ACS Sustainable Chemistry and Engineering

To improve the fractionation efficiency of lignins from Miscanthus × giganteus in the neutral DES (choline chloride/glycerol), three heteropoly acids with environmental origin and economic viability (phosphotungstic, phosphomolybdic, and silicotungstic acids) were utilized as catalysts. It was found that the silicotungstic acid–choline chloride/glycerol system resulted in a high lignin yield of 78.2% under mild conditions (120 °C, 3 h). This was attributed to silicotungstic acid acting as tetrahydric acid, which donated more active protons to selectively cleave ether bonds and further facilitated lignin removal. The following lignin profiling indicated that the recovered lignin had a high purity (92.7%), low molecular weight (Mw 1520–2470 g/mol), low polydispersity (PDI < 1.7), excellent thermal stability, and good solubility in dimethyl sulfoxide and dimethylacetamide. Additionally, phosphomolybdic acid (PMA) lignin exhibited a typical structure of HGS with a relatively higher O/C ratio due to more nativelike C–O-bonded structures (high β-aryl ether content) after treatment. Interestingly, nanoscaled lignin was defined in the DES fractionation procedure based on the SEM and TEM analyses. To further evaluate the potential application of the isolated lignin streams, the antioxidant activity was performed by in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability. The antioxidant performance (IC50 = 0.042 mg/mL) was better than that of the commercial antioxidant butylated hydroxytoluene (IC50 = 0.056 mg/mL). The above results demonstrated that the heteropoly acids–neutral DES system was significantly efficient for lignin extraction and provided a new source of lignin with good antioxidant activity.

Zongwei Guo

Deqiang Li

Tingting You

Xun Zhang

Feng Xu

Xueming Zhang

Yiqin Yang

ACS Sustainable Chemistry & Engineering

New Lignin Streams Derived from Heteropoly Acids Enhanced Neutral Deep Eutectic Solvent Fractionation: Toward Structural Elucidation and Antioxidant Performance

Chitin is a promising natural polymer to produce functional materials due to the attractive combination of abundance, price, favorable biological properties, and biodegradability. However, multiple literature examples often confuse processing of chitosan, the deacetylated version of chitin, due to chitosan's much higher solubility in traditional solvents. Nonetheless, despite current challenges to solubilize natural chitin, there is still a large body of literature demonstrating multiple ways to manipulate this polymer into materials of desired forms and properties. Here we review one such area where chitin promises both technological superiority and potential for commercial success, the use of chitin in biomedical research. We discuss techniques which have been utilized to process chitin and to prepare chitin-based functional materials, particularly in the production of fibers, films, beads, and hydrogels. Emphasis is given to the most recent methods and a compilation of a compelling collection of examples based on current research and existing products. These examples demonstrate the suitability of chitin for production of surgical sutures, wound care materials, tissue engineering biomaterials, and other various biomedical applications.

Julia L. Shamshina

Paula Berton

Robin D. Rogers

ACS Sustainable Chem. Eng.

Advances in Functional Chitin Materials: A Review

Hydrothermal liquefaction (HTL) transforms wet biomass and biowaste feedstock into water-insoluble biocrude and valuable water-soluble organic products. HTL takes advantage of the exceptional properties of water near the critical point to break bio-macromolecule linkages, and as a reaction medium, subcritical water ions allow the reaction and recondensation of intermediates into various structures and product phases. Among the different reaction mechanisms involved in the hydrothermal conversion, the synergetic interaction between protein and carbohydrate intermediates, known as the Maillard reactions, can boost the renewable biocrude yield up to 25% higher than solely free fatty acid hydrolysis from lipids. However, the reaction mechanisms and the effect of biomass composition are not fully understood. In this study, the Maillard reactions have been investigated with a central composite design to validate the impact of mass ratio (carbohydrate/protein) over temperature and residence time, via product response analysis, including product yields, boiling point distribution, aqueous tests, elemental, and chemical compositions. Then, the gas chromatography–mass spectrometry data is used to propose a potential pathway, followed by levulinic acid from carbohydrates as a candidate, to produce proline via Maillard interactions before amino acid condensation into piperazinediones and reduction into pyrazines among other complex degradations. The understanding of Maillard interactions under HTL conditions could lead to more robust compositional models, and the present results showed that a protein-to-carbohydrate mass ratio 2:1 would maximize the volatile fraction, elemental carbon, and higher heating value in the renewable crude, with a 90–95% of the maximum crude yield being obtained. The HTL experiments were run with glucose and soy protein as model compounds and spirulina in a batch reactor at 300 °C temperature, 20 min residence time, and 50% mass ratio as a central point, with an alpha (α) of 20 °C, at 10 min, and a 25% mass ratio.

