Engineering topics

Zhao, Peitao

Publications and source records attributed to Zhao, Peitao.

16 records

DOE OSTI2023

Synthesis of Mg–K-biochar bimetallic catalyst and its evaluation of glucose isomerization

Highly efficient isomerization of glucose to fructose is essential for valorizing cellulose fraction of biomass to value-added chemicals. This work provided an innovative method for preparing Mg-biochar and Mg–K-biochar catalysts by impregnating either MgCl 2 alone or in combination with different K compounds (Ding et al. in Bioresour Technol 341:125835, 2021, https://doi.org/10.1016/j.biortech.2021.125835 and KHCO 3 ) on cellulose-derived biochar, followed by hydrothermal carbonization and pyrolysis. Single active substance MgO existing in the 10 Mg–C could give better catalytic effect on glucose isomerization than the synergy of MgO and KCl crystalline material present in 10 Mg–KCl–C. But the catalytic effect of 10 Mg–C was decreased when the basic site of MgO was overloaded. Compared to other carbon-based metal catalysts, 10 Mg–KHCO3–C with 10 wt% MgCl 2 loading had excellent catalytic performance, which gave a higher fructose yield (36.7%) and selectivity (74.54%), and catalyzed excellent glucose conversion (53.99%) at 100 °C in 30 min. Scanning electron microscope–energy dispersive spectrometer and X-Ray diffraction revealed that the distribution of Mg 2+ and K+ in 10 Mg–KHCO 3 –C was uniform and the catalytic active substances (MgO, KCl and K2CO 3 ) were more than 10 Mg–C (only MgO). The synergy effects of MgO and K 2 CO 3 active sites enhanced the pH of reaction system and induced H 2 O ionization to form considerable OH– ions, thus easily realizing a deprotonation of glucose and effectively catalyzing the isomerization of glucose. In this study, we developed a highly efficient Mg–K-biochar bimetallic catalyst for glucose isomerization and provided an efficient method for cellulose valorization.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2023

Gradient synthesis of carbon quantum dots and activated carbon from pulp black liquor for photocatalytic hydrogen evolution and supercapacitor

Black liquor (BL) is a by-product of the chemical pulping industry and is mainly used as a low-value fuel; however, its potential to produce high-value products has not been fully exploited. In this study, a green and simple strategy is reported for the gradient production of Na + -functionalized carbon quantum dots (Na + -CQDs) for the first time, N and S co-doped CQDs (N/S-CQDs), and N and S co-doped KOH-activated carbon (N/S-KAC) from BL by dialysis, hydrothermal carbonization and activation-carbonization, respectively. Due to the good electron trapping ability, photoluminescence and promising up-conversion luminescence of CQDs, the hydrogen evolution efficiency of Na + -CQDs/TiO 2 and N/S-CQDs/TiO 2 photocatalysts was improved by 2.45 and 1.46 times, respectively, compared with pure TiO 2 . N/S-KAC with a high specific surface area of 2294 m 2 g -1 provides an excellent specific capacitance of 253 F g -1 at 0.5 A g -1 and a promising energy density of 26.92 Wh kg -1 under a power density of 566 W kg -1 for the fabricated symmetrical supercapacitor. Moreover, the electrode material has good cycling stability with a capacitance retention of ~ 93.91% after 5000 cycles. In conclusion, this pathway provides a versatile and scalable approach for the construction and co-production of nanostructured materials, photocatalysts and energy storage devices.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Regulating the properties of activated carbon for supercapacitors: impact of particle size and degree of aromatization of hydrochar

Hydrochar (HC), obtained by the hydrothermal carbonization (HTC) of biomass, is an excellent precursor for preparing activated carbon (AC). However, the effects of the intrinsic properties of HC on the microstructure and electrochemical properties of AC are largely unknown. Here, this study investigates the impact of particle size and the degree of aromatization of in-situ HC on the microstructure and electrochemical properties of AC. Our results show that a large particle size and a high degree of aromatization help protect the HC from overactivation by ZnCl 2 , resulting in an large specific surface area (SSA > 2000 m 2 /g) and high mesopore to micropore volume ratio value ( V mes /V mic > 0.3) of the AC. Electrochemical performance measurements show a maximum specific capacitance of 218 F/g at 0.5 A/g was achieved in all samples where the AC (AC180-10 h) was prepared by activating HC180-10 h with a large size, a high degree of aromatization, and abundant surface oxygen-containing functional groups. After AC180-10 h was assembled into a supercapacitor, the specific capacitance of AC180-10 h still reached 158 F/g at 0.5 A/g, and it showed excellent cycling stability. This study advances the understanding of the impact of HC particle size and degree of aromatization on AC properties, providing new insights into tailoring HC qualities so that improving improve the properties of AC.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Novel waste-derived non-noble metal catalysts to accelerate acidic and alkaline hydrogen evolution reaction

