A newly synthesized free fatty acids from waste palm oil functionalized magnetic nanoparticles immobilized on the surface of graphene oxide (FFA@MNP-GO) was successfully synthesized and characterized in this research. The combinations of long alkyl chain of free fatty acid with graphene oxide that consists of large delocalized 77-electron systems and abundant of hydrophilic groups with hydroxyl, epoxide and carboxylic groups offer the determination of simultaneous wide range of polarities of organic pollutants in real matrices through hydrogen bonding, hydrophobic and 77-77 interactions. The fabricated adsorbent was successfully applied as a magnetic solid phase extraction (MSPE) adsorbent for the simultaneous separation of selected phthalate esters (PAEs) and polycyclic aromatic hydrocarbons (PAHs) in apple and cabbage extracts prior to their high performance liquid chromatography with diode-array detector (HPLC-DAD) determination. Factors affecting the extraction efficiency such as amount of adsorbent, desorption solvent, volume of desorption solvent, extraction time, desorption time, pH and sample volume were investigated and optimized. The results revealed that under optimal conditions, the detection limit of selected PAEs and PAHs were in the range of 0.56-0.97 ng mL-1 and 0.02-0.93 ng mL-1, respectively. The spiked recoveries of real apple and cabbage extracts for PAEs and PAHs were in the range of 81.5-117.6% with good relative standard deviation (RSD) (n = 5) less than 10% and 86.7-118.2% with acceptable RSDs (n = 5) ranging from 1.5 to 11.0%, respectively. This study reported for the first time the use of MSPE procedure for simultaneous determination of chosen PAHs and PAEs in real samples including apple and cabbage extracts by using new adsorbent, FFA@MNP-GO.
The usefulness of carboxymethyl cellulose (CMC) as a matrix material in enhancing the controlled release formulations of bispyribac (BP) herbicide from the interlayer gallery of zinc hydroxide nitratesodium dodecylsulphate-bispyribac (ZHN-SDS-BP) nanocomposite was investigated. The CMC coated nanocomposite, ZHN-SDS-BP-CMC was characterised using several instruments for the determination of its physicochemical properties. The release rates of the BP were measured using a UV spectrophotometer, and the aqueous solutions containing PO3-₄ , SO2-₄ and Cl- were selected as release media in the release studies so as to mimic the real conditions of environmental soil. Significant release time delays, triggered by the gelation forming ability and hygroscopic nature of CMC, were observed in all release media, and the release processes were found to behave in a concentration-dependent manner in all release media. Fitting the release data into several kinetic models demonstrated that release in aqueous solutions of Na₃PO₄ and Na₂SO₄ was governed by pseudo second order processes, whereas the release in an aqueous NaCl solution was governed by the parabolic diffusion kinetic model. The potential of CMC in prolonging the release of BP from ZHN-SDS-BP-CMC can potentially help in reducing the pollution resulting from the overuse of pesticides.
The vanadium (V) and nitrogen (N) dopants on TiO₂ demonstrated superior photocatalytic performance for the degradation of methylene blue (MB) dye under visible light. The vanadium, V, N-co-doped TiO₂ was synthesized by a modified sol-gel method. It revealed that V and N codoping had a significant effect on the band gap (Eg) of TiO₂, where the pristine TiO₂ possessed a wide band gap (3.18 eV) compared to V-doped TiO₂ (2.89 eV) and N-doped TiO₂ (2.87 eV) while the V, N-co-doped TiO₂ depicted the narrowest band gap (2.65 eV). The greatly increased specific surface area for the V, N-co-doped TiO₂ (103.87 m²/g) as compared to P25 TiO₂ (51.68 m²/g) also contributed to the major improvement in the MB dye degradation efficiency (0.055 min-1). The V, N-co-doped TiO₂ exhibit rapid photocatalytic activity for the degradation of MB with almost 99% of degradation in 120 minutes.
