Sustainable conversion regenerated cellulose into cellulose oleate by sonochemistry

Derivatization has great potential for the high-value utilization of cellulose by enhancing its processability and functionality.However,due to the low reactivity of natural cellulose,it remains challenging to rapidly prepare cellulose derivatives with high degrees of substitution.The“cavitation effect”of ultrasound can reduce the particle size and crystalline index of cellulose,which provides a possible method for preparing cellulose derivatives.Herein,a feasible method was proposed for efficiently converting regenerated cellulose to cellulose oleate with the assistance of ultrasonic treatment.By adjusting the reaction conditions including ultrasonic intensity,feeding ratios of oleic acid,reaction time,and reaction solvent,a series of cellulose oleates with degrees of substitution ranging from 0.37 to 1.71 were synthesized.Additionally,the effects of different reaction conditions on the chemical structures,crystalline structures,and thermal behaviors were investigated thoroughly.Cellulose oleates with degrees of substitution exceeding 1.23 exhibited amorphous structures and thermoplasticity with glass transition temperatures at 159.8 to 172.6℃.This study presented a sustainable and practicable method for effectively derivatizing cellulose.

A study on effect of sonochemistry in a reverberation field

In this paper, an ultrasound with frequency of 815 kHz was used to research the sonochemical yield in a small-size reverberation field by the method of fluorescent spectrum analysis. There are two characteristics on the effect of sonochemistry in the reverberation field: First, the cavitation threshold was about 0.3 W / cm2 (it was 0.7 W / cm2 in travelling field); Second, when the sound intensity was larger than the threshold, the sonochemical yield increased as the intensity increased and increased rapidly after the intensity was at 1.69-2.13 W / cm2, so that there was a upturned point in the curve of the result (which would tend to saturation in the travelling field). The theoretical analysis shows that the reason of the threshold decrease is that the sound energy density becomes high in the reverberation field, and the upturned point results from the disturbance of the radiation pressure on the liquid surface. Therefore, by experiment and theory this paper shows that a reverberation field has to be built for the higher sonochemical yield.

Combined effect of US/PFS on the black liquor of making paper

The reed pulping black liquor is used as a sample. Researches of (1) combined effect of ultrasound(US)/polyferric sulphate(PFS)/hydrogen peroxide(H 2O 2); (2) effects of the horn tip areas; (3) effect of dose of PFS were carried. Extrapolation of these experiments indicated treatment results are possibly related to complex chemical compositions in the reed pulping black liquor.

Sonolysis and mineralization of pentachlorophenol by means of varying parameters

Degradation effect of organic pollutant on pentachlorophenol(PCP) is researched by ultrasound. PCP is treated by low frequency(16 kHz) and high frequency(800±1 kHz), and bi frequency. The results of investigation on the ultrasonic destruction of PCP showed that the rate of PCP degradation at the same conditions is the highest at bi frequency, and the lowest at 16 kHz. In the presence of Fenton type reagent the degradation rate of PCP is the highest at bi frequency(20 93 times) as compared to the stirring system. This ratio is 4 91 and 1 06 at 800 kHz and 16 kHz, respectively. The studies showed the bi frequency is an effective method for pollutants degradation, but it is need make further study. Taking 800 kHz for example, under the same conditions, the smaller pH of the solution, the higher is the reaction rate. A similar situation applied to TOC, but the TOC removal lags behind degradation of PCP. This indicated the PCP is not completely mineralized. The ultrasound is somewhat enhanced for degradation of PCP and mineralization with only addition of CuSO 4, but the combination of ultrasound and Fenton type reagent is effective method for PCP degradation and mineralization. The rate of PCP degradation and TOC removal appeared to follow pseudo first order reaction kinetic law.

Controlled Fabrication of Cd-Bi Nanoparticles via Sonochemical Method

A sonochemical method for the direct controlled synthesis of Cd-Bi nanoparticles from a bulk Cd-Bi alloy is introduced. The nanoparticles were found to be monodispersed and the size distribution can be easily controlled by adjusting the ultrasonic power. The formation and the constituent of the as-prepared Cd-Bi nanoparticles were revealed by means of X-ray diffraction, differential thermal analysis and thermogravimetry, transmission electron microscopy, and electron diffraction. It was found that the Cd-Bi eutectic alloy nanoparticles are made of the hexagonal phase of metal cadmium and the rhombohedral phase of metal bismuth. In addition, we also found through tribological tests that the powder has an excellent antiwear property.

Sonochemical Degradation of Polychlorinated Biphenyls in Aqueous Solution

Polychlorinated biphenyl (PCB) is a kind of persistent and dangerous environmental pollutants. This paper presented the research result of sonochemical degradation of 2-chloro- biphenyl (2-CBP), 4-chlorobiphenyl (4-CBP) and 4,4-dichlorobiphenyl (4,4-CBP)in water. The ultrasonic degradation kinetics of 2-CBP, 4-CBP and 4,4-CBP in water were found to be first-order and the degradation rate coefficients are 3.69?0-2, 3.19?0-2 and 2.06?0-2 at 25?C for 2-CBP, 4-CBP and 4,4-CBP respectively. The influence of initial concentrations, reaction temperature on the ultrasonic decomposition of 2-CBP were also investigated.

