A new article out of a collaboration between Dr. Ning Yan and Dr. Heyu Chen’s labs has been published in Bioresource Technology Journal written by Zhijiang Shao, Pitchaimari Gnanasekar, Nicole Tratnik, Nicolas R. Tanguy, Xiaohui Guo, Mingqiang Zhu, Ling Qiu, Ning Yan, and Heyu Chen.

You can find the article here.

Abstract

Low-temperature torrefaction assisted with solid-state KOH/urea applied onto wheat straw was proposed to break down the lignocellulosic material to enhance biomethane production in anaerobic digestion (AD). The optimization of key parameters applying the Box-Behnken design and response surface method showed that an addition of 0.1 g/g_straw KOH/urea at 180 ℃ while torrefying for 30 min was the optimal condition for producing biomethane. Results indicate that co-applying KOH and urea in torrefaction synergistically enhanced the biodegradability of straw by effectively removing lignin and largely retaining cellulose, giving rise to a 41 % increase in the cumulative methane production compared to untreated straw (213 mL/g-volatile solids (VS_raw)) from batch AD. Additionally, the nitrogen- and potassium-rich digestates helped to improve soil fertility, thus achieving a zero-waste discharge. This study demonstrated the feasibility of using solid-state KOH/urea assisted low-temperature torrefaction as an effective pretreatment method to promote methane production during AD.

A new article out of a collaboration between Dr. Ning Yan and Dr. Jing Chen’s labs has been published in Separation and Purification Technology Journal written by Jing Chen, Jialong Wu, Yinyan Zhong, Xiaozhen Ma, Wanrong Lv, Honglong Zhao, Jin Zhu, and Ning Yan.

You can find the article here.

Abstract

Superwettability can affect the performance of oil separation from water during the treatment of oily wastewater. Among various types of materials developed for cleaning oil pollution, foam is a popular choice due to its attractive lightweight properties and adjustable porosities. Foams with superwetting surfaces (superhydrophilic/superoleophobic underwater) are ideal for oil/water separations. In this study, lignin-based polyurethane foams (LPUFs) were synthesized first, and then polydopamine particles were deposited on the surface of the foam by in situ polymerization under weak alkaline conditions to increase its surface roughness. Afterwards, phytic acid was used to modify the foam to achieve surface superhydrophilicity and underwater superoleophobicity. Successful loading of polydopamine (PDA) particles and coating of phytic acid (PA) onto the foam was demonstrated by SEM, EDS, FTIR, XPS, and thermogravimetric analysis measurements. It was shown in the cyclic compression tests that LPUFs had good mechanical properties. Under 75 % compression strain, the maximum stress in the first cycle of LPUF/PDA/PA was 105.92 kPa. After 30 cyclic compression tests, the maximum stress of LPUF/PDA/PA under 75 % compression strain was 105.63 kPa, demonstrating a high mechanical stability. The contact angle of the foam modified by PDA and PA was 0° for water, 166.7° for chloroform, and 158.4° for hexane, which also demonstrated excellent underwater anti-oil adhesion performances. Oil-water separation tests by using PDA and PA modified lignin-based foam with mixtures of water and n-hexane, cyclohexane, toluene, and pump oil indicated a separation efficiency of over 99 % for the types of mixtures tested together with excellent repeatability. In addition, the PDA and PA modified lignin-based foams were able to adsorb 67.1 mg/g of methylene blue, 96.1 mg/g of rhodamine B, and 98.2 mg/g of copper sulfate. The lignin-based foam could completely degrade under weak alkaline conditions after usage. This study highlighted a novel strategy for synthesizing environmentally friendly high-performance adsorbents to efficiently treat polluted wastewater using lignin as a raw material.

A new article from Ning Yan’s lab has been published in ACS Applied Polymer Materials written by Shrestha Roy Goswami, Sen Wang and Ning Yan.

The first 50 people to click here will have access to a free e-print of the final published article until January 2024.

Abstract

Starch maleates with a high degree of maleic anhydride (MA) substitutions (DS) are in-demand for producing advanced composites. High-DS maleates are synthesized in imidazolium chloride-based ionic liquids because they could sustain starch-MA esterification, the precise mechanism of which, however, is largely unknown. In this study, we mapped chemical shifts of imidazolium cations before and after MA was added to each of the three starch-[C₂mim]Cl, starch-[Amim]Cl, and starch-[C₄mim]Cl systems. [C₄mim]⁺ and [Amim]⁺ cations were observed to form substantial H-bonds with hydroxyls of starch. These hydroxyls could further associate with MA, liberating the bound cations. The liberated [Amim]⁺ cations, unlike [C₄mim]⁺ cations, could readily donate their C2–H protons to activated MA, providing high-DS maleates (DS_NMR ≈ 0.1, DS_titration ≈ 1.20). The insights gained from this study would benefit the development of maleates from a wide range of biopolymers and expedite the screening of ionic liquids with varying cation–anion combinations for high-DS maleate synthesis.

