Loading Of ZnO Nanoparticles Research Articles

Synthesis of composite films for ZnO-based memristors with superior stability

Memristors have unique non-volatile characteristics that potentially can emulate biological synapses for applications in neural computing systems. However, the random formation of conductive filaments in these devices can cause various unreliability problems. In this work, films of a composite of ZnO nanoparticles and carbon nanotubes were prepared as functional layers for memristors by an in-situ growing strategy (ZnO@CNT-IS) using a straightforward high-temperature annealing treatment. This approach allowed for the formation of a high-quality films with uniform loading of ZnO nanoparticles on the carbon nanotubes, which contributed to a lower formation energy for oxygen vacancies and increased electron transfer rate. As a result, the memristors exhibited faster switching response speed, lower power consumption, and a stabilised switching ratio even after 2000 switching cycles. Based on the analog switching behaviour, the ZnO@CNT-IS-based devices showed significant biological synapse functions and plasticity, indicating their potential for high-density storage and neuromorphic computing.

Nanofibers with an Adjustable Core-Sheath Structure Constructed from Hyperbranched Polyester for Efficient Loading of ZnO Nanoparticles

Loading nanoparticles is a valuable way to construct functional fiber materials, yet the lack of homogeneity and easy agglomeration hinder its functional effect. Hyper-branched polyester (HBPE) has been identified as the ideal delivery vehicle for nanoparticles. Its application in nanofibers can be a promising approach to enhancing the loading efficiency. In this study, adjustable core-sheath structured polyacrylonitrile (PAN)/HBPE nanofibers were fabricated owing to the phase separation of two components during centrifugal spinning, and zinc oxide nanoparticles (ZnO NPs) were further introduced into the sheath. Scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, and so forth were utilized to characterize the morphology of the obtained nanofibers. Results indicated that the thickness of sheath in PAN/HBPE nanofibers could expand from 33.33 to 57.14% as the mass ratio of PAN/HBPE decreased from 8:2 to 5:5. Additionally, the ZnO NPs were encapsulated and dispersed by HBPE and successfully delivered to the sheath layer of the nanofibers. Therefore, the Zn content on the surface of PAN/HBPE/ZnO NP nanofibers can reach 17.86 wt % with only 6 wt % ZnO NPs doped, representing a 90% increase compared with HBPE-free nanofibers. Besides, the PAN/HBPE/ZnO NP nanofibers exhibited excellent air permeability and qualified biocompatibility, as well as outstanding functional release. The antibacterial rates against Escherichia coli and Staphylococcus aureus reached 96.62 ± 0.34 and 99.55 ± 0.78%, respectively. This facile processing strategy subtly combines the advantages of material and structure, providing insights to better achieve efficient loading of nanoparticles on nanofibers, enabling more researchers to customize functional materials.

MIL-68 (In) and ZIF-8 assisted construction of n-n heterostructure for the effective sensing of trace-level ozone

The crucial challenge to exploit effective ozone (O3) gas sensors lies in developing novel functional sensing materials to meet the requirement of trace-level detection threshold (50 ppb). Metal oxide semiconductors (MOSs) with controllable heterogenous composites as high-performance sensing layers are expected to break through this bottleneck. This work proposes the hybridization of MIL-68 (In) and ZIF-8, which are employed as dual metal organic frameworks (MOFs) sacrificial templates to design n-n heterostructures. The derived In2O3 backbone showed a hexagonal prismatic structure with a large aspect ratio. The robust architecture enabled the uniform decoration of mass of ZnO nanoparticles (NPs) on the surfaces without the damage of high porosity for the gas diffusion. Consequently, the optimal sensor with appropriate ZnO NPs loading amount exhibited trace O3 detection ability as low as 15 ppb, which was attributed to the smart design of n-n heterostructure, rich active sites and improved oxygen-adsorbing capacity. Thus, this work inspires a new way to utilize the versatile dual MOFs template for constructing heterogenous composites as O3 sensing materials.

