Displaying publications 41 - 60 of 127 in total

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  1. ZnO nanocubes with (101) basal plane photocatalyst prepared via a low-frequency ultrasonic assisted hydrolysis process
    Tan ST, Umar AA, Balouch A, Yahaya M, Yap CC, Salleh MM, et al.
    Ultrason Sonochem, 2014 Mar;21(2):754-60.
    PMID: 24184009 DOI: 10.1016/j.ultsonch.2013.10.009
    The crystallographic plane of the ZnO nanocrystals photocatalyst is considered as a key parameter for an effective photocatalysis, photoelectrochemical reaction and photosensitivity. In this paper, we report a simple method for the synthesis of a new (101) high-energy plane bounded ZnO nanocubes photocatalyst directly on the FTO surface, using a seed-mediated ultrasonic assisted hydrolysis process. In the typical procedure, high-density nanocubes and quasi-nanocubes can be grown on the substrate surface from a solution containing equimolar (0.04 M) zinc nitrate hydrate and hexamine. ZnO nanocubes, with average edge-length of ca. 50 nm, can be obtained on the surface in as quickly as 10 min. The heterogeneous photocatalytic property of the sample has been examined in the photodegradation of methyl orange (MO) by UV light irradiation. It was found that the ZnO nanocubes exhibit excellent catalytic and photocatalytic properties and demonstrate the photodegradation efficiency as high as 5.7 percent/μg mW. This is 200 times higher than those reported results using a relatively low-powered polychromatic UV light source (4 mW). The mechanism of ZnO nanocube formation using the present approach is discussed. The new-synthesized ZnO nanocubes with a unique (101) basal plane also find potential application in photoelectrochemical devices and sensing.
  2. Facile synthesis of calcium silicate hydrate using sodium dodecyl sulfate as a surfactant assisted by ultrasonic irradiation
    Mehrali M, Seyed Shirazi SF, Baradaran S, Mehrali M, Metselaar HS, Kadri NA, et al.
    Ultrason Sonochem, 2014 Mar;21(2):735-42.
    PMID: 24120175 DOI: 10.1016/j.ultsonch.2013.08.012
    Calcium silicate hydrate (CSH) consisting of nanosheets has been successfully synthesized assisted by a tip ultrasonic irradiation (UI) method using calcium nitrate (Ca(NO3)·4H2O), sodium silicate (Na2SiO3·9H2O) and sodium dodecyl sulfate (SDS) in water. Systematic studies found that reaction time of ultrasonic irradiation and concentrations of surfactant (SDS) in the system were important factors to control the crystallite size and morphologies. The products were characterized by X-ray power diffraction (XRD), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectrometry (FTIR). The size-strain plot (SSP) method was used to study the individual contributions of crystallite sizes and lattice strain on the peak broadening of the CSH. These characterization techniques revealed the successful formation of a crystalline phase with an average crystallite size of about 13 nm and nanosheet morphology at a reaction time of 10 min UI with 0.2 g SDS in solvent which were found to be optimum time and concentrations of SDS for the synthesis of CSH powders.
  3. Effective ultrasonication process for better colloidal dispersion of nanofluid
    Mahbubul IM, Saidur R, Amalina MA, Elcioglu EB, Okutucu-Ozyurt T
    Ultrason Sonochem, 2015 Sep;26:361-9.
    PMID: 25616639 DOI: 10.1016/j.ultsonch.2015.01.005
    Improving dispersion stability of nanofluids through ultrasonication has been shown to be effective. Determining specific conditions of ultrasonication for a certain nanofluid is necessary. For this purpose, nanofluids of varying nanoparticle concentrations were prepared and studied to find out a suitable and rather mono-dispersed concentration (i.e., 0.5 vol.%, determined through transmission electron microscopy (TEM) analyses). This study aims to report applicable ultrasonication conditions for the dispersion of Al2O3 nanoparticles within H2O through the two-step production method. The prepared samples were ultrasonicated via an ultrasonic horn for 1-5h at two different amplitudes (25% and 50%). The microstructure, particle size distribution (PSD), and zeta potentials were analyzed to investigate the dispersion characteristics. Better particle dispersion, smaller aggregate sizes, and higher zeta potentials were observed at 3 and 5h of ultrasonication duration for the 50% and 25% of sonicator power amplitudes, respectively.
