Esterification of free fatty acids in used cooking oil using ion-exchange resins as catalysts: An efficient pretreatment method for biodiesel feedstock

The esterification of used cooking oil (UCO) with methanol was studied using different types of ion-exchange resins, that is, Purolite D5081, Purolite D5082, and Amberlyst 36. Several catalyst characterization analyses (elemental analysis, surface area measurement, particle size distribution analysis, scanning electron microscopy analysis, true density measurement, and acid capacity analysis) have been conducted in the screening stage. Of all of the catalysts investigated, Purolite D5081 resin showed the best catalytic performance and was selected for further experimental studies. The esterification process was carried out in a jacketed stirred batch reactor for 8 h. Elimination of mass transfer resistances and the effect of catalyst loading (0.5–1.5% w/w), reaction temperature (50–65 °C), and methanol to UCO feed mole ratio (4:1–12:1) on the conversion of FFAs were investigated. The highest FFAs conversion was found to be 92%, at a catalyst loading of 1.25% w/w, 60 °C reaction temperature, 6:1 methanol to UCO molar ratio, and stirring speed of 475 rpm. During the reusability study, the conversion of catalyst dropped by 8–10% after each reutilization cycle. Several experiments have been conducted through the homogeneous contribution study, and the results confirmed that both resin pore blockage and sulfur leaching are dominant factors that decrease the catalytic performance of Purolite D5081 ion-exchange resin

За кадры. 1985. № 31 (2574)

Мир шагает по планетеВ фонд мира / З. ЧерноваНовые электромашиныДиплом из звездного / Р. ГорскаяПоступь первомая / В. ПетровКоммунистыБыть первымиСобрались отличники / Л. КоробейниковаУспех студентов / Т. Сидорова"Рабфак" набирает темп / И. УдутИдет пополнение / В. КощиевВ нем наша жизнь и наша месть святая… / Г. В. Яловская"Звездным войнам" -нет! / Л. ЛобачКуба, любовь моя / В. И. МихалевЗвучат песни борьбы / М. ШевчукОтмечая праздник / О. Т. ЛойкоБез страха и сомнений / Н. КуцанБольшие спортивные игры / Б. М. ПлотниковНовые старты / А. ДобужскийВремя весенних раздумий / А. СозиновРазмыли краски зимние весенние ветра / Ю. ЧервячковАлександрово / В. ДарменкоКуклы умеют не только смеяться / [беседа с] Р. М. Видерман ; [беседовал] Е. ВодопьяновРасписные терема / В. Яковле

Yb:YAG Innoslab amplifier: efficient high repetition rate subpicosecond pumping system for optical parametric chirped pulse amplification

We report on a Yb:YAG Innoslab laser amplifier system for generation of subpicsecond high energy pump pulses for optical parametric chirped pulse amplification (OPCPA) at high repetition rates. Pulse energies of up to 20 mJ (at 12.5 kHz) and repetition rates of up to 100 kHz were attained with pulse durations of 830 fs and average power in excess of 200 W. We further investigate the possibility to use subpicosecond pulses to derive a stable continuum in a YAG crystal for OPCPA seeding

Assessing written work by determining competence to achieve the module-specific learning outcomes.

This chapter describes lasers and other sources of coherent light that operate in a wide wavelength range. First, the general principles for the generation of coherent continuous-wave and pulsed radiation are treated including the interaction of radiation with matter, the properties of optical resonators and their modes as well as such processes as Q-switching and mode-locking. The general introduction is followed by sections on numerous types of lasers, the emphasis being on todayʼs most important sources of coherent light, in particular on solid-state lasers and several types of gas lasers. An important part of the chapter is devoted to the generation of coherent radiation by nonlinear processes with optical parametric oscillators, difference- and sum-frequency generation, and high-order harmonics. Radiation in the extended ultraviolet (EUV) and x-ray ranges can be generated by free electron lasers (FEL) and advanced x-ray sources. Ultrahigh light intensities up to 1021 W/cm2 open the door to studies of relativistic laser–matter interaction and laser particle acceleration. The chapter closes with a section on laser stabilization