Manisha J. Vaidya

The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated in a laboratory-scale batch-slurry reactor. Pt/C catalyst (1%) was chosen for optimization of reaction conditions and kinetic studies because of its higher catalytic activity compared to that of other heterogeneous transition metal catalysts. The average catalytic activity and initial rate of hydrogenation was found to increase with increase in the solvent polarity. To investigate the intrinsic kinetics of the reaction, the effect of catalyst loading, agitation speed, p-nitrophenol concentration, and hydrogen partial pressure on the initial rate of hydrogenation was studied at different temperatures. The analysis of initial rate data indicated that the mass-transfer resistances were not significant under the prevailing reaction conditions. A simple Langmuir−Hinschelwood (L−H)-type model was found to represent the kinetics of hydrogenation of p-nitrophenol to p-aminophenol satisfactorily. The apparent energy of activation was found to be 61 kJ/mol.

The present work describes the preparation of p-aminophenol via single-step catalytic hydrogenation of nitrobenzene in acid medium. A conventional method of synthesis of p-aminophenol is a two-step reaction involving iron−acid reduction of p-nitrophenol. This method causes serious effluent disposal problems due to the stoichiometric use of iron−acid, which leads to the formation of Fe−FeO sludge (≅1.2 kg/kg of product) in the process, which cannot be recycled. The single-step hydrogenation of nitrobenzene was carried out using platinum catalyst, and the process conditions were optimized. Complete conversion of nitrobenzene was achieved with selectivity to p-aminophenol as high as 75% under the best set of conditions. Furthermore, the catalyst can be easily recovered and efficiently recycled giving the TON as high as 1.38 × 10.5 This paper presents studies on the effect of various process parameters such as temperature, hydrogen pressure, and substrate and acid concentration on the rate of reaction and selectivity to p-aminophenol.

Preferred learning styles of learners are different, which depend on tastes, mentality preparedness, as well as physical condition, in terms of sensory modalities. Identifying and employing appropriate learning styles could play an important role in selecting teaching styles, which can improve education ultimately. The present study aimed to assess the diversity of learning styles amongfirst year Basic B.Sc. Nursing students of selected Nursing colleges of Aurangabad. A cross-sectional study conducted by using VAK learning style’s questionnaire.190 first year Basic B. Sc. Nursing students were selected from selected nursing colleges of Aurangabad. Results of the study show that, all samples preferred to use a single learning style (Uni-modal). Among all nursing students majority 48% preferred auditory style, followed by27% preferred the visual style and25% preferred kinaesthetic style. It is suggested that all nursing students must be tested to determine their desired learning styles by using VAK questionnaire and also to choose appropriate teaching methods and to improve educational goals.