Zinc Oxide Loading Research Articles

Dimensional Optimization for ZnO-Based Mechano-ATRP with Extraordinary Activity.

Various piezoelectric nanomaterials were utilized in ultrasound-mediated atom transfer radical polymerization (ATRP), owing to their outstanding piezoelectric effect. However, the relationship between the morphology of those piezocatalysts and polymerization has not been clearly established. Herein, we employed different piezoelectric zinc oxide (ZnO) nanomaterials to achieve novel mechano-induced ATRP (mechano-ATRP). Based on the synergistic effect of piezoelectric properties and specific surface area, the catalytic activity of 1D ZnO nanorods (1D-ZnO NRs) with increased aspect ratio outperformed that of 0D ZnO nanoparticles (0D-ZnO NPs). Compared to the conventional ATRP system, this system exhibited extraordinary activity toward the less activated monomer acrylonitrile (67% conversion after 6 h), with a narrow molecular weight distribution (polydispersity index ∼ 1.19). Furthermore, implications of ZnO loading, copper salt amount, degree of polymerization, monomer, and solvent were also studied for the highly efficient mechano-ATRP.

Synthesis of Hydroxyapatite/Zinc Oxide Nanoparticles from Fish Scales for the Removal of Hydrogen Sulfide

The presence of hydrogen sulfide (H2S) is an issue for industrial processing, such as gasoline, natural gas, and biogas. In this study, hydroxyapatite (HA) nanoparticles with high purity were successfully extracted from red tilapia fish scales and used as supporting materials for zinc oxide (ZnO) to remove H2S. Various amounts of ZnO decorated on HA nanoparticles were prepared from a zinc nitrate hexahydrate precursor. Powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) of the ZnO/HA samples demonstrated the successful synthesis of ZnO/HA with high purity. The scanning electron microscope (SEM) image analysis confirmed the uniform deposition of ZnO on HA nanoparticles which were smaller than 245 nm. The ZnO/HA samples with different ZnO loadings (i.e., 5, 10, and 15 wt%) were used to remove H2S at room temperature. The specific surface area of HA and ZnO/HA determined by the Brunauer-Emmett-Teller (BET) method was 37.022 (m2/g) and 111.609 (m2/g), respectively. The experimental results demonstrated the highest breakthrough sulfur capacity of 26.3 mg S/g with the sorbent ZnO (15 wt%)/HA nanoparticles. This H2S adsorption capacity was the highest capacity ever achieved for ZnO/HA.Therefore, there are great possibilities for effective removal of H2S at the ambient conditions using the ZnO (15 wt%)/HA nanoparticles, where HA nanoparticles could be sustainably extracted from the abundant organic source of red tilapia fish scales.

Dye removal efficiency of fresh and dry alginate beads incorporating zinc oxide

Alginate beads incorporating zinc oxide (ZnO) nanoparticles were shown as an alternative to treat water contaminated with sedge dye by combining photocatalytic activity with adsorption. Dry and fresh alginate beads were prepared by changing ZnO contents in the range of 0.5, 1, and 2% (w/w) and then characterized for their morphology as well as dye removal. The dye removal efficiency was increased by increasing the active surface area of the alginate beads and ZnO photocatalytic activity. Under ultraviolet irradiation for 24 h, the dye removal efficiency reached 64% in the case of 2% ZnO loading. The use of alginate beads dried at 80 °C before ZnO loading increased the maximum value to 78%. With more than 20% removal during the first 2 h through the adsorption and diffusion, the dye removal of alginate beads incorporating 1 and 2% ZnO was modeled as a function of time according to the Weber-Morris intra-particle diffusion equation. The dye adsorption per mass of the adsorbent having 0 and 0.5% ZnO loading fitted the Elovich equation better.

Entangled ZnO on Ultrathin Hollow Fibers for UV-Aided Pollutant Decomposition.

