One‐Pot Synthesis of Pentaalkyl 7‐[(Alkylamino)carbonyl]‐2‐oxa‐1‐azabicyclo[3.2.0]hept‐3‐ene‐3,4,5,6,7‐pentacarboxylate

Dialkyl acetylenedicarboxylates react with alkyl 2‐nitroethanoates in the presence of alkyl isocyanides in a one‐pot reaction to afford the title compounds in 78–90% yield.     

Evaluation of an activated carbon from olive stones used as an adsorbent for heavy metal removal from aqueous phases

The performance of a microporous activated carbon prepared chemically from olive stones for removing Cu(II), Cd(II) and Pb(II) from single and binary aqueous solutions was investigated via the batch technique. The activated carbon sample was characterized using N₂ adsorption–desorption isotherms, SEM, XRD, FTIR, and Boehm titration. The effect of initial pH and contact time were studied. Adsorption kinetic rates were found to be fast and kinetic experimental data fitted very well the pseudo-second-order equation. The adsorption isotherms fit the Redlich–Peterson model very well and maximum adsorption amounts of single metal ions solutions follow the trend Pb(II) > Cd(II) > Cu(II). The adsorption behavior of binary solution systems shows a relatively high affinity to Cu(II) at the activated carbon surface of the mixture with Cd(II) or Pb(II). An antagonistic competitive adsorption phenomenon was observed. Desorption experiments indicated that about 59.5% of Cu(II) and 23% of Cd(II) were desorbed using a diluted sulfuric acid solution.     

磷钼酸作为低温碳燃料电池的碳间接电氧化介质

以磷钼酸作为低温下碳间接电氧化的介质构建新型碳燃料电池。通过线性电位扫描和计时电流法研究不同碳材料、不同反应条件、不同反应时间、不同磷钼酸浓度对碳间接电氧化性能的影响。采用循环伏安法研究碳在磷钼酸介质中的间接电氧化机理。研究结果表明,椰壳活性炭的间接电氧化活性要明显高于煤和煤质活性炭。以磷钼酸为介质时,采用光照与升温80oC避光的条件均可以提高碳间接电氧化性能,且提高程度接近。由循环伏安测试分析出磷钼酸中+6价Mo可将碳氧化,且被还原成+5价Mo,随后又在阳极上重新被电氧化回+6价Mo,通过该过程将从碳材料上获得的电子转移到阳极上,从而实现碳在低温条件下的间接电氧化过程。并且通过对光照条件的分析,证实光对磷钼酸催化碳电氧化反应有两方面的促进作用:一方面光的热效应使反应温度升高,从而提高反应速率;另一方面磷钼酸利用其特有结构吸收光能,提高磷钼酸与碳的反应速率,且后者促进作用更明显。以VO2+/VO2+为阴极构建的碳燃料电池全电池室温下功率是0.087m W?cm-2,验证了碳燃料电池在常温条件下运行的可行性。     

Dye and its removal from aqueous solution by adsorption: A review

In this review article the authors presented up to-date development on the application of adsorption in the removal of dyes from aqueous solution. This review article provides extensive literature information about dyes, its classification and toxicity, various treatment methods, and dye adsorption characteristics by various adsorbents. One of the objectives of this review article is to organise the scattered available information on various aspects on a wide range of potentially effective adsorbents in the removal of dyes. Therefore, an extensive list of various adsorbents such as natural materials, waste materials from industry, agricultural by-products, and biomass based activated carbon in the removal of various dyes has been compiled here. Dye bearing waste treatment by adsorption using low cost alternative adsorbent is a demanding area as it has double benefits i.e. water treatment and waste management. Further, activated carbon from biomass has the advantage of offering an effected low cost replacement for non-renewable coal based granular activated carbon provided that they have similar or better adsorption on efficiency. The effectiveness of various adsorbents under different physico-chemical process parameters and their comparative adsorption capacity towards dye adsorption has also been presented. This review paper also includes the affective adsorption factors of dye such as solution pH, initial dye concentration, adsorbent dosage, and temperature. The applicability of various adsorption kinetic models and isotherm models for dye removal by wide range of adsorbents is also reported here. Conclusions have been drawn from the literature reviewed and few suggestions for future research are proposed.     

An efficient one-pot synthesis of pyrimido[2,1-b][1,3]thiazine derivatives by reaction of activated acetylenes, thiouracils, and isocyanides

The reactive 1:1 zwitterionic intermediate, formed by the addition of isocyanides to dialkyl acetylenedicarboxylates, was trapped by thiouracils to yield a ketenimine intermediate, which cyclized and then rearranged to afford pyrimido[2,1-b][1,3]thiazines in good yields.     