Role of ZnO Nanoparticles Loading in Modifying the Morphological, Optical, and Thermal Properties of Immiscible Polymer (PMMA/PEG) Blends

High-performance hybrid polymer blends can be prepared by blending different types of polymers to improve their properties. However, most polymer blends exhibit phase separation after blending. In this study, polymethylmethacrylate/polyethylene glycol (PMMA/PEG) polymer blends (70/30 and 30/70 w/w) were prepared by solution casting with and without ZnO nanoparticles (NPs) loading. The effect of loading ZnO nanoparticles on blend morphology, UV blocking, glass transition, melting, and crystallization were investigated. Without loading ZnO NP, the PMMA/PEG blends showed phase separation, especially the PEG-rich blend. Loading PMMA/PEG blend with ZnO NPs increased the miscibility of the blend and most of the ZnO NPs dispersed in the PEG phase. The interaction of the ZnO NPs with the blend polymers slightly decreased the intensity of infrared absorption of the functional groups. The UV-blocking properties of the blends increased by 15% and 20%, and the band gap energy values were 4.1 eV and 3.8 eV for the blends loaded with ZnO NPs with a PMMA/PEG ratio of 70/30 and 30/70, respectively. In addition, the glass transition temperature (Tg) increased by 14 °C, the crystallinity rate increased by 15%, the melting (Tm) and crystallization(Tc) temperatures increased by 2 °C and 14 °C, respectively, and the thermal stability increased by 25 °C compared to the PMMA/PEG blends without ZnO NP loading.

ZnO nanoparticles loaded rice husk biochar as an effective adsorbent for removing reactive red 24 from aqueous solution

In this study, rice husk biochar (RHB) and ZnO nanoparticles loaded rice husk biochar (RHB-ZnO-3 served to adsorb Reactive red 24 (RR24) in an aqueous solution. Effects of the ZnO nanoparticles loading ratio, solution pH, contact time, and initial RR24 concentration were evaluated utilizing detailed batch adsorption conditions. Isotherm and kinetic models helped to analyze the RR24 adsorption. Shown here is that the ratio of 3% (w/w) ZnO nanoparticles to RHB proved to be the best for fabricating highly effective modified rice husk biochar. In this scenario, the BET surface area of RHB-ZnO-3 was 13.84 m2/g, more than triple the original RHB (4.01 m2/g). Experimental results strongly suggest that RR24 highest adsorption capacities onto RHB-ZnO-3 and RHB were 174.91 mg/g and 88.51 mg/g, respectively. The best pH contact time and adsorbent rate for RR24 removal were 3, 60 min and 1.0 g/L, respectively. RR24 adsorption onto RHB and RHB-ZnO-3 were well described by Pseudo-second order kinetic and Langmuir isotherm models. Adsorption capacities of RHB and RHB-ZnO-3 did not diminish significantly after five cycles of adsorption-desorption. RHB and RHB-ZnO-3 could remove: firstly, more than half of the color and COD (50% color, 52.5% COD); and secondly, most of the turbidity (82.8%) from real textile wastewater. Electrostatic attraction, π-π interaction and pore filling were the main adsorption mechanisms of RR24 onto RHB and RHB-ZnO-3.

Preparation of bio-nano bandage from quince seed mucilage/ZnO nanoparticles and its application for the treatment of burn