  4. Effects of processing parameters in the sonic assisted water extraction (SAWE) of 6-gingerol
    Syed Jaapar SZ, Morad NA, Iwai Y, Nordin MFM
    Ultrason Sonochem, 2017 Sep;38:62-74.
    PMID: 28633858 DOI: 10.1016/j.ultsonch.2017.02.034
    The use of water in subcritical conditions for extraction has several drawbacks. These include the safety features, higher production costs and possible degradation of the bioactive compounds. To overcome these problems, sonic energy and an entrainer were used as external interventions to decrease the polarity of water at milder operating conditions. The effect of low (28kHz) and high (800kHz) frequencies of sonication in the extraction of the main ginger bioactive compound (6-gingerol) were compared. Six parameters were studied: mean particle size (MPS, mm), time of extraction, applied power, sample to solvent ratio (w/v), temperature of extraction, and the percentage of entrainer. The optimum conditions for high frequency SAWE prototype were MPS 0.89-1.77mm, 45min, 40W applied power, 1:30 (w/v), 45°C, and 15% of ethanol as entrainer. Two-way analysis of variance (ANOVA) gave the most significant parameter, which was power with F (1, 45.07), p<2.50×10-9. Although the effect of low frequency was stronger than high frequency, at the optimum conditions of the sample to solvent ratio 1:30 (w/v) with 700mL solvent and temperature 45°C, the concentration and recovery of 6-gingerol from high frequency of SAWE prototype was 2.69 times higher than at low frequency of SAWE. It was found that although the effects of high frequency (800kHz) were negligible in other studies, it could extract suitable compounds, such as 6-gingerol, at lower temperature. Therefore, the effects of sonication, which cause an enlargement in the cell wall of the ginger plant matrix, were observed using a Scanning Electron Microscope (SEM). It was found that the applied power of sonication was the most significant parameter compared to the other parameters.
  5. Formulation development and optimization of a novel Cremophore EL-based nanoemulsion using ultrasound cavitation
    Tang SY, Manickam S, Wei TK, Nashiru B
    Ultrason Sonochem, 2012 Mar;19(2):330-45.
    PMID: 21835676 DOI: 10.1016/j.ultsonch.2011.07.001
    In the present study, response surface methodology (RSM) based on central composite design (CCD) was employed to investigate the influence of main emulsion composition variables, namely drug loading, oil content, emulsifier content as well as the effect of the ultrasonic operating parameters such as pre-mixing time, ultrasonic amplitude, and irradiation time on the properties of aspirin-loaded nanoemulsions. The two main emulsion properties studied as response variables were: mean droplet size and polydispersity index. The ultimate goal of the present work was to determine the optimum level of the six independent variables in which an optimal aspirin nanoemulsion with desirable properties could be produced. The response surface analysis results clearly showed that the variability of two responses could be depicted as a linear function of the content of main emulsion compositions and ultrasonic processing variables. In the present investigation, it is evidently shown that ultrasound cavitation is a powerful yet promising approach in the controlled production of aspirin nanoemulsions with smaller average droplet size in a range of 200-300 nm and with a polydispersity index (PDI) of about 0.30. This study proved that the use of low frequency ultrasound is of considerable importance in the controlled production of pharmaceutical nanoemulsions in the drug delivery system.
  6. Ultrasound-assisted packed-bed extraction of hypericin from Hypericum perforatum L. and optimization by response surface methodology
    Tahmasebi-Boldaji R, Hatamipour MS, Khanahmadi M, Sadeh P, Najafipour I
    Ultrason Sonochem, 2019 Oct;57:89-97.
