In this investigation,
we report the synthesis of biodiesel using
benzimidazolium-based brønsted acid ionic liquid (BBAIL) catalyst
under the influence of ultrasonication. The prepared BBAIL catalyst
was characterized by Fourier transform infrared and NMR spectroscopy
techniques, and its acidity was determined by the Hammett method with
4-nitroaniline as the indicator. Ultrasonicator horn (22 kHz, 500
W) was used in this work with an on–off cycle of 50–20
s at 70% amplitude. The highest biodiesel yield of 96% was achieved
by ultrasonication when 1:10 molar ratio of castor oil to methyl alcohol
was used at 50 °C temperature with 9 mol % of the catalyst in
just 90 min, which is about 10 times lesser than the process without
ultrasonication. At similar conditions, 96% biodiesel yield was obtained
in 14 h without ultrasonication. In summary, ultrasonication proved
to be an efficient way to improve biodiesel synthesis in less time
and BBAIL showed excellent activity toward the conversion of glycerides
to synthesize biodiesel. Other important highlights are easy separation
of the catalyst and recyclability up to three cycles with small decrease
in its activity.
The ubiquity of nonbiodegradable
polyethylene terephthalate (PET)
materials has led to significant waste management challenges. Although
PET plastics can be recycled, blended materials, such as PET/cotton
fabrics, complicate the recycling process due to the labile glycosidic
bonds in cotton. In this study, we present a practical and scalable
approach for recycling of PET and PET/cotton interwoven fabrics via
catalytic glycolysis with ammonium bicarbonate (NH4HCO3), which decomposed to ammonia, carbon dioxide, and water.
This catalytic approach outperformed conventional acid/base and metal
catalysis in selectively recovering and upcycling cotton-based materials.
We demonstrated the large-scale recovery of textile from blended fabrics
(up to 213 g), showcasing the advantages of traceless catalysis using
ammonia and CO2 from ammonium bicarbonate. Owing to our
metal-free reaction conditions, high-purity bis(hydroxyethyl)terephthalate
(BHET) was obtained which was thermally repolymerized to PET. Through
thermal analysis, kinetics, and control experiments, we show that
ammonia and CO2 are crucial for achieving optimal glycolysis
via transesterification. Our method offered a traceless, environmentally
friendly, and practical approach for polyester recycling and cotton
recovery, representing a significant step toward sustainable, closed-loop
production of plastics and textiles.
We present Haptics Assisted Training (HAT) System, a force feedback workstation for transferring and improving handwriting skill. The HAT system is the first practical handwriting training system whose usability was tested both in typical and special education classrooms of a local school district. Simulating the role of occupational therapists (OT), the HAT system guides the user's hand along the sequence of strokes of the reference handwriting recorded by an expert or teacher. Since the handwriting data is formatted as a set of ordered paths, it can teach any form of pen strokes, such as words, shapes, and even drawings. Training tasks are presented as a 3D game which captures children's attention and more effective visual motor integration (VMI) is anticipated than traditional paper materials. In this paper we describe the design and implementation of the prototype. We also report a comparative study on handwriting performance of twenty participants grouped into four categories by education types (special vs. typical) and haptic devices (Phantom Omni™ vs. Novint Falcon™). As a result, we observed that the children quickly adjusted themselves to the system, and they sustained engagement at the word-writing tasks without any intervention. Results also showed improvements in tracing precision on the HAT system over time. Details of the results and lessons learned from the study are discussed.
Formic acid (FA) is an essential
chemical, but its process design
and control have not received much attention in the literature. This
contribution describes the design of a plantwide control (PWC) structure
for the intricate FA process having reactive distillation (RD), multiple
liquid and gas recycles, as well as a snowballing effect. In this
process, methyl formate (MF) is produced from methanol (MA) and carbon
monoxide (CO), and then it undergoes a hydrolysis reaction in RD to
produce FA and also MA for the first reaction. The presence of an
RD in addition to a continuous
stirred tank reactor (CSTR) coupled with three recycles makes control
of the FA process interesting and challenging. This work employs a
systematic method for PWC design, namely, an integrated framework
of simulation and heuristics (IFSH), which is easy to implement and
uses process simulators as well as heuristics in PWC design. The performance
of the developed PWC structure was evaluated for various disturbances,
using several criteria recommended for the evaluation of PWC design.
Results of dynamic simulations and these performance evaluations show
that the proposed PWC system is able to reject the tested disturbances
efficiently, while meeting FA purity and production requirements.
PWC for the two-step complex FA process is studied for the first time
in this contribution.
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