Zhen Wu

Catalytic conversion of carbohydrates into 5-hydroxymethylfurfural over cellulose-derived carbonaceous catalyst in ionic liquid

Three environmental-benign and low-cost carbon-based solid acid catalysts containing -SO3H, -COOH and phenolic -OH groups were prepared and used for the conversion of glucose into 5-hydroxymethylfurfural (HMF) in ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM]Cl). The results demonstrated that cellulose-derived carbonaceous catalyst (CCC) possessed the highest catalytic activity, which resulted in 46.4% HMF yield at 160°C for only 15 min. In addition, the reaction kinetics for the conversion of glucose into HMF over CCC was fitted with the first-order rate equation. The slightly-deactivated CCC after four successive reaction runs could be easily regenerated by a simple carbonization and sulfonation process. More gratifyingly, the combination of CCC and [BMIM]Cl were confirmed to be suitable for converting other carbohydrates such as fructose, sucrose, maltose, cellobiose, starch and cellulose into HMF. Particularly, a plausible mechanism involving hydrolysis, isomerization and dehydration for the conversion of carbohydrates into HMF was also proposed.

A novel ionic liquid-tolerant Fusarium oxysporum BN secreting ionic liquid-stable cellulase: Consolidated bioprocessing of pretreated lignocellulose containing residual ionic liquid

In this study, microbial communities from chemicals polluted microhabitats were cultured with the addition of imidazolium-based ionic liquid (IL) to enrich for IL-tolerant microbes. A strain of Fusarium oxysporum BN producing cellulase from these enrichments was capable of growing in 10% (w/v) 1-ethyl-3-methylimidazolium phosphinate, much higher than the normal IL concentrations in the lignocellulose regenerated from ILs. Cellulase secreted by the strain showed high resistance to ILs based on phosphate and sulfate radicals, evidencing of a high conformational stability in relevant media. Gratifyingly, F. oxysporum BN can directly convert IL-pretreated rice straw to bioethanol via consolidated bioprocessing (I-CBP). At optimum fermentation condition, a maximum ethanol yield of 0.125 g ethanol g(-1) of rice straw was finally obtained, corresponding to 64.2% of the theoretical yield.

Development of a traffic noise prediction model on inland waterway of China using the FHWA.

Based on the local environmental standards, vessels types and traffic conditions, an inland waterway traffic noise prediction model was developed for use in China. This model was modified from the US FHWA model by adding the ground absorption and water surface attenuation correction terms to the governing equations. The parameters that were input into the equations, including traffic flow, vessel speed, distance from the center of the inland waterway to the receiver, position and height of the barriers and buildings, location of the receiver, type of ground, percentage of soft ground cover within the segment, and water surface conditions were re-defined. The model was validated by comparing the measured noise levels obtained at 33 sampling sites from Shugang Channel, Yanhe Channel and Danjinlicaohe Channel in China with the predicted values. The deviation between the predicted and measured noise levels within the range of ±1.5dB(A) was 81.8%. The mean difference between the predicted and measured noise levels was 0.15±1.75dB(A). However, the noise levels predicted developed model are generally higher than the measured levels. Overall, the comparison has proved that the developed method is of a high precision, and that it can be applied to estimate the traffic noise exposure level on inland waterway in China.

Efficient hydrolysis of cellulose over a magnetic lignin-derived solid acid catalyst in 1-butyl-3-methylimidazolium chloride

A green and efficient strategy for the hydrolysis of cellulose was developed by using a magnetic lignin-derived solid acid catalyst (MLC-SO3H) in the presence of ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM]Cl). The results indicated that reaction temperature, reaction time, catalyst loading and water content have a big influence on the yield of total reducing sugars (TRS). By optimizing these reaction parameters, 69.3% TRS yield was observed at 140 °C for 150 min with the addition of 40 wt% MLC-SO3H and 1 wt% water. More importantly, MLC-SO3H could be easily separated from the reaction mixture with an external magnet and could be repeatedly used five times without an obvious loss of catalytic activity, demonstrating that it possessed excellent recyclability. Furthermore, a plausible mechanism involving three consecutive processes of dissolution, adsorption and catalysis for the hydrolysis of cellulose in [BMIM]Cl over a catalyst of MLC-SO3H was also proposed.