Biosynthesis of nanoparticles has now become a novel trend in addressing some of the environmental issues by adopting eco-friendly approaches in manoeuvring nanoparticles for various applications. Plants and micro-organisms have been the potential sources of the biological mode of synthesizing nanoparticles as part of their bioremediation process. This principle has been harnessed for synthesizing nanoparticles either extra or intracellularly. In this line of phyto-mediated synthesis, eucalyptus buds have been used for synthesizing gold nanoparticles (Au NPs) under optimized laboratory conditions. The UV-visible spectrum of the Au NPs showed typical surface plasmon resonance at 550 nm (λmax) with a crystalline phase measuring <100 nm in size and monodispersed as revealed from XRD, FESEM, and AFM analyses. The biological role of phytochemical concoction in reducing and stabilizing the Au NPs was clearly identified from FT-IR studies. The antimicrobial effect of the Au NPs against clinically important pathogens viz. Staphylococcus sp., Pseudomonas sp., Bacillus sp. and E. coli determined using the disk diffusion method showed no significant antibacterial effect at all concentrations. Cytotoxicity studies were carried using Vero and HEp-2 cell lines and the 50% inhibition concentration (IC50) was determined to be 1.25 mg and 0.625 mg/mL respectively. Au NPs with potential antimicrobial and anti-proliferative effects could found profound implications in the field of nanomedicine once the toxicity in vivo has been investigated.
Graphene oxide/Cuprous oxide (GO/Cu₂O) composite is a visible light photocatalyst for the degradation of dyes. A simple and efficient approach for preparing GO/Cu₂O composite adopted in this study involves reducing cuprous oxide precursors in the presence of graphene oxide using an aqueous solution of pulp derived from banana fruit. The GO/Cu₂O composite was characterized by Fourier transform infrared spectroscopy (FT-IR), Diffused reflectance Ultraviolet visible spectroscopy (DRS UV-Vis), Raman spectroscopy and Field Emission Scanning electron microscopy (FE-SEM). Cu₂O particles were distributed randomly on the graphene oxide sheets due to the template effect of GO. The results showed higher photocatalytic activity for the composite (band gap 2.13 eV), for the degradation of the organic dyes (Methylene blue and Rhodamine-B). The enhanced photocatalytic activity is due to effective charge transfer from GO to Cu₂O, and high specific surface area which improves the effective separation of the generated electron-hole pairs. Our present study is inspired by a facile, low cost, green production of (GO/Cu₂O) composite whose photocatalytic activity can be extended to degradation of all other water-born textile dyes.
This is our initial response towards preparation of nano-inductors garnet for high operating frequencies strontium iron garnet (Sr3Fe5O12) denoted as SrIG and yttrium iron garnet (Y3Fe5O12) denoted as YIG. The garnet nano crystals were prepared by novel sol-gel technique. The phase and crystal structure of the prepared samples were identified by using X-ray diffraction analysis. SEM images were done to reveal the surface morphology of the samples. Raman spectra was taken for yttrium iron garnet (Y3Fe5O12). The magnetic properties of the samples namely initial permeability (micro), relative loss factor (RLF) and quality factor (Q-Factor) were done by using LCR meter. From the XRD profile, both of the Y3Fe5O12 and Sr3Fe5O12 samples showed single phase garnet and crystallization had completely occurred at 900 degrees C for the SrIG and 950 degrees C for the YIG samples. The YIG sample showed extremely low RLF value (0.0082) and high density 4.623 g/cm3. Interesting however is the high Q factor (20-60) shown by the Sr3Fe5O12 sample from 20-100 MHz. This high performance magnetic property is attributed to the homogenous and cubical-like microstructure. The YIG particles were used as magnetic feeder for EM transmitter. It was observed that YIG magnetic feeder with the EM transmitter gave 39% higher magnetic field than without YIG magnetic feeder.