Burns and skin wounds require special care and treatment because the body skin is the first defense barrier against pathogens. Therefore, quick and suitable treatment of the wound is very important. Using nanotechnology, special wound dressings can be created for the all types of wounds that the time, place, and rate of drug release can be controlled. Also, nanobandages can be used as a cover for the wound to prevent of microorganisms entering to the body and creating an infection. Very fine and continuous fibers with diameters of micrometers to several nanometers range can be produced using electrospinning method and various materials such as natural and synthetic polymers. In this study, the nanoparticles of Zinc Oxide synthesized by the green method (using the walnut leaf extracts) with quince seed mucilage (as a new biopolymer)/chitosan/PEO were used for preparing antibacterial nanobandages. The best fibers with suitable diameters, shape and appropriate loading of ZnO nanoparticles were obtained in the ratio of 20: 80 quince seed mucilage to chitosan/PEO. Best effective parameters in the electrospinning were obtained as follows: voltage = 18 kV, feed rate of polymer solution 1 mL/h and Needle-to-collector distance 12 cm. The produced nanofibers were characterized by FT-IR spectroscopy, X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and tensile test. The results of animal test showed that nanobandage containing ZnO nanoparticles had a significant treatment effect on grade 2 burn wounds and the burn healed more quickly and no infections were detected in the wound. After 21 day the skin was completely restored and there was no evidence of burns on their bodies. The results showed that the effect of developed nanobandage on wound healing was much greater than the nanobandage without nanoparticles and control.

Gas separation through polyurethane–ZnO mixed matrix membranes and mathematical modeling of the interfacial morphology

AbstractA series of polyurethane/ZnO membranes was fabricated via thermal phase inversion of the solution of polymer/nanoparticle in N,N‐dimethylformamide solvent. The polyurethane synthesis was done via two‐step polymerization method using polytetramethylene glycol, isophorone diisocyanate, and 1,4‐butanediol in the ratio of 1:3:2. Different concentrations of zinc oxide nanoparticles (5, 10, 15, and 20) were incorporated into the polyurethane matrix. FTIR, SEM, and X‐Ray analysis were performed to characterize the membranes. FTIR and SEM results suggests an increment in the phase mixing of polyurethane with ZnO loading. Gas permeation performance through polyurethane‐ZnO mixed matrix membranes with ZnO loading by as much as 20 wt% were elucidated for pure N2, O2, CH4, and CO2 and gases. Based on the results, all permeability values decreased as the loading of ZnO nanoparticles increased, whereas CO2/N2 and CO2/CH4 selectivities increased. Moreover, interfacial structure of the polyurethane/ZnO nanocomposites were characterized by molecular probing approach. The results revealed the presence of a rigidified polymer chain layer with 65 ± 6 Å thickness around the ZnO nanoparticles.

Effect of ZnO nanoparticles loading in double‐layer polyvinylidene fluoride membrane for desalination via direct contact membrane distillation

AbstractIn this study, double‐layer flat sheet membranes consist of nanocomposite polyvinylidene fluoride (PVDF)–ZnO layer on the top, whereas pristine polymeric PVDF on the bottom was fabricated via the double‐casting phase inversion (DCPI) method. The nanocomposite layer was prepared by loading 0.5%, 1.0%, 1.5% and 2.0% of ZnO nanoparticles. The morphology of the membranes changed as ZnO nanoparticles were introduced in the top layer, where the structure is more rigid and porous than the bottom layer. The increment concentration of nanoparticles in the top layer of the double‐layer membrane gives an effect in increasing of water contact angle slightly, which is from 136° to 140°. Furthermore, the liquid entry pressure of water (LEPw) decreases gradually from 0.69 to 0.4 bar with a high concentration of ZnO due to the presence of large pores. The increment concentration of ZnO nanoparticles also resulted in high porosity and reduced pore size, which reduce the resistance of water vapour to pass through the pores as well as enhancing the performance of membrane distillation (MD). Direct contact membrane distillation (DCMD) experiments were carried out to evaluate the efficiency of the fabricated double‐layer membrane in the desalination of seawater from fish farm water for 6‐h operation. The optimal double‐layer membrane with 0.5% ZnO nanoparticles loading maintained a stable flux of 9.42 L/m2h with 99.9% salt rejection and has antifouling properties. The results indicated that the fabricated double‐layer membrane via the DCPI method fulfils the required properties for MD application with excellent salt rejection.

