Adsorbent for groundwater pollution control and preparation method thereof

Abstract

The present invention relates to the field of groundwater treatment technology, and in particular to an adsorbent for groundwater pollution treatment and a preparation method thereof, which specifically comprises the following steps: step 1: adding activated carbon powder, FeCl 2 Solution and FeCl 3 The solution was mixed and NaOH solution was added to prepare magnetic activated carbon; step 2, activated carbon powder was mixed with Ca(NO 3 ) 2 The solutions were mixed and Na 2 SiO 3 solution to prepare calcium silicate activated carbon; step three, mixing and grinding the magnetic activated carbon, calcium silicate activated carbon, dolomite, quartz sand and alumina particles, and mixing them with a binder and a flocculant and putting them into a bag to obtain an adsorbent for groundwater pollution control; the present invention uses green, environmentally friendly, non-toxic, harmless, and pollution-free raw materials, has little impact on the environment, and uses waste to prepare activated carbon materials, has low cost, and has significant pollutant treatment effect.

Description

Technical Field

[0001] The present invention relates to the technical field of groundwater treatment, and in particular to an adsorbent for groundwater pollution treatment and a preparation method thereof. Background Art

[0002] Groundwater is one of the most important freshwater resources on Earth. It supports the needs of human life, agricultural irrigation, industrial production and many other aspects. However, with the continuous increase of human activities, the problem of groundwater pollution is becoming increasingly serious. Especially in recent years, due to the acceleration of industrialization and urbanization, the content of pollutants in groundwater has continued to rise, seriously threatening human health and the balance of the ecological environment. In this context, the problem of groundwater environmental pollution is very prominent, and scientific governance measures are taken to ensure the safety and sustainable use of groundwater resources.

[0003] At present, the commonly used remediation technologies in groundwater remediation projects mainly include natural attenuation, chemical oxidation / reduction, and physical remediation. Among them, the natural attenuation method mainly relies on the adsorption of soil particles, microbial degradation of pollutants, and dilution and diffusion in groundwater. Microorganisms play a major role in the natural attenuation process, but the natural attenuation method is only applicable to sites with low pollution levels, and the remediation cycle is long. The chemical oxidation / reduction method converts pollutants into harmless substances through oxidation or reduction principles, and has the characteristics of high remediation efficiency and small disturbance, but the remediation process introduces more new chemical substances, resulting in secondary pollution. The physical remediation method achieves effective control of pollutants without introducing new pollutants. Among them, it mainly includes water control and material adsorption methods. Among them, the material adsorption method has the advantages of wide application range, low cost, fast processing speed, and low chemical pollution risk, and is the most widely used in engineering. However, the adsorbent method also has certain limitations, such as high requirements for sewage water quality. If the sewage contains a large amount of suspended matter and sediment, the adsorption efficiency will be reduced, and the saturated adsorbent remaining in the water is prone to secondary pollution.

[0004] Therefore, it is urgent to provide an adsorbent for groundwater treatment that is anti-clogging and easy to remove from water. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for preparing an adsorbent for groundwater pollution control, which specifically comprises the following steps:

[0006] Step 1: Dry the biomass at 60-90°C to constant weight, crush it through a 80-90 mesh sieve, then carbonize it, cool it to room temperature, and activate and modify it to obtain activated carbon powder.

[0007] Preferably, the biomass is one or more of kitchen waste, agricultural and forestry waste and waste paper products; the kitchen waste is preferably leftovers, fruit peels, eggshells and bone residues, the agricultural and forestry waste is preferably straw, rice husks and dead branches and leaves, and the waste paper products are preferably waste paper boxes, waste cardboard, paper for enterprises and units, paper for engineering projects, books, periodicals and newspapers, etc.

[0008] Preferably, the carbonization treatment is to preheat the tubular furnace to 140-160°C, maintain for 10-20 minutes, then put the biomass powder into the tubular furnace under nitrogen protection, increase the temperature to 450-550°C at a heating rate of 10-15°C / min, and maintain for 1.5-2 hours after reaching the target temperature.

