A mini review of recent findings in Cellulose-, Polymer- and Graphene-based membranes for Fluoride removal from drinking water

Effective fluoride removal from water is a persistent global concern both for drinking water and wastewater treatment. According to World Health Organization (WHO) standards the maximum contaminant level in drinking water cannot be higher than 1.5 mg F 12 L-1 since affects the skeletal and nervous systems of humans. Various technologies have been developed to decrease fluoride concentration from waters, such as adsorption, coagulation, precipitation and membrane separa-tion. Membrane technology found to be a very effective technology, significantly reducing fluo-ride to desired standards levels; however, has received less attention than other technologies because it is apparent as a costly process. This review aims to discuss the recent studies using modified membranes for fluoride removal. Emphasis is given on cellulose, polymer and gra-phene based membranes and is further discussing the modification of membranes with several metals that have been developed in the last years. It was observed that the main focus of the to-tal publications, has been on the use of polymer based membranes. Most of the membranes ap-plied for defluoridation exhibit greater efficiency at pH values close to that of drinking water (i.e., 6\u20138).and maximum treatment capacity was obtained with the use of a cellulose modified membrane Fe-Al-Mn@chitosan with a permeate flux of 2000 L m-2 h-1, following the carbon based amyloid fibril nano-ZrO2 composites (CAF-Zr) 1750 L m-2. A technical-economic comparison study of NF and RO is also referred, concluding that NF membrane is slightly less expensive

Mercury(II) Removal with Modified Magnetic Chitosan

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Metal Organic Frameworks: Synthesis and Application

The concept of metal–organic frameworks (MOFs) was first introduced in 1990; nowadays they are among the most promising novel materials [...

Application of promising carbonaceous materials in electrochemical DNA sensing

The data reported in literature demonstrate that carbon paste electrodes (CPEs) are very suitable for a variety of applications and many works have thus been devoted in the development of new sensitive and selective electrode surfaces based on carbon paste as the electrode material of choice. The application of novel and promising carbonaceous materials, as electrode surfaces, is an issue of great concern. In this work the experimental results of the characterization and comparison of electrode surfaces based on alternatively prepared carbonaceous materials (activated carbon (B), HNO3 oxidized activated carbon (B5), Ag impregnated activated carbon (B-Ag) and graphite oxide (GO), are being demonstrated. Scaning Electron Microscopy SEM), surface acidity, FTIR spectroscopy, XRD diffractometry and electrochemical techniques (cyclic voltammetry, differential pulse voltammetry) were applied in the characterization of novel carbonaceous materials aimed at electrochemical DNA sensing

Synthesis of Graphene Oxide Based Sponges and Their Study as Sorbents for Sample Preparation of Cow Milk Prior to HPLC Determination of Sulfonamides

In the present study, a novel, simple, and fast sample preparation technique is described for the determination of four sulfonamides (SAs), namely Sulfathiazole (STZ), sulfamethizole (SMT), sulfadiazine (SDZ), and sulfanilamide (SN) in cow milk prior to HPLC. This method takes advantage of a novel material that combines the extractive properties of graphene oxide (GO) and the known properties of common polyurethane sponge (PU) and that makes sample preparation easy, fast, cheap and efficient. The PU-GO sponge was prepared by an easy and fast procedure and was characterized with FTIR spectroscopy. After the preparation of the sorbent material, a specific extraction protocol was optimized and combined with HPLC-UV determination could be applied for the sensitive analysis of trace SAs in milk. The proposed method showed good linearity while the coefficients of determination (R2) were found to be high (0.991–0.998). Accuracy observed was within the range 90.2–112.1% and precision was less than 12.5%. Limit of quantification for all analytes in milk was 50 μg kg−1. Furthermore, the PU-GO sponge as sorbent material offered a very clean extract, since no matrix effect was observed

Adsorption of Pb Using Mesoporous Activated Carbon and its Effects on Surface Modifications