Carbon substrate support is a promising approach to facilitate catalytic activity of non-noble metal catalysts in hydrogen evolution reactions (HER). Here, in this paper, we report a waste-derived electrocatalyst P-CoNiO 2 @NC synthesized under mild condition. It exhibits outstanding HER performance in both acid (η 10 = 64.6 mV) and alkaline (η 10 = 96.4 mV) condition with good stability. Especially, it begins to outperform commercial Pt/C when the current density is over 74 mA/cm 2 in acid electrolyte and 29 mA/cm 2 in alkaline electrolyte. Moreover, the waste-derived carbon substrate could effectively promote HER activity of other dual 3d TMOs such as Fe and Co, Fe and Ni. The improved HER activity originates from electron transfer, electronic structure adjustment and optimization of intermediates adsorption according to X -ray photoelectron spectroscopy and density functional theory calculations. This work provides a new insight for converting wastes into value-added products and a sustainable and friendly strategy to facilitate hydrogen energy production.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

Advances in multi-dimensional cellulose-based fluorescent carbon dot composites

Recently, fluorescent materials composed of carbon dots (CDs) have attracted increasing attention in diverse fields, including the environment, food, biology, and medicine. Cellulose has emerged as a promising class of materials for carriers due to its low cost, fascinating biodegradability, and various morphologies, especially in available different dimensions. By taking advantage of the respective superiority of fluorescent materials and cellulose carriers, the performance of fluorescence composite materials can be optimized and their application may be extended. Here, in this review, the study emphasizes the synthesis and applications of cellulose-based fluorescent materials with different dimensions. Moreover, some effective strategies and potential challenges for further development of cellulose-based fluorescent materials are discussed. A deeper understanding will provide a guide for the materials with ideal fluorescent performances.

42 ENGINEERING↗

DOE OSTI2023

Lignin-based carbon quantum dots with high fluorescence performance prepared by supercritical catalysis and solvothermal treatment for tumor-targeted labeling

The poor fluorescence performance of lignin-based carbon quantum dots (L-CQDs) prepared using the bottom-up method has hindered their development. Here, in this study, a two-step strategy was proposed to efficiently enhance the fluorescence properties of L-CQDs. Lignin was first cracked using an ethanol supercritical/noble metal catalyst; then, the L-CQDs were prepared with the cracked lignin fragments as carbon precursors without adding any modified reagents. Compared with the OL-CQDs prepared by the traditional one-pot hydrothermal method, the L-CQDs-1 prepared from CL-1 containing much low molecular weight compounds, and have photoluminescence (increased from 63 to 975) and excellent up-conversion photoluminescence (enhanced by 16.3 to 963), which significantly enhanced by about 15 times and 60 times, respectively. They can emit bright blue fluorescence under both ultraviolet and near-infrared light irradiation owing to a large amount of surface defects caused by the rich compound composition. When L-CQDs-1 were combined with, and quenched by folic acid (FA), the prepared FA@L-CQDs-1 show the ability to target and label tumor cells. This study opens new avenues for the preparation of L-CQDs with high fluorescence performance using lignocellulosic material without heteroatom additives.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2022

Growth mechanism of glucose-based hydrochar under the effects of acid and temperature regulation

