Probing into Nucleation Mechanisms of Cooling Crystallization of Sodium Chlorate in a Stirred Tank Crystallizer and an Oscillatory Baffled Crystallizer

The Couette-Taylor (CT) crystallizer was developed to promote the size distribution of L-Lysine crystal product in cooling crystallization. When using the CT crystallizer, the size distribution of crystal product was much narrower than that of the conventional Stirred tank (ST) crystallizer. Here, the coefficient size distribution (n) in CT crystallizer was quite large as 3.43, while it was only 2.17 in ST crystallizer at the same 360 rpm of agitation or rotation speed. This result indicated that the CT crystallizer was much more effective than the ST crystallizer in terms of the size distribution of L-lysine crystal products in cooling crystallization. The advantage of CT crystallizer over the ST crystallizer was explained in terms of the high energy dissipation of Taylor vortices flow, where it was 7.6 times higher than that of random fluid motion in conventional ST crystallizer. As such, the supersaturation profile in the CT crystallizer was much more homogeneous than that in the ST crystallizer, which resulted in promotion of size distribution L-lysine crystal product.

Download Full-text

Chiral symmetry breaking due to impeller size in cooling crystallization of sodium chlorate

CrystEngComm ◽

10.1039/c8ce01318g ◽

2018 ◽

Vol 20 (43) ◽

pp. 6894-6899 ◽

Cited By ~ 2

Author(s):

Xiongwei Ni ◽

Rachel Shepherd ◽

Jennifer Whitehead ◽

Tao Liu

Keyword(s):

Symmetry Breaking ◽

Surface Area ◽

Chiral Symmetry ◽

Chiral Symmetry Breaking ◽

Sodium Chlorate ◽

Racemic Mixture ◽

Cooling Crystallization ◽

First Time

We report, for the first time, that the size of impellers is the exception to Denk and Botsaris's work where a stirrer of the smallest surface area led to close to 100% deracemization, while the data from the largest impeller agreed with the results of Denk and Botsaris, displaying a racemic mixture.

Download Full-text

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109513 ◽

1978 ◽

Vol 36 (1) ◽

pp. 474-475

Author(s):

P.P.K. Smith

Keyword(s):

High Temperature ◽

Low Temperature ◽

Homogeneous Nucleation ◽

Silicate Mineral ◽

Antiphase Boundaries ◽

Two Phase ◽

Primitive Form ◽

The Core ◽

Nucleation Mechanisms ◽

And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Download Full-text

Removal of lead by sulfate-reducing bacteria in anaerobic continuous stirred tank reactors

Vietnam Journal of Biotechnology ◽

10.15625/1811-4989/14/3/9873 ◽

2016 ◽

Vol 14 (3) ◽

pp. 557-561

Author(s):

Nguyễn Thị Yên ◽

Kiều Thị Quỳnh Hoa

Keyword(s):

Sulfate Reducing Bacteria ◽

Stirred Tank ◽

Synthetic Wastewater ◽

Terminal Electron Acceptor ◽

Stirred Tank Reactors ◽

Sulfate Reducing ◽

Sulfide Production ◽

Continuous Stirred Tank ◽

Continuous Stirred Tank Reactors ◽

Reducing Bacteria

Lead contaminated wastewater negatively impacts to living organisms as well as humans. In recent years, a highly promising biological process using the anaerobic production of sulfide ions by sulfate-reducing bacteria has presented itself as an alternative option for the removal of lead. This process is based on microbial utilization of electron donors, such as organic compounds (carbon sources), and sulfate as the terminal electron acceptor for sulfide production. The biogenic hydrogen sulfide reacts with dissolved heavy metals to form insoluble metal sulfide precipitates Removal of lead by an enriched consortium of sulfate-reducing bacteria (DM10) was evaluated sulfate reduction, sulfide production and lead precipitation. Four parallel anaerobic continuous stirred tank reactors (CSTR, V = 2L) (referred as R1 - R4) were fed with synthetic wastewater containing Pb2+ in the concentrations of 0, 100, 150 and 200 mg L-1 of lead and operated with a hydraulic retention time of 5 days for 40 days. The loading rates of each metal in R1- R4 were 0, 20, 30 and 40 mg L-1 d-1, respectively. The results showed that there was no inhibition of SRB growth and that lead removal efficiencies of 99-100% for Pb2+ were achieved in R2 (100 mg L-1) and R3 (150 mg L-1) throughout the experiment. For the highest lead concentration of 200 mg L-1, a decrease in efficiency of removal (from 100 to 96%) was observed at the end of the experiment. The obtained result of this study might help for a better control operation and performance improvements of reactors.

Download Full-text

Bounded Finite Time Control for Planar Feedback Linearizable Systems: Application to a Continuous Stirred Tank Reactor

1992 American Control Conference ◽

10.23919/acc.1992.4792239 ◽

1992 ◽

Cited By ~ 1

Author(s):

Julio Solis-Daun ◽

Jesus Alvarez ◽

Rodolfo Suarez

Keyword(s):

Finite Time ◽

Stirred Tank ◽

Continuous Stirred Tank Reactor ◽

Stirred Tank Reactor ◽

Tank Reactor ◽

Time Control ◽

Continuous Stirred Tank ◽

Feedback Linearizable Systems

Download Full-text

Bactericidal Effect of Sodium Chlorate onEscherichia coliConcentrations in Bovine Ruminal and Fecal ContentsIn Vivo

Microbial Ecology in Health and Disease ◽

10.3402/mehd.v14i1.8216 ◽

2002 ◽

Vol 14 (1) ◽

Author(s):

Robin C. Anderson ◽

Todd R. Callaway ◽

Timothy J. Anderson ◽

Leon F. Kubena ◽

Nancy K. Keith ◽

...

Keyword(s):

Sodium Chlorate ◽

Bactericidal Effect

Download Full-text

GREEN refining technology

Sugar Industry ◽

10.36961/si16692 ◽

2015 ◽

pp. 508-514 ◽

Cited By ~ 1

Author(s):

Craig Jensen ◽

David Love

Keyword(s):

Environmentally Friendly ◽

Step Change ◽

Energy Usage ◽

Capital Equipment ◽

Green Is ◽

Cooling Crystallization ◽

Sugar Refinery

The objective of this paper is to describe a “step-change” in refining technology being proposed by Tongaat Hulett. This patented technology is termed “GREEN” Refining Technology, where “GREEN” is an acronym for “Greatly Reduced Energy and Equipment Needs”. The name attempts to encapsulate the “environmentally friendly” benefits of reduced energy usage whilst also emphasising the major savings in both energy and capital equipment requirements of the technology. GREEN refining technology aims to substantially (and ultimately totally) replace evaporating crystallization with cooling crystallization in a sugar refinery.

Download Full-text