Zinc oxide (ZnO), a widely used ultraviolet (UV) degrading substance, offers high selectivity for wastewater treatment, but the leaching of ZnO into water could cause secondary contamination. Using porous substrates to fix and load ZnO is a promising technical method to improve the water purification efficiency and recycling durability of ZnO. However, limited by the slow kinetics and shielding effects, it is challenging to use traditional techniques to introduce ZnO into the interior of a hollow structure. Here, inspired by an ancient dyeing procedure, we formed a unique single-molecule bio-interfacial entanglement as an absorption layer to capture the catalyst for ZnO electroless deposition (ELD) on the surface of natural ultrathin hollow-structured Kapok fibers. With curcumin serving as a linking bridge, ELD allowed the spontaneous formation of intensive ZnO nanocrystals on both the outer and inner walls. ZnO-kapok as the catalyst for ultraviolet photodecomposition of organic pollutants (methylene blue (MB) and phenol as model pollutants) delivered a decomposition efficiency of 80% and outstanding durability. Further modification of the ZnO-kapok catalyst by doping with reduced graphene oxide (rGO) showed an improvement in photodegradation performance of 90% degradation under 2-h irradiation with 21.85 W/dm2 light power. Moreover, to the best of our knowledge, this is the first report featuring ZnO loading on both the outer and inner walls of a fiber-structured hollow kapok material, which provides inspiration for immobilization of metallic oxides on hollow-structured materials for further applications in renewable catalysis, chemical engineering, and energy storage fields.

Polyvinylidene Difluoride (PVDF) Hollow Fiber Membrane Incorporated with Antibacterial and Anti-Fouling by Zinc Oxide for Water and Wastewater Treatment.

The addition of antibacterial material to hollow fiber membranes improves the membrane anti-biofouling characteristics. Antibacterial membranes were fabricated in this study to improve membrane function while also extending membrane lifetime. Neat polyvinylidene difluoride (PVDF) and PVDF hollow fiber membrane with the incorporation of antibacterial agent zinc oxide (ZnO) nanoparticles with various loading (2.5–7.5 wt.%) were fabricated by using dry/wet spinning method. The membrane structure, particle distribution, functional group, hydrophilicity, and pore size of each membrane were all assessed. The result shows that all ZnO/PVDF hollow fiber membranes have the asymmetric structure with even dispersion of ZnO nanoparticles throughout the membranes. The results showed that increased ZnO loadings considerably improved membrane hydrophilicity, and average pore size, in addition to good performance of pure water flux. Antibacterial testing shows that ZnO incorporated in the membrane matrix and membrane surfaces prevents bacteria that cause biofouling from adhering to the membrane. ZnO/PVDF membrane recorded excellent bovine serum albumin (BSA) rejection at 93.4% ± 0.4 with flux recovery rate at 70.9% ± 2.1. These results suggest that antibacterial ZnO/PVDF hollow fiber membranes are promising in relation to reducing biofouling for various water and wastewater treatment.

Oil palm empty fruit bunch cellulose fillers as alternative fillers for carboxylated nitrile butadiene rubber latex films

Malaysia is one of the largest contributors to oil palm plantations and industries, resulting in the generation of a lot of oil palm waste such as oil palm empty fruit bunch (OPEFB). The main goal of this research is to investigate the effect of the OPEFB cellulose as one of the alternative fillers in the carboxylated nitrile butadiene rubber (XNBR) latex films. The OPEFB waste was subjected to ultrasonic with alkali and bleaching treatment prior to addition in XNBR latex compounds. The ultrasonic treatment shows better removal of wax, hemicellulose and lignin but leads to breaking down the crystalline structure of the cellulose particles resulted in reduction of the mechanical properties of the OPEFB cellulose filled XNBR latex films. The OPEFB cellulose filled XNBR latex compound is then subjected to different zinc oxide (ZnO) loading. It found that the increase in zinc oxide loading enhanced the ionic crosslink formation but disrupt the covalent crosslink formation since most of the metal cations Zn2+ tend to form ionic clusters for the ionic crosslinks and Zn-cellulose complex. Overall, the OPEFB cellulose fillers shows positive impact as alternative fillers in XNBR latex films.