Improving the tailorability of hydrochar synthesis is an effective way to enhance its performance and utilization efficiency. In this study, the growth rate, morphology, and molecular structure of hydrochar were controlled by regulating the pH and temperature of the hydrothermal carbonization process. Growth process analysis indicates that hydrochar has three growth periods: induction, rapid, and stable growth periods. It is mainly controlled by 5-hydroxymethylfurfural (HMF), which is formed by converting glucose and its transformation products. Further, the regulation of acid can significantly shorten the induction period of hydrochar, even under low-temperature conditions (<180 °C), and increase the growth rate of hydrochar. However, the degree of hydrochar adhesion varies: the lower the temperature, the greater the degree of its adhesion. Molecular structural analysis demonstrates that hydrochar mainly consists of furan structural domains and aromatic clusters, and its surface is rich in oxygen-containing functional groups. The degree at which hydrochar was aromatized was improved by increasing the reaction temperature (160–220 °C); whereas the regulation of acid reduced it and increased the content of oxygen-containing functional groups on the hydrochar surface. Based on these results, it is proposed that hydrochar formation has five stages and three growth periods with or without acid regulation.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2022

Role Evaluation of Active Groups in Lignin on UV-Shielding Performance

The contribution of the active groups in lignin to ultraviolet (UV)-shielding performance still remains unclear. In this study, we employed 16 lignin model compounds and theoretical calculations to ascertain the contribution of different functional groups to UV-shielding performance. These results showed that the order of UV-shielding performance on functional groups was -C=C–CHO > -C=C–COOH > -C=C–CH 2 OH > --C=C > quinone > -COOH > -OCH 3 ≈ -OH. Moreover, the synergism between the para-substituted electron-donating group -OH and the electron-withdrawing group allyl on the aromatic ring played a major role in UV-shielding performance of lignin models, whereas the additive effect of meta/ortho-substituted -OCH 3 played a secondary role. Furthermore, we found that the hydrophile–lipophile balance (HLB) value of lignin models also greatly affected the sunscreen protection factor (SPF) of lignin model-based sunscreens. A closer HLB value of lignin to 8.89 corresponded with a higher SPF of the lignin model-based sunscreen. The commercial photoprotective ingredient ethylhexyl methoxycinnamate (EHMC) and lignin models had a synergistic effect on UV-shielding performance caused by the π–π stacking interaction between the parallel-displaced stacked aromatic rings of lignin models and EHMC. Additionally, the UV irradiation test showed that these sunscreens prepared using lignin models and EHMC exhibited good photostability.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Enhancing thermal conductivity and toughness of cellulose nanofibril/boron nitride nanosheet composites

Generally, the thermal conductivity (TC) of composite based on cellulose nanofibrils (CNF) is improved by adding thermal conductive filler, which inevitably leads to the loss of its mechanical properties. Here, in this work, it is the first to simultaneously improve the toughness and TC of CNF/boron nitride nanosheets (BNNS) composite from the perspective of thermal conductive filler addition and CNF crystal change. The hydrophilic-modified BNNSs were successfully prepared by xylose-assisted ball-milling prior to adding into CNF. Compared with that of CNF film (1.34 W/(m·K)), the in-plane TC of CNF/BNNS composite (12.68 W/(m·K)) increased significantly by 846 % with loading 30 % BNNS. Afterwards, both toughness (8.0 MJ·m -3 , increased ~250 %) and TC (14.7 W/(m·K), increased ~16 %) of CNF/BNNS composite were further enhanced significantly by mercerization with 12.5 % NaOH solution. The simultaneously improvement of toughness and TC is unprecedented in related studies, which contributes to the effective preparation of thermal management materials.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Application of Box-Behnken design in optimizing product properties of supercritical methanol co -liquefaction of rice straw and linear low-density polyethylene

We report co-processing of plastic and biomass wastes to produce high-quality fuel has been attracting considerable interest in energy recovery. This work employed Box-Behnken Design (BBD) to optimize yield and properties of oil from supercritical methanol (scMeOH) co-liquefaction of rice straw (RS) and linear low-density polyethylene (LLDPE). Three independent variables of reaction temperature (270, 300, and 330°C), holding time (60, 90, and 120 mins), and RS/LLDPE mass ratio (0.15, 0.50, and 0.85) were selected for experiments. A maximum oil yield of 34.17 wt% was achieved at 303°C, 96 mins, and RS/LLDPE ratio of 0.59 according to BBD. Temperature and RS/LLDPE ratio dominated the oil yield and synergistic effects during co-liquefaction, whereas time was an insignificant factor. Optimum oil from co-liquefaction contained substantial hydrocarbons content of 32.91% compared to that from single RS-derived oil of 7.77%. Solid product obtained at the optimum condition could be used as solid fuel, due to its relatively high HHV of 43.08 MJ/kg compared to the other solid fuels (13.90–32.14 MJ/kg). This work provides a deep understanding of the co-processing of solid biomass and plastic wastes.

