Sonocatalytic Process Research Articles

Sonocatalytic removal of an organic dye using TiO2/Montmorillonite nanocomposite

The sonocatalytic performance of the synthesized TiO2/Montmorillonite K10 (TiO2/MMT) nanocomposite was studied in removal of Basic Blue 3 (BB3) from water. The TiO2/MMT nanocomposite was prepared by hydrothermal method. Scanning electron microscope, X-ray diffraction and Fourier transform infrared were used to characterize the synthesized nanocomposite. The average size of TiO2 nanoparticles decreased from 60–80nm to 40–60nm through the immobilization of this semiconductor on the surface of MMT. The obtained results indicated that the sonocatalytic activity of TiO2/MMT nanocomposite was higher than that of pure TiO2 nanoparticles and MMT particles. Furthermore, the main influence factors on the sonocatalytic activity such as the BB3 concentration, pH of solution, TiO2/MMT dose, power of ultrasonic generator, and inorganic salts were studied. The intermediates of BB3 degradation during the sonocatalytic process in the presence of the TiO2/MMT nanocomposite have been monitored by gas chromatography–mass spectrometry.

Sonophotocatalytic (42 kHz) degradation of Simazine in the presence of Au–TiO2 nanocatalysts

The nano-size gold loaded visible light driven Au–TiO2 nanophotocatalysts were synthesized using a commercial sonicator bath producing 42kHz ultrasound. The X-ray diffraction (XRD), transmission electron microscopy (TEM) and high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) analyses revealed the gold nanoparticles incorporated in the TiO2 resides at the surface of the nanocatalysts. An increased BET surface area was observed for the Au–TiO2 when compared with the bare TiO2 which gave the first notation that the gold nanoparticles modified the physicochemical characteristics of the TiO2. The RAMAN spectrum shows the shift by ∼5cm−1 at 639cm−1 which indicated that the loaded gold nanoparticles were loaded on the surface of TiO2 nanoparticles and thus confirms that the gold nanoparticles readily accepts the electronic charges created during the photoexcitation of Au–TiO2 nanocatalysts. The Simazine (triazine based pesticide) was taken as the model pollutant to evaluate its sonocatalytic, photocatalytic and sonophotocatalytic degradation in the presence of TiO2 and Au–TiO2 nanocatalysts. The first order kinetics was observed for the Simazine degradation. The observed rate constants indicate that the order of degradation of Simazine was, sonophotocatalysis>sonocatalysis>photocatalysis. The additive effect was observed for the Au–TiO2 assisted sonophotocatalytic degradation of Simazine. A 1.65 and 1.38 fold enhanced mineralization was achieved for the sonophotocatalytic degradation of Simazine when compared with the photocatalytic and sonocatalytic processes. The intermediates produced during the mineralization of Simazine were analyzed using ESI-MS analysis and based on that a suitable mechanism has been proposed.

Poster #M18 OLFACTORY IDENTIFICATION DEFICITS AS A MARKER OF IMPAIRED BRAIN DEVELOPMENT? A CROSS-SECTIONAL STUDY IN PATIENTS WITH SCHIZOPHRENIA AND HEALTHY CONTROLS

The degradation of Acid Blue 92 (AB92) solution was investigated using a sonocatalytic process with pure and neodymium (Nd)-doped ZnO nanoparticles. The nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The 1% Nd-doped ZnO nanoparticles demonstrated the highest sonocatalytic activity for the treatment of AB92 (10 mg/L) with a degradation efficiency (DE%) of 86.20% compared to pure ZnO (62.92%) and sonication (45.73%) after 150 min. The results reveal that the sonocatalytic degradation followed pseudo-first order kinetics. An empirical kinetic model was developed using nonlinear regression analysis to estimate the pseudo-first-order rate constant (kapp) as a function of the operational parameters, including the initial dye concentration (5–25 mg/L), doped-catalyst dosage (0.25–1 g/L), ultrasonic power (150–400 W), and dopant content (1–6% mol). The results from the kinetic model were consistent with the experimental results (R2 = 0.990). Moreover, DE% increases with addition of potassium periodate, peroxydisulfate, and hydrogen peroxide as radical enhancers by generating more free radicals. However, the addition of chloride, carbonate, sulfate, and t-butanol as radical scavengers declines DE%. Suitable reusability of the doped sonocatalyst was proven for several consecutive runs. Some of the produced intermediates were also detected by GC–MS analysis. The phytotoxicity test using Lemna minor (L. minor) plant confirmed the considerable toxicity removal of the AB92 solution after treatment process.

