Tag Archives: Chemical methods

Activation of Catalysts for Carbon Nanomaterial Production

The most important stage of preparing heterogeneous catalysts for carbon nanomaterial (CNM) is their activation, which is understood as a complex of physical influence on the catalytic material, which allows to significantly increase the efficiency of nanostructure synthesis.

This can be achieved by researching mechanical (dispersion) and physical (electromagnetic and ultrasonic) activation methods.

One of the most important factors defining catalyst efficiency is its granulometric composition. It is known that reduction of the particle size (less than 3 nanometers) causes capsulation inside nanotubes, while increasing it above 25 nanometers leads to uneven size distribution and defects in nanotubes. This is due to the fact the using large catalyst particles (25 to 100 nanometers) prevents carbon scattering from the surfaces where hydrocarbon decay occurs to the surfaces where carbon is deposited; as a consequence, no CNM growth occurs on such particles. Therefore, it is important to define reasonable catalyst particle size, as well as dispersion and classification methods.

Note that dispersion of catalyst microparticles causes both the reduction of size and the changes in the microstructure, e.g. destruction and reduction of pore depth, increasing the boundary of nano-seeds, where graphitized carbon is deposited.

Catalyst was activated in a drum mill and an electromagnetic vortex layer device (AVS). The distinguishing characteristic of the vortex layer in electromagnetic units is the multitude of high frequency and strength shocks, as well as friction, which not only break solid particles, but significantly activate their surfaces due to the deformation of their crystalline lattice. Enormous energy is concentrated in a volume of this process, which direct influence on the material. The influence is so high that it changes the structure as deeply as the atom’s valency shells. The process causes deep changes in the structure of the material.

Mean energy conducted to a volume of the vortex layer reaches 103 kW/m3. This is several orders of magnitude higher than in vibration mills, for instance. Besides, the energy is localized in certain areas, e.g. in the locations where the ferromagnetic particles collide, where mean power reaches even higher.

The electromagnetic vortex layer unit consisted of a process section and a control section, connected by oil tubes and a power cable. The process section consisted of a support, an enclosure, an induction coil for the rotating electromagnetic field, and a detachable operating chamber.

The catalyst activation process was performed with 1…1.5 mm by 10…15 mm PVC encapsulated ferromagnetic particles.

The chamber was loaded with 0.120 kg of the catalyst and 0.060 kg of ferromagnetic particles; retention time varied from 5 to 60 seconds. The granulometric composition of the Ni/MgO catalyst after the dispersion was done by fractionating sieve analysis. The catalyst after activation was separated into fractions and used for CNM synthesis under a unified method of testing various catalyst samples.

The results of the experiment show that the optimal duration time for the finest grinding constitutes 10 seconds, with initial catalyst particle size of 500 micron.

The observed increase of catalyst particle size after 10 or more seconds of dispersion is apparently due to the fact that with time the particles accumulate sufficient energy for spontaneous aggregation.

The analysis of the influence of the catalyst size composition on the mean output of CNM leads to the conclusion: the output increases in inverse proportion to catalyst particle size. This is due to the increased active surface of the catalyst. The experiments demonstrated that the actual method of catalyst dispersion has no significant influence on nanomaterial output.

GlobeCore extends invitation to the International Construction & Utility Equipment Exposition-2019

GlobeCore invites all businesses and parties interested in the implementation of innovative technologies to the International Construction & Utility Equipment Exposition.

This event is biannual, and this year will be hosted by Kentucky Exposition Center, Louisville, Kentucky on 1-3 October. The exhibition focuses, among other things, on electric power transmission and distribution, wastewater treatment, natural gas supply etc.

GlobeCore will be represented in the first two categories by the CMM-G designed to change oil in wind turbine gearboxes and the AVS vortex layer device. You can see these machines and speak with our specialists at booth 2240.

The CMM-G simplifies and accelerates oil change in wind turbines. To protect the new oil from instantly becoming contaminated with impurities left in the gearbox after draining the oil oil, the machine also washes the gearbox with special flushing oil. As for the vortex layer device, it increases the efficiency of the existing wastewater purification systems, reducing process duration and chemical consumption.

Looking forward to meeting you at International Construction & Utility Equipment Exposition-2019!

Removal of Phosphorus From Wastewater: a Review of Methods

Removal of Phosphorus From Wastewater. Wastewater generated by the industry and agriculture in many cases contains large amounts of ammonium and phosphorus. Insufficient removal of these from wastewater is a source of contamination of ground and surface water and causes eutrophication of water bodies. Biogenic elements cause proliferation of cyanobacteria. Excessive activity of algae degrades operation of water intakes and fishing, reduces the hydraulic parameters of the flow (the speed of flow near the banks); algal bloom reduces the amount of solved oxygen, has a negative impact on flora and fauna and disrupts normal functions of natural ecosystems.

High level of phosphates in wastewater has been a problem in the last decade, when the content of phosphate has grown from 6-8 mg/liter to 20-25 mg/liter. The main source of phosphates in sewage is, statistically, household wastewater and various industries, which use many synthetic detergents.

The problem of removing phosphates from wastewater has no optimal solution at this time and requires more research. Biological treatment of wastewater cannot achieve the required degree of contaminant removal, while the physical and chemical methods, while offering good results, require significant investment and create the problem of processing sediment, which forms in the process of chemical treatment.

Removal of Phosphorus From Wastewater. The biological method of phosphorous compound removal is based on the metabolism of biological sludge. Certain amounts of phosphorus are required for the formation of living cells, as well as a medium of transfer of energy, used to accumulate nutrients in a cell. The method of thorough removal of biogenic elements from wastewater is based on a traditional biological treatment combining aerobic and anaerobic processes. The biological phosphorus removal is based on the ability of several bacteria to accumulate soluble orthophosphates in cell in the form of insoluble polyphosphate. Oxidation of previously accumulated organic substances occurs in the aerobic part of the cell, and the energy is used by the bacteria to consume orthophosphate from the environment and turn it into polyphosphate to repeat the cycle of cell growth. However, the insoluble forms of phosphorus may hamper purification, since such compounds, in their solid form, cannot be consumed by microorganisms, thus requiring filtration or settling of the wastewater before biological treatment.

If the content of phosphorus is high, it may not always be possible to remove biologically. Chemical methods are used in this case. Reagent selection depends on its availability and cost in the area. The place of mixing the chemical with wastewater is determined individually based on previous laboratory research and later testing of the results in industrial applications.