Developing bioenergy to tackle climate change：Bioenergy path and practice of Tianguan group

Biomass energy would become the most potential renewable energies, for whether wind power or photovoltaic, would be restricted by the nature thus cannot provide stable power, while biomass energy is the only renewable energy that can be used in the form of gas, liquid or solid stage, it could replace the fossil energy, lead a positive influence on the control of the greenhouse gases. Across the globe, the biomass produced through photosynthesis is about 200 Gt, or 99 Gtce per year. If 10% of the biomass is utilized, more than 4 Gt of fuel ethanol and other bioenergy products can be produced, equivalent to 4.13 Gt of petroleum consumed by the world in 2014. Therefore, bioenergy can be a feasible alternative to fossil energy.

乙醇中超低酸催化葡萄糖醇解反应动力学(英文)

The kinetics for production of ethyl levulinate from glucose in ethanol medium was investigated.The experiments were performed in various temperatures(433-473 K)and initial glucose concentrations(0.056-0.168mol·L?1)with extremely low sulfuric acid as the catalyst.The results show that higher temperature can improve the conversion of glucose to ethyl levulinate,with higher yield of ethyl levulinate(44.79%,by mole)obtained at 473 K for 210 min.The kinetics follows a simplified first-order kinetic model.For the main and side reactions,the values of activation energy are 122.64 and 70.97 kJ·mol?1,and the reaction orders are 0.985 and 0.998,respectively.

Effect of poly(4-tert-butylstyrene)block length on the microphase structure of poly(ethylene oxide)-b-poly(4-vinylbenzyl chloride)-b-poly(4-tert-butylstyrene)triblock terpolymers

A series of linear poly(ethylene oxide)-b-poly(4-vinylbenzyl chloride)-b-poly(4-tert-butylstyrene)(PEO_(113)-b-PVBC_(130)-b-Pt BS_(x)or E_(113)V_(130)T_(x))triblock terpolymers with various lengths x(=20,33,66,104,215)of Pt BS block were synthesized via a two-step reversible addition-fragmentation chain transfer(RAFT)polymerization.The E_(113)V_(130)T_(x)triblock terpolymers were non-crystalline because the PVBC and Pt BS blocks strongly hindered the crystallization of PEO block.The effects of Pt BS block length x on the phase structures of E_(113)V_(130)T_(x)triblock terpolymers were investigated by combined techniques of small-angle X-ray scattering(SAXS)and transmission electron microscopy(TEM).It was found that with increasing x from20 to 215,the phase structure of E_(113)V_(130)T_(x)triblock terpolymers became more ordered and changed from disordered structure,hexagonally-packed cylinder(HEX),hexagonally perforated layer(HPL),to lamellar(LAM)phase structures.Temperature-variable SAXS measurements showed that the HEX,HPL and LAM phase structures obtained for E_(113)V_(130)T_(66),E_(113)V_(130)T_(104)and E_(113)V_(130)T_(215)by thermal annealing,respectively,were thermodynamically stable in the temperature range of 30-170℃.

Upcycling Polytetrahydrofuran to Polyester

One major remaining challenge in polymer chemistry is the development of efficient chemical recycling strategies to fully retrieve starting materials.Polytetrahydrofuran(PTHF)is widely used,but its stable ether bonds make it difficult to chemically reuse after disposal.Here,we propose a“polymer A→polymer B”strategy for one-step quantitative upcycling of PTHF to polyesters.The route undergoes a cascade process:PTHF is depolymerized to give tetrahydrofuran(THF)that then alternately copolymerizes with cyclic anhydrides in situ,thereby pushing the chemical equilibrium of“PTHF⇌THF”to the right.The protocol demonstrates facile features:the use of common and metal-free Brønsted/Lewis acid as catalyst,a favorable reaction temperature of 100℃,and no use of solvents.This method also accommodates 18 cyclic anhydrides to give a library of polyesters with alternating sequences,tunable thermal properties,and high-fidelity carboxyl terminals.This is an unprecedented strategy for chemical recycling of waste polyether.

Oxygen/Sulfur Atom Exchange Copolymerization of Carbon Disulfide and Propylene Oxide by a Highly Effective Heterogeneous Berlin Green Catalyst

In this study,we report that Berlin Green(FeFe-BG)framework exhibits superior performance in the catalytic coupling of carbon disulfide(CS_(2))and propylene oxide(PO)to generate a random copolymer containing thioether,propylene monothiocarbonate and ether units.Oxygen and sulfur atom exchange was detected in polymeric and cyclic thiocarbonate byproducts and utilized to modulate the copolymerization of CS_(2)and propylene oxide.The coupling of PO and CS_(2)was selective for copolymer formation under various reaction conditions.^(1)H and^(13)C NMR spectroscopy determined two distinct polymer linkages and two cyclic byproducts.Copolymer number average molecular weights ranged from 6.4 kg/mol to 10.5 kg/mol,with a comparatively low polydispersity of 1.3-1.7.The CS_(2)/PO molar feed ratio had a significant impact on the O/S exchange process;the ratio of cyclic thiocarbonate byproducts could be efficiently regulated by tuning the CS_(2)molar feed ratio.

Dynamic nano-Ag colloids cytotoxicity to and accumulation by Escherichia coli:Effects of Fe^3+,ionic strength and humic acid

Released Ag ions or/and Ag particles are believed to contribute to the cytotoxicity of Ag nanomaterials,and thus,the cytotoxicity and mechanism of Ag nanomaterials should be dynamic in water due to unfixed Ag particle:Ag+ ratios.Our recent research found that the cytotoxicity of PVP-Ag nanoparticles is attributable to Ag particles alone in 3 hr bioassays,and shifts to both Ag particles and released Ag^+ in 48 hr bioassays.Herein,as a continued study,the cytotoxicity and accumulation of 50 and 100 nm Ag colloids in Escherichia coli were determined dynamically.The cytotoxicity and mechanisms of nanoAg colloids are dynamic throughout exposure and are derived from both Ag ions and particles.Ag accumulation by E.coli is derived mainly from extracellular Ag particles during the initial 12 hr of exposure,and thereafter mainly from intracellular Ag ions.Fe^3+ accelerates the oxidative dissolution of nano-Ag colloids,which results In decreasing amounts of Ag particles and particle-related toxicity.Na^+ stabilizes nano-Ag colloids,thereby decreasing the bioavailability of Ag particles and particle-related toxicity.Humic acid(HA) binds Ag^+ to form Ag^+-HA,decreasing ion-related toxicity and binding to the E.coli surface,decreasing particle-related toxicity.HA in complex conditions showed a stronger relative contribution to toxicity and accumulation than Na^+ or Fe^3+.The results highlighted the cytotoxicity and mechanism of nano-Ag colloids are dynamic and affected by environmental factors,and therefore exposure duration and water chemistry should be seriously considered in environmental and health risk assessments.