Zehui Jiang

Comparison of bamboo green, timber and yellow in sulfite, sulfuric acid and sodium hydroxide pretreatments for enzymatic saccharification

The response and behavior of bamboo green, timber, and yellow of moso bamboo (Phyllostachys heterocycla) to three pretreatments, sulfite (SPORL), dilute acid (DA), and alkali (NaOH), were investigated and compared with varied chemical loadings at 180°C for 30 min with a 6.25:1 (v/w) liquor-to-bamboo ratio. All the pretreatments improved the enzymatic digestibility of bamboo substrates. Under the investigated conditions, the DA pretreatment achieved better enzymatic digestibility, but had lower sugar recovery yield, and formed more fermentation inhibitors. The results suggested that the SPORL pretreatment be able to generate more readily digestible bamboo substrate with higher sugar yield and fewer fermentation inhibitors than the corresponding DA pretreatment if hemicelluloses are sufficiently removed by adding more acid to bring down the pretreatment pH. Bamboo timber had higher sugar content and better enzymatic digestibility and therefore was a better feedstock for bioconversion than bamboo green and yellow.

Combustion characteristics of bamboo-biochars

Combustion characteristics of biomass are very important to directly utilize as an energy resource. Bamboo was carbonized using a XD-1200N muffle furnace in the nitrogen environment and its combustion characteristics were investigated. Results showed that bamboo-biochars had better combustion characteristics compared to bamboo materials, such as a lower content of moisture and volatiles, a higher energy density, HHV and EHC, a lower H/C and O/C ratios and a shorter TTI. Characteristic peak of bamboo-biochars shifted to higher temperature in thermal decomposition process, indicating a more steady-state burning and a higher combustion efficiency. Bamboo-biochars had a low content of S and N, which was helpful to decrease pollutant emissions. A higher content of K and Na was observed in the ash of bamboo-biochars, resulting in slagging, fouling, corrosion and agglomeration. The data from this research will be very helpful to efficiently design and operate its combustion systems.

Investigating pyrolysis and combustion characteristics of torrefied bamboo, torrefied wood and their blends.

Bamboo and masson pine was torrefied with 300°C of temperature for 2.0h of residence time using GSL 1600X tube furnace in the argon atmosphere. Torrefied bamboo and masson pine particles were uniform mixed with different weight ratios. Pyrolysis and combustion characteristics were investigated through thermogravimetry (TGA). The results showed that pyrolysis and combustion process of all samples included three steps even though their characteristics were different. Torrefied biomass had a higher pyrolysis and combustion temperature, due to moisture and volatile removal and thermal decomposition of hemicelluloses, cellulose and lignin during torrefaction process. Torrefaction also increased high heating value, ash content and C/H and C/O ratio of biomass. The synergy of torrefied bamboo and torrefied mason pine was not found during pyrolysis and combustion process of blends. The results from this research will be very important and helpful to develop and utilize the wastes of masson pine and bamboo for energy products.

Isolating nanocellulose fibrills from bamboo parenchymal cells with high intensity ultrasonication

Abstract The parenchymal cells in bamboo are an attractive source of raw materials due to their low degree of lignification and relatively loose cell wall structures. In this study, nanocellulose fibrils (NCFs) were isolated via a combined process of ultrasonication and chemical pretreatment of parenchymal cells separated from Moso bamboo (Phyllostachys pubescens) by means of a simple screening approach. As indicators of the fibrillation degree served the morphology, optical properties, and dynamic viscosity of the prepared NCF hydrogel as function of ultrasonication time. The mechanical properties of NCF derived films were also determined. The results show that high-quality NCFs can easily be prepared from bamboo parenchymal cells through the above-mentioned process, with an optimal ultrasonication time of 40 min. The utilization of bamboo processing residues via the ultrasonication route is promising and for energy saving production of high-quality NCFs at large scale.

Pretreatment of bamboo by ultra-high pressure explosion with a high-pressure homogenizer for enzymatic hydrolysis and ethanol fermentation.

Bamboo shoots, 2- and 5-year-old bamboo were treated by using a homogenizer in a constant suspended state, a process termed as ultra-high pressure explosion (UHPE). The bamboo powder was heated in 2% NaOH solution at 121°C, and then 100MPa UHPE-treated through a homogenizer. The results verified that UHPE changed the suspension solution of powder into a stick fluid. The contents of lignin were decreased significantly. The bamboo shoots and 2-year-old bamboo were completely hydrolyzed to glucose within 48h by enzymes loading of 15 FPU of cellulase and 30IU of β-glucosidase per gram glucan. Fermentation of enzymatic hydrolyzates with Saccharomyces cerevisiae resulted in about 89.7-95.1% of the theoretical ethanol yield after 24h. Therefore, NaOH+UHPE is argued to be a potential alternative technology for pretreatment of bamboo.