Zinc oxide doped arylidene based polyketones hybrid nanocomposites for enhanced biological activity

The application of Friedel-Craft reactions has been extended to the biological systems. Recently, these reactions have led to the generation of a new set of polyketones (PKa-c) along with the related zinc oxide doped nanocomposites (ZnOPKd-f). Prior to the process of polymerization, these newly synthesized monomers were subjected to spectral analysis to reveal their chemical structures. Three arylidene monomers based on three different moieties including benzylidene, thiophenylidene and furfurylidene were synthesized through a direct condensation reaction. These monomers interacted with terephthaloyl chloride in the presence of anhydrous AlCl3 in organic methanol solvent via Friedel–Crafts reaction, to produce the desired PKa-c. Further, a series of ZnOPKd-f nanocomposites were fabricated using a 10% loading of ZnO nanoparticles throughout the same experimental procedure as required to develop PKa-c. A common characterization tool was employed to prove the structures for PKa-c and its related ZnOPKd-f TGA results established enhancement in the thermal behavior of PK a-c with the different structures. PDTmax values showed that all the polymers had a similar identity which appeared in the range from 578° to 630°. Additionally, the morphological properties were assessed by using scanning electron microscopy which revealed the formation of ZnOPKd-f and ZnO nanoparticles. The latter are spherical particles, ranging in of 29 to 223 nm loaded on the polymer surface. The TEM images illustrated the uniform distribution of the ZnO nanoparticles in the polymer matrix. The ZnOPKd-f nanocomposites were examined for their antimicrobial activity against variable kinds of bacteria and fungi. Based on the biological screening, it was observed that the ZnOPKd-f nanocomposite materials can be used as moderate antibacterial and antifungal agents.

The fabrication of paper separation channel based SERS substrate and its recyclable separation and detection of pesticides.

In this article, a modified paper separation channel SERS substrate was fabricated by a pen writing method for the simultaneous separation and detection of thiuram and dimethoate. The hydrophilic channel was fabricated with both sides of hydrophobic barrier by the Alkylketene dimer (AKD) modified paper substrate, of which the flow dynamic was well conformed to the Lucas-Washburn model and could be used to separate pesticides effectively. As modified by Ag nanoparticles (AgNPs) and ZnO nanoparticles (ZnONPs), the hydrophilic channel exhibited high recyclable SERS detection activity and stability. The separation and detection performance with different target proportion, channel width and sample volume were studied in detail, which have significant influence on the diffusion process. Additionally, the Raman detects intensity on the substrate also showed linear relationship from 100 to 1000μg/L. The calculated limit of detects (LODs) under optimal experimental conditions were 54.57 and 19.16μg/L for dimethoate and thiuram, respectively. Due to the loading of ZnONPs, the substrate could be used repeatably with good stability. The convenient preparation, effective separation and repeatability make this paper based separation channel SERS substrate have great potential application on the fast separation and simultaneous detection of various pesticides in complex field.

Synergistic degradation of acid blue 113 dye in a thermally activated persulfate (TAP)/ZnO-GAC oxidation system: Degradation pathway and application for real textile wastewater

The performance of a binary persulfate activation system based on the simultaneous use of heat (TAP) and ZnO coated granular activated carbon (ZnO-GAC) catalyst was investigated for the degradation of Acid Blue 113 (AB113) azo dye and the treatment of textile industry wastewater. FESEM, XRD, FTIR, EDX-mapping and BET analyses confirmed the successful loading of ZnO nanoparticles onto the GAC substrate. The effect of five independent variables on AB113 removal in the TAP/ZnO-GAC oxidation system was optimized by a 5-level full central composite design (CCD). All experiments were performed in a 6250 mL volume reactor. Adequacy and validity of the proposed model were confirmed with p-value < 0.0001 and R2 = 0.9994. The optimum values for solution pH, reaction time, persulfate (PS) concentration, ZnO-GAC dosage, and solution temperature were obtained to be 4.7, 50 min, 4.2 mM, 2.5 g/L, and 70 °C, respectively. Under these conditions, the maximum removal efficiency of AB113 in PS/ZnO-GAC, TAP, and TAP/ZnO-GAC oxidation systems was 26, 83 and 94.2%, respectively. The synergistic effect of ZnO-GAC on TAP oxidation system reduced the apparent activation energy by approximately 83%. The naphthalen-1-ol, phthalic acid, malonic acid, ethane-1,2-diol, and oxalic acid were the most abundant intermediates produced during AB113 degradation. Radical scavenging experiments showed that SO4·- was the predominant radical species in the TAP/ZnO-GAC system. The optimized TAP/ZnO-GAC process effectively improved the biodegradability of real textile wastewater samples (BOD/COD>0.4).