This study explains the use of modified activated carbon (microporous or mesoporous) as adsorbents for the removal of lead ions from water. The modifications involved the following: (i) oxidation, to introduce oxygen-containing functional groups, and (ii) treatment with aqueous ammonia, to introduce basic nitrogen functional groups. The pristine materials, namely, those after surface modifications and those after adsorption, were characterized by the adsorption of nitrogen, Fourier transform infrared spectroscopy, scanning electron microscopy and thermal analyses. We conducted batch experiments to study the effect of initial concentration, pH and temperature on the removal of Pb 2+ . Our experiments showed that adsorption was pH dependent, and any rise in temperature results in increased adsorption, which indicates the endothermic nature of the process. Typical isotherm models were fitted to describe the data. In addition, during adsorption, homogeneous accumulation of lead ions on the carbonaceous surface was observed. The higher adsorption capacity of chemically oxidized mesoporous carbon for lead was mainly due to the presence of functional groups of oxygen and nitrogen on the surfaces of activated carbon, which presumably react with the metal ions to form salt or complexes that deposit on the carbon surface

Sample Preparation Using Graphene-Oxide-Derived Nanomaterials for the Extraction of Metals

Graphene oxide is a compound with a form similar to graphene, composed of carbon atoms in a sp2 single-atom layer of a hybrid connection. Due to its significant surface area and its good mechanical and thermal stability, graphene oxide has a plethora of applications in various scientific fields including heterogenous catalysis, gas storage, environmental remediation, etc. In analytical chemistry, graphene oxide has been successfully employed for the extraction and preconcentration of organic compounds, metal ions, and proteins. Since graphene oxide sheets are negatively charged in aqueous solutions, the material and its derivatives are ideal sorbents to bind with metal ions. To date, various graphene oxide nanocomposites have been successfully synthesized and evaluated for the extraction and preconcentration of metal ions from biological, environmental, agricultural, and food samples. In this review article, we aim to discuss the application of graphene oxide and functionalized graphene oxide nanocomposites for the extraction of metal ions prior to their determination via an instrumental analytical technique. Applications of ionic liquids and deep eutectic solvents for the modification of graphene oxide and its functionalized derivatives are also discussed

Nanocrystalline Akaganeite as Adsorbent for Surfactant Removal from Aqueous Solutions

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Magnetic Graphene Oxide: Effect of Preparation Route on Reactive Black 5 Adsorption

In this study, the effect of preparation route of magnetic graphene oxide (mGO) on Reactive Black 5 (RB5) adsorption was investigated. The synthesis of mGO was achieved both with (i) impregnation method (mGOi nanoparticles), and (ii) co-precipitation (mGOp nanoparticles). After synthesis, the full characterization with various techniques (SEM, FTIR, XRD, DTA, DTG, VSM) was achieved revealing many possible interactions/forces of dye-composite system. Effects of initial solution pH, effect of temperature, adsorption isotherms and kinetics were investigated in order to conclude about the aforementioned effect of the preparation method on dye adsorption performance of the magnetic nanocomposites. The adsorption evaluation of the magnetic nanoparticles presented higher adsorption capacity of mGOp derivative (188 mg/g) and lower of mGOi (164 mg/g). Equilibrium experiments are also performed studying the effect of contact time (pseudo-first and -second order equations) and temperature (isotherms at 25, 45 and 65 °C fitted to Langmuir and Freundlich model). A full thermodynamic evaluation was carried out, calculating the parameters of enthalpy, free energy and entropy (ΔH0, ΔG0 and ΔS0)

Applications of Metal-Organic Frameworks in Food Sample Preparation

Food samples such as milk, beverages, meat and chicken products, fish, etc. are complex and demanding matrices. Various novel materials such as molecular imprinted polymers (MIPs), carbon-based nanomaterials carbon nanotubes, graphene oxide and metal-organic frameworks (MOFs) have been recently introduced in sample preparation to improve clean up as well as to achieve better recoveries, all complying with green analytical chemistry demands. Metal-organic frameworks are hybrid organic inorganic materials, which have been used for gas storage, separation, catalysis and drug delivery. The last few years MOFs have been used for sample preparation of pharmaceutical, environmental samples and food matrices. Due to their high surface area MOFs can be used as adsorbents for the development of sample preparation techniques of food matrices prior to their analysis with chromatographic and spectrometric techniques with great performance characteristics