Influence of different curing regimes on properties of new copolymer of chloroprene and acrylonitrile

The curing system plays a vital role in designing rubber compounds for various industrial applications. Therefore, it is paramount to establish viable curing strategies for any new elastomer to explore its application potentials and commercial significance. Impacts of different curing regimes on the properties of a recently developed copolymer of chloroprene and acrylonitrile (acrylonitrile-chloroprene rubber, NCR) are reported here. Several primary accelerators (four from thiourea- and one from thiazolene product families) were used for curing the new rubber along with fixed loadings of zinc oxide (5 phr) and magnesium oxide (4 phr). Besides, curatives based on sulfur and peroxide were also evaluated. The influence of different curing systems on the rheological and physical properties of the copolymer was explored. It has been seen that the properties of the copolymer are considerably influenced by the different curing systems used. While ethylene thiourea (ETU) and propylene thiourea (PTU), as primary accelerators, provide the highest state of cure but may cause scorch. The use of trimethyl thiourea (TMU), on the other hand, results in the fastest rate and the most stable state of cure, good scorch safety, bin stability, and an overall good balance of properties. The sulfur-based crosslinking system induces good mechanical properties but causes limited bin stability, poor high-temperature compression set, and impaired heat resistance properties. As a curing agent, peroxide delivers the best bin stability in the rubber stocks but yields higher stiffness and limited aging resistance in the vulcanizates.

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) with zinc oxide nanoparticles for food packaging

AbstractPoly(3‐hydroxybutyrate) (PHB) is a biodegradable biopolyester synthesized via bacterial fermentation from renewable resources that has received great attention over the last years for medicine and food packaging applications. However, it shows several shortcomings such as narrow processing window and a high crystallinity (>50%), which leads to brittleness and low impact resistance. To solve these drawbacks, the hydroxybutyrate units can be copolymerized with other monomers like 3‐hydroxyhexanoate to yield poly(3‐hydroxybutyrate‐co‐3‐hydroxy‐hexanoate) (PHBHHx), a copolymer with higher ductility, improved impact strength, and lower melting point. However, PHBHHx displays lower crystallinity than PHB, hence reduced stiffness, and poorer barrier properties against moisture and gases, which is a disadvantage for its use as food packaging material. In this regard, (PHBHHx)‐based bionanocomposites incorporating 0.5, 1.0, 2.0, and 5.0 wt% zinc oxide (ZnO) nanoparticles were synthesized via solution casting technique. Their morphology, mechanical, thermal, barrier, and antibacterial properties were investigated via transmission electron microscopy, tensile and impact strength tests, thermogravimetric analysis, water vapor, and oxygen permeability measurements as well as antibacterial tests. In terms of gas permeability, the optimum performance was attained at 5.0 wt% ZnO loading, with reductions in the water vapor and oxygen permeability of 45 and 33%, respectively. Conversely, the impact strength decreased with increasing ZnO concentration, leading to 25% reduction for the highest ZnO loading tested. The bionanocomposite with 5.0 wt% ZnO is a promising alternative to synthetic plastics, with an optimal balance of toughness, barrier, and antibacterial properties to be used in packaging and disposable applications such as beverage and food containers.Practical applicationsThis study analyzes the morphology, thermal, mechanical, barrier, and antibacterial properties of biodegradable nanocomposites based on PHBHHx copolymer and ZnO nanoparticles. These safe and environmentally friendly nanomaterials can be used as a sustainable alternative to synthetic plastics for food and beverage containers.

