Synergistic effect of ZnO/Ag2O@g-C3N4 based nanocomposites embedded in carrageenan matrix for dye degradation in water.

This research achieved success by synthesizing innovative nanocomposite composed of zinc oxide (ZnO), graphitic carbon nitride (g-C3N4) and silver oxide (Ag2O) nanomaterials incorporated into a carrageenan matrix, thus creating an environmentally friendly and stable support structure. The synthesis process involved hydrothermal and chemical precipitation methods to create photocatalytic g-C3N4, ZnO, and Ag2O nanocomposites. The success is evident through the characterization results, which unveiled distinctive peaks corresponding to Zn-O (590-404 cm-1) and Ag-O (2072 cm-1) stretching in the Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses, conclusively confirming the successful synthesis of g-C3N4, ZnO, Ag2O, and their respective nanocomposites. Further validation through a scanning electron microscope coupled with an energy dispersive spectrometer (SEM-EDX) and elemental mapping affirmed the presence of Zn, O, Ag, C, and N. Additionally, transmission electron microscope (TEM) imaging unveiled the nanosheet morphology of g-C3N4, the nanorod structure of ZnO, and the spherical form of Ag2O nanomaterials. ZnO and Ag2O nanomaterials demonstrated a consistent 10-20 nm size range. To underscore their ability to harness visible light, the nanomaterials were excited at 380 nm, emitting visible light emission within the 400-450 nm range. The synthesized nanocomposites showcased outstanding adsorption and photocatalytic properties, achieving efficiency ranging from 80 % to 98 %, attributed to the synergistic interactions between the various components. These findings culminate in a confirmation of the research's success, validating the exceptional potential of these nanocomposites for various applications.

Influence of the Zeolite ZSM-22 Precursor on a UF-PES Selective Substrate Layer for Salts Rejection.

Fabrication of the ZSM-22/Polyethersulfone (ZSM-22/PES) membranes as selective salt filters represent a growing membrane technological area in separation with the potential of high economic reward based on its low energy requirements. The incorporation of ZSM-22 zeolite material as additives into the PES polymer matrix has the prospective advantage of combining both the zeolite and polymer features while overcoming the limitations associated with both materials. This work investigated the influence of the nature of the silica precursor on ZSM-22 zeolite hydrothermally synthesised using colloidal (C60) and fumed (C60) silica to Si/Al of 60. The successful synthesis of the highly crystalline zeolitic materials was confirmed through XRD, FTIR, and SEM with EDX. The ZSM-22 additives were directly dispersed into a PES polymeric matrix to form a casting solution for the preparation of the ZSM-22/PES selective substrate layers via a phase inversion method for salts rejection. The polymeric PES was selected as an organic network in which the content of the ZSM-22 zeolite (ranging between 0 and 1.0 wt.%), was obtained and characterised by XRD, FTIR, and SEM analysis, as well as water contact angle (WCA) measurement and dead-end filtration cell. The phase inversion preparation method has induced the resulting ZSM-22/PES NF substrates anisotropy, as attributed to a high water flux to the above 700 L·m-2·h-1; high selectivity and rejection of salts to above 80% is revealed by the obtained results. The materials also exhibited improved antifouling behavior to above 70% flux recovery ratios. As such, the nature of the silica precursor influences ZSM-22 zeolite synthesis as a potential additive in the PES polymer matrix and led to the enhanced performance of the pure PES ultrafiltration membrane.

Recent Advances in Biopolymeric Membranes towards the Removal of Emerging Organic Pollutants from Water.

Herein, this paper details a comprehensive review on the biopolymeric membrane applications in micropollutants' removal from wastewater. As such, the implications of utilising non-biodegradable membrane materials are outlined. In comparison, considerations on the concept of utilising nanostructured biodegradable polymeric membranes are also outlined. Such biodegradable polymers under considerations include biopolymers-derived cellulose and carrageenan. The advantages of these biopolymer materials include renewability, biocompatibility, biodegradability, and cost-effectiveness when compared to non-biodegradable polymers. The modifications of the biopolymeric membranes were also deliberated in detail. This included the utilisation of cellulose as matrix support for nanomaterials. Furthermore, attention towards the recent advances on using nanofillers towards the stabilisation and enhancement of biopolymeric membrane performances towards organic contaminants removal. It was noted that most of the biopolymeric membrane applications focused on organic dyes (methyl blue, Congo red, azo dyes), crude oil, hexane, and pharmaceutical chemicals such as tetracycline. However, more studies should be dedicated towards emerging pollutants such as micropollutants. The biopolymeric membrane performances such as rejection capabilities, fouling resistance, and water permeability properties were also outlined.

