibrinogen were also investigated, to gain insight into their hemocompatibility, and revealed protein-repellence of MNPs@s-dext against blood proteins. The study also addressed comprehensive cytotoxicity studies of prepared nanocomposites, and provided valuable insights into potential applicability of MNPs@s-dext as a promising magnetic anticoagulant in biomedical contexts.

Advancements in heavy metals removal from effluents employing nano-adsorbents: Way towards cleaner production

Due to the development in science field which gives not only benefit but also introducesundesirable pollution to the environment. This pollution is due to poor discharge activities of industrial effluents into the soil and water bodies, surface run off from fields of agricultural lands, dumping of untreated wastes by municipalities, and mining activites, which deteriorates the cardinal virtue of our environment and causes menace to human health and life. Heavy metal(s), a natural constituent on earth's crust and economic important mineral, due to its recalcitrant effects creates heavy metal pollution which affects food chain and also reduces the quality of water. For this, many researchers have performed studies to find efficient methods for wastewater remediation. One of the most promising methods from economic point of view is adsorption, which is simple in design, but leads to use of a wide range of adsorbents and ease of operations. Due to advances in nanotechnology, many nanomaterials were used as adsorbents for wastewater remediation, because of their efficiency. Many researchers have reported that nanoadsorbents are unmitigatedly a fruitful solution to address this world's problem. This review presents a potent view on various classes of nanoadsorbents and their application to wastewater treatment. It provides a bird's eye view of the suitability of different types of nanomaterials for remediation of wastewater and Backspace gives up-to-date information about polymer based and silica-based nanoadsorbents.

Amino-modified hollow alumina spheres: effective adsorbent for Cd2+, Pb2+, As(V), and diclofenac removal

A simple sol-gel method and external gelatinization method of hollow alumina spheres synthesis were developed in this study. The spheres were modified with polyethyleneimine (PEI) producing PEI-Al₂O₃ via (3-glycidyloxypropyl)trimethoxy-silane, GLYMO, linker. Characterization results, obtained using XRD and SEM microscopy revealed spherical geometry with a hollow core of PEI-Al₂O₃ adsorbent. Introduction of a large number of the amino group, 6.9 mmol g^-1, contributes to achieving high adsorption capacities, q_m, of 95.6, 124.9, 61.3, and 125.9 mg g^-1 for Cd²⁺, Pb²⁺, As(V), and DCF, respectively, which is obtained by using the Langmuir model. Thermodynamic studies indicated feasible adsorption and higher spontaneity with temperature increase. The kinetic study conveniently modeled using pseudo-second-order (PSO) and Weber-Morris kinetic model, as well as single resistance mass transfer model, indicated a change of the contribution of diffusional processes during adsorption with a dominance of intra-particle diffusion. The fixed-bed column adsorption data, fitted using Bohart-Adams, Clark, Yoon-Nelson, and Thomas models, showed lower capacity in comparison to batch study, and thus clear potential applicability of PEI-Al₂O₃ was deduced even at a high loading of feed water.

Magnetic nanostructures functionalized with a derived lysine coating applied to simultaneously remove heavy metal pollutants from environmental systems

The pollution of environmental systems with heavy metals is becoming a serious problem worldwide. These contaminants are one of the main issues in sludge (which is considered waste) and can even have harmful effects if the sludge is not treated properly. Thus, the development of a novel functional magnetic nanoadsorbent based on a derived lysine is reported here, which can be efficiently applied for metal removal from sludge. Magnetic nanoparticles were coated with silica layer and further modified by covalent bonding of derived lysine. The morphology of the nanomaterial, its nano-size and the silica layer thickness were analyzed by transmission electron microscopy. The successful silanization of the lysine derivative to the silica-coated magnetic nanostructures was investigated by several physicochemical characterization techniques, while the magnetic properties were measured with a vibrating sample magnetometer. The synthesized nanostructures were used as adsorbents for simultaneous removal of most critical heavy metals (Cr, Zn, Cu) from real complex sludge suspensions. The main practical adsorption parameters, pH of the native stabilized sludge, adsorbent amount, time, and adsorbent regeneration were investigated. The results show promising adsorption properties among currently available adsorbents (the total equilibrium adsorption capacity was 24.5 mg/g) from the sludge with satisfactory nanoadsorbent reusability and its rapid removal. The stability of the nanoadsorbent in the sludge, an important but often neglected practical parameter for efficient removal, was verified. This work opens up new possibilities for the development of high-quality magnetic nanoadsorbents for metal pollutants applied in various complicated environmental fields and enables waste recovery.