Spectroscopic investigation on sonodynamic and sonocatalytic damage of BSA molecules by Thymol Blue (TB) derivants under ultrasonic irradiation

In this paper, the Thymol Blue derivants including Thymol Blue (thymolsulfonphthalein), Thymol Blue-DA (3,3′-Bis [N,N-bis (carboxymethyl) aminomethyl] thymolsulfonphthalein) and Thymol Blue-DA-Fe(III) (3,3′-Bis [N,N-bis (carboxymethyl) aminomethyl] thymolsulfonphthalein-Ferrous(III)) were adopted as sonosensitizers to study the sonodynamic and sonocatalytic activities under ultrasonic irradiation. At first, the interaction of Thymol Blue derivants with bovine serum albumin (BSA) was studied by fluorescence spectroscopy. On that basis, the sonodynamic and sonocatalytic damages of Thymol Blue derivants to BSA under ultrasonic irradiation were investigated by the combination of UV–vis, circular dichroism (CD) and fluorescence spectroscopy. Meanwhile, some influenced factors (ultrasonic irradiation time, Thymol Blue derivants concentration and ionic strength) on the damaging degree of BSA molecules were also reviewed. In addition, synchronous fluorescence spectra were used to estimate the binding and damage sites of Thymol Blue derivants to BSA. Finally, the generation of ROS during sonodynamic and sonocatalytic processes was confirmed by the method of Oxidation–Extraction Spectrometry (OEP). Perhaps, this paper may offer some important subjects for the study of Thymol Blue derivants in sonodynamic therapy (SDT) and sonocatalytic therapy (SCT) technologies for tumor treatment and the effect of the amino acid and central metal.

Sonosynthesis of gold nanoparticles from a geranium leaf extract

A rapid in situ biosynthesis of gold nanoparticles (AuNPs) is proposed in which a geranium (Pelargonium zonale) leaf extract was used as a non-toxic reducing and stabilizing agent in a sonocatalysis process based on high-power ultrasound. The synthesis process took only 3.5min in aqueous solution under ambient conditions. The stability of the nanoparticles was studied by UV–Vis absorption spectroscopy with reference to the surface plasmon resonance (SPR) band. AuNPs have an average lifetime of about 8weeks at 4°C in the absence of light. The morphology and crystalline phase of the gold nanoparticles were characterized by transmission electron microscopy (TEM). The composition of the nanoparticles was evaluated by electron diffraction and X-ray energy dispersive spectroscopy (EDS). A total of 80% of the gold nanoparticles obtained in this way have a diameter in the range 8–20nm, with an average size of 12±3nm. Fourier transform infrared spectroscopy (FTIR) indicated the presence of biomolecules that could be responsible for reducing and capping the biosynthesized gold nanoparticles. A hypothesis concerning the type of organic molecules involved in this process is also given. Experimental design linked to the simplex method was used to optimize the experimental conditions for this green synthesis route. To the best of our knowledge, this is the first time that a high-power ultrasound-based sonocatalytic process and experimental design coupled to a simplex optimization process has been used in the biosynthesis of AuNPs.