Characterization and reusability suggestions of the sludge generated from a synthetic acid mine drainage treatment using sodium ferrate (VI).

Mining activities are the main cause of generation of the voluminous sludge waste, loaded with metals precipitated from the treatment of acid mine drainage (AMD) and this is always disposed to the landfill. This study aimed at characterizing and suggesting the reusability potential of AMD sludge to reduce the environmental problem caused by its accumulation so that it could become a valuable material. The sludge was obtained after treating a synthetic AMD with a green oxidant sodium ferrate (VI) (Na2FeO4) that was prepared by a wet oxidation method. Chemical and physical characterization of a dried sludge generated after treatment was then performed using the Fourier Transform-Infrared and X-Ray powder Diffraction spectroscopy. Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy also served to identify the surface morphology of the sludge. The sludge presented a high weight percentage of Fe and O and lower concentrations of other metals such as Al, Mn, Si, and Na. Nitrogen adsorption/desorption isotherms or Brunauer-Emmett-Teller (BET) was used to assess the surface area, pore volume and diameter of the sludge. The BET results showed that the surface area of the sludge obtained after treating the synthetic AMD using Na2FeO4 was 31.50 ± 0.03 m2/g with pore diameter and volume of 52.50 nm and 0.41 cm3/g, respectively. However, the produced sludge could serve as an adsorbent to remove pollutants from water or to synthesize different magnetic nanocomposites due to its high surface area (>natural zeolite) and high composition of Fe and O.

Development of ZSM-22/Polyethersulfone Membrane for Effective Salt Rejection.

ZSM-22/polyethersulfone membranes were prepared for salt rejection using modelled brackish water. The membranes were fabricated via direct ZSM-22 incorporation into a polymer matrix, thereby inducing the water permeability, hydrophilicity and fouling resistance of the pristine polyethersulfone (PES) membrane. A ZSM-22 zeolite material with a 60 Si/Al ratio, high crystallinity and needle-like morphologies was produced and effectively used as a nanoadditive in the development of ZSM-22/PES membranes with nominal loadings of 0-0.75 wt.%. The characterisation and membrane performance evaluation of the resulting materials with XRD, BET, FTIR, TEM, SEM and contact angle as well as dead-end cell, respectively, showed improved water permeability in comparison with the pristine PES membrane. These ZSM-22/PES membranes were found to be more effective and superior in the processing of modelled brackish water. The salt rejection of the prepared membranes for NaCl and MgCl2 was effective, while they exhibited quite improved water flux and flux recovery ratios in the membrane permeability and anti-fouling test. This indicates that different amounts of ZSM-22 nanoadditives produce widely divergent influences on the performance of the pristine PES membrane. As such, over 55% of salt rejection is observed, which means that the obtained membranes are effective in salt removal from water.

Microwave-assisted green synthesis of xanthan gum grafted diethylamino ethyl methacrylate: An efficient adsorption of hexavalent chromium.

We report the development of a novel graft copolymer, diethylamino ethyl methacrylate grafted xanthan gum (mwXG-g-DEAEMA), by microwave heating. The synthesized graft copolymer was used for potential application of Cr(VI) adsorption. The structure, thermal stability and morphologies of XG and mwXG-g-DEAEMA were characterized to verify the adsorbent formed under optimized reaction conditions. FTIR, XRD, TGA and SEM techniques were used for characterization of XG and mwXG-g-DEAEMA. Furthermore, 1H NMR spectroscopic analyses predict the probable structure of copolymer. Based on the NMR data, a plausible mechanism for copolymer formation has been proposed. The effects of adsorbent loading, pH, contact time and equilibrium concentration of the Cr(VI) adsorption were investigated batch wise. The Cr(VI) adsorption process followed the pseudo-second-order rate model and equilibrium data were best described by Freundlich isotherm model. This work will encourage researchers to focus on this facile green technique for the synthesis of adsorbent with enhanced adsorption capacity.