    PMID: 31208622 DOI: 10.1016/j.ultsonch.2019.05.018
    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.
  7. An expeditious synthetic approach towards the synthesis of Bis-Schiff bases (aldazines) using ultrasound
    Khan KM, Jamil W, Ambreen N, Taha M, Perveen S, Morales GA
    Ultrason Sonochem, 2014 May;21(3):1200-5.
    PMID: 24398059 DOI: 10.1016/j.ultsonch.2013.12.011
    Aldazines (Bis-Schiff bases) 1-24 were synthesized using aromatic aldehydes (heterocyclic and benzaldehydes) and hydrazine hydrate under reflux using conventional heating and/or via ultrasound irradiation using BiCl3 as catalyst. Ultrasonication conditions with cat. BiCl3 proved to be an effective, environmentally friendly synthetic procedure. This methodology is robust in the presence of electron donating and electron withdrawing groups affording desired products with high yields (>95%) in just a couple of minutes vs. hours using conventional heating.
  8. Fulltext Ultrasound-assisted encapsulation of Pandan (Pandanus amaryllifolius) extract
    Omer N, Choo YM, Ahmad N, Mohd Yusof NS
    Ultrason Sonochem, 2021 Nov;79:105793.
    PMID: 34673338 DOI: 10.1016/j.ultsonch.2021.105793
    Pandan (Pandanus amaryllifolius) is commonly used as a food ingredient in Southeast Asia due to its delicious flavor, appetizing aroma and bright green colour. Pandan plant is uniquely found only in certain parts of the world. Despite its increasing popularity worldwide, its export market is limited by practical issues. One of the main problems for exporting Pandan to global market is its stability during transport. Due to the volatility of its active constituent, the functional properties of Pandan are lost during storage and shipment. In this study, we explored the ability of ultrasound processing technology to encapsulate the aromatic Pandan extract using lysozyme or chitosan as a shell material. 20 kHz ultrasonicator was used to encapsulate the pandan extract at 150 W of applied power. Two parameters, the ultrasonic probe tip and the core-to-shell ratio were varied to control the properties of the encapsulates. The diameters of the probe tip used were 0.3 and 1.0 cm. The core-to-shell volume ratios used were 1:160 and 1:40. The size distribution and the stability of the synthesized microspheres were characterized to understand and explore the possible parameters variation impact. Both size and size distribution of the microspheres were found to be influenced by the parameters varied to certain extent. The results showed that the mean size of the microspheres was generally smallest when using 1 cm probe tip with lower core-to-shell volume ratio but largest when using the 3 mm tip with higher core-to-shell volume ratio. This indicates that the sonication parameters could be fine-tuned to achieve the encapsulation of Pandan extract for storage and export. The pandan-encapsulated microspheres were also found to be stable during storage at least for one month.
  9. Fulltext The effect of sonication on the ion exchange constant, KXBr of CTABr/chlorobenzoates micellar systems
    Mohd Yusof NS
    Ultrason Sonochem, 2021 Mar;71:105360.
    PMID: 33125959 DOI: 10.1016/j.ultsonch.2020.105360
    The ion exchange constant, KXBr (for the case of cetyltrimethylammonium bromide, CTABr, in this study) is a method dependant characterization of ion exchange process by counterions, X and Br with different relative binding ratios. In this report, the ion exchange constant, KXBr values for micelle systems irradiated under 2 min of sonication at 120 W power using a probe sonicator with 1 cm tip were determined to be 85.2, 125.6 and 122.4 when X  = o-, m- and p-chlorobenzoates, respectively. The values were quantified using a semiempirical kinetic method coupled with Pseudophase Micellar model, and later compared to the same system in the absence of sonication. The sonication was found to amplify the KXBr values by ~ 13-fold for X  = o-chlorobenzoate and ~ 2.5-fold for X  = m- and p-chlorobenzoates. This is due to the improvement of ion exchange process by the oscillation of bubbles generated by acoustic cavitation. An active ion exchange process indicates better stabilization of the micelle aggregational structure by the penetration of the introduced counterions, X into the micelle Stern layer leading to the growth of the micelle. This is supported by the remarkable increase in the viscosity of the micelle system by > 7-fold for X  = o-chlorobenzoate and by > 2-folds for X  = m- and p-chlorobenzoates. Sonication was also found to induce maximum viscoelasticity at lower concentration ratio of [CTABr]:[X]. The ability of ultrasound to induce micelle growth and exhibiting viscoelasticity at lower concentration of counterionic additive will be very useful in technologies where viscoelastic solution is desired such as in oil drilling and centralized heating and cooling system.