Applying the RLS 90 to Develop an Inland Waterway Traffic Noise Prediction Model in China that Considers Water Surface Influence

Based on the traffic situation, vessel type and atmospheric condition, an inland waterway traffic noise prediction model was developed for environmental assessment in China. This model was developed from the Germany Richtlinien für den Lärmschutz an Straßen (RLS 90) model by adding the water surface condition, absorption and gradient along vessel travel direction correction terms to the governing equations. The re-described parameters, including traffic flow and composition, vessel speed, air absorption, and water surface, ground and atmospheric conditions, etc., were chosen as inputs into the calculating equations. The verification results showed that the absolute error between the predicted and measured noise levels within the range of ± 1.4 dBA was 82.9%. The mean difference between the predicted and measured noise levels was 0.02 ± 1.25 dBA. The comparison results with the RLS 90 model and the modified Federal Highway Administration (FHWA) model also showed that the developed model in this study had better precision and accuracy.

Adsorption and separation of lignin-based aromatic aldehydes using macroporous resins

Lignin-based aromatic aldehydes (p-hydroxybenzaldehyde, vanillaldehyde and syringaldehyde) have wide applications in flavoring. However, their separation using chromatographic methods has not been explored. We studied the adsorption and desorption behaviors of aromatic aldehydes on macroporous resins and four macroporous resins X-5, CAD-40, AB-8 and D101 were screened for separation of aromatic aldehydes. The results demonstrated that X-5 showed the highest adsorption and desorption capacities. The adsorption capacities for p-hydroxybenzaldehyde, vanillaldehyde and syringaldehyde on X-5 were 33.5mg/g, 46.6mg/g and 47.0mg/g at 20 °C, respectively, higher than that of CAD-40, AB-8 and D101. Adsorption isotherms of aromatic aldehydes on X-5 were confirmed to fit to Freundlich equation which was calculated by lnQe=0.6933lnCe+6.788, lnQe=0.7031lnCe+7.7358 and lnQe=0.7107lnCe+ 8.2412 for p-hydroxybenzaldehyde, vanillaldehyde and syringaldehyde, respectively. The results of dynamic adsorption and desorption experiments demonstrated that 50% (v/v) ethanol solution was an effective elution solvent for aromatic aldehydes. The maximum concentration of the three kinds of aromatic aldehydes in eluent reached 3.74 g/L, 5.44 g/L and 7.03 g/L, which indicated that the elution process was also an effective enrichment process for sorbate.

Urea (CO(NH2)2) Pretreatment Improve Biogas Production Performance of Rice Straw

To discuss the internal effect of urea (CO(NH2)2) pretreatment on anaerobic digestion biogas production of rice straw waste, a self-designed laboratory-scale continuous anaerobic biogas digester was used in this study. Anaerobic biogas slurry, urea pretreatment and anaerobic digestion were evaluated for biogas production from rice straw. The results showed that the peak value of biogas production was attained on the 17th day by using 6% urea pretreatment on rice straw. However, the highest CH4 content was 49.8% on the 15th day for the 8% urea-treated rice straw. The cumulative biogas production of 6% urea pretreatment was the highest, about 16 540 mL, which was followed by 2% urea (12 283 mL), 8% urea (9 883 mL), and 4% urea (5 668 mL).

Effect of CaCO3 Pretreatment on Methane Production from Anaerobic Digestion of Rice Straw

The chemical pretreatment of rice straw was achieved via the liquid-state dissolution of CaCO3. Pretreatment effects on the biodegradability and subsequent anaerobic production of methane were investigated. The results showed that the peak value of biogas production was attained of 4% CaCO3 pretreatment on the 20th day, which is 1 589 mL. The test daily methane content of different pretreatment conditions mainly ranges from 3.4% to 47.4%. The cumulative biogas production of 6% CaCO3 pretreatment was the highest, about 19 917 mL.

Anaerobic Fermentation Characteristic of Rice Straw Pretreated by HCl

The anaerobic fermentation characteristic of rice straw pretreated by HCl was studied. The results showed that the test pH values of different pretreatment conditions mainly range from 5.09 to 7.52. The peak value of biogas production was attained of 2% HCl pretreatment on the 20th day, which is 1 180 mL. The test daily methane content of different pretreatment conditions mainly ranges from 3.2% to 58.1%. However, the cumulative biogas production by using HCl pretreatment of rice straw during anaerobic fermentation is poor.

Optimization of Sodium Carbonate Pretreatment on Enzymatic Digestibility of Bioenergy Material: Miscanthus

Pretreatment is a critical step in the conversion of lignocellulose to fermentable sugars. In this work, Miscanthus straw was pretreated with ammonium carbonate (Na2CO3), which was shown by earlier works to be an effective pretreatment of grass stovers and other plant materials in the context of ethanol production. Here, we explored several key parameters including Na2CO3 concentration (2–6%), temperature (120–160°C), and reaction time (10–30 min) to evaluate their effects on enzymatic digestibility using response surface methodology. The best conditions were found to be Na2CO3 of 4.4%, temperature of 150.7°C, and reaction time of 20.0 min, under which glucose yield reached to 294.5 g/Kg biomass.