Sonochemical effect of a bifrequency irradiation

The sonochemical effect of a bifrequency orthogonal ultrasonic irradiation has been studied by using two different detecting methods. It has been shown that the sonochemical yield produced by the bifrequency irradiation appears to be much more than the sum of the yields produced separately by the two irradiations. The bifrequency irradiation, therefore, can be expected to exert a great influence on the development of sonohemical

Selective Cytotoxic Effect of ZnO Nanoparticles on Glioma Cells

In this study we examined the cytotoxic effect of ZnO nanoparticles on various human cancer and normal cells.We found that the ZnO nanoparticles exerted a cytotoxic effect on the human glioma cell lines A172,U87,LNZ308,LN18,and LN229,whereas no cytotoxic effect was observed on normal human astrocytes.Similarly,the ZnO nanoparticles induced cell death in breast and prostate cancer cell lines while no major effect was observed in the respective normal breast and prostate cell lines.Using the fl uorescent dye 2,7-dichlorofl uorescein diacetate,we found that treatment of the glioma cells with ZnO nanoparticles induced a large increase in the generation of reactive oxygen species(ROS)and treatment of the cells with N-acetyl cysteine decreased the cytotoxic effect of the ZnO nanoparticles.In contrast,a smaller effect on ROS generation was observed in the normal astrocytes.These results suggest that ZnO nanoparticles may be employed as a selective cytotoxic agent for the eradication of cancer cells.

A novel two-step processing method for fabrication of in situ Al_2O_(3np)/Al-Al_(11)Ce_3 nanocomposite

In situ Al2O3np/Al-Al11Ce3 nanocomposite was successfully synthesized from Al-CeO2 system using a novel two-step processing method that combines liquid-state mechanical mixing（step-Ⅰ） and sonochemistry melt reaction（step-Ⅱ）. The microstructural evolution and mechanical properties were investigated by optical microscopy（OM）, scanning electron microscopy（SEM）, transmission electron spectroscopy（TEM） and tensile tests, respectively. A good spatial distribution of CeO2 particles in the Al melt was achieved due to reactive wetting during step-Ⅰ, and the following formation of Al2O3 np during step-Ⅱ was attributed to the cavitation-accelerated interfacial reaction. The solidified microstructure comprised uniformly dispersed Al2O3 np in the matrix and ultrafine lamellar Al-Al11Ce3 at the grain boundaries. Such unique microstructure endowed Al2O3np/Al-Al11Ce3 nanocomposite with a good balance between tensile strength（175 MPa） and ductility（18.5%）. The strengthening mechanisms of the nanocomposite included grain refinement, Orowan strengthening and quench strengthening, among which Orowan strengthening contributed the most to the yield strength of the nanocomposite.

Sonochemical synthesis of photocatalysts and their applications

Sonochemical synthesis has flourished significantly in the last few decades for the preparation of photocatalysts.A large number of photocatalysts have been prepared through sonochemical techniques.This review highlights the scope of sonochemistry in the preparation of photocatalysts,and their applications in energy production and environmental remediation.Beside,the sonochemical degradation of pollutants is discussed in detail.The progress made in sonochemical synthesis and the future perspective for this technique are summarized here.This review may create more enthusiasm among researchers to pay extra attention to the sonochemical synthesis of materials and add their useful contribution to the investigation of new materials for photocatalytic and other applications.This will propel this technique toward commercial sonosynthesis of nanomaterials.

Amorphous nickel-iron oxides/carbon nanohybrids for an efficient and durable oxygen evolution reaction

Highly efficient and durable water oxidation electrocatalysts are critically important in a wide range of clean energy technologies,including water electrolyzers and rechargeable metal-air batteries.Here,we report a novel sonochemical approach to synthesize amorphous nickel-iron oxides/carbon nanohybrids with tunable compositions for the oxygen evolution reaction （OER）.The sonochemically synthesized amorphous electrocatalysts with optimal composition exhibit a low overpotential of 290 mV at 10 mA＆#183;cm-2 and a Tafel slope of 31 mV＆#183;decade-1 in a 0.1 M KOH electrolyte,outperforming the benchmark RuO2 catalyst.Meanwhile,these nanohybrids are also highly stable and remain amorphous even after prolonged cycling.In addition to amorphism,sonochemistry endows as-prepared nickel-iron oxides/carbon nanohybrids with a simultaneously formed carbon scaffold and internal Ni（0）,which can enhance the stability and activity for the OER.This work demonstrates that sonochemistry is a unique method for synthesizing amorphous metal oxides toward an efficient and durable OER.

Sonochemical synthesis of silver nanoparticles coated copper wire for low-temperature solid state bonding on silicon substrate

Silver nanoparticles (AgNPs) are directly grown on surface of ~25 μm copper wire by ultrasound-assisted chemical reduction. Silver nitrate is used as precursors, when polyvinylpyrrolidone (PVP) is added as a controller of the dimension of AgNPs. Influence of growth parameters such as precursor's concentration, ratio proportion of PVP and ultra-sonication on the growth of AgNPs coating are determined. The best morphology, size of the AgNPs are observed on copper wire. The results show that the copper wire coated with AgNPs of^100 nm diameter exhibits good antioxidation and ohmic contact after sinter on Si substrate at a temperature as low as 320℃, is especially suitable as a substitute for silver paste electrode used in silicon solar cells.