CN106311138A - Preparation method of bagasse charcoal and magnesium-iron hydrotalcite composite adsorbent - Google Patents

Abstract

The invention discloses a preparation method of bagasse carbon/magnesium iron hydrotalcite composite adsorbent. (1) Dry bagasse, crush it, and carbonize it to obtain bagasse carbon; (2) Mix magnesium chloride solution and ferrous chloride solution, add cetyltrimethylammonium bromide dropwise, mix well, and add step ( 1) The obtained bagasse charcoal is ultrasonically oscillated and left to stand; (3) The mixed solution of sodium hydroxide and sodium carbonate is added dropwise to adjust the pH to 9.0~11; (4) 200 rpm is oscillated and aged in a water bath; (5) Cooled and filtered with suction , washed 3 to 5 times with ultrapure water, when the pH of the washing filtrate = 7.0 ± 0.1, the solid phase precipitate was repeatedly washed with ultrapure water to neutrality, and then dried to obtain bagasse carbon/magnesium iron hydrotalcite composite, That is, bagasse carbon/magnesium-iron LDH; (6) roasting and grinding to obtain bagasse carbon/magnesium-iron hydrotalcite composite adsorbent, namely bagasse carbon/magnesium-iron LDO. The process of the invention is simple and the cost is low; the prepared product can be widely used in the process of advanced treatment of arsenic-containing wastewater in industrial and mining enterprises.

Description

A kind of preparation method of bagasse carbon/magnesium iron hydrotalcite composite adsorbent

technical field

The invention relates to a preparation method of a bagasse carbon/magnesium iron hydrotalcite composite adsorbent, in particular to a method for preparing the bagasse carbon/magnesium iron hydrotalcite composite adsorbent by using bagasse as a main material.

Background technique

With the frequent industrial activities of human beings, the discharge of arsenic-containing wastewater is increasing, and the migration and transformation of arsenic in the water environment are also accelerating, resulting in the accumulation of arsenic in local waters, and the water environment is the source of human and all living things. Essential substances necessary for survival. If organisms ingest polluted water through the food chain, arsenic cannot be degraded in the organism, and it will accumulate in the body, thereby endangering various system organs in the body, leading to some diseases, and milder ones can cause Raynaud's, black skin Disease, hyperkeratosis, etc., seriously lead to cardiovascular and cerebrovascular diseases and various visceral cancers, and even directly lead to death. The current methods for treating arsenic-containing wastewater are generally divided into physical methods, chemical methods and biological methods. There are many researches at home and abroad mainly include coagulation precipitation method, ion exchange method, solvent extraction method, adsorption method, membrane separation method and so on. The precipitation method has great limitations in the treatment of the final product, and a large amount of waste residue containing arsenic and other metals produced cannot be used, which is easy to cause secondary pollution; the ion exchange method has a complicated treatment process, high treatment costs, and is difficult to industrialize; Separation requires a certain amount of drive during operation, which consumes a lot of electric energy; the biological method has a long cycle. The adsorption method has a short period and remarkable effect, and the adsorption material can be regenerated many times, and the cost is low. Therefore, in recent years, many researchers have taken the removal of arsenic by adsorption as a research direction.

Hydrotalcite (Layered Double Hydroxides, abbreviated as LDH) is a layered compound composed of positively charged and negatively charged anions filled between layers, also known as layered double metal hydroxide or anionic clay, is a class of A new type of inorganic functional material with a layered microporous structure. Its general chemical formula is: [M ²⁺ _1-x M ³⁺ _x (OH) ₂ ](A ^n- ) _x/n mH ₂ O, where M ²⁺ and M ³⁺ are respectively located on the main layer The divalent and trivalent metal cations of A ^n- are interlayer inorganic, organic, and complex ions that can be stabilized in alkaline solutions, and X is the molar ratio of M ³⁺ /( M ²⁺ + M ³⁺ ), m is the number of water of crystallization. The main layer of LDH and the interlayer anions are mainly connected by hydrogen bonds, van der Waals force or electrostatic attraction, which makes the interlayer anions of LDH exchangeable. Layered double oxides (Layered Double Oxides, abbreviated as LDO) are the roasted products of LDH. LDO can restore and reconstruct the crystal structure of LDH by obtaining water molecules and anions in the solution, so its saturated adsorption capacity and the stability of the adsorption product are higher than LDH, thus becoming a new type of environmental adsorption material that has attracted much attention. A large amount of literature shows that LDH and LDO have a significant effect on the removal of arsenic. However, hydrotalcite is a powdery solid with a fineness of 0.4-0.6 μm, which has certain difficulties in engineering applications. Bagasse is agricultural waste, which can be converted into bagasse charcoal after carbonization, which has a certain adsorption effect. How to organically combine bagasse charcoal and hydrotalcite to achieve high-efficiency adsorption of arsenic-containing wastewater has a relatively favorable development prospect and practical significance.

