Biodiesel production via esterification/transesterification reactions can be catalyzed by homogenous or heterogeneous catalysts. Development of heterogeneous catalysts for biodiesel production is highly advantageous due to the ease of product purification and of catalyst recyclability. In this current work, a novel acidic [DABCODBS][CF3SO3]2 dicationic ionic liquid (DIL) was used as heterogeneous catalyst to produce biodiesel using oleic acid as model oil. The esterification was conducted under ultrasonic irradiation (20 kHz) using a 14 mm ultrasonic horn transducer operated at various duty cycles. It was observed that the duty cycle, amplitude, methanol to oil molar ratio, catalyst amount and reaction temperature were the major factors that greatly impact the necessary reaction time to lead to a high yield of biodiesel. The reaction conditions were optimized with the aid of Response Surface Methodology (RSM) designed according to the Quadratic model of the Box Behnken method. The optimum conditions were found to be at catalyst amount of 0.64 mol%, methanol to oil ratio of 14.3:1, temperature of 59 °C, reaction time of 83 min and amplitude of 60% in continuous mode. The results showed that the oleic acid was successfully converted into esters with conversion value of 93.20% together with significant reduction of reaction time from 7 h (using mechanical stirring) to 83 min (using ultrasonication). The results also showed that the acidic DIL catalyst we designed purposely was efficient to catalyze the ultrasonic-assisted esterification yielding high conversion of oleic acid to methyl oleate on short times. The DIL was also recycled and reused for at least five times without significant reduction in performance. Overall, the procedureoffersadvantages including short reaction time, good yield, operational simplicity and environmentally benign characteristics.
An upsurge in sustainable energy demands has ultimately made supercapattery one of the important choice for energy storage, owing to highly advantageous energy density and long life span. In this work, novel strontium based mixed phased nanostructures were synthesized by using probe sonicator with sonication power 500 W at frequency of 20 kHz. The synthesized material was subsequently calcined at different temperature ranging from 200 to 800 °C. Structural and morphological analysis of the synthesized materials reveals the formation of mixed particle and rod like nanostructures with multiple crystal phases of strontium oxides and carbonates. Crystallinity, grain size and morphology of grown nanomaterials significantly improved with the increase of calcination temperature due to sufficient particle growth and low agglomeration. The electrochemical performance analysis confirms the redox activeness of the Sr-based electrode materials. Material calcined at 600 °C show high specific capacitance of 350 F g-1 and specific capacity of 175 C g-1 at current density of 0.3 A g-1 due to less particle agglomeration, good charge transfer and more contribution of electrochemical active sites for redox reactions. In addition, the developed supercapattery of Sr-based nanomaterials//activated carbon demonstrated high performance with maximum energy density of 21.8 Wh kg-1 and an excellent power density of 2400 W kg-1 for the lower and higher current densities. Furthermore, the supercapattery retain 87% of its capacity after continuous 3000 charge/discharge cycles. The device characteristics were further investigated by analyzing the capacitive and diffusion controlled contributions. The versatile strategy of developing mixed phased nanomaterials pave the way to synthesize other transition metal based nanomaterials with superior electrochemical performance for hybrid energy storage devices.
The leaf extract of a medicinally important plant, watercress (Nasturtium officinale), was obtained through an ultrasound-facilitated method and utilized for the preparation of ZnO nanoparticles via a joint ultrasound-microwave assisted procedure. The characteristics of the extract enriched nanoparticles (Ext/ZnO) were determined by SEM, TEM, XRD, EDX, BET, FTIR, TGA, and UV-Vis DRS analyses and compared to that of ZnO prepared in the absence of the extract (ZnO). The presence of carbon and carbonaceous bonds, changes in the morphology, size, band gap energy, and weight-decay percentage were a number of differences between ZnO and Ext/ZnO that confirmed the link of extract over nanoparticles. Ext/ZnO, watercress leaf extract, ZnO, and insulin therapies were administrated to treat alloxan-diabetic Wister rats and their healing effectiveness results were compared to one another. The serum levels of the main diabetic indices such as insulin, fasting blood glucose, and lipid profile (total triglyceride, total cholesterol, and high-density lipoprotein cholesterol) were estimated for healthy, diabetic, and the rats rehabilitated with the studied therapeutic agents. The watercress extract-enriched ZnO nanoparticles offered the best performance and suppressed the diabetic status of rats. Moreover, both ZnO samples satisfactory inhibited the activities of Staphylococcus aureus and Escherichia coli bacteria. Based on the results, the application of Nasturtium officinale leaf extract can strongly empower ZnO nanoparticles towards superior antidiabetic and enhanced antibacterial activities.