Microwave assisted preparation of efficient activated carbon from grapevine rhytidome for the removal of methyl violet from aqueous solution

Grapevine rhytidome (the outer layer of bark on trunk), as an abundant and low-cost precursor, was used to prepare granular activated carbon with high surface area for the removal of methyl violet from aqueous solution. Microwave heating source was used to reduce the treatment time and energy consumption. To optimize the preparation, the effects of the different parameters, such as phosphoric acid concentration, acid/precursor weight ratio, impregnation time, microwave power, radiation time, and oven heating time on the ability of the samples for removal of methyl violet were studied. The obtained activated carbon was characterized by N₂ adsorption/desorption, SAXS, TEM and SEM methods. The adsorption of methyl violet onto the activated carbon was studied from both equilibrium and kinetic point of view and the results were compared with the commercial granular activated carbon. The rate of adsorption onto the prepared activated carbon was faster than commercial activated carbon. Different kinetic models were used to analyze the experimental kinetic data. The obtained activated carbon showed higher adsorption capacity (more than twice) for the adsorption of methyl violet in comparison with the commercial one. The equilibrium data were analyzed using different isotherm models. Adsorption was found to be maximum in the pH range 7-9.     

Powdered activated carbons as effective phases for bar adsorptive micro-extraction (BAμE) to monitor levels of triazinic herbicides in environmental water matrices

Bar adsorptive micro-extraction using three powdered activated carbons (ACs) as adsorbent phases followed by liquid desorption and high performance liquid chromatography with diode array detection (BAμE(ACs)-LD/HPLC-DAD), was developed to monitor triazinic herbicides (atrazine, simazine and terbutylazine) in environmental water matrices. ACs used present apparent surface areas around 1000 m² g⁻¹ with an important mesoporous volume and distinct surface chemistry characteristics (pH_PZC ranging from 6.5 to 10.4). The textural and surface chemistry properties of the ACs adsorbent phases were correlated with the analytical data for a better understanding of the overall enrichment process. Assays performed on 10 mL water samples spiked at the 10.0 μg L⁻¹ levels under optimized experimental conditions yielded recoveries around 100% for the three herbicides under study. The analytical performance showed good precision (RSD < 15.0%), convenient detection limits (≈0.1 μg L⁻¹) and suitable linearity (1.0-12.0 μg L⁻¹) with good correlation coefficients (r² > 0.9914). By using the standard addition method, the application of the present method on real water matrices, such as surface water and wastewater, allowed very good performances at the trace level. The proposed methodology proved to be a suitable sorptive extraction alternative for the analysis of priority pollutants with polar characteristics, showing to be easy to implement, reliable, sensitive and requiring a low sample volume to monitor triazinic compounds in water matrices.     

Determination of some phthalate acid esters in artificial saliva by gas chromatography-mass spectrometry after activated carbon enrichment

The determination of six phthalate acid esters was achieved in artificial saliva using gas chromatography-mass spectrometry following activated carbon enrichment of samples. Central composite experimental design was applied to optimize method parameters, such as pH, adsorption time and amount of activated carbon. The best compromise of analytical conditions for the simultaneous determination of analytes from spiked artificial saliva were found to be: pH (3), adsorption time (30 min), activated carbon amount (1.8 g L⁻¹) and elution solvent (chloroform). These conditions were applied to study the migration of phthalate acid esters from different children's toys into saliva. A horizontal agitation method was applied to extract the analytes from plastic toys into saliva for 2 h at 37 °C. The detection limits of the method were in the range of 1.3-5.1 μg L⁻¹, while the relative standard deviation (%) values for the analysis of 100 μg L⁻¹ of the analytes were below 3.0% (n = 5). Di-2-ethylhexyl phthalate was the main analyte found in these samples.     

电解质浓度和温度对活性炭电容性能的影响

采用循环伏安、交流阻抗和恒流充放电技术考察了电解质浓度和温度对活性炭电容性能的影响. 活性炭电容器在0.1、0.5、1.0和6.0 mol·L^-1 KOH溶液中性能测试结果表明: 活性炭在高浓度电解质中具有高电容和低内阻, 但电位窗口较窄; 电容和内阻与KOH浓度的对数成正比. 活性炭电容在不同温度(20、40、80 °C)的性能测试结果表明: 高温能够增加电容和降低内阻, 但是却加速了长期充放电过程中电容的衰减.     

PREPARATION OF ACTIVATED CARBON FIBERS AND THEIR XENON ADSORPTION PROPERTIES (I)-PREPARATION AND PORE STRUCTURE CHARACTERIZATION

1. INTRODUCTION Xenon isotopics are products of nuclear fission. The nuclear plant operation may release radioactive xenon to environment, thus result in serious damage to the environment and human health. Therefore, the adsorption and concentrating of x…