Continuous synthesis of N,N-dicyanoethylaniline in microreactors:Reaction kinetics and process intensification

Cyanoethylation of phenylamine is one of the important steps for the production of dicyanoethyl-based disperse dyes.However,the exothermic nature of this reaction and the inherent instability of intermittent dynamic operation pose challenges in achieving both high safety and reaction efficiency.In this study,a continuous cyanoethylation of phenylamine for synthesizing N,N-dicyanoethylaniline in a microreactor system has been developed.By optimizing the reaction conditions,the reaction time was significantly reduced from over 2 h in batch operation to approximately 14 min in the microreactor,while high conversion and selectivity were maintained.Based on the reaction network constructed,the reaction kinetics was established,and the kinetic parameters were then determined.These findings provide valuable insights into a controllable cyanoethylation reaction,which would be helpful for the design of efficient processes and optimization of reactors.

Could natural phytochemicals be used to reduce nitrogen excretion and excreta‑derived N_(2)O emissions from ruminants?

Ruminants play a critical role in our food system by converting plant biomass that humans cannot or choose not to consume into edible high-quality food.However,ruminant excreta is a significant source of nitrous oxide(N_(2)O),a potent greenhouse gas with a long-term global warming potential 298 times that of carbon dioxide.Natural phytochemicals or forages containing phytochemicals have shown the potential to improve the efficiency of nitrogen(N)utilization and decrease N_(2)O emissions from the excreta of ruminants.Dietary inclusion of tannins can shift more of the excreted N to the feces,alter the urinary N composition and consequently reduce N_(2)O emissions from excreta.Essential oils or saponins could inhibit rumen ammonia production and decrease urinary N excretion.In grazed pastures,large amounts of glucosinolates or aucubin can be introduced into pasture soils when animals consume plants rich in these compounds and then excrete them or their metabolites in the urine or feces.If inhibitory compounds are excreted in the urine,they would be directly applied to the urine patch to reduce nitrification and subsequent N_(2)O emissions.The phytochemicals’role in sustainable ruminant production is undeniable,but much uncertainty remains.Inconsistency,transient effects,and adverse effects limit the effectiveness of these phytochemicals for reducing N losses.In this review,we will identify some current phytochemicals found in feed that have the potential to manipulate ruminant N excretion or mitigate N_(2)O production and deliberate the challenges and opportunities associated with using phytochemicals or forages rich in phytochemicals as dietary strategies for reducing N excretion and excreta-derived N_(2)O emissions.

Green aerobic oxidative desulfurization of diesel by constructing an Fe-Anderson type polyoxometalate and benzene sulfonic acid-based deep eutectic solvent biomimetic cycle

A unique redox-coupled biomimetic system was developed, in which Fe-Anderson type polyoxometalates(POMs) were employed as electron transfer mediators(ETMs) and benzenesulfonic acid(BSA)-based deep eutectic solvents(DESs) were used as electron-donors for aerobic oxidative desulfurization(AODS) of diesel fuel. Different compositions of DESs were used and the polyethylene glycol 2000(PEG2000)/2.5 BSA system showed the highest desulfurization activity, with the removal of dibenzothiophene(DBT) at 60 ℃ reaching 95% in 60 min. The excellent desulfurization activity of the system is due to the in situ formation of peroxysulfonate via a biomimetic process. By constructing a coupled redox system, Fe-Anderson type POMs as ETMs reduce the activation energy of oxygen-activated sulfonate. The physical characteristics of four different DESs were tested. The results show that the conductivity of DESs is correlated with the composition of BSA-based DESs. However, there is no similar trend in viscosity testing at the same temperature, and the maximum viscosity value is obtained for the PEG2000/2.5 BSA system at 60 ℃, which may be associated with the stronger hydrogen bonds. It is worth noting that the PEG2000/2.5 BSA system also possesses the best desulfurization activity, which suggests that the activity of the desulfurization system is related to the strength of the hydrogen bond in DESs. Finally, the biomimetic desulfurization system exhibits excellent performance and good stability under mild reaction conditions(60 ℃, atmospheric pressure, oxygen as the oxidant).

Effects of channel wall wettability on gas-liquid dynamics mass transfer under Taylor flow in a serpentine microchannel

The wall wettability of microchannels plays an important role in the gas-liquid mass transfer dynamics under Taylor flow.In this study,we regulated the contact angle of the wall surface through surface chemical grafting polymerization under controlled experimental conditions.The dynamic changes of CO_(2)bubbles flowing along the microchannel were captured by a high-speed video camera mounted on a stereo microscope,whilst a unit cell model was employed to theoretically investigate the gas-liquid mass transfer dynamics.We quantitatively characterized the effects of wall wettability,specifically the contact angle,on the formation mechanism of gas bubbles and mass transfer process experimentally.The results revealed that the gas bubble velocity,the overall volumetric liquid phase mass transfer coefficients(kLa),and the specific interfacial area(a)all increased with the increase of the contact angle.Conversely,gas bubble length and leakage flow decreased.Furthermore,we proposed a new modified model to predict the gas-liquid two-phase mass transfer performance,based on van Baten’s and Yao’s models.Our proposed model was observed to agree reasonably well with experimental observations.