  10. Mechanisms of effective gold shell on Fe3O4 core nanoparticles formation using sonochemistry method
    Dheyab MA, Aziz AA, Jameel MS, Khaniabadi PM, Mehrdel B
    Ultrason Sonochem, 2020 Jun;64:104865.
    PMID: 31983562 DOI: 10.1016/j.ultsonch.2019.104865
    Sonochemical synthesis (sonochemistry) is one of the most effective techniques of breaking down large clusters of nanoparticles (NPs) into smaller clusters or even individual NPs, which ensures their dispersibility (stability) in a solution over a long duration. This paper demonstrates the potential of sonochemistry becoming a valuable tool for the deposition of gold (Au) shell on iron oxide nanoparticles (Fe3O4 NPs) by explaining the underlying complex processes that control the deposition mechanism. This review summarizes the principles of the sonochemistry method and highlights the resulting phenomenon of acoustic cavitation and its associated physical, chemical and thermal effects. The effect of sonochemistry on the deposition of Au NPs on the Fe3O4 surface of various sizes is presented and discussed. A Vibra-Cell ultrasonic solid horn with tip size, frequency, power output of ½ inch, 20 kHz and 750 W respectively was used in core@shell synthesis. The sonochemical process was shown to affect the surface and structure of Fe3O4 NPs via acoustic cavitation, which prevents the agglomeration of clusters in a solution, resulting in a more stable dispersion. Deciphering the mechanism that governs the formation of Au shell on Fe3O4 core NPs has emphasized the potential of sonication in enhancing the chemical activity in solutions.
  11. Fulltext Controlling the critical parameters of ultrasonication to affect the dispersion state, isolation, and chiral nematic assembly of cellulose nanocrystals
    Nugroho RWN, Tardy BL, Eldin SM, Ilyas RA, Mahardika M, Masruchin N
    Ultrason Sonochem, 2023 Oct;99:106581.
    PMID: 37690260 DOI: 10.1016/j.ultsonch.2023.106581
    Cellulose nanocrystals (CNCs) are typically extracted from plants and present a range of opto-mechanical properties that warrant their use for the fabrication of sustainable materials. While their commercialization is ongoing, their sustainable extraction at large scale is still being optimized. Ultrasonication is a well-established and routinely used technology for (re-) dispersing and/or isolating plant-based CNCs without the need for additional reagents or chemical processes. Several critical ultrasonication parameters, such as time, amplitude, and energy input, play dominant roles in reducing the particle size and altering the morphology of CNCs. Interestingly, this technology can be coupled with other methods to generate moderate and high yields of CNCs. Besides, the ultrasonics treatment also has a significant impact on the dispersion state and the surface chemistry of CNCs. Accordingly, their ability to self-assemble into liquid crystals and subsequent superstructures can, for example, imbue materials with finely tuned structural colors. This article gives an overview of the primary functions arising from the ultrasonication parameters for stabilizing CNCs, producing CNCs in combination with other promising methods, and highlighting examples where the design of photonic materials using nanocrystal-based celluloses is substantially impacted.
  12. Optimization of ultrasound induced emulsification on the formulation of palm-olein based nanoemulsions for the incorporation of antioxidant β-d-glucan polysaccharides
    Alzorqi I, Ketabchi MR, Sudheer S, Manickam S
    Ultrason Sonochem, 2016 Jul;31:71-84.