Andrés D. Chacón-Parra

Philip A. Hall

David M. Lewis

Marianne Glasius

Philip J. van Eyk

Elucidating the Maillard Reaction Mechanism in the Hydrothermal Liquefaction of Binary Model Compound Mixtures and Spirulina

As a consequence of lead pollution, low efficiency, and high energy consumption in the current pyrometallurgical processing of copper anode slime, a novel metallurgical recycling technology for processing copper anode slime was developed in this research. The new process uses bismuth instead of lead to realize high-efficiency enrichment of silver with lower energy consumption and higher capture efficiency. In this study, to determine the mechanism of silver capture by bismuth and confirm the possibility of low-temperature silver capture, the effects of coke powder, Na2CO3, SiO2, Bi2O3, and temperature on the silver content in slag during bismuth capture of precious metals were investigated. The results show that the silver content remaining in slag is only 0.157% with a Bi2O3 addition of 25% and a Na2O/SiO2 ratio of 0.417 at 950 °C for 8 h. The silver content in slag obtained from the proposed process was significantly lower than the allowable residue standard of China (silver content in slag <1%). The obtained bismuth–silver alloy can facilitate the recycling of bismuth through the blowing process. Considering that bismuth is a green metal, the pollution of lead in the silver recovery process is avoided, and the capture temperature of silver is only 950 °C, which is significantly lower than that of lead capture (1100–1200 °C). The energy consumption is significantly reduced, so the proposed process can accomplish the clean recovery of rare and precious metals in copper anode slime and promote the green development of the copper metallurgy industry.

Hong Zeng

Fupeng Liu

Feixiong Chen

Chunfa Liao

Yanliang Zeng

Songlin Zhou

Xingbang Wan

Green Capture of Silver by Bismuth from Decoppered Anode Slime with Low Energy Consumption

Composite fibers comprised of lignin, polyacrylonitrile (PAN), and carbon nanotubes (CNT) were successfully fabricated by gel-spinning technology. Wide angle X-ray diffraction (WAXD), infrared spectroscopy, and thermal characterizations were used to identify the effects of lignin and CNT on the physical structure and stabilization process of gel-spun precursor fibers. PAN, PAN/lignin, and PAN/lignin/CNT precursors have been converted to carbon fibers under identical stabilization and carbonization conditions. When carbonized at 1100 °C, PAN/lignin carbon fiber exhibits comparable mechanical properties to PAN carbon fiber. Raman spectroscopy studies suggested differences between the carbon fibers when lignin and CNTs were incorporated.

H. Clive Liu

An-Ting Chien

Bradley A. Newcomb

Yaodong Liu

Satish Kumar

Processing, Structure, and Properties of Lignin- and CNT-Incorporated Polyacrylonitrile-Based Carbon Fibers

Wanqing Zhang

Miao Lv

Jin Shi

Jianzhong Jiang

CO2-Switchable High Internal Phase Pickering Emulsions Stabilized by Small-Molecular Surfactants and Hydrophilic Silica Nanoparticles

二氧化碳可切换的高内相Pickering乳液：由小分子表面活性剂和亲水性二氧化硅纳米颗粒稳定

Cholesterol sulfate (CS), a sulfated derivative of cholesterol, has important applications in the medical field, because of its extensive biological and pharmacological activities. As the supply of CS heavily relies on chemical conversion of cholesterol extracted from wool grease, there is growing interest in engineering microbial cell factories for large-scale production of CS. This study reports microbial production of CS in the yeast, Komagataella phaffii (also known as Pichia pastoris), for the first time. Through combinatorial metabolic engineering strategies, including blocking the competing branches, overexpressing the rate-limiting mevalonate pathway genes, manipulating lipid metabolism, and enhancing the supply of key cofactor 3′-phosphoadenosine-5′-phosphosulfate (PAPS), CS production was increased more than 6.8-fold when compared with the parent strain. The optimal strain (CHS0505) produced CS with titers reaching 249 mg/L in a shake flask and 545 mg/L in a fed-batch fermenter, highlighting the potential of K. phaffii as a cell factory for steroid production. More importantly, the development of a CS-producing cell factory will advance microbial production of glycosaminoglycans and other sulfated natural products via synthetic biology.

Feng Xiao

Dongfang Li

Yingjia Pan

Binying Lv

Jucan Gao

Yimeng Zuo

Lei Huang

Jiazhang Lian

Establishing Komagataella phaffii as a Cell Factory for Efficient Production of Cholesterol Sulfate

建立Komagataella phaffii作为胆固醇硫酸盐高效生产的细胞工厂

We report on the aldol condensation of furfural and cyclopentanone in aqueous and biphasic mediums as a promising step for producing sustainable aviation fuel. Key parameters, including catalyst concentration, reactant concentration, temperature, and solvent, were found to significantly influence conversion and product selectivity. Alkaline conditions were essential for aldol coupling, with significant conversion observed at pH 12 and higher. The activation energies for the formation of the dimeric and trimeric aldol adducts were similar at 74 and 76 kJ/mol, respectively. Biphasic conditions were employed to prevent product precipitation, leading to reactor and equipment fouling. For biphasic conditions, the extraction of the reactants and dimeric intermediates to the organic phase affected rate and selectivity, resulting in the dilemma. Good product extraction leads to inevitable reactant extraction. Based on these findings, an integrated biphasic process design was proposed, utilizing process-owned solvents to optimize the separation and recycling of aqueous streams and improve the overall process efficiency.