Tensile behaviour and fracture mechanism of moso bamboo (Phyllostachys pubescens)

Abstract The present work is aiming at the elucidation of the tensile behaviour and fracture performance of moso bamboo (Phyllostachys pubescens Mazei ex H. de Lebaie) by means of digital speckle correlation method (DSCM) and microscopic techniques. Results indicated that fibres play a major role in longitudinal tension and impeding crack radial propagation. Hybrid I-II failure mode was observed, i.e., crack opening (in tensile stress) and shear sliding (in shear stress). According to microscopic fracture characteristics, fibres extraction and stretching, filament formation in parenchyma with fibres bridging, interface debonding and the helix fracture of fibres happened in tension, which created more interfaces and dissipated more energy. The graded composite structure of bamboo provides intrinsic and extrinsic toughening mechanisms which contribute to improved toughness and physical properties.

Porous nanoplatelets wrapped carbon aerogels by pyrolysis of regenerated bamboo cellulose aerogels as supercapacitor electrodes

Herein NaOH/urea aqueous solution was assisted to dissolve bamboo cellulose fibers for the fabrication of porous nanoplatelets wrapped carbon aerogel as an economic and sustainable way in application of supercapacitor. The architecture displayed favorable features, such as a large specific surface area and a great flexibility of 86% at stress of 23kPa. The effects of the KOH activation on the morphology and porous texture of cellulose carbon aerogel were further investigated and correlated with their electrochemical behavior. In aqueous electrolyte of 6M KOH, activated carbon aerogel exhibited a high specific capacitance of 381F/g which was improved by 150% compared to unactivated sample. Notably, the reasonable micropores and mesopores contributed to an excellent retention rate of 90% at high scan rate of 200mV/s. The low equivalent series resistance and small charge transfer resistance in activated carbon aerogel also suggested an inspiring capacitor behavior.

The effect of freezing speed and hydrogel concentration on the microstructure and compressive performance of bamboo-based cellulose aerogel

Cellulose aerogel is a kind of ultra-light solid material which resulting from natural cellulose materials, and its performance is highly related to its structure. In this study, we prepared cellulose aerogels with different densities by regulating the concentration of microfibrillated cellulose (MFC) hydrogel using bamboo parenchymal cells as a starting material. The effects of the freezing speed and hydrogel concentration on the microstructure and compression performance of the resultant aerogels were investigated. The results demonstrated that higher freezing speed can inhibit the aggregation of MFC, resulting in aerogel with higher porosity. Conversely, increasing hydrogel concentration facilitated the aggregation of MFC, generating a distinct conversion from a looser fibril network structure (low density) to a more compact sheet-like structure (high density). Moreover, the results showed an expected positive correlation between the density of the aerogel and its compression performance, both in compression modulus and energy absorption.

Compression properties of vascular boundles and parenchyma of rattan (Plectocomia assamica Griff)

Abstract Rattan is a unique unidirectional vascular bundles-reinforced biocomposite with many nodes along its canes. Mechanical compression tests have been performed from rattan samples taken from different parts of the cross section. Compression strength increased with increasing amounts of vascular bundles (VBs) in the tissues was investigated. Samples including the outer ring with many VBs have the highest apparent Young’s modulus of 1.08 GPa and the highest compression strength of 17.6 MPa. However, samples consisting of parenchyma cells had an apparent Young’s modulus of 25 MPa, and the compression strength of 1.81 MPa. The compression properties of core samples improved with increasing amounts of VB. The apparent Young’s modulus and compression strength of a single VB were 730 MPa and 6.87 MPa, respectively, and were calculated according to the rule of mixture of composites.

Detection of complex vascular system in bamboo node by X-ray mu CT imaging technique

Abstract Bamboo is one of the world’s fastest growing plants. They reach a final height of 15–40 m during a period of 40–120 days. The full height is reached by intercalary growth of each node. However, it is very difficult to detect the complex vascular system in a bamboo node using traditional methods. X-ray computed microtomography (μCT) is a noninvasive novel approach to the three-dimensional (3D) visualization and quantification of biological structures. In the present article, μCT has been applied to provide insights into the internal structure of bamboo node, where three branches are connected. The picture obtained could hardly be obtained by any other means. The bamboo nodal characteristics of three transverse and axial sections are presented. The complex 3D network of vascular bundles has been directly obtained for the first time.