Decolorizing of azo dye Reactive red 24 aqueous solution using exfoliated graphite and H2O2 under ultrasound irradiation

At its natural pH (6.95), the decolorization of Reactive red 24 in ultrasound, ultrasound/H₂O₂, exfoliated graphite, ultrasound/exfoliated graphite, exfoliated graphite/H₂O₂ and ultrasound/exfoliated graphite/H₂O₂ systems were compared. An enhancement was observed for the decolorization in ultrasound/exfoliated graphite/H₂O₂ system. The effect of solution pH, H₂O₂ and exfoliated graphite dosages, and temperature on the decolorization of Reactive red 24 was investigated. The sonochemical treatment in combination with exfoliated graphite/H₂O₂ showed a synergistic effect for the decolorization of Reactive red 24. The results indicated that under proper conditions, there was a possibility to remove Reactive red 24 very efficient from aqueous solution.

The decolorization of other azo dyes (Reactive red 2, Methyl orange, Acid red 1, Acid red 73, Acid red 249, Acid orange 7, Acid blue 113, Acid brown 75, Acid green 20, Acid yellow 42, Acid mordant brown 33, Acid mordant yellow 10 and Direct green 1) was also investigated, at their natural pH.     

Removal of disperse blue 2BLN from aqueous solution by combination of ultrasound and exfoliated graphite

This paper reports an efficient and convenient removal of disperse blue 2BLN from aqueous solution by the combination of ultrasound and exfoliated graphite. The various affecting factors were studied. The removal ratio of disperse blue 2BLN is 96.9% for the initial concentration of 200 mg/L using 600 mg/L exfoliated graphite (exfoliation volume of 300 mL/g) at 45 degrees C within 120 min under ultrasound. The combination method was more effective than sonolysis or exfoliated graphite treatment individually.     

The removal of MO molecules from aqueous solution by the combination of ultrasound/adsorption/photocatalysis

Methyl orange (MO) molecules had been removed from aqueous solution by nano-TiO(2)/exfoliated graphite composites with the combination of ultrasound/adsorption/photocatalysis. The experimental results had showed that nano-TiO(2)/exfoliated graphite composites provided with the adsorptive capability of exfoliated graphite and the photocatalysis capability of nano-TiO(2) synchronously. It had been proved that the removal ratios related to the adsorption and photocatalysis capability of the composites and were influenced by US and UV irradiation, the reaction times, the reaction temperatures, the initial pH values, the dosages and the initial MO solution concentrations. Moreover, it had been illuminated that the combination was very effective and useful on removing MO molecules from aqueous solution.     

Decolorization of azo dye direct scarlet 4BS solution using exfoliated graphite under ultrasonic irradiation

A combination of ultrasound and exfoliated graphite has been used to treat wastewater containing direct scarlet 4BS for colour removal and for the reduction of absorption at a wavelength of 242 nm. The results show that the ultrasound/exfoliated graphite process is effective in removing direct scarlet 4BS from aqueous solution. Furthermore, it can achieve better results than either exfoliated graphite or ultrasound alone.     

Degradation of C.I. Acid Orange 7 by the advanced Fenton process in combination with ultrasonic irradiation

The combination of ultrasound and the advanced Fenton process (AFP, zero-valent iron and hydrogen peroxide) for the degradation of C.I. Acid Orange 7 was studied. The effect of hydrogen peroxide concentration, initial pH, ultrasonic power density, dissolved gas, and iron powder addition on the decolorization of C.I. Acid Orange 7 was investigated. A modified pseudo-first order kinetic model was used to simulate the experimental results. The results showed that the decolorization rate increased with the increase of hydrogen peroxide concentration and power density, but decreased with the increase of initial pH value. There existed an optimal iron powder addition when decolorization rate was concerned. The decolorization efficiency also increased with the increase of hydrogen peroxide concentration, but decreased with the increase of initial pH value. It varied little at different power densities or iron powder additions at the fixed hydrogen peroxide concentration. The presence of dissolved gas would enhance color removal, and the enhancement was more significant when dissolved oxygen was present. More hydrogen peroxide dosage and reaction duration are required to achieve a relatively high COD removal than those employed to simply break the chromophore group.     