Hydroquinone (HQ), a phenolic compound is expansively used in many industrial applications and due to the utilization of HQ, water pollution tragedies frequently found by the improper handling and accidental outflows. When HQ is adsorbed directly through the skin that create toxic effects to human by affecting kidney, liver, lungs, and urinary tract and hence, a highly selective and sensitive technique is required for its quantification. Herein, we have developed the ultrasonic synthesis of copper oxide nanoflakes (CuO-NFs) using ultrasonic bath (20 kHz, 100 W) and successfully employed for the sensitive detection of the environmental hazardous pollutant HQ. The formed CuO-NFs were confirmed by X-ray diffraction, field emission scanning electron microscopy (FE-SEM), FT-IR spectroscopy and UV-visible spectroscopy and fabricated with the screen-printed carbon electrode (SPCE). The SEM images exhibited the uniform CuO-NFs with an average width of 85 nm. The linker-free CuO-NFs fabricated electrode showed the appropriate wide range of concentrations from 0.1 to 1400 µM and the limit of detection was found to be 10.4 nM towards HQ. The fabricated sensor having long term stability and sensitivity was successfully applied for the environmental and commercial real sample analysis and exhibited good recovery percentage, implying that the SPCE/CuO-NFs is an economically viable and benign robust scaffold for the determination of HQ.
This study demonstrated the effect of two-pot sequential pretreatment, comprising of ultrasound assisted deep eutectic solvent (DES) with the aim to investigate the effects of ultrasound amplitude and duration in enhancing delignification. Oil palm fronds (OPF) were ultrasonicated in a water medium, followed by a pretreatment using DES (choline chloride:urea). Fourier transform infra-red spectroscopy, X-ray diffraction, field emission scanning electron microscope, Brunauer-Emmet-Teller and solubilised lignin concentration were conducted to confirm the effectiveness of ultrasound assisted DES on the pretreatment of OPF. The recommended ultrasound conditions were determined to be 70% amplitude and duration of 30 min, where the sequential DES pretreatment was able to reduce lignin content of OPF to 14.01%, while improving xylose recovery by 58%.
This paper presents the successful application of ultrasound-assisted packed-bed (UAE-PB) method for the extraction of hypericin from the Hypericum perfuratum L. The Soxhlet system was utilized for the determination of suitable solvent from ethanol, methanol or from the mixture of different proportions of ethanol-methanol. The mixture of 50:50 v/v ethanol-methanol was obtained to be the most suitable solvent since it led to the highest extraction amount of hypericin. The extraction amount of hypericin increased by 13.6% and 21.4% when the solvent changed from pure methanol to the mixture of 50:50 v/v ethanol-methanol for the extraction time of 3 and 8 h, respectively. Subsequently, the extraction was conducted through the UAE-PB, and the effects of temperature, time, and the ratio of solvent to the dried plant were studied. The response surface method (RSM) was used to investigate the effect of parameters on the extraction in the UAE-PB system. At the temperature of 60 °C, extraction time of 105 min, and the solvent to plant ratio of 15.3, the maximum extraction yield of hypericin was achieved. In the optimal conditions, the amount of extraction was 0.112 mg hypericin/g dried plant, which was in accordance with the optimized predicted value (0.111 mg hypericin/g dried plant) from Design-Expert software.