09 BIOMASS FUELS↗

DOE OSTI2022

Preparation, Properties, and Application of Lignocellulosic-Based Fluorescent Carbon Dots

We report that carbon dots (CDs) are a relatively new type of fluorescent carbon material with excellent performance and widespread application. As the most readily available and widely distributed biomass resource, lignocellulosics are a renewable bioresource with great potential. Research into the preparation of CDs with lignocellulose (LC-CDs) has become the focus of numerous researchers. Compared with other carbon sources, lignocellulose is low cost, rich in structural variety, exhibits excellent biocompatibility, and the structures of CDs prepared by lignin, cellulose, and hemicellulose are similar. This Review summarized research progress in the preparation of CDs from lignocellulosics in recent years and reviewed traditional and new preparation methods, physical and chemical properties, optical properties, and applications of LC-CDs, providing guidance for the formation and improvement of LC-CDs. In addition, the challenges of synthesizing LC-CDs were also highlighted, including the interaction of different lignocellulose components on the formation of LC-CDs and the nucleation and growth mechanism of LC-CDs; from this, current trends and opportunities of LC-CDs were examined, and some research methods for future research were put forward.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Effects of temperature and time on supercritical methanol Co-Liquefaction of rice straw and linear low-density polyethylene wastes

We report that biofuels are particularly attractive and play an increasingly important role in sustainable energy. However, biofuels originating from lignocellulosic biomass (LCB) are extremely challenging because of their low carbon content, low stability, and high oxygen content. This work evaluates the supercritical methanol (scMeOH) co-liquefaction of rice straw and linear low-density polyethylene (LLDPE) at temperature range of 240-340 °C for 0-2 h, to obtain hydrocarbons (HCs)-rich oil and carbon-rich solid product. Results show that reaction temperature dominated the yield and properties of products, but not the holding time. Among parameters tested, 30.07 wt% oil yield with 75.79% HCs content and 33.05 wt% oil yield with 70.91% HCs content were obtained at 300 °C for 1 h and 1.5 h, respectively. Simultaneously, the remaining solid products were still as high as 53.85 wt% with a carbon content of 79.59% and 48.28 wt% with carbon content of 81.34% under 300 °C for 1 h and 1.5 h, respectively. Ultimate analysis, FT-IR, TGA, and SEM show that solid products could be used as sustainable carbon resources, and solid fuel rather than soil amendment because of risk of micro plastic or adsorbent due to smooth surface without pores.

09 BIOMASS FUELS↗

DOE OSTI2021

Fluorescence Enhancement of Lignin-Based Carbon Quantum Dots by Concentration-Dependent and Electron-Donating Substituent Synergy and Their Cell Imaging Applications

Black liquor is an important pollutant in the pulp industry, but it also has the potential for high-value utilization. In this study, lignin extracted from black liquor was hydrothermally prepared into lignin-based carbon quantum dots (L-CQDs) using a one-pot method. Physicochemical characterization suggested that the L-CQDs exhibited a lamellar core–shell multilayered graphene structure surrounded by oxygen-containing functional groups. Here, the fluorescence intensity of the L-CQDs was strengthened depending on their own concentration dependence and the doping of external groups. The fluorescence intensity of L-CQDs varied between 89.09 and 183.66 under different concentrations, and the most intense fluorescence (183.66) was obtained at 0.1 mg mL –1 . At hydroxyl and amino adsorption capacities of 11.08 and 0.98 mmol g –1 , the hydroxylated RL-CQDs-5 and aminated NL-CQDs-3 exhibited the highest fluorescence intensities at 689.22 and 605.39, respectively. Moreover, when pristine L-CQDs were sequentially aminated and hydroxylated, the NRL-CQDs’ fluorescence intensity reached 1224.92. Cell imaging experiments proved that cells cultivated with NRL-CQDs have brighter fluorescence compared with L-CQDs. The results will render L-CQDs more suitable for practical applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Product Characteristics and Synergy Study on Supercritical Methanol Liquefaction of Lignocellulosic Biomass and Plastic

