Characterization of slow pyrolysis products from three different cashew wastes

A huge amount of waste is generated by the cashew processing industries. This study aims to valorise these cashew wastes generated at different levels while processing cashew nuts in factories. The feedstocks include cashew skin, cashew shell and cashew shell de-oiled cake. Slow pyrolysis of these three different cashew wastes was performed at varying temperatures (300-500℃) at a heating rate of 10℃/min in a lab scale glass-tubular reactor under inert atmosphere of nitrogen with flow rate of 50 ml/min. The total bio-oil yield for cashew skin and the de-oiled shell cake was 37.1 and 48.6 wt% at 400℃ and 450℃, respectively. However, the maximum bio-oil yield obtained for cashew shell waste was 54.9 wt% at 500℃. The bio-oil was analysed using GC-MS, FTIR, and NMR. Along with the various functionalities observed in bio-oil through GC-MS, phenolics were observed to have maximum area% for all the feedstocks at all temperatures. At all the slow pyrolysis temperatures, cashew skin led to more biochar yield (40 wt%) as compared to cashew de-oiled cake (26 wt%) and cashew shell waste (22 wt%). Biochar was characterized by various analytical tools such as XRD, FTIR, Proximate analyser, CHNS, Py-GC/MS and SEM. Characterization of biochar revealed its carbonaceous and amorphous nature along with porosity.

Evaluation of electrochemical parameters for an EC mechanism from a global analysis of current-potential-time data: application to reductive cleavage of methylcobalamin

Simultaneous evaluation of electron-transfer rate constant, k degree, following chemical reaction rate constant, kf, electron-transfer coefficient, alpha, and standard potential, E degree', for electron transfer coupled to a following chemical reaction (EC mechanism) is described. A mathematical model for the current response to a potential step is developed by incorporating the appropriate concentration terms into the Butler-Volmer equation. Experimental current-potential-time (i-E-t) surfaces are fit to this model to evaluate the parameters. Fitting individual i-t or i-E curves did not yield unique parameter values whereas an i-E-t surface constituted by several i-t or i-E curves could be fitted to obtain unique values. A generalized kinetic zone diagram for the EC reaction is drawn by examining the limiting forms of the expression for current. Theoretical limits of measurable rate constants are estimated from the zone diagram. The three-dimensional electro-chemistry described above was used to study the reductive cleavage of methylcobalamin in dimethyl sulfoxide (DMSO) solvent and 0.1 M tetrabutyl-ammonium perchlorate supporting electrolyte. The parameters estimated are as follows: alpha = 0.552 +/- 0.004; k degree = 0.011 +/- 0.0015 cm s-1; kf = 1500 +/- 140 s-1; E degree' = -1.54 +/- 0.01 V. The rate constant for the following reaction, kf, in DMSO solvent is approximately 4000-fold faster than the similar process in aqueous medium. It is suggested that this enhancement is relevant to methyl group transfer in enzymatic reactions, e.g., methionine synthase, if the enzyme mechanism involves a reductive cleavage which produces a methyl radical.