In the field of ultrasonic emulsification, the formation and cavitation collapse is one major factor contributing to the formation of micro- and nano-sized emulsion droplets. In this work, a series of experiments were conducted to examine the effects of varying the ultrasonic horn's position to the sizes of emulsion droplets formed, in an attempt to compare the influence of the simulated acoustic pressure fields to the experimental results. Results showed that the intensity of the acoustic pressure played a vital role in the formation of smaller emulsion droplets. Larger areas with acoustic pressure above the cavitation threshold in the water phase have resulted in the formation of smaller emulsion droplets ca. 250 nm and with polydispersity index of 0.2-0.3. Placing the ultrasonic horn at the oil-water interface has hindered the formation of small emulsion droplets, due to the transfer of energy to overcome the interfacial surface tension of oil and water, resulting in a slight reduction in the maximum acoustic pressure, as well as the total area with acoustic pressures above the cavitation threshold. This work has demonstrated the influence of the position of the ultrasonic horn in the oil and water system on the final emulsion droplets formed and can conclude the importance of generating acoustic pressure above the cavitation threshold to achieve small and stable oil-in-water emulsion.
The dynamics of droplet breakup during emulsification is a complicated process due to the interplay between multiple physico-chemical and hydrodynamic factors, especially in an energy-intensive ultrasound-assisted emulsification process. In this work, by mapping the physical processing parameters of ultrasound emulsification into a reduced domain that is governed by the power density and the initial average droplet diameter, a dimensionless parameter that resembles the dynamic breakup potential (η) was established via dimensional analysis. In addition to shedding important insights into the emulsification process, η further facilitates the establishment of a transient scaling relationship that is a function of the characteristic value (a) of the emulsion system. Experimental case study on a cellulose nanocrystals (CNC)-based olein-in-water emulsion system prepared via ultrasound cavitation confirmed the validity of the scaling relationship and sub-universal self-similarity was observed. Using the proposed model, good predictions of the transient of droplet size evolution were attained where the value of η, i.e. the proportionality constant, can be conveniently computed using data from a single time point. Application on other emulsion systems further suggested that the value of a possibly indicates the relative minimum size limit of a particular fluids-emulsifier system. Our approach is general, which encourages widespread adoption for emulsification related studies.
The synthesis of nanoparticles often result in the generation of harmful chemical pollutants. As such, many researchers have focused on developing green processes, which include the biosynthesis. In this research, ZnO nanoparticles were prepared using the leaf extract of whortleberry (Vaccinium arctostaphylos L.) via a simple ultrasonic-assisted method. The morphology, crystal size and structure, surface, thermal, and optical properties of the bio-mediated ZnO sample (ZnOext) were analyzed and compared with that produced without incorporating the extract (ZnOchem). The ZnO samples were evaluated for their antidiabetic, antibacterial, as well as their sono- and photo-catalytic performances. Initially, the samples were intraperitoneal injected to alloxan-diabetic rats to examine their treatment efficiency in terms of effects on fasting blood glucose, insulin, cholesterol, high-density lipoprotein, and total triglyceride levels. The ZnOext showed significantly higher efficiency for improving the health status of alloxan-diabetic rats in contrast with other tested treatments, vis. ZnOchem, insulin, and only leaf extract. In addition, both the ZnO samples were assessed against gram-negative and gram-positive bacteria and through sono- and photo-catalytic processes for removing rhodamine B, respectively. The results of this study indicated that not only the ZnOext sample was pollution free, it also exhibited higher potentials for treating diabetic rats, bacterial decontamination, and also oxidative removal of organic compounds under the influences of ultrasound and UV irradiations when compared with ZnOchem sample.
