Columnar activated carbon for treating floating oil on water surface and preparation method of columnar activated carbon

Abstract

The invention discloses columnar activated carbon for water surface floating oil treatment and a preparation method thereof, and relates to the technical field of adsorption material preparation, and the preparation method comprises the following steps: carrying out semi-coking treatment on bituminous coal as raw material coal, grinding the raw material coal subjected to semi-coking treatment into powder, taking 100 parts of coal powder, 35 parts of coal tar and 10 parts of water, uniformly mixing to prepare coal paste, carrying out compression stretching molding, and carrying out cold air drying under negative pressure to obtain the columnar activated carbon for water surface floating oil treatment. A dry forming material is prepared; and carbonizing at the temperature of 550-650 DEG C to obtain a carbonized material, and activating at the temperature of 880-960 DEG C for 4-6 hours to obtain the activated carbon. The preparation method is simple in preparation process, free of any auxiliary agent except a binder and easy to operate; the prepared activated carbon has high adsorption capacity, low water absorption rate and high floating rate, and can effectively adsorb floating oil on the water surface and float on the water surface.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of adsorption materials, in particular to columnar activated carbon for treating floating oil on water surface and a preparation method thereof. Background Art

[0002] Oily wastewater comes from a wide range of sources, including steel refining, chemical pharmaceuticals, oil extraction, and food processing. Oily wastewater can pollute drinking water sources, rivers, lakes, and soil. These oil pollutants exist in water in many forms, and the oil film floating on the water surface is called oil slick.

[0003] As a non-polar porous adsorption material, activated carbon has a strong adsorption capacity for organic matter and can effectively adsorb floating oil on the water surface. Moreover, after absorbing oil, the activated carbon can be desorbed by changing temperature and pressure, and the desorbed activated carbon can be reused.

[0004] However, the existing activated carbon has a high stack density and a fast water adsorption rate. It will absorb water within a few seconds and quickly sink to the bottom of the water. The contact time with floating oil is very short, and it is difficult to have an adsorption effect on floating oil on the water surface. Summary of the invention

[0005] The present invention provides a columnar activated carbon for treating floating oil on water surface and a preparation method thereof in order to solve the problems that the existing activated carbon has a high stack density, a fast water adsorption rate, quickly absorbs water and sinks to the bottom of the water, and cannot effectively adsorb and treat floating oil on the water surface.

[0006] The present invention is implemented by the following technologies: The present invention provides a method for preparing columnar activated carbon for treating floating oil on water surface, comprising the following steps: a. Coal preparation Bituminous coal with moisture content ≤5%, ash content ≤3%, and volatile matter content of 35-40% is taken as raw coal; the characteristics of the raw coal itself make the activated carbon prepared from it have obvious ink bottle-type nano-scale pore structure characteristics. The ratio of adsorption rate to adsorption capacity of activated carbon with ink bottle-type pore structure is significantly lower than that of activated carbon with slit-type pore structure. The most intuitive manifestation is the slow water absorption rate and high floating rate.

[0007] b. Semi-coking The raw coal is semi-coked in a rotary kiln. The initial temperature is 150-200°C, and the temperature is raised to 450-500°C at a rate of 5-10°C / min, and maintained for 5-15min until the volatile matter of the raw coal is reduced to 15%.

[0008] c. Flour milling The raw coal after the semi-coking treatment in step b is ground in a vibration mill, and the ash content of the pulverized coal is ≤3.5%, and the 200-mesh pass rate is ≥92%, thereby obtaining pulverized coal.

[0009] d, mixed 100 parts of coal powder, 25-60 parts of coal tar and 5-20 parts of water are placed in a mixer and mixed evenly for 15 minutes to obtain coal paste.

[0010] e. Press forming The coal paste prepared in step d is pressed and stretched into shape. Specifically, it is sent to a pusher by a screw conveyor, and then sent to a hydraulic press cylinder through the pusher for pressing and stretching. The pressing and stretching pressure is 13-14 MPa, and a Φ4.0 mm carbon bar is obtained.

[0011] f, cold air drying The formed carbon bars obtained in step e are cold-dried under negative pressure. Specifically, the carbon bars pressed out from the press cylinder are transported to a cold-air dryer via a belt conveyor and an elevator to remove most of the moisture to obtain a dry formed material.

[0012] g, carbonization The dried molding material obtained in step f is placed in a rotary carbonization furnace for carbonization at a carbonization temperature of 550-650°C and a heating rate of 15-30°C / min; until the ash content of the carbonized molding material is ≤5.0%, the volatile matter is 8-23%, and the water capacity is 20-45%, thereby obtaining a carbonized material; and the free carbon formed in the pyrolysis process is coked at the edge of the pores by rapidly heating the temperature, thereby reducing the entrance of the pores and forming more "ink bottle" type pore structures.

[0013] h, activation The carbonized material obtained in step g is placed in a rotary activation furnace and activated at 880-960° C. for 4-6 hours to obtain activated carbon.