[0009] Preferably, the activation modification operation is to mix the powder and the activator in a mass ratio of 1:5, stir at 80-90r / min for 15-20min, take out and put into a tube furnace, and raise the temperature to 550-650°C at a heating rate of 10-15°C / min and maintain for 1-1.5h. Preferably, the activator is (1-2) mol / L NaOH solution or (1-2) mol / L KOH solution.

[0010] Step 2: Add activated carbon powder, FeCl 2 Solution and FeCl 3 The solution was mixed and stirred for 10-15 minutes at a speed of 60-70 r / min, and then NaOH solution was added and stirred for 10-15 minutes, and then ultrasonic treatment was performed for 10-20 minutes, and the filtrate was filtered to obtain magnetic activated carbon;

[0011] Preferably, the activated carbon powder, FeCl 2 Solution, FeCl 3 The ratio of the solution and the NaOH solution is 1g:10ml:10ml:30ml; most preferably, the FeCl 2 The concentration of the solution is 0.15-0.25 g / ml, the FeCl 3 The concentration of the solution is 0.35-0.45 g / ml, and the concentration of the NaOH solution is 4-5 mol / L.

[0012] Step 3: Mix the activated carbon powder with Ca(NO 3 ) 2 The solution was mixed and stirred for 20-30 minutes at a speed of 80-90 r / min, and then Na 2 SiO 3 The solution is stirred for 10-15 minutes, then ultrasonically treated for 10-20 minutes, and the filtrate is filtered to obtain calcium silicate activated carbon;

[0013] Preferably, the activated carbon powder, Ca(NO 3 ) 2 Solution and Na 2 SiO 3 The ratio of the solution is 5g:8ml:4ml. Most preferably, the Ca(NO 3 ) 2 The concentration of the solution is 0.1-0.2 g / ml, and the Na 2 SiO 3 The concentration of the solution is 0.2-0.3 g / ml;

[0014] Step 4: Mix and grind the magnetic activated carbon, calcium silicate activated carbon, dolomite, quartz sand and alumina particles to a particle size of 1-3 mm, mix the binder, binder and flocculant and load them into the outer film to obtain an adsorbent for groundwater pollution control.

[0015] Preferably, the mass ratio of the magnetic activated carbon, calcium silicate activated carbon, dolomite, quartz sand, alumina particles, binder and flocculant is 10:10:8:7:5:5:5.

[0016] Most preferably, the binder is polyvinyl alcohol, attapulgite and resin in a mass ratio of 3:4:3. The flocculant is polyacrylamide, and the outer film is one of a non-woven bag, a nylon bag or a water-permeable bag.

[0017] The present invention has the following advantages:

[0018] (1) Activated carbon has a porous structure and a large surface area, which can effectively adsorb heavy metals, ammonia nitrogen, phenol and other common organic compounds in groundwater, as well as insoluble colloidal particles. Calcium silicate can effectively adsorb heavy metals, pollutants, sulfates and other harmful substances in water. Therefore, activated carbon-loaded calcium silicate composite materials have a significant adsorption effect on heavy metal and organic pollutants.

[0019] (2) Magnetic Fe 3 O 4 The particles have a significant adsorption effect on heavy metal ions such as copper, nickel, chromium, cadmium and lead. After being loaded with activated carbon, on the one hand, the adsorption of organic matter is enhanced, and on the other hand, the activated carbon can adsorb some impurities with larger particle sizes to prevent clogging of the magnetic Fe 3 O 4 Particles.

[0020] (3) Dolomite and quartz sand can adsorb suspended matter and colloidal substances in water on their surfaces, thereby improving water quality and preventing clogging of other adsorbents. In addition, dolomite can also adsorb pollutants, and quartz sand has good acid and alkali resistance, making it suitable for complex groundwater environments with various pH values.