Effects of dietary inclusion with rapeseed cake containing high glucosinolates on nitrogen metabolism and urine nitrous oxide emissions in steers

Two consecutive trials were conducted to investigate the effects of glucosinolates(GLS)in rapeseed cake(RSC)on nitrogen(N)metabolism and urine nitrous oxide(N_(2)O)emissions in steers.In trial 1,8 steers and 4 levels of RSC,i.e.0,2.7%,5.4%and 8.0%dry matter(DM)(0,6.0,12.1,18.1 mmol GLS/g DM)were allocated in a replicated 4×4 Latin square.In trial 2,the static incubation technique was used for measuring the N_(2)O emissions of the urine samples collected from trial 1.The results of trial 1 indicated that dietary inclusion of RSC decreased the digested N and increased the fecal N excretion(P<0.01),whereas it did not affect the urinary N excretion,total N excretion and N retention(P>0.10).Dietary inclusion of RSC decreased the urinary excretion of urea while it increased allantoin,total purine derivatives,the predicted rumen microbial N flow and thiocyanate(SCN)(P<0.05).Dietary inclusion of RSC did not affect the plasma triiodothyronine and thyroxine while it down-regulated the plasma relative concentrations of 4-aminohippuric acid,3a,7a-dihydroxycoprostanic acid,phosphatidylserine(14:0/16:0),6b-hydroxyprogesterone,pyrrhoxanthinol,tatridin B,mandelonitrile rutinoside,taraxacoside(P<0.05),and up-regulated hypoglycin B,neuromedin N(1-4),dhurrin,5-deoxykievitone(P<0.01).The results of trial 2 indicated that dietary RSC increased the steer urine N_(2)OeN fluxes,the ratio of N_(2)OeN to N application and the estimated steer urine N_(2)OeN emissions(P<0.01).A close correlation was found between the estimated steer urine N_(2)OeN emissions and the output of urinary SCN(P<0.001).In conclusion,dietary RSC increased the fecal N excretion,whereas it did not affect the urinary N excretion and the N retention rate in steers.Dietary RSC increased rather than decreased the urine N_(2)OeN emissions even though it decreased the urinary excretion of urea.The SCN excreted in urine could be the major factor in increasing the urine N_(2)OeN emissions.Whether other metabolites excreted into urine from RSC have an impact on the urine N_(2)OeN emissions in steers needs to be investigated in the future.

Decreasing ruminal methane production through enhancing the sulfate reduction pathway

Methane(CH4)production from ruminants accounts for 16%of the global greenhouse gas emissions and represents 2%to 12%of feed energy.Mitigating CH_(4) production from ruminants is of great importance for sustainable development of the ruminant industry.H_(2) is the primary substrate for CH_(4) production in the processes of ruminal methanogenesis.Sulfate reducing bacteria are able to compete with methanogens for H_(2) in the rumen,and consequently inhibit the methanogenesis.Enhancing the ruminal sulfate reducing pathway is an important approach to mitigate CH_(4) emissions in ruminants.The review summarized the effects of sulfate and elemental S on ruminal methanogenesis,and clarified the related mechanisms through the impacts of sulfate and elemental S on major ruminal sulfate reducing bacteria.Enhancing the activities of the major ruminal sulfate reducing bacteria including Desulfovibrio,Desulfohalobium and Sulfolobus through dietary sulfate addition,elemental S and dried distillers grains with solubles can effectively decrease the ruminal CH_(4) emissions.Suitable levels of dietary addition with different S sources for reducing the ruminal CH_(4) production,as well as maintaining the performance and health of ruminants,need to be investigated in the future.

Feeding citrus flavonoid extracts decreases bacterial endotoxin and systemic inflammation and improves immunometabolic status by modulating hindgut microbiome and metabolome in lactating dairy cows

The objectives of this study were to determine the effects of dietary supplementation with citrus flavonoid extracts(CFE)on milk performance,serum biochemistry parameters,fecal volatile fatty acids,fecal microbial community,and fecal metabolites in dairy cows.Eight multiparous lactating Holstein cows were used in a replicated 4×4 Latin square design(21-day period).Cows were fed a basal diet without addition(CON)or basal diet with added CFE at 50(CFE50),100(CFE10),and 150 g/d(CFE150).Feeding CFE up to 150 g/d increased milk yield and milk lactose percentage.Supplementary CFE linearly decreased milk somatic cell count.Serum cytokines interleukin-1β(IL-1β),IL-2,IL-6,and tumor necrosis factor-α(TNF-α)concentrations decreased linearly as the levels of CFE increased.Cows in CFE150 had lower serum lipopolysaccharide and lipopolysaccharide binding protein compared with CON.These results indicate feeding CFE decreased systemic inflammation and endotoxin levels in dairy cows.Furthermore,feeding CFE linearly increased the concentrations of total volatile fatty acids,acetate,and butyrate in feces.The relative abundances of beneficial bacteria Bifidobacterium spp.,Clostridium coccoides-Eubacterium rectale group,and Faecalibacterium prausnitzii in feces increased linearly with increasing CFE supplementation.The diversity and community structure of fecal microbiota were un-affected by CFE supplementation.However,supplementing CFE reduced the relative abundances of genera Ruminococcus_torques_group,Roseburia,and Lachnospira,but increased genera Bacteroides and Phascolarctobacterium.Metabolomics analysis showed that supplementary CFE resulted in a significant modification in the fecal metabolites profile.Compared with CON,fecal naringenin,hesperetin,hippuric acid,and sphingosine concentrations were greater in CFE150 cows,while fecal GlcCer(d18:1/20:0),Cer(d18:0/24:0),Cer(d18:0/22:0),sphinganine,and deoxycholic acid concentrations were less in CFE150 cows.Predicted pathway analysis suggested that"sphingolipid metabolism"was significantly enriched.Overall,these results indicate that citrus flavonoids could exert health-promoting effects by modulating hindgut microbiome and metabolism in lactating cows.