High flux polysulfone braided hollow fiber membrane for wastewater treatment role of zinc oxide as hydrophilic enhancer

Incorporation of zinc oxide (ZnO) nanoparticles has played an important role on the improvement of unique membrane characterization and performance, most notably the hydrophilic modification of the membrane for higher pure water permeability. Additionally, the permeability of the membrane can be improved via introduction of braid support by reducing the thickness of the membrane separation layer. Moreover, the braided hollow fiber membrane (BHFM) is able to perform under higher pressure conditions compared to hollow fiber membranes. In this paper, hybrid polysulfone (PSf)/ZnO BHFMs were fabricated via phase inversion method. Hydrophilic 10 ± 1.8 nm polycrystalline ZnO nanoparticles synthesized via sol-gel method were incorporated on BHFM to improve the hydrophilicity and increase flux with constant rejection under high pressure and the effect of the ZnO loading on the membrane properties and performance were thoroughly studied. The fabricated BHFMs with 0.0, 0.5, 1.0 and 1.5 wt% of ZnO nanoparticles concentration were defined as BHFM1, BHFM2, BHFM3 and BHFM4 respectively. Scanning electron microscopy (SEM), contact angle, mechanical strength, flux performance, rejection with bovine serum albumin (BSA) and fouling of best performed membrane were conducted to achieve the target of this paper. The performance of these hybrid ZnO/PSf BHFMs were compared with neat PSf hollow fiber membrane (HFM) and previous studies. The findings from this research work shows that BHFM4 has the most desired properties for wastewater treatment application. The ZnO nanoparticles in BHFM4 have improved hydrophilicity from 108.79° to 71.02°, and thus BHFM4 has increased flux performance from 36.20 to 919.12 L/m2 h at 1.0 bar pressure and 193.48 to 1909.11 L/m2h at 4.0 bar pressure when compared with BHFM1. Constant BSA rejection rates (> 90%) were observed in all BHFMs. The improved hydrophilicity and pure flux performance with constant rejection rate in high pressure conditions illustrates the suitability of fabricated ZnO/PSf BHFMs in wastewater treatment applications.

Facile Preparation of Activated Carbon/Zinc Oxide Nanocomposite for Supercapacitor Application

Objective: An efficient and facile preparation route has been developed to prepare activated carbon (AC)/zinc oxide (ZnO) nanocomposite electrodes for the supercapacitor electrode. Methods: The zinc oxide nanostructure was synthesized via the sol-gel method by using conventional hexamethylenetetramine (HMTA) reagent as the reducing agent. Results: The physicochemical and electrochemical properties of the nanocomposites were characterized by X-ray diffraction analysis (XRD) and cyclic voltammetry (CV) analysis, respectively. 10 wt% of ZnO loading shows an optimum specific capacitance of 398 F/g at a scan rate of 50 mV/s. The optimum sample retained 96% of its initial specific capacitance upon 100 consecutive cycles. Conclusion: The enhanced specific capacitance can be ascribed to the synergistic effect of the individual properties of AC and ZnO.

Hyaluronic Acid (HA)-Based Silk Fibroin/Zinc Oxide Core-Shell Electrospun Dressing for Burn Wound Management.

Burn injuries represent a major life-threatening event that impacts the quality of life of patients, and places enormous demands on the global healthcare systems. This study introduces the fabrication and characterization of a novel wound dressing made of core-shell hyaluronic acid-silk fibroin/zinc oxide (ZO) nanofibers for treatment of burn injuries. The core-shell configuration enables loading ZO-an antibacterial agent-in the core of nanofibers, which in return improves the sustained release of the drug and maintains its bioactivity. Successful formation of core-shell nanofibers and loading of zinc oxide are confirmed by transmission electron microscopy, Fourier-transform infrared spectroscopy, and energy dispersive X-ray. The antibacterial activity of the dressings are examined against Escherichia coli and Staphylococcus aureus and it is shown that addition of ZO improves the antibacterial property of the dressing in a dose-dependent fashion. However, in vitro cytotoxicity studies show that high concentration of ZO (>3 wt%) is toxic to the cells. In vivo studies indicate that the wound dressings loaded with ZO (3 wt%) substantially improves the wound healing procedure and significantly reduces the inflammatory response at the wound site. Overall, the dressing introduced herein holds great promise for the management of burn injuries.