In-situ one pot synthesis of graphene-ZnO nanohybrid and its application to UV light detection

The development of molecular/nanoscale level assemblies allows the foundation of many potential novel applications. Chemical approach is one of the most favoured techniques to manipulate the nano-materials in a controllable manner. Herein, we report a simple and reliable one pot technique for preparing graphene-ZnO nanohybrid by coordinating zinc metal ions from precursor, which further led to the growth of ZnO nanoparticles on graphene sheets. The developed heterostructures were characterized through X-ray diffractometry, Fourier transformed infra-red (FTIR) spectroscopy, UV-visible spectroscopy and field emission scanning electron microscopy (FESEM). Morphological details revealed the dense loading of ZnO nanoparticles onto the surface of graphene. The nanohybrid was found to be electrically more responsive to the incident UV light compared to ZnO nanoparticles alone. The proposed method can lead to the fabrication of highly sensitive flexible light detector.

COMPARATIVE STUDY BETWEEN ZINC OXIDE NANOPARTICLES SYNTHESIZED BY CHEMICAL AND BIOLOGICAL METHODS IN VIEW OF CHARACTERISTICS, ANTIBACTERIAL ACTIVITY AND LOADING ON ANTIBIOTICS IN VITRO

ZnO nanoparticles (ZnO-NPs) can be synthesized by chemical, physical and biological methods; many studies have indicated that biologically synthesized ZnO-NPs have ecofriendly benefits over physically and chemically synthesized ZnO-NPs. This study was carried out to evaluate the differences in characteristics and effects on pathogenic bacteria between ZnO-NPs synthesized by a chemical method and a biological method using the marine green alga Ulva fasciata. Additionally, the synergistic or antagonistic effects of loading ZnO-NPs synthesized by chemical and biological methods on antibiotics are investigated. The results show that there are differences in the characteristics of ZnO-NPs synthesized by the various methods, as determined by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). ZnO-NPs had antibacterial activity against Staphylococcus aureus, , Salmonella enterica subsp. salamae (Em.1-EGY015), Aeromonas hydrophila, Escherichia coli O157 (KY797670) and Bacillus cereus SH06; moreover, green-synthesized ZnO-NPs were more effective against pathogenic bacteria than chemically synthesized ZnO-NPs. The minimum inhibitory concentration (MIC) of ZnO-NPs synthesized by the green method was less than that of ZnO-NPs synthesized by the chemical method. The results demonstrated that the synergistic or antagonistic effects of ZnO-NP loading on antibiotics (ampicillin/sulbactam, tobramycin, flucloxacillin, chloramphenicol, amoxicillin, cephalexin, ofloxacin, and neomycin) varied according to the type of pathogenic bacteria, antibiotic, and method of synthesis of ZnO-NPs.

Polypyrrole coatings for corrosion protection of Al alloy2024: influence of electrodeposition methods, solvents, and ZnO nanoparticle concentrations