Bio-oil originating from lignocellulosic biomass (LCB) is a potential next-generation fuel because of its abundant, renewable, and sustainable resources compared to other types. However, these bio-oils are typically of low quality compared to petroleum-derived oils due to their low calorific value, high acidity, and oxygen content. This work intends to provide a feasible method for producing hydrocarbon-rich oils by supercritical methanol (scMeOH) coliquefaction of LCB and plastic waste. Both rice straw (RS) and linear low-density polyethylene (LLDPE) are coliquefied under 300 °C for 60 min in scMeOH at various RS/LLDPE mass ratios of 2:1, 1:1, and 1:2. Positive effects were found in terms of oil yield and fuel quality, such as higher hydrocarbons content and calorific value. The oil yield increased from 26.72 to 30.07 wt % with LLDPE addition of 67%. Around 79.15–92.24% of the oil was hydrocarbons, phenols, ketones, and diverse functional group compounds. The complex compounds led to various degrees of the synergetic effect on oil chemical compositions. Among various RS/LLDPE ratios in this work, RS/LLDPE of 1:2 was supposed to be an optimal ratio for hydrocarbon-rich fuel production because it presented the highest oil yield of 30.07 wt % and quality-high oil with 71.42% hydrocarbons. In addition, scMeOH coliquefaction of LCB and plastic waste shows a synergetic effect on the improvement of carbon and hydrogen contents in solid products. These results indicate that scMeOH coliquefaction of LCB with plastic is a feasible and promising means to improve fuel quality and also to realize the thermal recycling of plastic wastes.

09 BIOMASS FUELS↗

DOE OSTI2021

Supercritical water co-liquefaction of LLDPE and PP into oil: properties and synergy

The major plastic wastes are always mixtures, which are difficult to separate to treat in practice. Because of some possible cross-reactions, the degradation behaviors of plastics could not be mathematically represented by a simple addition of each polymer according to their proportions. This work examines supercritical water (scH 2 O) to liquefy poly-ethylene and poly-propylene mixtures into an oil with special interest in the oil quality and positive effect. Additionally, linear low-density polyethylene (LLDPE) and polypropylene (PP) were chosen as parent materials because of their high proportions in plastic wastes. The results show that a high conversion rate of around 99.75% was achieved with as high as 90.7 wt% oil yield without additional catalysts or hydrogen. The scH 2 O co-liquefaction of the LLDPE/PP mixture was different from that of the single polymer along with an improvement in the oil yield. Cyclic hydrocarbon ( i.e. , cyclic) generation was promoted while the production of paraffins was hindered in scH 2 O co-liquefaction using a mixture of LLDPE/PP. TGA reveals that the scH 2 O co-liquefaction of LLDPE/PP mixtures generated more diesel and lubricant oils and less gasoline and (jet fuel + light diesel) oils, thus slightly lowering the oil quality. Overall, the supercritical fluid technology was a powerful and promising means to liquefy mixed plastic wastes into oil at a high conversion rate free of catalysts or hydrogen.

42 ENGINEERING↗

DOE OSTI2020

Effect of endoglucanase and high-pressure homogenization post-treatments on mechanically grinded cellulose nanofibrils and their film performance

In this study, the effects of mechanical grinding (G) assisted by endoglucanase (E) and high-pressure homogenization (H) post-treated cellulose nanofibrils (CNFs) and its film properties were investigated. Compared to only mechanical grinding, these two post-treatment processes improved the size uniformity of CNFs in width. Additionally, the crystallinity of GECNFs was increased by 4.3 % and the resulting film exhibited low oxygen permeability rate (6.33 mL/m 2 ·day). Moreover, the combination post-treatments of enzyme and homogenization improved the tensile strength and transparency of CNFs films from 132.31 MPa, 27.52 %– to 177.99 MPa, 61.75 %, respectively. Besides, a composite of acrylic resin ABPE-10 and GEHCNFs film under negative pressure improved the transparency (85.68 %) and water contact angle (104.11°) of film. This work also provides insight on the relationship between the CNFs morphology and their film properties, which can be used to improve the CNFs film performance and promote future applications of CNFs.

59 BASIC BIOLOGICAL SCIENCES↗