The present work deals with degradation of aqueous solution of Rhodamine 6G (Rh 6G) using sonocatalytic and sonophotocatalytic treatment schemes based on the use of cupric oxide (CuO) and titanium dioxide (TiO2) as the solid catalysts. Experiments have been carried out at the operating capacity of 2 L and constant initial pH of 12.5. The effect of catalyst loading on the sonochemical degradation has been investigated by varying the loading over the range of 1.5-4.5 g/L. It has been observed that the maximum degradation of 52.2% was obtained at an optimum concentration of CuO as 1.5 g/L whereas for TiO2 maximum degradation was observed as 51.2% at a loading of 4 g/L over similar treatment period. Studies with presence of radical scavengers such as methanol (CH3OH) and n-butanol (C4H9OH) indicated lower extents of degradation confirming the dominance of radical mechanism. The combined approach of ultrasound, solid catalyst and scavengers has also been investigated at optimum loadings to simulate real conditions. The optimal solid loading was used for studies involving oxidation using UV irradiations where 26.4% and 28.9% of degradation was achieved at optimal loading of CuO and TiO2, respectively. Studies using combination of UV and US irradiations have also been carried out using the optimal concentration of the catalysts. It has been observed that maximum degradation of 63.3% is achieved using combined US and UV with TiO2 (4 g/L) as the photocatalyst. Overall it can be said that the combined processes give higher extent of degradation as compared to the individual processes based on US or UV irradiations.
The present work deals with achieving viscosity reduction in polymer solutions using ultrasound-based treatment approaches. Use of simple additives such as salts, or surfactants and introduction of air at varying flow rates as process intensifying parameters have been investigated for enhancing the degradation of polyvinyl pyrrolidone (PVP) using ultrasonic irradiation. Sonication is carried out using an ultrasonic horn at 36 kHz frequency at an optimized concentration (1%) of the polymer. The degradation behavior has been characterized in terms of the change in the viscosity of the aqueous solution of PVP. The intrinsic viscosity of the polymer has been shown to decrease to a limiting value, which is dependent on the operating conditions and use of different additives. Similar extent of viscosity reduction has been observed with 1% NaCl or 0.1% TiO2 at optimized depth of horn and 27°C, indicating the superiority of titanium dioxide as an additive. The combination of ultrasound and ultraviolet (UV) irradiation results in a significantly faster viscosity reduction as compared to the individual operations. A kinetic analysis for the degradation of PVP has also been carried out. The work provides a detailed understanding of the role of the operating parameters and additives in deciding the extent of reduction in the intrinsic viscosity of PVP solutions.
The configuration of thin film polycarbonate (PC) is formulated, aiming for a financially efficient approach of the solvent casting method by grafting waste fly ash cenosphere (FAC) encapsulated with tetraethoxysilane (TEOS) as a grafting agent. The research study emphasized on the routine practice of controlled thermal dissipative electronic widgets by a systematic characterization analysis. FTIR exemplifies the surface adherence characteristics of the GFAC (Grafted Fly Ash Cenosphere) over PC, by confirming the efficient grafting between silane and FAC at 2950 cm À1 due to the flexible vibrations by the -OH group. The PC-FAC composite showed the characteristic triplet signature peaks of PC at 1152, 1188 and 1227 cm À1 .Following the hierarchy, the morphological study analyzes the surface molecular interaction between the PC/GFAC and their electronic properties by FESEM. AFM confers the topographical study of pristine PC, which measures the surface roughness of pristine PC as 4.5 nm which mitigates to 0.7 nm for the PC/GFAC and justifies the homogenous dispersion of GFAC in PC, thus directing the consequential study of TGA. It examines controlled surface thermal conduction and authenticates the noble thermal stability of the PC/GFAC with a char yield of 36% (approximately more than twice that of pristine PC) at 800 C by TGA. The PC/GFAC affirms a 70 C lag in the onset of thermal degradation, at 430 C, as compared with pristine PC, which starts to decompose at 360 C. Thus, the silane grafted nano composites of PC expands the operable temperature range for the electronic elemental properties usage. The present investigation procures attention on the thermal characteristics of the PC/GFAC, illustrated by the conduction modeling parameter across the spherical wall of the cenosphere and the interfacial heat transfer for the PC/GFAC composite, pertaining to a worthwhile and serviceable thermal management praxis.
The solution behaviors of the binary mixture of double chain cationic surfactant didodecyldimethylammonium bromide (DDAB) with nonionic surfactants of varied head groups, EO-9 and EO-40, in the presence and absence of electrolytes were studied and found nonideal behavior. The different physicochemical properties such as Gibb’s surface excess (Γ), minimum area per molecule (A min), and interaction parameters at bulk (β M ) and interface (β σ ) were calculated. In the presence of nonionic surfactants, lowering of CMC, CVC, and surface tension at these two concentrations of DDAB were observed. The β M and β σ values indicate strong interaction between DDAB and EO-40 mixed system. Further, addition of electrolytes to the mixed systems show increased interaction and change of physicochemical properties because of the combination of electrical and salting out effects.
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