Rick Baldenhofer

Jean-Paul Lange

Sascha R. A. Kersten

M. Pilar Ruiz

Aqueous and Biphasic Coupling of Furfural and Cyclopentanone for the Synthesis of Bio-Jet Fuel Precursors

糠醛与环戊酮在水相和双相体系中的耦合用于合成生物喷气燃料前体

Traditional flame retardants, often derived from petrochemical sources, pose significant environmental and health concerns due to their potential toxicity and persistence in the environment. In this study, a biobased hyperbranched polymer flame retardant named QB was synthesized using quercetin and phenylphosphoryl dichloride by a one-step method. The QB copolymer was characterized via Fourier transform infrared spectroscopy, thermogravimetric analysis, and gel permeation chromatography, revealing its high thermal stability and polymeric nature, with a weight-average molecular weight of 78 299 g/mol. QB was subsequently incorporated into bisphenol A-type epoxy resins using 4–4 diamino diphenylmethane as a curing agent to prepare the flame-retardant epoxy composite. With additions of only 1 wt % QB, EQB-1 achieved a UL 94 V-0 rating in the vertical burning test and an impressive limiting oxygen index (LOI) value of 28.2%. Moreover, the addition of the 3 wt % QB in EP resulted in a maximum reduction of 32.9% in the peak of heat release rate and a 37.4% reduction in the smoke produce rate, indicating its outstanding flame-retardant and smoke suppression properties, which are attributed to a mainly condensed-phase flame-retardant mechanism. Furthermore, the impact and flexural strength of the composite were maintained and a slight improvement was observed. The findings of this research are expected to contribute to the development of environmentally friendly flame-retardant epoxy systems that meet industry standards while promoting the use of renewable materials. This work supports sustainability by replacing petrochemical flame retardants with renewable quercetin-based materials, reducing toxicity and environmental impact.

Yun Zhao

Chengshu Yan

Jiatao Cao

Shuai He

Zhenfeng Huang

Nanlan Shen

Zongmin Zhu

Hai-Bo Zhao

Wenhui Rao

Efficient Hyperbranched Flame Retardant Derived from Quercetin for Use in Epoxy Resin with Well-Balanced Comprehensive Performance

由槲皮素衍生的高效超支化阻燃剂用于环氧树脂，具有均衡的综合性能

Lipoxygenases catalyze the dioxygenation of polyunsaturated fatty acids. Notably, most microbial lipoxygenases including the lipoxygenase from Pseudomonas aeruginosa (Pa-LOX) catalyze oxygenation of linoleic acid and arachidonic acid into 13S-hydroperoxyoctadecenoic acid (13S-HPODE) and 15S-hydroperoxyeicosatetraenoic acid (15S-HPETE), respectively. Therefore, this study has focused on modification of positional specificity or regioselectivity of Pa-LOX. The linoleic acid oxygenations and substrate-docking simulations suggested that the regioselectivity of Pa-LOX might depend on the geometry of the hydrocarbon tail-binding cavity. Therefore, the interior end of the substrate-binding cavity was enlarged to make C10 instead of C13 face the iron active site. Remarkably, the M434G mutation led to alteration of the oxygenation products from 15S-hydroxyeicosatetraenoic acid (15S-HPETE) to 11S-HPETE as the major product from arachidonic acid. On the other hand, the Y609G substitution allowed the formation of 8S-HPETE from arachidonic acid. 8S-HPETE was recovered after reduction by tris(2-carboxyethyl)phosphine hydrochloride with an isolated yield of 62% with a purity of 94% via Escherichia coli-based whole-cell biocatalysis, solvent extraction, and silica gel chromatography. This is the first report of the production of 11S-HPETE and 8S-HPETE from arachidonic acid at high conversions. Therefore, this study contributes to the preparation of biologically active oxylipins from renewable fatty acids in a sustainable way.

Eun-Ji Seo

Hyo-Ran Lee

Se-Yeun Hwang

Deok-Kun Oh

Yong-Uk Kwon

Katharina Köchl

Bettina Nestl

Jin-Byung Park

Uwe T. Bornscheuer

Substrate-Binding Cavity Engineering of the Lipoxygenase from Pseudomonas aeruginosa to Produce 8S- and 11S-Hydroxyeicosatetraenoic Acids

铜绿假单胞菌脂氧合酶底物结合腔工程制备8S-和11S-羟基二十碳四烯酸

Abbreviation	ACS Sustainable Chem. Eng.
Journal Impact	7.08
Quartiles(Global)	GREEN & SUSTAINABLE SCIENCE & TECHNOLOGY(Q1)

ISSN	2168-0485
h-index	173
Top Journals	Yes

Publication Information	Publisher: American Chemical Society，Publishing cycle: ，Journal Type: journal，Open Access Journals: No
Basic data	Year of publication: 2013，Proportion of original research papers: 99.75%，Self Citation Rate:5.60%， Gold OA Rate: 9.40%

ACS Sustainable Chemistry and Engineering

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