Xian Zhu

Amino Acids Production from Fish Proteins Hydrolysis in Subcritical Water

The hydrolysis technology and reaction kinetics for amino acids production from fish proteins in subcritical water reactor without catalysts were investigated in a reactor with volume of 400 ml under the conditions of reaction temperature from 180–320°C, pressure from 5-26 MPa, and time from 5-60 min. The quality and quantity of amino acids in hydrolysate were determined by bioLiquid chromatography, and 17 kinds of amino acids were obtained. For the important 8 amino acids, the experiments were conducted to examine the effects of reaction temperature, pressure and time on amino acids yield. The optimum conditions for high yield are obtained from the experimental results. It is found that the nitrogen and carbon dioxide atmosphere should be used for leucine, isoleucine and histidine production while the air atmosphere might be used for other amino acids. The reaction time of 30 min and the experimental temperature of 220°C, 240°C and 260°C were adopted for reaction kinetic research. The total yield of amino acids versus reaction time have been examined experimentally. According to these experimental data and under the condition of water excess, the macroscopic reaction kinetic equation of fish proteins hydrolysis was obtained with the hydrolysis reaction order of 1.615 and the rate constants being 0.0017,0.0045 and 0.0097 at 220°C, 240°C and 260°C respectively. The activation energy is 145.1 kJ·mol−1.

Pyrolysis characteristics of bean dregs and in situ visualization of pyrolysis transformation

Biomass is an important renewable and sustainable source of energy. Waste products from biomass are considered as attractive feedstocks for the production of fuel. This work deals with the pyrolysis of bean dregs, a biomass waste from soybean processing industry. A technique has been developed to study bean dregs pyrolysis by in situ visualization of bean dregs transformation in a quartz capillary under a microscope using a charge-coupled device (CCD) camera monitoring system. The technique enables us to observe directly the processes and temperatures of bean dregs transformation during pyrolysis. In situ visualization of reaction revealed that how oily liquids are generated and expulsed concurrently from bean dregs during pyrolysis. Pyrolysis characteristics were investigated under a highly purified N(2) atmosphere using a thermogravimetric analyzer from room temperature to 800 °C at different heating rates of 10, 30 and 50 °C/min. The results showed that three stages appeared in this thermal degradation process. The initial decomposition temperature and the peak shifted towards higher temperature with an increase in heating rate. Kinetic parameters in terms of apparent activation energy and pre-exponential factor were determined.

Kinetics of Glucose Production from Cellulose by Hydrolysis in Sub-Critical Water

Biomass is an important renewable and sustainable source of energy. Cellulose is the primary component of plant-derived biomass. Glucose, which can be further transformed to fuel alcohol in a fermentation process, is a biomass energy precursor. This study investigated the production of glucose from cellulose by hydrolysis in sub-critical water and the hydrolysis kinetics of cellulose. Kinetics was conducted in a temperature range of 240-260°C using a 200 ml stainless steel batch reactor. A simplified kinetic model base on parallel and consecutive reaction was proposed. The differential equations resulting from the model were fit to experimental data to obtain kinetic rate constants. The activation energy and the pre-exponential factor were determined. A good agreement between the simplified model and the experimental data was obtained. The experimental results show that the best hydrolysis technology is: reaction temperature 260°C, reaction time 120s. Under this condition, the glucose yield reaches 46.05%.