Applying Pebax-1657/ZnO mixed matrix membranes for CO2/CH4 separation

Membrane technologies as conservative approaches have absorbed much attention in chemical and petroleum engineering, recently. The current research presents the preparation of effectively mixed matrix membranes (MMMs) using polyether-block-amide (Pebax-1657) as a polymeric matrix and zinc oxide (ZnO) nanoparticles with various contents (0.0, 2.5, 5.0, 7.5, and 10.0 wt%) as a filler. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and field emission scanning microscopy (FESEM) were conducted to characterize the prepared membranes. The membrane performance was evaluated by caring out permeation experiments of the CO2 and CH4 at a pressure of 3 bar and temperature of 30 °C. Based on the obtained results, the CO2 permeability and ideal CO2/CH4 selectivity increased about 13 and 21%, respectively at 10.0 wt% loading of ZnO in the polymer matrix.

Intensified desulfurization of simulated crude diesel containing thiophene using ultrasound and ultraviolet irradiation.

A novel desulfurization approach involving ultrasound, ultraviolet irradiation and additives (catalyst and/or oxidants) was investigated for degradation of thiophene (model sulphur compound) present in n-hexane considered as simulated crude diesel. The approaches based on ultrasonic horn also involved combination with various additives such as titanium oxide, zinc oxide, peracetic acid and hydrogen peroxide (H2O2) operated under ambient conditions. All the lab scale studies were performed under fixed condition of 100 W as power and 80% as duty cycle at 500 ml as the operating capacity. The combination of ultrasound and peracetic acid at optimum loading of 8% resulted in higher extent of desulfurization (actual value as 23.4%) compared to the desulfurization obtained using 0.3% loading of zinc oxide and 0.3% loading of titanium oxide combined with ultrasound with desulfurization extent as 13.5 and 22.5% respectively under optimized conditions. The approach of ultrasound and UV light combined with titanium oxide and hydrogen peroxide at optimized loading has also been studied. Maximum desulfurization was obtained as 99% for the combined approach of ultrasound, ultraviolet irradiation, titanium oxide at loading of 0.3 g/L and H2O2 at loading of 300 ppm. Higher degree of desulfurization with the minimum sulphur retention up to 1-2 PPM under intensified processing conditions in terms of lesser treatment time, lesser requirement of oxidants and better cost effectiveness were the main advantages of the combined approach established in the current work as compared to the conventional desulfurization approaches.

Effects of zinc oxide particle shape on properties of a prevulcanized latex

From a zinc precursor of zinc nitrate hexahydrate and a precipitating agent of sodium hydroxide, zinc oxide (ZnO) was hydrothermally synthesized. Using different formulations and different reaction conditions of time and temperature, the obtained ZnO presented two different morphologies: short prism-like, and flower-like. X-ray diffraction data confirmed the wurtzite structure of the obtained ZnO. The short prism ZnO presented a higher specific surface area than the flower-like and the conventional forms. The synthesized ZnO was then compounded with natural rubber (NR) latex at loading contents of 0.1–0.6 phr and NR with conventional ZnO (CZnO) at 1 phr which was used for comparison. The tensile and tear strength of all vulcanizates increased with increased loadings of ZnO, except the vulcanizate containing flower-like ZnO. NR vulcanized films containing short prism ZnO at 0.4 phr showed the highest mechanical properties and they were higher than those of the film containing CZnO at 1 phr. Modulus of all samples tended to increase with increasing content of the synthesized ZnO and it was comparable with the modulus of the sample contained CZnO. NR films containing either short prism or flower-like ZnO showed nearly the same elongation-at-break. The cross-link density of short prism ZnO-incorporated NR was higher than NR comprising flower-like ZnO and CZnO. Furthermore, the aging properties of films containing synthesized ZnO were comparable with the properties of rubber films containing CZnO. Hence, 0.4 phr short prism ZnO was the optimum content for the preparation of prevulcanized latex.