Small sized electrocatalysts, which can be obtained by rapid nucleation and high supersaturation are imperative for outstanding methanol oxidation reaction (MOR). Conventional microwave synthesis processes of electrocatalysts include ultrasonication, stirring, pH adjustment, and microwave irradiation of the precursor mixture. Ethylene glycol (EG), which serves as a reductant and solvent was added during the ultrasonication or stirring stage. However, this step and pH adjustment resulted in unintended multi-stage gradual nucleation. In this study, the microwave reduction approach was used to induce rapid nucleation and high supersaturation in order to fabricate small-sized reduced graphene oxide-supported palladium (Pd/rGO) electrocatalysts via the delayed addition of EG, elimination of the pH adjustment step, addition of sodium carbonate (Na₂CO₃), prior microwave irradiation of the EG mixed with Na₂CO₃, and addition of room temperature precursor mixture. Besides its role as a second reducing agent, the addition of Na₂CO₃ was primarily intended to generate an alkaline condition, which is essential for the high-performance of electrocatalysts. Moreover, the microwave irradiation of the EG and Na₂CO₃ mixture generated highly reactive free radicals that facilitate rapid nucleation. Meanwhile, the room temperature precursor mixture increased supersaturation. Results showed improved electrochemically active surface area (78.97 m² g-1, 23.79% larger), MOR (434.49 mA mg-1, 37.96% higher) and stability.
Au-Ag alloy nanoparticles are physically synthesized using rapid, simple and efficient Q-switched Nd:YAG pulsed laser ablation in liquid technique (PLAL). Au and Ag colloidal solutions are separately prepared by 1064 nm laser ablation of metallic target (gold and silver) which is immersed in deionized water. Au-Ag alloy nanoparticles are prepared by irradiating the mixture of Au and Ag colloidal solutions with 532 nm of second harmonic wavelength of Nd:YAG laser at three different ratio, 3:1, 1:1 and 1:3 within different exposure times. The three of plasmon absorption bands of Au-Ag nanoparticles are shifted linearly to the lower wavelength [499.67 nm (3:1), 481.25 nm (1:1), 467.91 nm (1:3)], as compared to plasmon absorption spectra of pure Au (520 nm) and Ag (400 nm). Moreover, the change in colors are also observed from red (Au) and yellow (Ag) to orange, brown and green color due to the Au-Ag alloy formations, respectively. Transmission electron microscopy shows the Ag shell around the inner core of Au spherical metal with broad size distribution due to the three different volume ratio, respectively (1.7 nm, 0.7 nm, 1.4 nm). Energy-dispersive X-ray spectroscopy analysis confirms the presence of Au and Ag elements in Au-Ag alloy nanoparticles without any contaminations. Attenuated total reflectance fourier transform infrared spectroscopy analysis also confirms the homogenous Au-Ag alloys chemical bonding.
Recently, the graphite based materials have gained interest as excellent platforms to remove aqueous pollutants via adsorption routes. This is given that such materials possess large specific surface area and low density. In the present work, a comparative study of two facile and effective approaches is conventional thermal heating and microwave irradiation methods to fabricate expanded graphite from available flake graphite sources of Vietnam for oil-contaminated water purification. The as-prepared expanded graphite was characterized by using FT-IR, SEM, XRD and BET analysis. The results exhibited that expanded graphite has multilevel pore structures and the surface area of expanded graphite obtained from microwave irradiation and conventional heating was 147.5 (m²/g) and 100.97 (m²/g) under optimal processing conditions. The as-synthesized expanded graphite from the microwave irradiation method was found to have higher adsorption capacities for diesel oil, crude oil, and fuel oil compared to conventional heating method.
This study reports the biosynthesis of silver nanoparticles (AgNPs) using methanolic leaf extract of Pogostemon cablin Benth. (Patchouli) as a reducing agent, and their potent biological (antibacterial, antioxidant and anticancer) activities. The P. cablin extract when exposed to silver nitrate reduced silver ions to form crystalline AgNPs within 1 h of incubation at room-temperature. UV-visible spectra showed a sharp surface plasmon resonance (SPR) at around 430 nm for the biosynthesized AgNPs and the XRD pattern indicated the crystalline planes of the face centered cubic silver. The FE-SEM analysis revealed the occurrence of predominant spherical shaped AgNPs with a huge disparity in their particle size distribution with an average size of 25 nm, while, the FTIR data confirmed the bio-reduction and capping of AgNPs by several phytocompounds present in the methanolic leaf extract. AgNPs effectively inhibited the growth of all the tested human pathogenic bacterial strains (Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli), while, the methanolic leaf extract failed to inhibit the growth of S. aureus and P. aeruginosa. AgNPs showed the highest free radical scavenging activity (79.0 ± 0.76%) compared to methanolic leaf extract (68.3 ± 0.68%) at 100 μg/ml. Further, the cytotoxicity study using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) confirmed that AgNPs successfully inhibited the human colon adenocarcinoma cell line (HT-29) in a dose dependent manner. At higher concentrations (500 μg/ml), only 4% of cells survived after 72 hrs of exposure with IC50 value of 120 μg/ml. Thus, these findings offer a new source of biomolecules with diverse biological activities.