Advances in Methods for Recovery of Ferrous, Alumina, and Silica Nanoparticles from Fly Ash Waste

Fly ash or coal fly ash causes major global pollution in the form of solid waste and is classified as a “hazardous waste”, which is a by-product of thermal power plants produced during electricity production. Si, Al, Fe Ca, and Mg alone form more than 85% of the chemical compounds and glasses of most fly ashes. Fly ash has a chemical composition of 70–90%, as well as glasses of ferrous, alumina, silica, and CaO. Therefore, fly ash could act as a reliable and alternative source for ferrous, alumina, and silica. The ferrous fractions can be recovered by a simple magnetic separation method, while alumina and silica can be extracted by chemical or biological approaches. Alumina extraction is possible using both alkali- and acid-based methods, while silica is extracted by strong alkali, such as NaOH. Chemical extraction has a higher yield than the biological approaches, but the bio-based approaches are more environmentally friendly. Fly ash can also be used for the synthesis of zeolites by NaOH treatment of variable types, as fly ash is rich in alumino-silicates. The present review work deals with the recent advances in the field of the recovery and synthesis of ferrous, alumina, and silica micro and nanoparticles from fly ash.

Applicability of electro-osmotic flow for the analysis of the surface zeta potential

The analysis of the surface zeta potential (SZP) opens up new possibilities in the characterization of various materials used for scientific or industrial applications. It provides at the same time insight into the material surface chemistry and elucidates the interactions with charged species in the aqueous test solution. For this purpose, an accurate, reliable and repeatable analysis of the SZP is the key factor. This work focuses on a detailed and systematic comparison of two electrokinetic techniques, i.e. the mapping of the electro-osmotic flow (EOF) and the measurement of the streaming potential (SP), for the surface zeta potential (SZP) determination of several materials with varying properties. Both techniques have advantages as well as drawbacks. The applicability of latex polymer material and inorganic tracer particles at varying ionic strength, the interaction between oppositely charged tracer particles and solid surfaces, the assessment of the pH dependence of the SZP and the isoelectric point (IEP), and the effects of sample porosity and conductance have been investigated. Although in some cases the EOF method gives a SZP similar to the streaming potential measurement, especially when the tracer particle exhibits the same charge as the solid surface, it was revealed that reliable results were only obtained with the streaming potential and streaming current method. Several obstacles such as elevated conductivity at higher ionic strength, the applied voltage for the EM measurement, and the nature of tracer particles lower the accuracy and reliability of the SZP determined by the EOF method. It was shown that the EOF method is not applicable to oppositely charged surface and tracer particles and also limited to low salinity conditions especially when using polymeric tracer particles. Although the EOF method does not require the formation of a capillary flow channel, it disables a non-destructive SZP of fragile or valuable samples, such as QCM-D sensors, in comparison to the SP approach.

Detail comparison of two different electrokinetic phenomena EOF and SP method for the SZP determination with taking into account various materials with different surface and bulk properties.

Influence of Selective Conditions on Various Composite Sorbents for Enhanced Removal of Copper (II) Ions from Aqueous Environments

Numerous pollutants, including dyes, heavy metals, pesticides, and microorganisms, are found in wastewater and have great consequences when discharged onto natural freshwater sources. Heavy metals are predominantly reported in wastewater. Heavy metals are persistent, non-biodegradable and toxic, transforming from a less toxic form to more toxic forms in environmental media under favourable conditions. Among heavy metals, copper is dominantly found in wastewater effluent. In this review, the effects of high concentration of copper in plants and living tissues of both aquatic animals and humans are identified. The performance of different polymer adsorbents and the established optimum conditions to assess the resultant remediation effect as well as the amount of copper removed are presented. This procedure allows the establishment of a valid conclusion of reduced time and improved Cu (II) ion removal in association with recent nano-polymer adsorbents. Nano-polymer composites are therefore seen as good candidates for remediation of Cu ions while pH range 5-6 and room temperature were mostly reported for optimum performance. The optimum conditions reported can be applied for other metal remediation and development of potent novel adsorbents and process conditions.