Enhancing visible light photocatalytic activity of bismuth vanadate with the loading of zinc oxide

ZnO/Bi4V2O[Formula: see text] nanocomposites were prepared via a facile hydrothermal method by loading different amounts of ZnO onto the surface of Bi4V2O[Formula: see text]. The resulting ZnO/Bi4V2O[Formula: see text] composites showed excellent photocatalytic activity than that of pure ZnO under visible light irradiation. When the ratio of ZnO to Bi4V2O[Formula: see text] was 1:1 (ZB2), the photocatalytic activity was best, which could degrade RhB almost completely within 30[Formula: see text]min. The enhanced photocatalytic activity of ZnO/Bi4V2O[Formula: see text] composites could be mainly ascribed to the efficient charge separation and the increased specific surface area. Based on the experimental and bandgap calculations, a possible photocatalytic mechanism was proposed.

Characterization of Polyvinyl Alcohol/ZnO Nanocomposite Hydrogels for Wound Dressings

Polymeric hydrogels, as novel soft biomaterials, have found various applications in the medical field; for instance, as wound dressings and wound care management. In this study, in order to achieve wound dressings with improved properties, nanocomposite hydrogels using incorporation of nano zinc oxide (ZnO) in polyvinyl alcohol (PVA), were prepared by a freezing-thawing method. The effect of ZnO loading on the mechanical, structural, physical and antibacterial properties of the samples was investigated and the morphology of the prepared nanocomposite hydrogels was determined by field emission scanning electron microscopy (FESEM). The results of mechanical tests of the nanocomposite hydrogels, using compressive and hardness tests, indicated that by adding increasingly amounts of the ZnO nanoparticles, the mechanical properties of the nanocomposite hydrogels were improved. Structure-related properties of the hydrogels, such as swelling and gel fraction measurements, showed that the increase in ZnO content lead to a decrease in the swelling rate and increase in the gel fraction of the nanocomposites. Antibacterial and biocompatibility analysis revealed that, with increasing nano ZnO content, the antibacterial properties of the nanocomposite significantly increased and the cells viability rose, leading to slightly reduced toxicity. The results of this work indicated that the presence and quantity of added ZnO in the PVA hydrogels were very influential factors to obtain the desirable characteristics of wound dressings, such as absorbing the wound fluids and exudates, being biocompatible, anti-bacterial and nontoxic, and having mechanical stability and flexibility.

Effects of nano- and micro-sized inorganic filers on the performance of epoxy hybrid nanocoatings

Epoxy-based composite coatings were prepared using nanosilica (silicon dioxide (SiO2)) and zinc oxide (ZnO). Different concentrations (5.0, 10.0 and 15.0 wt%) of micro-sized ZnO particles were used along with a fixed amount (20.0 wt%) of nanosilica particles. The functional groups of the composite coatings were confirmed by the Fourier transform infrared spectroscopy. This result indicated that SiO2–ZnO particles were cross-linked with the epoxy. The scanning electron microscopy images of the samples revealed a good dispersion of ZnO particles. In addition, the samples showed an improved adhesive and chemical resistance properties as measured by the cross-cut tape test and chemical resistivity testing. At higher loading of ZnO, the composite coating showed poor properties. Besides that, thermogravimetric analysis, differential scanning calorimetry and ultraviolet–visible spectrophotometer were used to characterize the composite coatings. The properties were enhanced at higher loading of ZnO particles. The oxygen transmission rate was also impressive compare with the neat epoxy.