Microwave assisted synthesis of xanthan gum-cl-poly (acrylic acid) based-reduced graphene oxide hydrogel composite for adsorption of methylene blue and methyl violet from aqueous solution.

In the present study, facile and efficient method was adopted for the synthesis of graft copolymer hydrogel by graft copolymerization of acrylic acid (AA) onto xanthan gum (XG) biopolymer in the presence of N,N'-Methylenebisacrylamide (MBA), and ammonium persulfate (APS) as a cross-linking agent and initiator, respectively, under microwave irradiation. The optimization of hydrogel were selected based on the maximum swelling degree in water media and an optimum hydrogel was further impregnated with reduced graphene oxide (rGO) to form XG-cl-pAA/rGO hydrogel composite. The Fourier transform infrared (FT-IR), X-ray diffraction analysis (XRD), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) were used to study the structure, thermal stability and morphology of XG-cl-pAA and XG-cl-pAA/rGO. The adsorption of methyl violet (MV) and methylene blue (MB) were study in batch mode and results shows adsorption highly dependent on solution pH, contact time, concentration and adsorbent loading. The XG-cl-pAA/rGO exhibited a very high adsorption potential, and the adsorption process followed the pseudo-second-order rate model and Langmuir adsorption isotherm with a maximum adsorption capacity (Qmax) of 1052.63 mg/g and 793.65 mg/g at 25 °C for MV and MB, respectively. We recommend XG-cl-pAA/rGO as environmentally benign, readily recoverable/recyclable material with excellent adsorption capacity for application in dyes removal.

Preparation and characterization of xanthan gum-cl-poly(acrylic acid)/o-MWCNTs hydrogel nanocomposite as highly effective re-usable adsorbent for removal of methylene blue from aqueous solutions.

In this work, xanthan gum-cl-poly acrylic acid (XG-cl-pAA) hydrogel and xanthan gum-cl-poly acrylic acid/oxidized MWCNTs (XG-cl-pAA/o-MWCNTs) hydrogel nanocomposite was successfully surface modify by microwave assisted copolymerization, in which N, N'-methylenebisacrylamide (MBA) was used as a cross-linking agent. A copolymerization of acrylic acid (AA) onto xanthan gum (XG) initiated by microwave radiation method. Different weight percentages of oxidized MWCNTs were incorporated into the hydrogel matrix during the grafting reaction. An optimum hydrogel based on maximum swelling capacity further incorporated with oxidized MWCNTs to form XG-cl-pAA/o-MWCNTs. The structure, thermal stability, wettability and morphology of XG-cl-PAA and XG-cl-PAA/o-MWCNTs were characterized by fourier transform infrared (FTIR), Raman, X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Contact angle, and scanning electron microscope (SEM). The effects of pH, contact time and equilibrium concentration on the MB dye adsorption were investigated batch wise. Optimal conditions were obtained at pH⩾6 due to the generation of negatively charged groups (COO-) in the adsorbent, which can strongly interact with the positive charges from MB and time of adsorption equilibrium was achieved in 30 min. The XG-cl-PAA/o-MWCNTs hydrogel nanocomposite exhibited a very high adsorption potential, and its adsorption capacities calculated based on the Langmuir isotherm for MB was 521.0 mg/g at 30 °C. The dye adsorption data fitted well to the pseudo-first-order model and Langmuir model. The adsorption-desorption cycle of hydrogel nanocomposite was repeated several times without significant loss of adsorption capacity.

Fast microwave-assisted green synthesis of xanthan gum grafted acrylic acid for enhanced methylene blue dye removal from aqueous solution.