    PMID: 26964925 DOI: 10.1016/j.ultsonch.2015.12.004
    Polysaccharides of β-d-glucan configuration have well-known antioxidant activity against reactive free radicals generated from the oxidation of metabolic processes. In this study, β-d-glucan-polysaccharides extracted from Ganoderma lucidum were incorporated in palm olein based nanoemulsions which act as carrier systems to enhance the delivery and bioactivity of these polysaccharides and could be potentially useful for skin care applications. Initially response surface statistical design (Central Composite Design - CCD) was subjected to optimize the formulation variables of oil-in-water (O/W) nanoemulsions induced by ultrasound. The optimal formulation variables as predicted by CCD resulted in considerably improving the physical characteristics of ultrasonically formulated nanoemulsions by minimizing their droplet size, polydispersity index and viscosity. Moreover, the β-d-glucan-loaded nanoemulsions exhibited good stability over 90days under different storage conditions (4°C and 25°C). The studies using palm olein based β-d-glucan-loaded nanoemulsion generated using ultrasound confirm higher antioxidant activity as compared to free β-d-glucan.
  13. Identification of active sonochemical zones in a triple frequency ultrasonic reactor via physical and chemical characterization techniques
    Tiong TJ, Liew DK, Gondipon RC, Wong RW, Loo YL, Lok MS, et al.
    Ultrason Sonochem, 2017 Mar;35(Pt B):569-576.
    PMID: 27156122 DOI: 10.1016/j.ultsonch.2016.04.029
    Coupling multiple frequencies in ultrasonic systems is one of the highly desired area of research for sonochemists, as it is known for producing synergistic effects on various ultrasonic reactions. In this study, the characteristics of a hexagonal-shaped triple frequency ultrasonic reactor with the combination frequencies of 28, 40 and 70kHz were studied. The results showed that uniform temperature increment was achieved throughout the reactor at all frequency combinations. On the other hand, sonochemiluminescence emission and degradation rate of Rhodamine B varies throughout different areas of the reactor, indicating the presence of acoustic 'hot spots' at certain areas of the reactor. Also, coupling dual and triple frequencies showed a decrease in the hydroxyl radical (OH) production, suggesting probable wave cancelling effect in the system. The results can therefore be served as a guide to optimize the usage of a triple frequency ultrasonic reactor for future applications.
  14. Ultrasonically extracted β-d-glucan from artificially cultivated mushroom, characteristic properties and antioxidant activity
    Alzorqi I, Sudheer S, Lu TJ, Manickam S
    Ultrason Sonochem, 2017 Mar;35(Pt B):531-540.
    PMID: 27161557 DOI: 10.1016/j.ultsonch.2016.04.017
    Ganoderma mushroom cultivated recently in Malaysia to produce chemically different nutritional fibers has attracted the attention of the local market. The extraction methods, molecular weight and degree of branching of (1-3; 1-6)-β-d-glucan polysaccharides is of prime importance to determine its antioxidant bioactivity. Therefore three extraction methods i.e. hot water extraction (HWE), soxhlet extraction (SE) and ultrasound assisted extraction (US) were employed to study the total content of (1-3; 1-6)-β-d-glucans, degree of branching, structural characteristics, monosaccharides composition, as well as the total yield of polysaccharides that could be obtained from the artificially cultivated Ganoderma. The physical characteristics by HPAEC-PAD, HPGPC and FTIR, as well as the antioxidant in vitro assays of DPPH scavenging activity and ferric reducing power (FRAP) indicated that (1-3; 1-6)-β-d-glucans of Malaysian mushroom have better antioxidant activity, higher molecular weight and optimal degree of branching when extracted by US in comparison with conventional methods.
