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Catalysts play a significant role in transesterification of vegetable oils. Currently, chemical and biological catalysts are being investigated, and both have their inherent merits and demerits. In large-scale applications, these catalysts are expected to be cost effective and environmentally friendly. If the catalyst is homogeneous in its physical form it is more effective than is the heterogeneous catalyst, but its separation from the mixture is a major issue. Some of the heterogeneous catalysts suffer leaching in harsh reaction conditions. Of late, nanocatalysts that demonstrate high efficiency are being studed. Nanoparticles are used in biological catalysts as solid carriers for lipase immobilization. Lipase immobilized on magnetic nanoparticles has proved to be a versatile biocatalyst for biodiesel production. This article reviews the role of various catalytic systems commonly used in the transesterification reaction of oils in biodiesel generation.

Experimental studies were carried out on the reducibility of two different chromite ores using different reducing carbonaceous reducing agents in the temperature range 1173 to 1573 K. "Friable lumpy" ores and "hard lumpy" ores were used in the experiments. Petroleum coke, devolatilized coke, (DVC) and graphite were used as reducing agents. It was found that iron was practically completely reduced before the commencement of the reduction of chromium in the ore. The reduction of iron was controlled by diffusion. The activation energy for this process was estimated to be 130 kJ/mole. The reduction of chromium was controlled by either chemical reaction or nucleation. Rate of reduction was highest when raw petroleum coke was used as the reducing agent. The DVC was less effective compared to raw coke, whereas the rate of reduction was lowest when graphite was used as the reducing agent.

Quantum dots (QDs) have received much attention due to their extraordinary optical application in medical diagnostics, optoelectronics and in energy storage devices. The most conventional QDs are based on semiconductors that comprise heavy metals whose applications are limited due to toxicity and potential environmental hazard. Of late, researchers are focusing on carbon-based quantum dots, which have recently emerged as a new family of zero-dimensional nanostructured materials. They are spherical in shape with a size below 10 nm and exhibit excitation-wavelength-dependent photoluminescence (PL). Carbon quantum dots (CQDs) have unique optical, photoluminescence and electrochemical properties. They are environment-friendly with low toxicity as compared to toxic heavy metal quantum dots. Generally, CQDs are derived from chemical precursor materials, but recently researchers have focused their attention on the production of CQDs from waste biomass materials due to the economic and environmental exigency. In this review, recent advances in the synthesis of CQDs from waste biomass materials, functionalization and modulation of CQDs and their potential application of biosensing are focused. This review also brings out some challenges and future perspectives for developing smart biosensing gadgets based on CQDs.

The kinetics of cellulose and hemicellulose hydrolysis of wheat straw was studied using both isothermal and non‐isothermal techniques in a batch reactor. Reactions were carried out between 100 and 210°C and product sugars were analyzed using a Bio‐Rad HPX‐87P liquid chromatographic column. A simple first order series reaction model was used for both cellulose and hemicellulose hydrolysis reactions and kinetic parameters were obtained for the Arrhenius rate equations for three different sulphuric acid concentrations (0.5, 1.O and 1.5%). Activation energies remained constant with acid concentration but the pre‐exponential factors showed an increase with acid concentration. To minimize the amount of experimental data required and to achieve a unique solution to the kinetic parameters, the technique of combining isothermal and non‐isothermal reaction data was studied.