Drastically enhanced ultrasonic decolorization of methyl orange by adding CCl4

Effects of CCl(4) were investigated on the ultrasonic decolorization of azo dye methyl orange (MO). The decolorization of MO was observed to behave as a pseudo-first reaction in kinetics under all the conditions tested in the present work. The apparent rate constant of the decolorization was demonstrated to be dependent on CCl(4) concentration, MO concentration and the solution pH value. Under appropriate conditions, the rate constant of the ultrasonic decolorization of MO was able to be increased more than 100 times by adding CCl(4) into the MO solution. A reaction mechanism was proposed to explain the promoting effect of CCl(4) on the ultrasonic decolorization of MO, which was attributed to the generation of highly-oxidizing such as (*)Cl radical and HClO species, and then their attack at the azo bond of MO.     

An optimization study using response surface methods on the decolorization of Reactive Blue 19 from aqueous solution by ultrasound

The decolorization of reactive dye C.I. Reactive Blue 19 from aqueous solution was studied by using ultrasound, activated carbon and combined ultrasound/activated carbon. The combined effects of independent variables, such as ultrasound power, temperature, time, activated carbon concentration, dye concentration and initial pH were investigated on the decolorization by using the central composite design. The decolorization of RB 19 was modelled statistically and optimized by means of the Matlab computer software. The decolorization were accomplished at optimum conditions by using ultrasound, activated carbon and combined ultrasound/activated carbon as 36%, 91% and 99.9%, respectively. The application of ultrasonic irradiation was found to be beneficial for decolorization of RB 19 from aqueous solution by adsorption.     

Hydrothermal conversion of graphite to carbon nanotubes (CNTs) induced by bubble collapse

Cu–Fe–CNTs and Ni–Fe–CNTs coatings were deposited on gray cast iron by a hydrothermal approach. It was demonstrated that, the flaky graphite of gray cast iron was exfoliated to graphene nanosheets under hydrothermal reactions, and graphene nanosheets were scrolled to CNTs. After high temperature treatments, the volume losses of Cu–Fe–CNTs and Ni–Fe–CNTs coatings were 52.6 % and 40.0 % of gray cast iron substrate at 60 min wear tests, respectively, obviously increasing the wear properties of gray cast iron. During hydrothermal reactions, water jets and shock waves were produced by bubble collapse. Induced by the water jets and shock waves, exfoliation of flaky graphite was performed, producing exfoliated graphene nanosheets. Attacked by the radially distributed water jets and shock waves, graphene nanosheets were curved, shaped to semicircle morphology and eventually scrolled to tubular CNTs.     

C.I. Reactive Black 5 decolorization by combined sonolysis and ozonation

Decolorization of the azo dye C.I. Reactive Black 5 (RB5) in solution by a combination of sonolysis and ozonation was investigated. The results showed that the optimum pH for the reaction was 11.0, and both lower and higher pH decreased the decolorization rate. Increasing the initial concentration of RB5 led to a decreasing decolorization rate. Under the experimental conditions, the decolorization rate increased with an increase in temperature. The decolorization of RB5 followed pseudo-first-order reaction kinetics. Based on the decolorization rate constants obtained at different temperatures within the range 287-338K and the Arrhenius equation, the apparent activation energy (E(a)) was calculated to be 11.2kJmol(-1). This indicated that the reaction has little dependence on temperature. The color decay was considerably faster than the decrease in total organic carbon (TOC), which was attributed to the ease of chromophore destruction. Hence the efficiency of decolorization was 84% compared with 4% of TOC removal after 5min reaction. Additionally, muconic acid, (2Z)-pent-2-enedioic acid and maleic acid were identified as main oxidation products by gas chromatography coupled with mass spectrometry (GC-MS) after 150min of reaction.     

Effect of ultrasound power on HCl leaching kinetics of impurity removal of aphanitic graphite

This study aimed to investigate the effect of ultrasonic power and temperature on the impurity removal rate during conventional and ultrasonic-assisted leaching of aphanitic graphite. The results showed that the ash removal rate increased gradually (∼50 %) with the increase in ultrasonic power and temperature but deteriorated at high power and temperature. The unreacted shrinkage core model was found to fit the experimental results better than other models. The Arrhenius equation was used to calculate the finger front factor and activation energy under different ultrasonic power conditions. The ultrasonic leaching process was significantly influenced by temperature, and the enhancement of the leaching reaction rate constant by ultrasound was mainly reflected in the increase of the pre-exponential factor A. Ultrasound treatment improved the efficiency of impurity mineral removal by destroying the inert layer formed on the graphite surface, promoting particle fragmentation, and generating oxidation radicals. The poor reactivity of hydrochloric acid with quartz and some silicate minerals is a bottleneck limiting the further improvement of impurity removal efficiency in ultrasound-assisted aphanitic graphite. Finally, the study suggests that introducing fluoride salts may be a promising method for deep impurity removal in the ultrasound-assisted hydrochloric acid leaching process of aphanitic graphite.     