The current work proposed an alternative ultrasound (US) technology, namely the high-intensity ultrasonic tubular reactor (HUTR) for preparing Pickering emulsions. Using the non-toxic and environmentally friendly cellulose nanocrystal (CNC) as a solid stabilizer, Pickering emulsions were produced using the HUTR and the results showed that Pickering emulsions as small as 1.5 µm can be produced using HUTR at the US power and sonication time of 300 W and 15 min respectively. Additionally, the sizes of Pickering emulsion obtained are found to remain the same upon 30 days of storage. The performance of HUTR in emulsion preparation is compared to conventional US horn system at the same US power. It was observed that the use of HUTR allowed generation of Pickering emulsion that is significantly smaller (around 7.40 μm) and with better droplet size distribution (Coefficient of variation, CV = 31%) as compared to those prepared with US horn method (12.75 µm, CV = 36%). This is owing to the better distribution of cavitation activity in the treatment chamber of HUTR as compared to those in the horn, according to the sonochemiluminescence (SCL) study. From the 30-days storage stability analysis, the CNC-PE prepared using HUTR was found to more stable against droplet coalescence in comparison to those prepared using US horn. Our findings suggested that the HUTR possessed superior Pickering emulsification capacity when compared to conventional US horn. Further work will be necessary to evaluate the feasibility of such intensifying tubular reactor technology for larger scale emulsification and other process intensification applications.
This work studied the influences of water blanching pretreatment (30 s), surface contacting ultrasound (492.3 and 1131.1 W/m2) assisted air drying, and their combination on drying kinetics and quality of white cabbage. Contacting sonication was performed by placing samples on an ultrasonic vibration plate, and the drying temperature was 60 °C. Through drying kinetic analysis and numerical simulation considering internal and external resistances and shrinkage, it was found that both blanching pretreatment and contacting sonication during drying intensified internal water diffusion and external water exchange to shorten cabbage drying time. Meanwhile, blanching pretreatment was more effective to enhance the drying process. The largest reduction of drying time (from 145 min to 24 min) was obtained when sequential blanching and contacting sonication at 1131.1 W/m2 were conducted. Dehydrated cabbages with blanching pretreatment were characterized by green color and high retention of vitamin C, while a severe loss of vitamin C was found in dried cabbages without blanching pretreatment. Moreover, although both blanching and contacting sonication shortened the drying time, the losses of phenolics, glucosinolates and resulting breakdown products were not alleviated. Contents of total phenolics, one glucosinolates (sinigrin) and one glucobrassicin breakdown product (indole-3-acetoritrile) in only air dried cabbages were significantly (p
This study aimed to formulate a stable palm oil-based water-in-oil (W/O) nano-emulsion. Emphasis was placed on the effects of polyglycerol polyricinoleate (PGPR), medium chain triglyceride (MCT), lecithin and sodium chloride (NaCl) addition towards the stability of nano-emulsion. Among the performed analyses were mean droplet diameter (MDD), dispersity index (DI), critical micelle concentration (CMC), lipid peroxidation, viscosity, sedimentation index (SI) and surface morphology. The most stable optimized palm oil-based W/O nano-emulsion was produced using 61.25 wt% of palm oil, 26.25 wt% of MCT, 2.5 wt% of PGPR and 10 wt% of water (0.5 M of NaCl). The MDD and DI of the obtained W/O nano-emulsion were 143.1 ± 8.8 and 0.131 ± 0.094, respectively. After 2 weeks, no sedimentation was observed in W/O nano-emulsion with MDD and DI were 151.2 ± 6.5 nm and 0.156 ± 0.025 respectively. This study clearly found that polyricinoleate non-polar fatty acids of PGPR bound to non-polar fatty acids of palm oil through van der Waals intermolecular forces. While, polyglycerol polar head of PGPR interacts with water molecules through hydrogen bonding, as well as by the bound glyceride units of palm oil. The addition of NaCl further reduced MDD by 70 nm and improved the stability of nano-emulsion through electrostatic and steric repulsions attributed to the dissociation of Na+ and Cl- ions. This study aids to widen the knowledge and interest on the utilization of palm oil for the generation of W/O nano-emulsion, as well as to better understand the interaction between palm oil and PGPR/NaCl in producing nano-emulsion.