Mesoporous silica supported adsorbents have been used towards metal ion removal from water due to their thermally stability and good sorption capacity. Thus, mesoporous silica-based methyl acrylate monomer (Silica-APTES-DPNO) was converted into hydroxamic acid (SBHA) by using oximation reaction and all products are analyzed by by FT-IR. The SBHA showed satisfactory binding properties with copper, cobalt, nickel and lead are 242, 206, 195 and 516 mg g-1, respectively, with the batch adsorption system was set to pH 6. The kinetics of metal ions binding obeyed the pseudo-1st-order process up to 60 min. In this study also consider the Langmuir and Freundlich isotherm to find out the sorption behavior. The isotherm study demonstrated the well fit with Freundlich isotherm (R² > 0.99). Thus, adsorption take place as a multilayer system, therefore, SBHA material is useful for the metal ions removal from water.
Ion-imprinting polymers (IIPs) materials draw the great recognition because of the powerful selectivity to the desired metal ions. Therefore, the ion-imprinting polymer (Ce-IIP) was prepared by using cerium metal with amidoxime ligand as the complexing agent, in addition ethylene glycol dimethacrylate (EGDMA) and 2,2-azobisisobutyronitrile (AIBN) are crosslinking agent and free radical initiator, respectively. Aqueous HCl was applied to leach the cerium ions from the imprinted polymer for the creation of cavities of template, which is utilized for further cerium ions adsorption with high selectivity. The Ce-IIP was characterized by using ICP-MS, FE-SEM and also solid state analysis by UV-vis NIR spectroscopy. FT-IR study confirmed the complexation of the Ce-IIP was successful. The optimum pH was found to be 6 and the highest adsorption capacity was estimated about 145 mg g-1. Thus, the prepared Ce-IIP gave very good selectivity to cerium ions in the presence of lanthanide ions and also Ce-IIP can be reused 10 times without a substantial loss in adsorption capacity.
In this study, Single-Walled and Multi-Walled Carbon Nanotubes in their perfect forms were investigated by the Finite Element Method. Details on the modeling of the structure are provided in this paper, including the appropriate elements, the element properties that should be defined based on the atomic structure of Carbon Nanotubes and the corresponding chemical bonds. Non-covalent van der Waals interactions between two neighbor atoms as well as the required approximations for the modeling of the structures with this kind of interaction are also presented. Specific attention was dedicated to the necessity of using some time- and energy-consuming steps in the simulation process. First, the effect of simulating only a single ring of the whole structure is studied to find out if it would represent the same mechanical behavior as the long structure. Results show that by applying an appropriate set of boundary conditions, the stiffness of the shortened structure is practically equal to the long perfect structure. Furthermore, Multi-Walled Carbon Nanotube structures with and without defining the van der Waals force are studied. Based on the observations, applying the van der Waals force does not significantly influence the obtained Young's modulus of the structure in the case of a uniaxial tensile test.