[0014] The activated carbon obtained by testing has a carbon tetrachloride adsorption rate of ≥80%, a floating rate of ≥95% and a specific surface area of ​​≥1200m 2 / g, pore volume ≥ 0.7cm 3 / g.

[0015] The present invention also provides a columnar activated carbon for treating floating oil on water surface prepared according to the method.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The method for preparing columnar activated carbon for treating floating oil on water surface provided by the present invention is to prepare columnar activated carbon that can effectively treat floating oil on water surface by subjecting specific bituminous coal to semi-coking, carbonization and other process treatments. The preparation process is simple, and no auxiliary agent other than a binder is used. The preparation can be completed by columnar activated carbon production equipment without the need to purchase additional new equipment. The preparation process is simple and easy to operate.

[0017] The activated carbon prepared by the present invention has a high adsorption capacity, a slow water absorption rate, a high floating rate, and can effectively absorb floating oil on the water surface and float on the water surface; from the detection value, the carbon tetrachloride adsorption rate is ≥80%, the floating rate is ≥95%; the specific surface area is ≥1200m 2 / g, pore volume ≥ 0.7cm 3 / g, with the characteristics of "ink bottle-shaped" pore structure, it can effectively adsorb oil floating on the water surface, and the adsorbed oil can be desorbed and recycled by temperature and pressure changes. The activated carbon after desorption can also be reused, which is of great significance for purifying water pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 shows the adsorption isotherms of the examples of the present invention.

[0019] Figure 2 The adsorption isotherm of the comparative example of the present invention is shown.

[0020] Figure 3 The floating conditions of the embodiments of the present invention and the comparative examples in water are shown. DETAILED DESCRIPTION

[0021] The specific embodiments of the present invention are described in detail below. Example

[0022] A method for preparing columnar activated carbon for treating floating oil on water surface, the specific steps are as follows: a. Coal preparation Bituminous coal from a mine in Xinjiang was used as raw coal, with a moisture content of 4.0%, an ash content of 1.63%, and a volatile content of 39.3%.

[0023] b. Semi-coking The raw coal is semi-coked in a rotary kiln with an initial temperature of 180°C, and the temperature is raised to 480°C at a rate of 7°C / min and maintained for 6 minutes until the volatile matter of the raw coal is reduced to 15%.

[0024] c. Flour milling The raw coal after the semi-coking treatment in step b is ground in a vibration mill, and the ash content of the pulverized coal is ≤3.5%, and the 200-mesh pass rate is ≥92%, thereby obtaining pulverized coal.

[0025] d, mixed Take 100 parts of coal powder, 35 parts of coal tar and 10 parts of water, put them in a mixer and mix them evenly for 15 minutes to form a paste to prepare coal paste.

[0026] e. Press forming The coal paste prepared in step d is delivered to a pusher by a screw conveyor, and then delivered to a hydraulic press cylinder through the pusher for compression and stretching at 13-14 MPa to obtain a Φ4.0 mm carbon bar.

[0027] f, cold air drying The carbon bars pressed out from the press cylinder are transported to the cold air dryer through belt conveyors and elevators, and run along the chain plates with holes. Most of the moisture is removed by cold air under negative pressure to obtain dry molding materials.

[0028] g, carbonization The dried molding material obtained in step f is placed in a rotary carbonization furnace for carbonization at a carbonization temperature of 600°C and a heating rate of 20°C / min; until the ash content of the carbonized molding material is ≤5.0%, the volatile content is 8-23%, and the water content is 20-45%, thereby obtaining a carbonized material.

[0029] h, activation The carbonized material obtained in step g was placed in a rotary activation furnace and activated at 910° C. for 4.5 h to obtain activated carbon. Comparative Example

[0030] Ordinary columnar activated carbon was taken as a comparative example.

[0031] 1. Index detection The carbon tetrachloride adsorption rate, floating rate, specific surface area and pore volume of the embodiments and comparative examples were tested with reference to GB / T7702-2008 "Test method for coal-based granular activated carbon". The specific surface area refers to the BET specific surface area, and the pore volume refers to the total pore volume by adsorption method. The test results are shown in the following table.

[0032]

[0033] Comparing the embodiments with the comparative examples, the carbon tetrachloride adsorption rate, floating rate, specific surface area and pore volume of the embodiments are better than those of the comparative examples, especially the floating rate, which is significantly improved compared with the comparative examples.

[0034] 2. Adsorption Isotherm The adsorption isotherms of the embodiments and comparative examples are plotted as follows: Figure 1 , 2 shown.

[0035] Depend on Figure 1It can be seen that in the embodiment, the adsorption branch line and the desorption branch line of the adsorption hysteresis loop are well parallel in the range close to the focus of the hysteresis loop; but near the starting point of the hysteresis loop, the desorption branch line shows a downward trend, and the entire hysteresis loop is closer to the combination of H4 type and H2 type.

[0036] The adsorption branch line and desorption branch line of the comparative example are almost parallel, and the hysteresis loop is H4 type.

