Tag Archives: Absorption Fields

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!

Wastewater Treatment: Absorption Fields, Biofilters and Aerotanks

Wastewater Treatment:. Aerobic wastewater treatment methods is classified according to the type of reservoir where the contaminants are oxidized. The reservoirs can be such structures as absorption fields, ponds, biofilters and aerotanks.

The aerobic oxidation (mineralization) occurs in biological ponds due to the microbes, algae and higher plants. The small depth, no currents, abundance of microalgae saturating water with oxygen and simple organisms feeding on bacteria etc.

Cultivation of higher water plants in such ponds to absorb not only a large part of biogenic elements, but also toxic substances (heavy metals, oil, phenol, nitric compounds, pesticides etc) intensifies the treatment process. Using biological ponds, both household and industrial wastewater can be treated, included mining wastewater.

Absorption fields are special plots of land populated with aerobic microbes which biochemically transform biological contamination into water and carbon dioxide.

Wide use of biological ponds and absorption fields is limited by the seasonal variations, low throughput, as well as the large areas required, along with constant control of ground water level. Artificial reservoirs, such as biofilters and aerotanks do not have these limitations.

Biofilters are special biological reactors loaded with a filtering element, which is covered with a biological film.

Thanks to the biological film, which consists of microorganisms, intensive biological oxidation processes occur. The film plays the chief role in treatment of wastewater.

The contaminated water in biofilters passes through a layer of loaded material (crushed minerals, pieces of plastic, synthetic fabrics etc), covered with biological film. Unsolved contaminants, colloids and organic materials in the water are captured by the biological film and remain in the filter material. The thickness of the biofilm formed by the microorganisms depends on the mean surface area of the material, concentration of organic material and external factors. After die-off, the film is carried out of the reservoir with water.

If the average yearly temperature in the environment does not exceed +3°С, it is recommended to place biofilters indoors with heating, if the average temperature is higher, they can be operated without external heating.

Biofilters are rectangular or round with double bottom: the lower bottom is solid, the upper is perforated. In the course of filtration, microbial film grows on the surfaces of the filter. Air is supplied through the lower part of the filter in the direction opposite to the flow of water.

Processed water goes to a settling tank where particles of the biofilm are deposited. Immobilization of biomass cells facilitates several stages of purification, with specific types of microbes.

Aerotanks are homogeneous bioreactors. They are typically concrete rectangular tanks, 3-6 meters high, equipped with aeration devices and connected to a settling tank. Aerotanks are divided into three or four corridors by screens. The types of these reactors are defined by the method of oxygen supply, the design of the reactor and the volume to material load. Treatment of water in an aerotank occurs when aerated mixture of wastewater and biological sludge pass through the tank.

Biological sludge has a complex structure; it contains many microorganisms, (thread bacteria and nitrification bacteria) and simple organisms (infusoria), with ferments to remove contaminants from wastewater. The treatment process is the continuous fermentation of contaminants. Particles of the sludge, formed by thread bacteria, on the one hand form adsorption skeleton, around which flocсules form, and on the other hand prevent formation of foam and stimulate sedimentation. The simple organisms consume bacteria, clarifying the water.

After treatment in aerotanks, water goes to settling tanks, where bio sludge is sedimented and partially returned to the aerotank.

It should be noted that most biogenic elements required for the development of microorganisms (carbon, oxygen, nitrogen etc), solve and are concentrated in wastewater. When the concentration of one of the elements in insufficient, such as nitrogen, phosphorus, potassium, such element is added to the wastewater in the form of salts.