  15. Variation in performance at different positions of an ultrasonic VialTweeter--A study based on various physical and chemical activities
    Tiong TJ, Low LE, Teoh HJ, Chin JK, Manickam S
    Ultrason Sonochem, 2015 Nov;27:165-70.
    PMID: 26186833 DOI: 10.1016/j.ultsonch.2015.04.033
    Ultrasonic VialTweeter is used for the sonication of small volume samples. It contains a titanium block with 8 holes for vial insertion, to be used simultaneously for batch operation. In this investigation, the ultrasonic and sonochemical performance of ultrasonic VialTweeter has been evaluated at its different positions. Experimental results using calorimetry, ultrasonic capillary effect, sonochemiluminescence and degradation of Rhodamine B showed that the sonochemical activity differs greatly at different positions along the VialTweeter, with positions 3 and 4 showing the maximum efficiency whereas the positions 1 and 2 being the least effective positions. These results were further verified by acoustic pressure simulation, confirming that certain locations in the VialTweeter may not perform in the same way as others due to the variation in acoustic pressure at different locations.
  16. State of the art and recent advances in the ultrasound-assisted synthesis, exfoliation and functionalization of graphene derivatives
    Muthoosamy K, Manickam S
    Ultrason Sonochem, 2017 Nov;39:478-493.
    PMID: 28732972 DOI: 10.1016/j.ultsonch.2017.05.019
    Sonochemistry, an almost a century old technique was predominantly employed in the cleaning and extraction processes but this tool has now slowly gained tremendous attention in the synthesis of nanoparticles (NPs) where particles of sub-micron have been produced with great stability. Following this, ultrasonication techniques have been largely employed in graphene synthesis and its dispersion in various solvents which would conventionally take days and offers poor yield. Ultrasonic irradiation allows the production of thin-layered graphene oxide (GO) and reduced graphene oxide (RGO) of up to 1nm thickness and can be produced in single layers. With ultrasonic treatment, reactions were made easy whereby graphite can be directly exfoliated to graphene layers. Oxidation to GO can also be carried out within minutes and reduction to RGO is possible without the use of any reducing agents. In addition, various geometry of graphene can be produced such as scrolled graphene, sponge or foam graphene, smooth as well as those with rough edges, each serving its own unique purpose in various applications such as supercapacitor, catalysis, biomedical, etc. In ultrasonic-assisted reaction, deposition of metal NPs on graphene was more homogeneous with custom-made patterns such as core-shell formation, discs, clusters and specific deposition at the edges of graphene sheets. Graphene derivatives with the aid of ultrasonication are the perfect catalyst for various organic reactions as well as an excellent adsorbent. Reactions which used to take hours and days were significantly reduced to minutes with exceedingly high yields. In a more recent approach, sonophotocatalysis was employed for the combined effect of sonication and photocatalysis of metal deposited graphene. The system was highly efficient in organic dye adsorption. This review provides detailed fundamental concepts of ultrasonochemistry for the synthesis of graphene, its dispersion, exfoliation as well as its functionalization, with great emphasis only based on recent publications. Necessary parameters of sonication such as frequency, power input, sonication time, type of sonication as well as temperature and dual-frequency sonication are discussed in great length to provide an overview of the resultant graphene products.
  17. Enhancements in crystallinity, thermal stability, tensile modulus and strength of sisal fibres and their PP composites induced by the synergistic effects of alkali and high intensity ultrasound (HIU) treatments
    Krishnaiah P, Ratnam CT, Manickam S
    Ultrason Sonochem, 2017 01;34:729-742.