Sonochemical Degradation of Reactive Black 5 with a Composite Catalyst of TiO2/Single-Walled Carbon Nanotubes

In the sonocatalytic process, composites of TiO2-carbon were used because carbon provides more adsorption sites and acts like an electron sink to prevent the recombination of an electron/hole. Therefore, in the present study, the characteristics of a TiO2/single-walled carbon nanotubes catalyst (TiO2/SWCNTs) have been investigated, and the optimal weight ratio of SWCNTs and the dose for degradation of reactive black 5 (RB5) were also evaluated. TiO2/SWCNT composite was characterized using Brunauer–Emmett–Teller analysis, scanning electron microscopy, energy-dispersive X-ray diffraction microanalysis and spectra, and X-ray diffraction patterns. The degradation rate constants of RB5 with the ratio of SWCNTs were found to depend on the adsorption phenomenon of a surface catalyst, light absorbance, and the recombination of electrons and holes. As a result, the optimal ratio of carbon in the sono-TiO2/SWCNTs process for degradation of RB5 was TiO2:SWCNTs= 200:1. Additionally, the optimal dose of the catalyst was 0.5 g/L.

Spectroscopic Investigation on Sonocatalytic Damage of BSA Molecules by FeIII Complexes with Binary Organic Acid Ligands Under Ultrasonic Irradiation

The interaction between bovine serum albumin (BSA) and FeIII complexes with three binary organic acid (biorga) ligands, [FeIII(oxa)(H2O)4]+ (oxa = oxalic acid), [FeIII(pra)(H2O)4]+ (pra = propanedioic acid) and [FeIII(sua)(H2O)4]+ (sua = succinic acid), as well as the sonocatalytic damage of BSA in the presence of these three FeIII–biorga complexes under ultrasonic irradiation, were studied by UV–vis and fluorescence spectra. The experimental results show that the fluorescence quenching process of BSA caused by three FeIII–biorga complexes are all static quenching and the corresponding quenching rate constants (K q), equilibrium constants (K A) and the binding site numbers (n) were calculated. The results reveal that, under ultrasonic irradiation, the BSA molecules were obviously damaged by these FeIII–biorga complexes. In addition, the effects of several factors on the damage of BSA molecules were examined. The experimental results demonstrate that the damage degree of BSA increased with an increase of ultrasonic irradiation time, FeIII–biorga complex concentration, and ionic strength. In comparison, [FeIII(pra)(H2O)4]+ exhibited higher sonocatalytic activity than [FeIII(oxa)(H2O)4]+ and [FeIII(sua)(H2O)4]+. Finally, the extent of generation of \( \cdot {\text{O}}_{2}^{ - } \)and ·OH during sonocatalytic processes was estimated. Perhaps, the results will be significant for promoting sonodynamic treatment (SDT) of tumors at the molecular level.

Investigation on Sonocatalytic Damage to Bovine Serum Albumin (BSA) Under Ultrasonic Irradiation in the Presence of Fe(III)–Citrate Complexes

The interaction of bovine serum albumin (BSA) with Fe(III)–citrate complexes ([FeIII(cit)(H2O)3]− and [FeIII(cit)2]5−) and the sonocatalytic damage of BSA under ultrasonic irradiation were studied. Additionally, the various factors influencing the sonocatalytic damage of BSA were also studied by means of UV–Vis and fluorescence spectra. The experimental results indicate that the probable fluorescence quenching mechanisms of BSA by Fe(III)–citrate complexes ([FeIII(cit)(H2O)3]− and [FeIII(cit)2]5−) are both static quenching. Under certain conditions, the degree of damage to BSA is aggravated with increases of ultrasonic irradiation time, Fe(III)–citrate complex concentration, pH value and ionic strength. Moreover, all of the results demonstrate that [FeIII(cit)2]5− displays higher sonocatalytic activity than [FeIII(cit)(H2O)3]− under the same experimental conditions during the damage process of BSA. Finally, the generation of ·O2− and ·OH during sonocatalytic processes was estimated using scavengers. Perhaps, the results will be significant for promoting sonodynamic treatment to treat tumors at the molecular level.