Since ZnO nanoparticles increase the electrical conductivity of the polypyrrole (PPy) coatings, an investigation was carried out to evaluate the effect of ZnO nanoparticles loading on the corrosion protection performance of PPy coatings on AA2024 Al alloy in 3.5% NaCl solution. At first, some measurements were carried out to find the best experimental conditions containing the electrodeposition method, electrosynthesis solvent composition, and ZnO nanoparticles’ concentration for preparing the optimum PPy coating on Al alloy2024. Three different methods of electrodeposition, namely: cyclic voltammetry, galvanostatic, and potentiostatic techniques were analyzed. The anti-corrosion performance of the PPy coatings was evaluated by electrochemical impedance spectroscopy and Tafel polarization methods. The PPy prepared by potentiostatic method exhibited the best performance against corrosion of Al alloy2024 in 3.5% NaCl solution. Then, different mixtures of H2O/ethanol were tested as electrosynthesis solvents for preparation of PPy coatings on the alloy by optimized electrodeposition mode (i.e., potentiostatic). In evaluation of the prepared coatings, the pure water was introduced as the optimum solvent in electrodeposition of PPy. The investigation of different ZnO nanoparticles’ concentrations proved that the PPy coating containing 0.025% ZnO nanoparticles was the optimum coating against the corrosion of Al alloy in NaCl solution. Finally, the long-term evaluation of the corrosion protection performance of the coatings revealed that the optimum coating provided suitable protection against corrosion up to 14 days after immersion.

Intensified convective heat transfer using ZnO nanofluids in heat exchanger with helical coiled geometry at constant wall temperature

The present work deals with the experimental determination of enhancement in the heat transfer using ZnO nanofluid in helical copper tube heat exchanger at constant wall temperature. ZnO nanoparticles were prepared with aid of ultrasonic irradiations using zinc nitrate and KOH as raw materials. The effect of Reynolds number and ZnO nanoparticle addition to the base fluid on heat transfer coefficient and Nusselt number was examined. Around 62.80% and 136% enhancement in thermal conductivity ratio at 40 °C and 50 °C, respectively, was observed for 0.5 vol% loading of ZnO nanoparticles in nanofluids. 18.6% enhancement in the Nusselt number was observed for 0.25 vol% of ZnO nanoparticles in nanofluid at the exit of the test section. This is attributed to the combination of helical coil with ZnO nanofluid which gives significant effect on heat transfer enhancement.

In-situ loading of ZnO nanoparticles on carbon felt as novel binder-free flexible anode for high performance lithium-ion batteries

The paper reports a novel ZnO/carbon felt (CF) flexible electrode via a facile solvothermal method. The flexible electrode presents a unique architecture with well-dispersed ZnO nanoparticles on shallow grooves of carbon felt. As a binder-free LIB anode, it exhibits a stable reversible capacity of 520.2 mA h g−1 after 100 cycles at a current density of 100 mA g−1. The improved lithium storage properties can be attributed to the combined effect of both CF matrix and nano-sized embedded ZnO. The shallow grooves of elastic carbon fibers are favorable to accommodate the large volume expansion of ZnO and sustain good cycle stability. Moreover, the conductive network of CF may promote the electrical contact of the flexible electrode, making contribution to the enhanced rate performance. The structure, morphology and the electrochemical performances of ZnO/CF electrode for flexible LIBs are analyzed in details.

Uniform distribution of ZnO nanoparticles on the surface of grpahene and its enhanced photocatalytic performance

Herein, a ZnO-graphene nanocomposite photocatalyst was obtained by a facile one-step photochemical method. Both the reduction of graphene oxide (GO) and uniform loading of ZnO nanoparticles (NPs) on the surface of graphene were achieved during the photochemical reaction process using GO as the precursor of graphene and zinc chloride (ZnCl2) as the single source of ZnO. The products were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and ultraviolet–visible spectroscopy. The photocatalytic activity of ZnO/rGO composites was studied by the photodegradation of methylene blue (MB) dye. The as-prepared ZnO/rGO photocatalyst possesses great adsorptivity of dyes (e.g., MB) and high charge separation properties. After receiving the photoelectrons from ZnO, graphene plane can effectively transfer the photoelectrons, thereby showing highly efficient photocatalytic degradation towards pollutants. The effective introduction of rGO significantly improved the photocatalysis and sensing properties of ZnO, and we believe that the as-prepared ZnO/rGO nanocomposite would be promising for practical applications in future nanotechnology.