In this study, a series of copper-ion-doped titanium dioxide (Cu-ion-doped TiO₂) nanotubes (NTs) were synthesized via a hydrothermal method by the concentration variation of doped Cu ions (0.00, 0.50, 1.00, 2.50, and 5.00 mmol). In addition, the samples were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), nitrogen gas adsorption measurements, and ultraviolet-visible (UV-Vis) diffuse-reflectance spectroscopy. The photocatalytic activity of the Cu-iondoped TiO₂ NTs was investigated for the degradation of methyl orange (MO) under sunlight. The results obtained from the structural and morphological studies revealed that, at low concentrations of Cu-doped TiO₂ NTs, Cu is incorporated into the interstitial positions of the TiO₂ lattice, affording a new phase of TiO₂ (hexagonal) instead of the anatase TiO₂ (tetragonal) observed for undoped TiO₂ NTs. EDX analysis confirmed the presence of Cu in the TiO₂-based photocatalyst. All of the investigated samples exhibited a hollow fibrous-like structure, indicative of an NT morphology. The inner and outer diameters of the NTs were 4 nm and 10 nm, respectively. The photocatalysts exhibited a large surface area due to the NT morphology and a type IV isotherm and H3 hysteresis, corresponding to the mesopores and slit-shaped pores. The Cu-ion-doped TiO₂ NTs were excited by sunlight because of their low bandgap energy; and after the incorporation of Cu ions into the interstitial positions of the TiO₂ lattice, the NTs exhibited high visible-light activity owing to the low bandgap.
This investigation aims at the reclamation of Cr(VI) from synthetic electroplating industrial effluent by electroextraction process namely electrochemical ion exchange (EIX). An electrochemical ion exchange reactor of desired dimensions was fabricated with the help of ion-permeable membranes, stainless steel cathode and PbO₂ coated Ti expanded mesh anode. The performance of the reactor was studied in batch recirculation mode, continuous flow mode at different experimental conditions. The influence of various experimental factors, for instance, initial metal ion concentration (20, 300, 1000 mg/L of Cr(VI)), applied voltages (2.5 V, 5 V, 7.5 V, 10 V) and flow rates of the process stream (2, 4, 6, 8, 10, 12 and 14 ml/min) on removal/reclamation efficiency was deliberated. For comparison purposes, an electrodialysis process was conducted at the same optimal conditions. It was found that the EIX process with three compartments has more removal efficiency at optimum experimental conditions than the electrodialysis process. The continuous flow process of the reactor with 300 mg/L of Cr(VI) as inlet concentration has studied to predict the breakeven point of the reactor. It was noted that Cr(VI) ion concentration in the treated wastewater is almost zero up to the discharge of 20 liters of treated rinse water.
Porous ZnO nanostructures have become the subject of research interest--due to their special structures with high surface to volume ratio that may produce peculiar properties for use in optoelectronics, sensing and catalysis applications. A microwave-assisted hydrothermal method has been used for effecting the formation of porous nanostructure of metaloxide materials, such as CoO and SnO2, in solution. Here, by adopting the unique performance of a microwave-assisted-hydrothermal method, we realized the formation of highly porous ZnO nanostructures directly on the substrate surface, instead of in solution. The effects of the ambient reaction conditions and the microwave power on the structural growth of the ZnO nanostructures were studied in detail. Two different ambient reaction conditions, namely refluxed and isolated in autoclave systems, were used in this work. Porous ZnO (PZO) nanostructures with networked-nanoflakes morphology is the typical result for this approach. It was found that the morphology of the ZnO nanostructures was strongly depended on the ambient conditions of the reaction; the isolated-autoclave system may produce reasonably high porous ZnO that is constituted by vertically oriented grainy-flakes structures, whereas the refluxed system produced solid vertically-oriented flake structures. The microwave power did not influence the structural growth of the ZnO. It was also found that both the ambient reaction conditions and the microwave power used influenced the crystallographic orientation of the PZO. For instance, PZO with dominant (002) Bragg plane could be obtained by using refluxed system, whereas PZO with dominant (101) plane could be realized if using isolated system. For the case of microwave power, the crystallographic orientation of PZO prepared using both systems changed from dominant (002) to (101) planes if the power was increased. The mechanism for the formation of porous ZnO nanostructures using the present approach is proposed. The ZnO nanostructures prepared using the present method should find an extensive use in currently existing application due to its property of reasonably high porosity.