The characteristic study and sonocatalytic performance of CdSe–graphene as catalyst in the degradation of azo dyes in aqueous solution under dark conditions

The sonocatalytic degradation of azo dyes; methyl orange (MO) and rhodamine B (RhB) were studied catalyzed by cadmium selenide (CdSe)-graphene in dark ambiance. The CdSe–graphene composites were prepared by simple hydrothermal method. The characterizations of composites were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), specific surface area (BET) and with energy dispersive X-ray (EDX). The UV-spectroscopic analysis of the dyes was done by measuring the change in absorbance. The degradation of the organic dyes was calculated based on the decrease in concentration of the dyes with respect to regular time intervals. The rate coefficients for the sonocatalytic process were successfully established and the reusability tests were done to test the stability of the used catalysts.

RETRACTED ARTICLE]Use of a sonocatalytic process to improve the biodegradability of landfill leachate

Abstract - Landfill leachate is one of the most important sources of toxic organic compounds for ground and surface waters. Advanced oxidation processes can offer an effective and environmentally friendly method for pretreatment of landfill leachates. In this study, an ultrasonic process was used for the pre-treatment of landfill leachate with the objective of improving its overall biodegradability, evaluated in terms of the BOD 5 /COD ratio, up to a value compatible with biological treatment. Under optimized experimental conditions (pH of 10, power of 110 watts, frequency of 60 kHz, TiO 2 concentration of 5 mg/L and exposure time of 120 min), this method showed suitability for partial removal of chemical oxygen demand (COD). The biodegradability was significantly improved (BOD 5 /COD increased from 0.210 to 0.786) which allowed an almost total removal of COD by a sequential activated sludge process. Keywords : Landfill leachate; Biodegradability; ultrasound. INTRODUCTION Leachate consists of many different organic and inorganic compounds that may be either dissolved or suspended (Bila

Spectroscopic study on the sonodynamic and sonocatalytic damage of anthraquinone derivants to bovine serum albumin under ultrasonic irradiation

In this work, three anthraquinone derivants (Alizarin: 1,2-dihydroxy-9, 10-anthraquinone, Alizarin–DA: 1,2-dihydroxy-9, 10-anthraquinone-3-aminomethyl-N, N-diacetic acid and Alizarin–DA–Fe: 1,2-dihydroxy-9, 10-anthraquinone-3-aminomethyl-N, N-diacetate-Ferrous(III)) were used to study the sonodynamic and sonocatalytic damage of bovine serum albumin (BSA) molecules according to the hyperchromic effect of UV–vis spectra and quenching effect of intrinsic fluorescence. Meanwhile, some influencing factors such as ultrasonic irradiation time, anthraquinone derivants concentration and ionic strength on the damage of BSA molecules were also considered. The results show that the synergetic effect of anthraquinone derivants and ultrasonic irradiation can efficiently damage the BSA molecules. Finally, some special radical scavengers were used to determine the kind of generated reactive oxygen species (ROS) in the presence of three anthraquinone derivants under ultrasonic irradiation. The results show that the ROS, at least, including singlet oxygen ( 1O 2) and hydroxyl radicals (OH) are generated during the sonodynamic and sonocatalytic processes. It is wished that this paper could offer some valuable references for the application of anthraquinone derivants in sonodynamic therapy (SDT) and sonocatalytic therapy (SCT) for tumor treatment.

Process behavior of TiO 2 nanotube-enhanced sonocatalytic degradation of Rhodamine B in aqueous solution

Sonocatalytic degradation of Rhodamine B was investigated using titanium dioxide (TiO 2) powder and titanium dioxide nanotubes (TiO 2 NTs) which were synthesized using sol–gel and hydrothermal method, respectively. Structural and crystalline information for both types of catalyst were characterized using transmission electron microscope (TEM), X-ray diffractometer (XRD) and surface analyzer. Remarkable improvement in the sonocatalytic activity of TiO 2 NTs was achieved due to their high specific surface area and unique pore system. Effects of reaction parameters such as pH (2–10), ultrasonic power (20–100 W), ultrasonic frequency (35 kHz and 130 kHz) and the presence of air flow (1 L/min) were also investigated. Under optimum conditions, i.e., with 8 millimolar (mM) of hydrogen peroxide (H 2O 2) and 1 L/min of air flow at neutral pH, 85% degradation of 50 mg/L Rhodamine B could be achieved in 120 min by the system with 2 g/L of TiO 2 NTs. The sonocatalytic process was observed to behave according to a pseudo-first-order kinetics under different experimental conditions. In conclusion, sonocatalytic degradation in the presence of TiO 2 NTs shows a great potential for the efficient treatment of organic dyes in wastewater.