In this work, sonication (20-kHz) was conducted to assist the biosorption of phenolics from blueberry pomace extracts by brewery waste yeast biomass. The adsorption capacity of yeast increased markedly under ultrasonic fields. After sonication at 394.2 W/L and 40 °C for 120 min, the adsorption capacity was increased by 62.7% compared with that under reciprocating shaking. An artificial neural network was used to model and visualize the effects of different parameters on yeast biosorption capacity. Both biosorption time and acoustic energy density had positive influences on yeast biosorption capacity, whereas no clear influence of temperature on biosorption process was observed. Regarding the mechanism of ultrasound-enhanced biosorption process, the amino and carboxyl groups in yeast were considered to be associated with the yeast biosorption property. Meanwhile, ultrasound promoted the decline of the structure order of yeast cells induced by phenolic uptake. The interactions between yeast cells and phenolics were also affected by the structures of phenolics. Moreover, the mass transfer process was simulated by a surface diffusional model considering the ultrasound-induced yeast cell disruption. The modeling results showed that the external mass transfer coefficient in liquid phase and the surface diffusion coefficient under sonication at 394.2 W/L and 40 °C were 128.5% and 74.3% higher than that under reciprocating shaking, respectively.
Dicofol, a recommended Stockholm convention persistent organic pollutants (POPs) candidate is well known for its endocrine disruptive properties and has been extensively used as an organochlorine pesticide worldwide. The hydrodynamic cavitation (HC) treatment of Dicofol in aqueous media induced by a liquid whistle hydrodynamic cavitaion reactor (LWHCR) has been investigated while considering important parameters such as inlet pressure, initial concentration of Dicofol, solution temperature, pH, addition of H2O2 and radical scavenger for the extent of degradation. The pseudo-first-order degradation rate constant (k) was determined to be 0.073 min-1 with a cavitational yield of 1.26 × 10-5 mg/J at optimum operating conditions and a complete removal of Dicofol was achieved within 1 h of treatment. Considering the removal rate and energy efficiency, the optimal inlet pressure was found to be 7 bar, resulting in a cavitation number of 0.17. High performance liquid chromatography (HPLC) and Gas chromatography mass spectroscopy (GC-MS) analyses indicated a sharp decline in the concentration of Dicofol with treatment time and indicated the presence of degraded products. An 85% total organic carbon (TOC) removal was achieved within 1 h of treatment time, demonstrating successful mineralization of Dicofol. The obtained results suggest that the degradation of Dicofol followed thermal decomposition and successive recombination reactions at bubble-vapor interface. Overall, the attempted hydrodynamic cavitation demonstrated successful and rapid removal of endocrine disruptive chemicals such as Dicofol and is expected to provide efficient solution for wastewater treatment.
The main objective of this review is to derive the salient features of previously developed ultrasound-assisted methods for hydroxylating graphene and Buckminsterfullerene (C60). The pros and cons associated to ultrasound-assisted synthesis of hydroxy-carbon nanomaterials in designing the strategical methods for the industrial bulk production are also discussed. A guideline on the statistical methods has also been considered to further provide the scopes towards the application of the previously reported methods. Irrespective of many useful methods that have been developed in order to functionalize C60 and graphene by diverse oxygenated functional groups e.g. epoxide, hydroxyl, carboxyl as well as metal/metal oxide via a combination of organic chemistry and sonochemistry, there is no report dealing exclusively on the application of ultrasonic cavitation particularly to synthesising polyhydroxylated carbon nanomaterials. On this context, this review emphasizes in investigating the critical aspects of sono-nanochemistry and the statistical approaches to optimize the variables in the sonochemical process towards a large-scale synthesis of polyhydroxylated graphene and C60.