Preparation of Degradable Sago Starch Film Incorporated with Zinc Oxide (ZnO) Nanoparticles for Enhanced Chemical Barrier and Mechanical Properties

The main objective of this study is to reinforce the mechanical strength and water resistance abilities of sago starch biopolymer by incorporating ZnO nanofillers. The biopolymer based nanocomposite films were cast utilizing different weight percentages of ZnO nanofillers (0, 1, 3 or 5 wt%) in sago starch matrix through solution casting technique. Uniform dispersing of ZnO nanofillers throughout the sago starch matrix was achieved by sonication and also to prevent the formation of ZnO nanoparticles aggregates. This was to further reinforce the chemical barrier properties of the film The results illustrated that with the increase of loading of ZnO nanoparticles from 0 to 5 wt%, the tensile strength and elastic modulus improved from 0.180 to 0.980 MPa and from 3.410 to 6.401 MPa respectively for the films, attributing to the high surface to volume ratios, the high mechanical strength of ZnO nanoparticles and the strong nanofiller-matrix interfacial adhesion. The elongation at break also enhanced owing to the slippage of ZnO nanofillers and the oriented sago starch polymer which activated the shear flow of the sago starch polymer. Sago starch nanocomposites with ZnO loadings varied from 0 to 5 wt% demonstrated decreased water vapour permeability from 4.992 × 10−10 g m−1 s−1 Pa−1 to 2.723 × 10−10 g m−1 s−1 Pa−1.

Room-temperature hydrogen sulfide removal with zinc oxide nanoparticle/molecular sieve prepared by melt infiltration

Melt infiltration was used to prepare supported zinc oxide (ZnO) adsorbents for hydrogen sulfide (H2S) removal at room temperature, with three molecular sieves (MCM-41, SBA-15, and MCM-48) as carriers. The physical/chemical properties and the performance of these adsorbents were compared with those prepared by impregnation. Low- and wide-angle X-ray diffraction, nitrogen adsorption and transmission electron microscopy characterizations revealed that because precursor penetrated into the pores of carrier by capillary force, melt infiltration can yield more evenly dispersed ZnO in the pores of molecular sieve compared with the impregnation. Based on the breakthrough capacity, the best ZnO loading contents were 20 wt% on MCM-41 and SBA-15, and 30 wt% on MCM-48, and their corresponding utilization ration reached 69.8%, 52.2%, and 45.1%. With the same loading, the utilization ration of adsorbents prepared by impregnation was only 26.8%, 38.2% and 28.3%. Breakthrough tests and multiple adsorption/regeneration cycles showed that adsorbents with a large specific surface area, large pore size, and high strength were favorable. However, carrier with a small pore size and high strength could benefit much more from the melt infiltration.

Nanomechanical characterization of SU8/ZnO nanocomposite films for applications in energy-harvesting microsystems

Integration of piezoelectric zinc oxide (ZnO) nanoparticles with SU8 in the form of photo-patternable nanocomposite films can lead to the development of a new generation of energy-harvesting microdevices. Design of such energy-harvesting micro/nano-systems will require knowledge of the mechanical properties of the SU8/ZnO nanocomposite thin films for various loadings of ZnO. This work presents characterization of mechanical properties of SU8/ZnO nanocomposite films with ZnO concentration varying in the range of 0–25 wt% via quasi-static and dynamic nanoindentation. These films were fabricated using conventional microfabrication steps involving dispersion of ZnO in SU8 by ultrasonication, followed by spin-coating and UV exposure. The elastic modulus obtained via quasi-static nanoindentation varies from ~6.2 GPa for pristine SU8 to ~8.8 GPa for SU8/25 wt% ZnO nanocomposite, while hardness varies from 402 MPa to ~520 MPa for SU8/ZnO nanocomposites in the same range of ZnO wt%. The experimentally-obtained elastic modulus has also been compared with estimates obtained via Eshelby–Mori–Tanaka micromechanics. Storage modulus, loss modulus and loss factor obtained via dynamic nanoindentation tests indicate that the SU8/ZnO nanocomposites exhibit viscoelastic behavior in the studied frequency-range of 10 Hz to 201.5 Hz. Microstructural characterization via scanning electron microscopy and optical characterization via UV–vis spectrometry of the nanocomposites have also been reported.