In the present project, graft polymerization was employed to synthesis a novel adsorbent using acrylic acid (AA) and xanthan gum (XG) for cationic methylene dye (MB+) removal from aqueous solution. The XG was rapidly grafted with acrylic acid (CH2=CHCOOH) under microwave heating. Fourier-transform infrared spectroscopy (FTIR), Proton Nuclear magnetic resonance spectroscopy (1H NMR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Thermal gravimetric analysis (TGA) techniques were used to verify the adsorbent formed under optimized reaction conditions. Optimum reaction conditions [AA (0.4M), APS (0.05M), XG (2gL-1), MW power (100%), MW time (80s)] offer maximum %G and %GE of 484 and 78.3, respectively. The removal ratio of adsorbent to MB+ reached to 92.8% at 100mgL-1. Equilibrium and kinetic adsorptions of dyes were better explained by the Langmuir isotherm and pseudo second-order kinetic model respectively. The results demonstrate xanthan gum grafted polyacrylic acid (mw XG-g-PAA) absorbent had the universality for removal of dyes through the chemical adsorption mechanism.

Determination of antimony and tin in beverages using inductively coupled plasma-optical emission spectrometry after ultrasound-assisted ionic liquid dispersive liquid-liquid phase microextraction.

The aim of this study was to develop a simple and fast ultrasound-assisted ionic liquid dispersive liquid-liquid phase microextraction (UA-IL-DLLME) method for preconcetration of trace antimony and tin in beverage samples. The novelty of this study was based on the application of ligandless UA-IL-DLLME using low-density ionic liquid and organic solvents for preconcentration of Sb and Sn. The concentration of Sb and Sn were quantified using ICP-OES. Under the optimum conditions, the calibration graph was found to be LOQ-250µgL-1 (r2=0.9987) for Sb and LOQ-350µgL-1 for Sn. The LOD and LOQ of Sb and Sn ranged from 1.2to 2.5ngL-1 and 4.0 to 8.3ngL-1, respectively, with high preconcentration factors. The precisions (%RSD) of the proposed method ranged from 2.1% to 2.5% and 3.9% to 4.7% for Sb and Sn, respectively. The proposed method was successfully applied for determination of Sb and Sn in beverages.

Sodium alginate stabilized silver nanoparticles-silica nanohybrid and their antibacterial characteristics.

Due to the problem of resistance of many infectious agents to the usual treatments, this study addresses the ways of obtaining and using new sodium alginate stabilized-silver/mesoporous silica (Na-Alg-s-AgNPs@SiO2) nanohybrid as antimicrobial agents. Capping AgNPs with a shell of mesoporous SiO2 is a system to build the increase biocompatibility of AgNPs. In this work, we report a simple and green way to deal with setting up a uniform sodium alginate-stabilized silver nanoparticles embedded mesoporous silica (Na-Alg-s-AgNPs@SiO2 nanohybrid). The synthesized nanocomposite was characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, and ultraviolet-visible (UV-vis) absorption spectra, which exhibited that AgNPs with average of size of ∼7nm were consistently and compactly deposited in the nanocomposite. The nanohybrid demonstrated excellent antibacterial activity against both Gram negative (-ve) and Gram positive (+ve) bacteria. Thus, the developed Na-Alg-s-AgNPs@SiO2 nanohybrid has a potential to be used for various antibacterial applications in biotechnology and biomedical fields.

Rapid, facile microwave-assisted synthesis of xanthan gum grafted polyaniline for chemical sensor.

Grafting method, through microwave radiation procedure is extremely productive in terms of time consumption, cost effectiveness and environmental friendliness. In this study, conductive and thermally stable composite (mwXG-g-PANi) was synthesized by grafting of aniline (ANi) on to xanthan gum (XG) using catalytic weight of initiator, ammonium peroxydisulfate in the process of microwave irradiation in an aqueous medium. The synthesis of mwXG-g-PANi were confirm by FTIR, XRD, TGA, and SEM. The influence of altering the microwave power, exposure time of microwave, concentration of monomer and the amount of initiator of graft polymerization were studied over the grafting parameters, for example, grafting percentage (%G) and grafting efficiency (%E). The maximum %G and %E achieved was 172 and 74.13 respectively. The outcome demonstrates that the microwave irradiation strategy can increase the reaction rate by 72 times over the conventional method. Electrical conductivity of XG and mwXG-g-PANi composite film was performed. The fabricated grafted sample film were then examined for the chemical sensor. The mwXG-g-PANi, effectively integrated and handled, are NH3 sensitive and exhibit a rapid sensing in presence of NH3 vapor. Chemiresistive NH3 sensors with superior room temperature sensing performance were produced with sensor response of 905 at 1ppb and 90% recovery within few second.