Ultrafiltration has been proven to be very effective in the treatment of oil-in-water emulsions, since no chemical additives are required. However, ultrafiltration has its limitations, the main limits are concentration polarization resulting to permeate flux decline with time. Adsorption, accumulation of oil and particles on the membrane surface which causes fouling of the membrane. Studies have shown that the ultrasonic is effective in cleaning of fouled membrane and enhancing membrane filtration performance. But the effectiveness also, depends on the selection of appropriate membrane material, membrane geometry, ultrasonic module design, operational and processing condition. In this study, a hollow and flat-sheet polyurethane (PU) membranes synthesized with different additives and solvent were used and their performance evaluated with oil-in-water emulsion. The steady-state permeate flux and the rejection of oil in percentage (%) at two different modes were determined. A dry/wet spinning technique was used to fabricate the flat-sheet and hollow fibre membrane (HFMs) using Polyethersulfone (PES) polymer base, Polyvinylpyrrolidone (PVP) additive and N, N-Dimethylacetamide (DMAc) solvent. Ultrasonic assisted cross-flow ultrafiltration module was built to avoid loss of ultrasonic to the surrounding. The polyurethane (PU) was synthesized by polymerization and sulphonation to have an anionic group (-OH; -COOH; and -SO3H) on the membrane surface. Changes in morphological properties of the membrane had a significant effect on the permeate flow rate and oil removal. Generation of cavitation and Brownian motion by the ultrasonic were the dominant mechanisms responsible for ultrafiltration by cracking the cake layers and reducing concentration polarization at the membrane surface. The percentage of oil after ultrafiltration process with ultrasonic is about 90% compared to 49% without ultrasonic. Ultrasonic is effective in enhancing the membrane permeate flux and controlling membrane fouling.
Hydrodeoxygenation is one of the promising technologies for the transformation of triglycerides into long-chain hydrocarbon fuel commonly known as green diesel. The hydrodeoxygenation (HDO) of rubber seed oil into diesel range (C15-C18) hydrocarbon over non-sulphided bimetallic (Ni-Mo/γ-Al2O3 solid catalysts were studied. The catalysts were synthesized via wet impregnation method as well as sonochemical method. The synthesized catalysts were subjected to characterization methods including FESEM coupled with EDX, XRD, BET, TEM, XPS, NH3-TPD, CO-chemisorption and H2-TPR in order to investigate the effects of ultrasound irradiations on physicochemical properties of the catalyst. All the catalysts were tested for HDO reaction at 350 °C, 35 bar, H2/oil 1000 N (cm3/cm3) and WHSV = 1 h-1 in fixed bed tubular reactor. The catalyst prepared via sonochemical method showed comparatively higher specific surface area, particles in nano-size and uniform distribution of particle on the external surface of the support, higher crystallinity and lower reduction temperature as well as higher concentration of Mo4+ deoxygenating metal species. These physicochemical properties improved the catalytic activity compared to conventionally synthesized catalyst for HDO of rubber seed oil. The catalytic performance of sonochemically synthesized Ni-Mo/γ-Al2O3 catalyst (80.87%) was higher than the catalyst prepared via wet impregnation method (63.3%). The sonochemically synthesized Ni-Mo/γ-Al2O3 catalyst is found to be active, produces 80.87 wt% of diesel range hydrocarbons, and it gives high selectivity for Pentadecane (18.7 wt%), Hexadecane (16.65 wt%), Heptadecane (24.45 wt%) and Octadecane (21.0 wt%). The product distribution revealed that the deoxygenation reaction pathway was preferred. Higher conversion and higher HDO yield in this study are associated mainly with the change in concentration ratio between oxidation states of molybdenum (Mo4+, Mo5+, and Mo6+) on the external surface of the catalyst due to ultrasound irradiation during the synthesis process. Consequently, the application of sonochemically synthesized non-sulphided catalysts favored mainly hydrodeoxygenation of diesel range hydrocarbon.