A new article from Ning Yan’s lab has been published in Chemical Engineering Journal written by Pandeng Li, Cheng Hao, Huihui Wnag, Tian He, Tong Su, Cong Lo, Longjiang Yu and Ning Yan.

Click here for the article.

Abstract

The huge and increasing amount of plastic waste harms wildlife and releases chemical hazards to the environment. Using cellulosic fibers to prepare natural fiber-reinforced plastic composites (NFRPCs) is a promising strategy to decrease plastic wastes and lower their negative impacts because cellulosic fibers are renewable, degradable, and conducive to carbon neutrality. However, the low tensile strength and recycling difficulty of NFRPCs prevent them from substituting nondegradable plastics on an industrial scale. This study prepared high-performance ramie yarn-reinforced polyimine vitrimer composites (RY-PI) that could be recycled both chemically and physically. The polyimine matrix formed a robust bonding interface with ramie yarn via hydrogen bonding. The tensile strength of RY-PI (144MPa) was superior to that of most NFRPCs available in the market and was the highest amongst the NFRPCS with the same fiber fraction (wt%). RY-PI was also lightweight and had good toughness, self-healing ability, moldability, durability to organic solvents, and moisture barrier resistance. A box prepared by four-layer RY-PI laminates could support more than 3,000 times its own weight. The RY-PI was closed-loop recycled through a chemical strategy without any loss of performance. More importantly, a highly efficient (11 minutes for each recycling), low-cost, and eco-friendly (without adding any chemicals) physical recycling method of RY-PI was demonstrated. RY-PI could be physically recycled at least 9 times without any loss of performance. The high performance and good recyclability of RY-PI make it a promising environmental-friendly alternative to many conventional plastic products to help achieve zero plastic waste.

A new article out of a collaboration between Dr. Ning Yan and Dr. Jing Chen’s labs has been published in Science of The Total Environment written by Xiaozhen Ma, Shuqi Li, Fan Wang, Jialong Wu, Yeyan Chao, Xu Chen, Peng Chen, Jin Zhu, Ning Yan and Jing Chen.

You can find the article here.

Abstract

Here a new strategy of catalyst-free direct synthesis of covalent adaptable network polyurethanes (LPUs) from lignin with editable shape memory effect is reported. Using unmodified lignin, PEG, and isocyanate under the condition of the isocyanate index less than 1.0 (NCO/OH <1.0), a variety of LPUs were obtained. When NCO/OH=0.8, a stable cross-linked network could be formed (ex. the gel content of LPU50-0.8 was 98 ± 0.3 %). The activation energy (Ea) value of LPUs was similar to that of polyhydroxyurethanes (PHUs), at around 110 kJ/mol. With an increase of lignin content, the LPUs showed a transition from ductile fracture to brittle fracture mode. And the mechanical properties of LPUs were significantly enhanced after extrusion processing, with the maximum modulus reaching 649 ± 26 MPa and the maximum toughness up to 9927 ± 111 kJ/m3. The improvement in mechanical properties was due to the homogenization of complex cross-linked network under the powerful external force of the extruder and the lignin that originally was free in the system participated in the exchange reactions. Moreover, LPUs could also be prepared continuously in one step by using an extruder as the reactor. In addition, LPU50-0.8 had an editable shape memory effect. This study developed a novel method for the synthesis of LPU from lignin with NCO/OH<1.0, showcasing new possibilities for value-added utilization of lignin, and expanding the bio-based products portfolio from biomass feedstock to help meet future green manufacturing demands.

A new article out of a collaboration between Dr. Ning Yan and Dr. Jing Chen’s labs has been published in Science of The Total Environment written by Jialong Wu, Xiaozhen Ma, Pitchaimari Gnanasekar, Fan Wang, Jin Zhu, Ning Yan and Jing Chen.

You can find the article here.

Abstract

Superhydrophobic polyurethane foam is one of the most promising materials for oil-water separation. However, there are only limited studies prepared matrix superhydrophobic foams as adsorbents. In this paper, SiO₂ modified by 1H, 1H, 2H, 2H-perfluorododecyl trichlorosilane (F-SiO₂) was added into the lignin-based foam matrix by a one-step foaming technique. The average diameter of F-SiO₂ was about 480 nm with an water contact angle (WCA) of 160.3°. The lignin-based polyurethane foam with F-SiO₂ had a superhydrophobic water contact angle of 151.3°. There is no obvious change in contact angle after 100 cycles of compression or after cutting and abrasion. Scanning electron microscopy (SEM) analysis showed that F-SiO₂ was distributed both on the surface and inside of the foam. The efficiency for oil-water separation reached 99 %. Under the light intensity of 1 kW/m², the surface temperature of the lignin-based foam rose to 77.6 °C. In addition, the foam exhibited self-cleaning properties and degraded within 2 h in an alcoholic alkali solution. Thus, in this study, we developed a novel matrix superhydrophobic lignin-based polyurethane foam with an excellent promise to be used as oil water separation adsorbents in industrial wastewater treatment and oil spill clean-up processes.