[0021] (4) Polyacrylamide can aggregate colloidal particles in groundwater to form larger aggregates, remove insoluble impurities and pollutants, and then use adsorbents to fix these impurities and pollutants to prevent clogging of the adsorbent and secondary pollution.

[0022] (5) The adsorbent is placed in a non-woven bag, a nylon bag or a permeable bag and buried in the aquifer. When the adsorbent is close to saturation, the bag containing the adsorbent can be easily taken out and the adsorbent can be subsequently treated in an environmentally friendly manner to prevent the saturated adsorbent from remaining in the groundwater and causing secondary pollution.

[0023] (6) The raw materials used in the present invention are green, environmentally friendly, non-toxic, harmless, and pollution-free, with little impact on the environment. In addition, the activated carbon material is prepared from waste, which has a low cost and a significant pollutant removal effect. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the invention, not all of the embodiments. Based on the embodiments of the invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the invention.

[0025] Example 1

[0026] Step 1: Collect local kitchen waste, agricultural and forestry waste and waste paper products, dry them at 75°C to constant weight, and crush them through an 85-mesh sieve. Preheat the tubular furnace to 150°C and hold for 15 minutes. Then, under nitrogen protection, put the biomass powder into the tubular furnace, raise the temperature to 500°C at a heating rate of 12°C / min, and hold for 2 hours after reaching the target temperature. Take out the powder and cool it to room temperature. Mix the powder with 2mol / LNaOH at a mass ratio of 1:5, stir at 65°C and 85r / min, take it out after 20 minutes and put it into the tubular furnace. Raise the temperature to 600°C at a heating rate of 15°C / min and hold for 1.5 hours to obtain activated carbon powder.

[0027] Step 2: Add activated carbon powder, FeCl 2 Solution and FeCl 3 The solution was mixed and stirred for 15 minutes at a temperature of 70°C and a speed of 65 r / min, and then NaOH solution was added and stirred for 15 minutes, and then ultrasonic treatment was performed for 15 minutes, and the filtrate was filtered out to obtain magnetic activated carbon; the activated carbon powder, FeCl 2 Solution, FeCl 3 The ratio of solution and NaOH solution is 1g:10ml:10ml:30ml; the FeCl 2 The concentration of the solution is 0.2 g / ml, the FeCl 3The concentration of the solution is 0.4 g / ml, and the concentration of the NaOH solution is 5 mol / L.

[0028] Step 3: Mix the activated carbon powder with Ca(NO 3 ) 2 The solution was mixed and stirred for 30 min at 70 °C and 85 r / min, and then Na 2 SiO 3 The solution was stirred for 15 min, then ultrasonicated for 20 min, and the filtrate was filtered to obtain calcium silicate activated carbon. 3 ) 2 Solution and Na 2 SiO 3 The ratio of the solution is 5g:8ml:4ml. 3 ) 2 The concentration of the solution is 0.15 g / ml, and the Na 2 SiO 3 The concentration of the solution was 0.25 g / ml.

[0029] Step 4: Mix and grind the magnetic activated carbon, calcium silicate activated carbon, dolomite, quartz sand and alumina particles to a particle size of 2 mm, mix with a binder and a flocculant and load them into an outer film to obtain an adsorbent for groundwater pollution control. The mass ratio of the magnetic activated carbon, calcium silicate activated carbon, dolomite, quartz sand, alumina particles, binder and flocculant is 10:10:8:7:5:5:5. The binder is polyvinyl alcohol, attapulgite and resin, with a mass ratio of 3:4:3. The flocculant is polyacrylamide, and the outer film is a non-woven bag.

[0030] Test Example 1

[0031] 1L of pollutant solution was prepared as shown in Table 1 to simulate contaminated groundwater. Soil and sediment were added to each group of solutions to control the turbidity of the solution to 300±10. 100g of the adsorbent prepared in the embodiment was added to each group of solutions, and the temperature was 25°C and the speed was 90r / min for stirring for 1h. Then each group of solutions was placed in a centrifuge for separation, and the supernatant was taken to detect the component concentration and turbidity after treatment. The results were repeated 3 times, and the results are shown in Table 1.