Photocatalytic Degradation of Pentachlorophenol Using ZnO Nanoparticles: Study of Intermediates and Toxicity

The photocatalytic degradation of pentachlorophenol (PCP) was carried out using ZnO nanoparticles (NPs) in the presence of sunlight. The effect of different ZnO NPs sizes was synthesized by sol–gel method as well as loading of ZnO NPs on degradation of PCP was investigated. The results showed that the sunny condition was the best to achieve higher efficiency due to the fact that higher energy of photon was available to accelerate rate of reaction. The highest degradation efficiency of PCP was achieved by smaller size of ZnO NPs as 20 nm with band gap and surface area as 3.198 eV and 26.23 m2/g, respectively. The optimum loading of ZnO NP to achieve higher efficiency of 99.6% was 1.0 g/l under 2 h of irradiation time. The photodegradation of PCP followed a pseudo-first order reaction and the observed rate constant was dependent on the ZnO NP loading. The pathway of PCP degradation was suggested according to the HPLC analysis where PCP was converted to nontoxic compounds such as acetic acid and oxalic acid. The toxicity of PCP before and after degradation was evaluated which indicated the removal of toxicity after degradation as sequence with degradation efficiency and confirmed within fragmentation of PCP degradation.

Photocatalytic removal of doxycycline from aqueous solution using ZnO nano-particles: a comparison between UV-C and visible light.

Zinc oxide nano-particles were synthesized, characterized and used for photocatalytic degradation of doxycycline using UV-C and visible light. Effects of several operational factors including initial pH of antibiotic solution, initial antibiotic concentration and ZnO nano-particles loading amount were investigated. Comparing photocatalytic degradation and mineralization of doxycycline under UV-C and visible light showed successful application of the method under both light sources. However, reaction rate was higher under UV-C irradiation, which degraded doxycycline almost completely in 5 hours, and 68% mineralization was achieved. Synthesized ZnO nano-particles were successfully applied for photocatalytic degradation of doxycycline in a pharmaceutical wastewater sample. The process was fitted to the pseudo first order kinetic model with rate constants in the range of 6-22(×10-3) mg L-1 min-1 with respect to initial concentration of doxycycline under UV-C irradiation. The Langmuir-Hinshelwood model was also employed for describing the photocatalytic reaction with surface reaction kinetic constant kc and equilibrium adsorption constant KLH values calculated as 0.12 mg L-1 min-1 and 2.2 L mg-1, respectively. Degradation of doxycycline was followed by UV-visible spectroscopy and a validated stability indicating high-performance liquid chromatography method that was developed using stressed samples of doxycycline and could selectively determine doxycycline in the presence of its degradation products. Mass spectrometry was used for determining final degradation products.

Cure Characteristics and Mechanical Properties of ZnO Nanoparticles as Activator in Unfilled Natural Rubber

In this work, the effect of ZnO nanoparticles as activator is studied in unfilled natural rubber and compared with conventional ZnO on cure characteristics and mechanical properties. ZnO nanoparticles are synthesized by precipitation method using zinc nitrate tetrahydrate and sodium hydroxide as precursor. Particle size of ZnO nanoparticles can be controlled by polymeric additive. It is found that the average primary size of synthesized ZnO nanoparticles around 28.71 nm and the specific surface area around 31.45 m2/g. The crystalline structure exhibits hexagonal structure with wurtzite. The rheological properties of unfilled natural rubber show that the maximum torque (MH) and the optimum cure time (t90) increase with increasing synthesized ZnO nanoparticles loading. The minimum torque (ML) of unfilled natural rubber which uses synthesized ZnO nanoparticles loading higher than conventional ZnO. Compression set and tension set are the permanent deformation also investigated. It is found that deformation reduces when increase synthesized ZnO nanoparticles loading. The mechanical properties such as hardness, tensile strength, 100% and 300% modulus, tear strength, elongation at break are improved, without detrimental effect on properties. For unfilled natural rubber, synthesized ZnO nanoparticles can be reduced successfully from 5 to 2 phr and stearic acid 1 to 0.3 phr, respectively.