Heat treatment effects on the characteristics and sonocatalytic performance of TiO 2 in the degradation of organic dyes in aqueous solution

The ambient sonocatalytic degradation of congo red, methyl orange, and methylene blue by titanium dioxide (TiO 2) catalyst at initial concentrations between 10 and 50 mg/L, catalyst loadings between 1.0 and 3.0 mg/L and hydrogen peroxide (H 2O 2) concentrations up to 600 mg/L is reported. A 20 kHz ultrasonic processor at 50 W was used to accelerate the reaction. The catalysts were exposed to heat treatments between 400 and 1000 °C for up to 4 h to induce phase change. Sonocatalysts with small amount of rutile phase showed better sonocatalytic activity but excessive rutile phase should be avoided. TiO 2 heated to 800 °C for 2 h showed the highest sonocatalytic activity and the degradation of dyes was influenced by their chemical structures, chemical phases and characteristics of the catalysts. Congo red exhibited the highest degradation rate, attributed to multiple labile azo bonds to cause highest reactivity with the free radicals generated. An initial concentration of 10 mg/L, 1.5 g/L of catalyst loading and 450 ppm of H 2O 2 gave the best congo red removal efficiency of above 80% in 180 min. Rate coefficients for the sonocatalytic process was successfully established and the reused catalyst showed an activity drop by merely 10%.

Kinetics of Sonophotocatalytic Degradation of Anionic Dyes with Nano-TiO2

The current research work focuses on the combination of photocatalytic and sonocatalytic (sonophotocatalytic) degradation of anionic dyes, viz., Orange G, Remazol Brilliant Blue R, Alizarin Red S, Methyl Blue, and Indigo Carmine, with solution combustion synthesized TiO2 (CS TiO2) and commercial Degussa P-25 TiO2 (DP-25). The rate of sonophotocatalytic degradation of all the dyes and the reduction of total organic carbon was higher compared to the individual photo- and sonocatalytic processes. The effect of dissolved gases and ultrasonic intensity on the sonophotocatalytic degradation of the dyes was evaluated. A dual-pathway network mechanism of sonophotocatalytic degradation was proposed for the first time, and the rate equations were modeled using the network reduction technique. The kinetic rate coefficients of the individual steps were evaluated for all the systems by fitting the model with experimental data.

Enhanced Sonocatalytic Degradation of Azo Dyes by Au/TiO2

Au-loaded TiO2 (Au/TiO2) has been reported for the first time as a sonocatalyst. It was found that the catalyst Au/TiO2, with a low Au loading 0.5 wt % and under common and commercial frequency (40 kHz) ultrasonic irradiation, greatly accelerated both the discoloration and total organic carbon (TOC) removal of azo dyes such as orange II (Org II), ethyl orange (EO), and acid red G (ARG), as compared to bare TiO2 and nano-Au catalyst. About 80% TOC removal was achieved after complete discoloration of 2.5 x 10(-4) M Org II. H2O2 and H2 formation as well as their accumulation was greatly enhanced due to Au loading on TiO2. Both oxidative and reductive degradation intermediates have been detected, and thus the mechanism involves both enhanced oxidation and enhanced reduction via the accelerated formation of active *OH and *H radicals due to Au loading on TiO2, which is supported by electron spin resonance (EPR) and other evidence. The study provides an admirable way to raise the efficiency of sonication and to treat azo dye-containing wastewaters with sonocatalytic processes.