The present work highlights the facile synthesis of hydrophobic palm fatty acid functionalized Fe3O4 nanoparticles (MNP-FA) for the efficient removal of oils from the surface of water. An intense hydrophobic layer was introduced on the surface of Fe3O4 nanoparticles functionalized by the palm fatty acid obtained from the hydrolysis of palm olein. Scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), Energy dispersive X-ray spectroscopy (EDX) and water contact angle analysis (WCA) measurements were used to characterize the newly fabricated palm fatty acid adorned magnetic Fe3O4 nanoparticles (MNP-FA). The obtained results confirmed the successful synthesis of palm fatty acid-functionalized magnetic nanoparticles. Oil removal tests performed with MNP-FA revealed that this newly prepared material could selectively adsorb lubricating oil up to 3.5 times of the particles' weight while completely repelling water. The main parameters affecting the adsorption of oil i.e., sorption time, mass of sorbent and pH of water were optimized.
In this work, a simple, co-precipitation technique was used to prepare un-doped, pure tin oxide (SnO₂). As synthesized SnO₂ nanoparticles were doped with Cu2+ ions. Detailed characterization was carried out to observe the crystalline phase, morphological features and chemical constituents with opto-electrical and magnetic properties of the synthesized nanoparticles (NPs). X-ray diffraction analysis showed the existence of crystalline, tetragonal structure of SnO₂. Both the sample synthesized here showed different crystalline morphology. The band gap energy (Eg) of the synthesized sample was estimated and it was found to decrease from 3.60 to 3.26 eV. The band gap energy reduced due to increase in Cu2+ dopant amount inside the SnO₂ lattice. Optical properties were analyzed using absorption spectra and Photoluminescence (PL) spectra. It was observed that Cu2+ ions incorporated SnO₂ NPs exhibited more degradation efficiencies for Rhodamine B (RhB) dye compared to un-doped sample under UV-Visible irradiation. The dielectric characteristics of un-doped, pure and Cu2+ incorporated SnO₂ nanoparticles were studied at different frequency region under different temperatures. The ac conductivity and impedance analysis of pure and Cu2+ incorporated SnO₂ nanoparticles was also studied. The magnetic properties of the synthesized samples were analysed. Both the sample showed ferromagnetic properties. The research indicated that the Cu2+ ions doping can make the sample a promising candidate for using in the field of optoelectronics, magneto electronics, and microwave devices.
Herein, we report the effect of synthesis temperature on the morphologies, optical and electronic properties of magnesium oxide (MgO) nanostructures. The MgO nanostructures were synthesized at different temperatures, i.e., 100 °C, 300 °C, and 600 °C by simple chemical reaction process and their morphology, particle size, optical, and electrical properties were examined by different techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and UV-Vis. spectroscopy. The morphological investigations revealed that various morphologies of MgO nanostructures, i.e., nanoparticles, nanosheet networks, and nanoneedles were synthesized at 100 °C, 300 °C, and 600 °C. The XRD results confirmed that with increasing the synthesis temperature, the crystallinity of the synthesized nanostructures increases. Further, the dielectric properties and AC conductivity at various frequencies for MgO nanostructures were studied which revealed that the dielectric losses decrease with increase in frequency and temperature. In addition, the observed band gap decreases from 4.89 eV to 4.438 eV (100 °C to 600 °C) representing its increase in the conductivity.
Nanostructure materials are of interest in last few decades due to their unique size-dependent physio-chemical properties. In this paper, zinc oxide (ZnO) and barium doped ZnO nanodisks (NDs) were synthesized using sonochemical method and characterized by various techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), UV-vis absorption and dielectric measurements. The XRD and FTIR studies confirm the crystalline nature of ZnO NDs, and the average crystallite size was found to be ~25 nm for pure ZnO and ~22 nm for Ba doped ZnO NDs. SEM study confirmed the spherical shaped ZnO NDs with average sizes in the range of 20-30 nm. The maximum absorbance was obtained in the 200-500 nm regions with a prominent peak absorbance were observed by UV-vis spectra. The corresponding band gap for ZnO NDs and Ba doped ZnO NDs were calculated using Tauc's plot and was found to be 3.12 and 3.04, respectively. The conductivity and dielectric measurements as a function of frequency have been studied.