[0032] Table 1

[0033]

[0034]

[0035] As can be seen from Table 1, the adsorbent prepared in Example 1 has a significant adsorption effect on pollutants, heavy metal ions and chlorides in groundwater, and has a good aggregation and adsorption effect on colloidal particles and larger impurities (soil, silt, etc.) in water. While improving water quality, it can prevent the adsorbent from being blocked and improve the adsorption efficiency and adsorption effect.

[0036] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an adsorbent for groundwater pollution control, characterized in that: The following steps are involved: Step 1, mixing activated carbon powder, FeCl2 solution and FeCl3 solution and stirring for 10-15 minutes at a speed of 60-70 r / min, then adding NaOH solution and continuing stirring for 10-15 minutes, then ultrasonically treating for 10-20 minutes, filtering out the filtrate to obtain magnetic activated carbon; Step 2: Mix the activated carbon powder and the Ca(NO3)2 solution and stir for 20-30 minutes at a speed of 80-90 r / min, then add the Na2SiO3 solution and continue stirring for 10-15 minutes, then ultrasonically treat for 10-20 minutes, filter out the filtrate, and obtain calcium silicate activated carbon; Step 3: Mix and grind the magnetic activated carbon, calcium silicate activated carbon, dolomite, quartz sand and alumina particles to a particle size of 1-3 mm, mix with a binder and a flocculant and load them into an outer film to obtain an adsorbent for groundwater pollution control; The preparation method of the activated carbon powder comprises drying the biomass at 60-90° C. to a constant weight, crushing the biomass through a 50-60 mesh sieve to obtain biomass powder, then carbonizing the biomass powder, taking out the powder, cooling it to room temperature, and activating and modifying the powder to obtain the activated carbon powder. The activation modification operation is to mix the powder and the activator in a mass ratio of 1:5, stir at 80-90r / min for 15-20min, take out and put into a tube furnace, and raise the temperature to 550-650°C at a heating rate of 10-15°C / min and maintain for 1-1.5h; The activator is (1-2) mol / L NaOH solution or (1-2) mol / L KOH solution.

2. The method for preparing an adsorbent for groundwater pollution control according to claim 1, characterized in that: The carbonization treatment is to preheat the tubular furnace to 140-160°C, maintain it for 10-20 minutes, then put the biomass powder into the tubular furnace under nitrogen protection, increase the temperature to 450-550°C at a heating rate of 10-15°C / min, and maintain it for 1.5-2 hours after reaching the target temperature.

3. The method for preparing an adsorbent for groundwater pollution control according to claim 1, characterized in that: The ratio of activated carbon powder, FeCl2 solution, FeCl3 solution and NaOH solution in step one is 1g:10ml:10ml:30ml; the ratio of activated carbon powder, Ca(NO3)2 solution and Na2SiO3 solution in step two is 5g:8ml:4ml.

4. The method for preparing an adsorbent for groundwater pollution control according to claim 1, characterized in that: In step 1, the concentration of the FeCl2 solution is 0.15-0.25 g / ml, the concentration of the FeCl3 solution is 0.35-0.45 g / ml, and the concentration of the NaOH solution is 4-5 mol / L; in step 2, the concentration of the Ca(NO3)2 solution is 0.1-0.2 g / ml, and the concentration of the Na2SiO3 solution is 0.2-0.3 g / ml.

5. The method for preparing an adsorbent for groundwater pollution control according to claim 1, characterized in that: The mass ratio of the magnetic activated carbon, calcium silicate activated carbon, dolomite, quartz sand, alumina particles, binder and flocculant in step three is 10:10:8:7:5:5:

5.

6. The method for preparing an adsorbent for groundwater pollution control according to claim 5, characterized in that: The binder is polyvinyl alcohol, attapulgite and resin, with a mass ratio of 3:4:3; the flocculant is polyacrylamide, and the outer film is one of a non-woven bag, a nylon bag or a permeable bag.

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