Paul Chen

Effect of Physical Treatments on the Enzymatic Hydrolysis of Corn Stover

Pretreatment is one of the key factors affecting the enzymatic hydrolysis of corn stover. The mild chemical pretreatment combined with physical pretreatments for the enzymatic hydrolysis of corn stover was studied. The ground corn stover with different particle sizes were soaked in the 0.1N-1N NaOH solution for 2 hours at room temperature using a solid:liquid ratio of 0.1g/ml. After washing, the pretreated ground corn stover was dispersed uniformly in water. The effect of dispersing, cellulase loading (20 to 100 GCU/g solid), alkaline concentration (0.1 to 1.0N), and particle sizes (2mm, 25 mesh, and 60mesh) on the saccharification rate of the corn stover samples were studied. It was found that increasing the cellulase loading from 20 to 100 GCU/g solid raised the hydrolysis rate of corn stover by only 13%. Reducing the product size (from 2mm to 60 mesh) through grinding before NaOH treatment resulted in only minimal increases in the enzymatic cellulose conversions, while the dispersing process after NaOH soaking increased the hydrolysis rate by as much as 40%. The hydrolysis rate of dispersed sample pretreated with 0.2-0.3N alkaline is close to that of the traditional ground sample pretreated with 1.0 N alkaline. The lower the concentration of alkaline was, the higher the effect of dispersing process. It seems that the dispersing process not only reduces the particle size, but also makes the material more accessible to the cellulase.

Microwave‐Assisted Pyrolysis of Biomass for Bio‐Oil Production

Microwave‐assisted pyrolysis (MAP) is a new thermochemical process that converts bio‐ mass to bio‐oil. Compared with the conventional electrical heating pyrolysis, MAP is more rapid, efficient, selective, controllable, and flexible. This chapter provides an up‐to‐ date knowledge of bio‐oil production from microwave‐assisted pyrolysis of biomass. The chemical, physical, and energy properties of bio‐oils obtained from microwave‐assisted pyrolysis of biomass are described in comparison with those from conventional pyroly‐ sis, the characteristics of microwave‐assisted pyrolysis as affected by biomass feedstock properties, microwave heating operations, use of exogenous microwave absorbents, and catalysts are discussed. With the advantages it offers and the further research and devel‐ opment recommended, microwave‐assisted pyrolysis has a bright future in production of bio‐oils that can effectively narrow the energy gap and reduce negative environmental impacts of our energy production and application practice.

Effect of Various Pretreatments on Crude Algal Lipid Extraction

In order to enhance the release of lipids from algae cellular structures and the access of extracting solvent to fatty acids, pretreatment must be used to disrupt cellular structures and ensure effective lipid extraction. This study investigated mainly the effect of ultrasonication, homogenization, grinding, supercritical CO2 , and nano dispersion on crude algal lipid extraction. Results showed that the amount of extracted crude lipid was significantly influenced by the pretreatment applied. Higher crude lipid extracted was observed with samples pretreated with super critical CO2 , and nano dispersion.

Growing green microalgae for biofuel production in nutrient-rich centrate from municipal wastewater treatment plant

The wastewater generated from centrifuging activated sludge, named centrate, contains highest amount of ammonia nitrogen and active phosphorus among several wastewaters after different processes in municipal wastewater treatment plant, which could be used as a valuable growth media for microalgae for the dual purpose of removing nutrients and obtaining a feedstock for biofuel production. This research was conducted step by step, resolving question by question which might account for the inhibition of fast algal growth in the centrate. Finally, the conclusion that all the possible inhibitions of (1) residual polymer, (2) unbalanced N/P ratio, and (3) deficient trace element Zn were not present was made. Algae could grow well in 100% centrate without any addition of supplementary elements. Further study will focus on scale-up, algal lipid content analysis.

Pyrolysis Characteristics and Kinetics of Corn Residue Studied by Diffrential Thermogravimetry

The kinetics of biomass pyrolysis plays a major role in the design and control of thermochemical conversion of biomass to bio crude and fuel gas. Moreover, commercial energy production requires knowledge of the kinetics and mechanisms of biomass degradation, a process in which pyrolysis is an attractive and practicable method. Thermoanalytical techniques, especially thermogravimetric analysis and derivative thermogravimetry, allow us to obtain dynamic data. Mathematical modeling of the thermal decompositions will help us in checking the validity of assumptions and in drawing quantitative conclusions. The pyrolysis characteristics of corn residues will be investigated in this research. The purpose of this study is to obtain detailed information on the pyrolysis characteristics and chemical kinetics of corn stovers and corn cobs. A thermogravimetric analysis including determination of kinetic parameters will be performed at a constant heating rate of 5K/min, 10 K/min, and 30 K/min. The degradation of corn sotvers and corn cobs was modeled by three first order independent parallel reactions, describing the degradation of hemicellulose, cellulose and lignin. The effect of the heating rate on the pyrolysis behavior will also be presented. Kinetic models will be established and evaluated using actual experiment data.

Study of Moisture Diffusion between Bread and Cheese

Magnetic resonance imaging(MRI) measurements were carried out on bread and cheese binary system to investigate the relationship between the moisture mobility of bread and cheese. MRI 3D images of bread and cheese are acquired at designed time periods to present the water density distributions in both bread and cheese. Based on the 3D images, the average water distributions on one dimension are calculated and used to calculate the water diffusion rates for various types of bread and cheese, such as different density bread, and different water content bread and cheese. T2 mapping state diagram of the systems was calculated to map out the mobility of water molecules during storage. The objective of this work is to illustrate the possibilities of MRI for characterizing water mobility in bread and cheese binary system. The behavior of water in cheese diffuse to bread during storage is observed in the same temperature range.

Water Mobility and Mold Susceptibility in Engineered Wood Products—a Magnetic Resonance Aspect

There are significant environmental benefits of understanding the water characteristics in engineered wood products as it is related to their fungi/mold susceptibility. The primary goal of this investigation was to gain a fundamental understanding of the water characteristics in oriented strandboard (OSB) using magnetic resonance (NMR) approaches. Isotherm sorption tests were conducted on commercial OSB panels made from different wood type and adhesive combinations. Moisture content (MC) determination, water activity (aw) measurement, and magnetic resonance relaxometry plus Distributed Exponential Analysis were performed on the OSB specimens during isotherm sorption tests. The results showed that neither MC nor aw is a reliable indicator of mold susceptibility of OSB. NMR relaxometry together with chemometric analysis detected that the state of water with the longest spin-spin relaxation time is responsible for the mold susceptibility of OSB. OSB made from pine had higher mold susceptibility than that from aspen because the pine OSB had a third water component with very long spin-spin relaxation time. The results suggest that new protocol for quality control in OSB production based on MR relaxometry could replace the current moisture content measurement.