In this study, high-frequency ultrasound wave (1.8 MHz) at low intensity was applied to improve activated sludge settleability at high MLSS concentration. The effect of irradiation intensity, sonication mode, MLSS concentration and sample volume on the physical characteristics of sludge in a pilot scale settling column were investigated for optimizing the conditions. The obtained results showed that high-frequency ultrasound decreased the height of sludge (44%) and effluent turbidity (82.2%) and increased sludge settling velocity about 3 times at high biomass concentration. Irradiation intensity of 0.4 w/cm2 and sonication mode with interval times of 10 s showed the best results on the performance of the system at MLSS concentration of 8000 mg/L with a sample volume of 3 L.
Vertically aligned Zinc oxide nanorods (ZnO NRs) were successfully synthesized in this study using the sonochemical method to improve the intrinsic properties of UV photodetector (PD). Three different thin films: Ti/Zn, Ti/ZnO, and Ti/ZnO/Zn, with the thicknesses of 10 nm/55 nm, 10 nm/85 nm, and 10 nm/85 nm/55 nm respectively, were deposited on glass substrates using the RF-sputtering technique. The synthesized ZnO NRs were investigated using XRD, FESEM and Raman spectroscopy to determine the effect of Zn and ZnO as seed layers, and ZnO as a buffer layer on the surface morphology, crystal structure, optical properties of ZnO NRs. The ZnO NRs grown on Zn/Ti, ZnO/Ti, and Zn/ZnO/Ti are characterized by hexagonal crystal structure with preferential growth in the c-axis direction. The ZnO NRs grown on Zn/ZnO/Ti displayed the highest density, uniform size distribution, vertically aligned rods and aspect ratio. The UV device fabricated from the ZnO NRs grown on Zn /ZnO/Ti also showed the highest photocurrent (360 µA) and responsivity of (878 mA/W). ZnO NRs grown on Zn/ZnO/Ti were also observed to be highly stable and exhibited a relatively rapid response and recovery times for different time intervals when exposed to the UV light of 365 nm wavelength. Thus, the inclusion of the ZnO as a buffer layer (Zn as a seed layer/ZnO as buffer layer/Ti as a buffer layer) improve the properties of the ZnO NRs. In addition, the current gain of ZnO NRs grown on Zn (55 nm)/ZnO (85 nm)/Ti (10 nm) - based ultraviolet (UV) photodetector (PD) is about two times higher than that of conventional Zn (55 nm)/ZnO (85 nm)/Ti (10 nm) thin-films UV PD, which is due to the higher surface-to-volume ratio of ZnO nanorods (NRs) compared with their thin films. This study confirms the possibility of sonochemically fabricating vertically aligned ZnO nanorods as well as its applicability as a viable UV photodetector.
Ultrasound was applied simultaneously with adsorption process in most of the previous studies. However, this method is not practical to treat huge amounts of coloured wastewater effluent. In this study, the efficiency of ultrasound pre-treated peanut husk powder at different power levels (1.5-3.5 W) in dye adsorption with several conditions of initial dye concentration (20-100 mg/L), contact time (0.5-5 h), solution pH (2-8), and dosage (0.1-0.3 g) was studied and compared with ultrasound simultaneous adsorption process and the control. Adsorption efficiency of indirect ultrasound pre-treated peanut husk powder has increased 25.78%, 13.64% and 1.5% compared with the control, ultrasound simultaneous adsorption and direct ultrasound pre-treated sample respectively at 60 mg/L of initial dye concentration. Indirect ultrasound pre-treated sample at 3.5 W has achieved the highest adsorption efficiency of 89.96% at solution pH 8 and 94.83% at 0.3 g dose for 3 h. The surface feature and textural properties of samples were characterized by using scanning electron microscopy and surface characterization analyser. The result indicated that more porous structure was created on the ultrasound pre-treated sample at increasing power levels.