[0037] By comparison, it can be seen that the hole type of the embodiment is generally a slit type, but has obvious structural features of an ink bottle type.

[0038] 3. Simulation Testing Take two identical 200ml beakers, add equal amounts of water, add the activated carbon prepared in Example and Comparative Example respectively, and observe the floating conditions in water. Figure 3 shown.

[0039] It can be observed that the activated carbon in the examples can float on the water surface, while the activated carbon in the comparative example quickly sinks to the bottom of the water.

[0040] The scope of protection claimed by the present invention is not limited to the above specific embodiments. For those skilled in the art, the present invention may have various deformations and changes. Any modifications, improvements and equivalent substitutions made within the concept and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing columnar activated carbon for treating floating oil on water surface, characterized in that: The following steps are involved: a. Coal preparation Take bituminous coal with moisture content ≤5%, ash content ≤3%, and volatile matter content of 35-40% as raw coal; b. Semi-coking The raw coal is subjected to semi-coking treatment. The initial temperature of the semi-coking treatment is 150-200°C, and the temperature is increased to 450-500°C at a rate of 5-10°C / min, and maintained for 5-15min until the volatile matter of the raw coal is reduced to 15%; c. Flour milling Grind the raw coal after the semi-coking treatment in step b, wherein the ash content of the pulverized coal is ≤3.5% and the passing rate of 200 mesh is ≥92%, to obtain pulverized coal; d, mixed Take 100 parts of coal powder, 25-60 parts of coal tar, and 5-20 parts of water and mix them evenly to prepare coal paste; e. Press forming The coal paste prepared in step d is pressed and stretched to obtain a Φ4.0 mm carbon bar; f, cold air drying The formed carbon strip obtained in step e is dried by cold air under negative pressure to obtain a dry forming material; g, carbonization The dried molding material obtained in step f is carbonized at a carbonization temperature of 550-650° C. and a heating rate of 15-30° C. / min until the ash content of the carbonized molding material is ≤5.0%, the volatile content is 8-23%, and the water content is 20-45%, thereby obtaining a carbonized material; h, activation The carbonized material obtained in step g is activated at 880-960° C. for 4-6 hours to obtain activated carbon.

2. The method for preparing columnar activated carbon for treating floating oil on water surface according to claim 1, characterized in that: In step b, semi-coking is carried out in a rotary kiln; In step c, grinding is performed using a vibration mill; In step d, mixing is carried out in a mixer for 15 min; In step g, carbonization is carried out in a rotary carbonization furnace; In step h, activation is carried out in a rotary activation furnace.

3. The method for preparing columnar activated carbon for treating floating oil on water surface according to claim 1, characterized in that: In step e, the coal paste prepared in step d is delivered to a pusher by a screw conveyor, and then delivered to a hydraulic press cylinder for compression molding by the pusher, and the compression pressure is 13-14 MPa; In step f, the carbon strips compressed in the cylinder of the press in step e are transported to the cold air dryer via a belt conveyor and an elevator.

4. The method for preparing columnar activated carbon for treating floating oil on water surface according to claim 1, characterized in that: The specific steps include: a. Coal preparation Xinjiang bituminous coal was used as raw coal, the moisture content of the raw coal was 4.0%, the ash content was 1.63%, and the volatile content was 39.3%; b. Semi-coking The raw coal is semi-coked in a rotary kiln with a temperature gradient of 200-350-500°C and a heating rate of 10°C / min until the volatile matter of the raw coal is reduced to 15%. c. Flour milling The raw coal after the semi-coking treatment in step b is ground in a vibration mill, and the ash content of the pulverized coal is ≤3.5%, and the passing rate of 200 mesh is ≥92%, so as to obtain pulverized coal; d, mixed 100 parts of coal powder, 35 parts of coal tar and 10 parts of water were placed in a mixer and mixed evenly for 15 minutes to form a paste to prepare coal paste; e. Press forming The coal paste prepared in step d is sent to a pusher by a screw conveyor, and then sent to a hydraulic press cylinder by the pusher for compression and stretching at 13-14 MPa to obtain a Φ4.0 mm carbon bar; f, cold air drying The carbon strips obtained by pressing and stretching from the press cylinder are transported to the cold air dryer through a belt conveyor and an elevator, and run along the chain plate with holes. Most of the moisture is removed by cold air under negative pressure to obtain dry molding materials. g, carbonization The dried molding material obtained in step f is placed in a rotary carbonization furnace for carbonization at a carbonization temperature of 600° C. and a heating rate of 20° C. / min; until the ash content of the carbonized molding material is ≤5.0%, the volatile content is 8-23%, and the water content is 20-45%, thereby obtaining a carbonized material; h, activation The carbonized material obtained in step g was placed in a rotary activation furnace and activated at 910° C. for 4.5 h to obtain activated carbon.

5. A columnar activated carbon for treating floating oil on water surface prepared according to claim 1.

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