Curcumin-assisted ultrasound exfoliation of graphite to graphene in ethanol

In this paper, we demonstrated a simple and cost-effective method to produce graphene from graphite in ethanol using ultrasound assisted with curcumin. The influence of curcumin concentration, starting graphite amount, sonication power, and sonication time on the graphene concentration was studied schematically. The π-π interaction between curcumin and graphene, being confirmed by FTIR spectrum, facilitate the exfoliation of the graphite into graphene. The concentration of the graphene in the ethanol reached up to 1.44 mg mL⁻¹ and the exfoliated suspension was relatively stable. The content of monolayer, bilayer, and multilayer in the exfoliated graphene suspension were 21%, 37%, and 42%, respectively. The as-prepared graphene sheets were free-defect. This novel approach may not only enable to exfoliate the graphite into graphene but also to make the graphene-curcumin hybrid which might find applications in pharmaceutical industry.     

海参胶囊中海参多糖的提取方法

对海参胶囊中海参多糖进行提取纯化。分别探讨了酶解法、超声波提取方法;双氧水、活性炭脱色法及乙酸钾、三氯乙酸法除蛋白方法对海参多糖的得率的影响。确定最适提取条件:1g胶囊在胰蛋白酶加酶量为8000U/g,温度为37℃,pH 8.1,酶解3h后酶解完全;醇沉得到粗多糖后,经双氧水脱色、乙酸钾除蛋白。     

Comparison of the adsorptive properties of papyex and uncompressed exfoliated graphite

The adsorption isotherms of krypton at 77.3 and 90 K, methane at 77.3 K and xenon at 105 K have been compared when respectively determined on uncompressed exfoliated graphite and Papyex (compressed exfoliated graphite), in the first monolayer range. An alteration of the isotherms on Papyex has been observed, due to the compression of the initial exfoliated graphite. This compression leads to an increase of the surface heterogeneity and a decrease of the uniform patch size. Nevertheless, the main characteristics of the isotherms are preserved. Moreover, during the first monolayer formation, according to the state of the film, some differences in the kinetics appear, which are not noticeable in the case of uncompressed exfoliated graphite: high speed of adsorption when the film is mobile, and low speed in the case of a 2D solid.     

Ultrasonic-assisted ozone degradation of organic pollutants in industrial sulfuric acid

In this work, a combination of ozone (O₃) and ultrasound (US) has been firstly used to decolorize black concentrated sulfuric acid with high organic content. The effect of different reaction factors on the transparency, extent of decolorization, H₂SO₄ mass fraction, and organic pollutants removal is studied. In addition, the systematic interaction between ultrasound and ozone on the decolorization process is reviewed through comparative experiments of O₃, US and US/O₃. A sulfuric acid product that meets the requirements for first-class products in national standards, with an extent of decolorization of 74.07%, transparency of 70 mm, and a mass fraction of 98.04%, is obtained under the optimized conditions. Under the same conditions, it has been established that the treatment time can be saved by 25% using the US/O₃ process compared to using O₃. Further, the production of oxidative free radicals (•OH) in a concentrated sulfuric acid system is enhanced using the US/O₃ process compared with O₃. In addition, the degree of effectiveness of different oxidizing components on the decolorization process is revealed by adding different free radical shielding agents when the US/O₃ process is used.     

Raman and surface-enhanced Raman spectroscopy evidence for oxidation-induced decomposition of graphite

It has been proposed that reduction of exfoliated graphite oxide could be a potential method for producing large quantities of graphene. Raman and surface-enhanced Raman spectroscopy are used to show that oxidation of graphite and exfoliated graphite significantly increases the defect structure of both materials. This would likely lead to a heavily defected graphene structure when oxygen is removed. To insure the observed decomposition is not due to the laser light, the effect of laser intensity on the materials was investigated. It was found that at the highest laser intensity (1.4 × 10⁸ W/M²) there was a significant increase in defects. However, lower laser intensity was found which did not produce defects and was used in the studies of the effect of oxidation on the spectra.     