    PMID: 27773300 DOI: 10.1016/j.ultsonch.2016.07.008
    In this investigation, sisal fibres were treated with the combination of alkali and high intensity ultrasound (HIU) and their effects on the morphology, thermal properties of fibres and mechanical properties of their reinforced PP composites were studied. FTIR and FE-SEM results confirmed the removal of amorphous materials such as hemicellulose, lignin and other waxy materials after the combined treatments of alkali and ultrasound. X-ray diffraction analysis revealed an increase in the crystallinity of sisal fibres with an increase in the concentration of alkali. Thermogravimetric results revealed that the thermal stability of sisal fibres obtained with the combination of both alkali and ultrasound treatment was increased by 38.5°C as compared to the untreated fibres. Morphology of sisal fibre reinforced composites showed good interfacial interaction between fibres and matrix after the combined treatment. Tensile properties were increased for the combined treated sisal fibres reinforced PP composites as compared to the untreated and pure PP. Tensile modulus and strength increased by more than 50% and 10% respectively as compared to the untreated sisal fibre reinforced composite. It has been found that the combined treatment of alkali and ultrasound is effective and useful to remove the amorphous materials and hence to improve the mechanical and thermal properties.
  18. Hydrodynamic cavitation assisted degradation of persistent endocrine-disrupting organochlorine pesticide Dicofol: Optimization of operating parameters and investigations on the mechanism of intensification
    Panda D, Manickam S
    Ultrason Sonochem, 2019 Mar;51:526-532.
    PMID: 30224289 DOI: 10.1016/j.ultsonch.2018.04.003
    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.
  19. Sono-nano chemistry: A new era of synthesising polyhydroxylated carbon nanomaterials with hydroxyl groups and their industrial aspects
    Afreen S, Muthoosamy K, Manickam S
    Ultrason Sonochem, 2019 Mar;51:451-461.
    PMID: 30224290 DOI: 10.1016/j.ultsonch.2018.07.015
    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.
  20. Recent advancements in the sonophotocatalysis (SPC) and doped-sonophotocatalysis (DSPC) for the treatment of recalcitrant hazardous organic water pollutants
    Panda D, Manickam S
    Ultrason Sonochem, 2017 May;36:481-496.
    PMID: 28069236 DOI: 10.1016/j.ultsonch.2016.12.022
    Sonophotocatalysis (SPC) is considered to be one of the important wastewater treatment techniques and hence attracted the attention of researchers to eliminate recalcitrant hazardous organic pollutants from aqueous phase. In general, SPC refers to the integrated use of ultrasonic sound waves, ultraviolet radiation and the addition of a semiconductor material which functions as a photocatalyst. Current research has brought numerous improvements in the SPC based treatment by opting visible light irradiation, nanocomposite catalysts and numerous catalyst supports for better stability and performance. This review accomplishes a critical analysis with respect to the recent advancements. The efficiency of SPC based treatments has been analyzed by considering the individual methods i.e. sonolysis, photocatalysis, sonophotolysis, sono-ozone, photo-Fenton and sono-Fenton. Besides, the essential parameters such as solution temperature, concentrations of initial pollutant and catalyst, initial pH, dosages of Fenton's reagent and hydrogen peroxide (H2O2), ultrasonic power density, gas sparging, addition of radical scavenger, addition of carbon tetrachloride and methanol have been discussed with suggestions for the selection of optimum parameters. A higher synergistic pollutant removal rate has been reported during SPC treatment as compared to individual methods and the implementation of numerous doping materials and supports for the photocatalyst enhances the degradation rate of pollutants using DSPC under both visible and UV irradiation. Overall, SPC and DSPC based wastewater treatments are emerging as potential techniques as they provide effective solution in removing the recalcitrant organic pollutants and progressive research is expected to bring out superior treatment efficiency using these advanced technologies.

    IMPORTANCE OF THIS REVIEW: The review has accomplished a thorough and a critical analysis of sonophotocatalysis (SPC) based on the recently published journals. Recent advancements in the doped sonophotocatalysis (DSPC) and the mechanisms behind synergistic enhancement in the pollutant degradation rate have been discussed with justifications. Besides, the possible future works are suggested for the advancements in sonophotocatalysis based treatment. This review will be beneficial for electing a SPC based method because of the accomplished sharp comparisons among the published results. The review includes current advancements of SPC based methods which aid for a low-cost and a large-scale wastewater treatment application.

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