A combination of ultrasound and a bio-catalyst: removal of 2-chlorophenol from aqueous solution

Phenolic compounds have become a cause for worldwide concern due to their persistence, toxicity and health risks. This paper reports a three-step approach to remove 2-chlorophenol from dilute aqueous solution and compares each technique. The first step utilizes Horse Radish Peroxidase (HRP) in presence of hydrogen peroxide to oxidize this organic pollutant (enzyme treatment). For a more efficient removal of 2-chlorophenol, it is necessary to add the enzyme solution gradually to the contents of the reactor instead of rapid addition. The second step, involving ultrasonic waves eliminated 2-chlorophenol through hydroxyl radical generated by the cavitation process (sono-degradation). In the third step, a combination of ultrasonic waves and enzyme was used (sono-enzyme degradation). It should be mentioned that, the enzyme can be active in the presence of ultrasonic waves under the proper sonication. The degradation has been studied at different temperatures, intensities of irradiation, and concentrations of enzyme. The rate of degradation exhibited pseudo-first order behavior and the combination method was more effective than sonolysis and enzyme treatment individually.     

Degradation of a cationic dye (Rhodamine 6G) using hydrodynamic cavitation coupled with other oxidative agents: Reaction mechanism and pathway

In the present study, decolorization and mineralization of a cationic dye, Rhodamine 6G (Rh6G), has been carried out using hydrodynamic cavitation (HC). Two cavitating devices such as slit and circular venturi were used to generate cavitation in HC reactor. The process parameters such as initial dye concentration, solution pH, operating inlet pressure, and cavitation number were investigated in detail to evaluate their effects on the decolorization efficiency of Rh6G. Decolorization of Rh6G was marginally higher in the case of slit venturi as compared to circular venturi. The kinetic study showed that decolorization and mineralization of the dye fitted first-order kinetics. The loadings of H₂O₂ and ozone have been optimized to intensify the decolorization and mineralization efficiency of Rh6G using HC. Nearly 54% decolorization of Rh6G was obtained using a combination of HC and H₂O₂ at a dye to H₂O₂ molar ratio of 1:30. The combination of HC with ozone resulted in 100% decolorization in almost 5–10 min of processing time depending upon the initial dye concentration. To quantify the extent of mineralization, total organic carbon (TOC) analysis was also performed using various processes and almost 84% TOC removal was obtained using HC coupled with 3 g/h of ozone. The degradation by-products formed during the complete degradation process were qualitatively identified by liquid chromatography-mass spectrometry (LC-MS) and a detailed degradation pathway has been proposed.     

Emulsion Polymerization: A New Approach to Prepare Graphite Oxide Coated with Polyaniline

A novel approach is used to synthesize graphite oxide (GO) coated with polyaniline (PANI) by in-situ emulsion polymerization. The dispersion behavior of exfoliated graphite oxide in aqueous solution under ultrasonic vibration is investigated by atomic force microscopy (AFM). Strong interactions owing to hydrogen bonds and electrostatic effects between PANI and GO surfaces are revealed by FT-IR and Raman spectra. Scanning electron microscopy (SEM) further confirms that GO is well-coated with PANI, and a uniform appearance is seen. The increased crystallinity of PANI/GO is characterized by X-ray diffraction (XRD). The product is also characterized by thermogravimetry(TG) and electrical conductivity.     

Ultrasound assisted enzymatic degumming of crude soybean oil

The present work deals with ultrasound assisted enzymatic degumming (UAED) of crude soybean oil quantifying the extent of degumming (EOD), cavitational yield and synergistic index (f) for the combination approaches. The effect of different operating parameters such as enzyme loading, pH, presence of water, temperature and ultrasonic power on the EOD has been investigated. Ultrasound combined with enzyme at loading of 2.0 ml/L resulted in EOD as 92.2% under ambient conditions. Addition of water (5%) in combination with ultrasound and enzyme at 2.0 ml/L loading and pH of 5 resulted in maximum EOD (98.4%) in 120 min of treatment. The extent of phospholipid separation was also observed to be dependent on the power dissipation and maximum phospholipids separation was obtained at 100 W. Scale-up studies were performed at 500 ml and 1 L operating volume under optimized conditions of 2.0 ml/L as the enzyme loading, pH of 5, 5% water addition and ultrasonic power of 100 W where 93.63% and 91.15% phospholipid separation respectively was obtained. The effects of ultrasonic treatment were also quantified in terms of the acid value reduction and oxidative stability for the processed oil. It was demonstrated that suitable reduction in acid value (final value less than 1) and oxidative stability (TOTOX less than 4) is effectively obtained using UAED. Overall the approach of UAED was established to show much higher efficacy for soybean oil processing as compared to only ultrasound or only enzymatic treatment.     

新生MnO2对酸性媒介黑T的吸附

以化学法合成的新生MnO2为吸附剂，对水中酸性媒介黑T（染料之一）进行了吸附脱色研究，并探讨了影响吸附的因素。结果表明，酸性媒介黑T的脱色率达95%。且PH是影响染料脱色的主要因素。