Contents of the invention

The object of the present invention is to provide a kind of adopting co-precipitation method and calcination method under normal pressure, with bagasse as main raw material, and magnesium chloride and ferrous chloride as auxiliary materials, to prepare bagasse carbon/magnesium iron hydrotalcite composite adsorbent.

At present, among the arsenic removal materials that have been studied more, the single substances include goethite, nano-iron oxide, nano-metal aluminum powder, activated carbon fiber and titanium dioxide, etc.; the composite substances include hydroxyapatite/bagasse activated carbon, iron oxide Loaded diatomite, ferroferric oxide modified coal slag, alumina loaded porous zeolite balls, iron manganese oxide modified zeolite, etc. The main components of some of these adsorption materials are iron-aluminum oxides, which are also the main substances for arsenic adsorption, while the main components of some adsorption materials are carbon, diatomaceous earth, zeolite and other substances with large specific surface areas. In order to overcome the low adsorption capacity and limited adsorption capacity of the existing arsenic-removing adsorbents, and make full use of the abundant bagasse resources in Guangxi. The invention provides a preparation method of arsenic-removing adsorption material—bagasse carbon/magnesium-iron hydrotalcite composite adsorbent. The composite adsorbent of bagasse charcoal/magnesium iron hydrotalcite not only has a large adsorption capacity, but also when the initial concentration of arsenic-containing water sample is lower than 2.0 mg·L ^-1 . The concentration of arsenic in water samples after adsorption equilibrium was lower than 0.01 mg·L ^-1 .

Concrete preparation steps are:

(1) Dry the bagasse in an oven at 60°C~80°C, crush it with a universal crusher and pass through a 20~40 mesh sieve, and carbonize it in a muffle furnace at 400°C~650°C for 2~4 hours, Obtain bagasse charcoal and set aside.

(2) Add 200 ml of magnesium chloride solution with a concentration of 0.1 mol/L~1.0 mol/L into a 1000 mL beaker, then add 200 mL of ferrous chloride solution with a concentration of 0.025 mol/L~0.25 mol/L dropwise with stirring, and then Stir and drop 100 mL of cetyltrimethylammonium bromide with a concentration of 0.005 mol/L, mix well, add 10 g~25 g of bagasse charcoal obtained in step (1), oscillate with ultrasonic waves for 20~40 minutes, and let stand for 24 ~48 hours.

(3) Add a mixed solution of 1 mol/L sodium hydroxide and 0.5 mol/L sodium carbonate dropwise to the product of step (2) under stirring to adjust the pH at the end of the reaction to 9.0~11.

(4) Place the product obtained in step (3) on a full-temperature biological shaker at 200 rpm for 30 to 60 minutes, then place it in a digital constant temperature water bath and age it in a water bath at 60 ℃ to 90 ℃ for 4 to 8 hours .

(5) Cool the product obtained in step (4) naturally, filter with suction, wash the solid phase precipitate with ultrapure water for 3~5 times, when the pH of the washing filtrate=7.0±0.1, wash the solid phase precipitate with ultrapure water After repeated washing to neutrality, the filter cake was placed in a porcelain plate and dried at 80°C to 110°C for 10 hours to obtain a bagasse charcoal/magnesium-iron hydrotalcite composite, namely bagasse charcoal/magnesium-iron LDH.

(6) Calcining the bagasse carbon/magnesium-iron hydrotalcite composite obtained in step (5) at 400°C-550°C for 2-5 hours, then grinding and passing through a 100-mesh sieve to obtain the bagasse-carbon/magnesium-iron hydrotalcite composite adsorbent, namely Bagasse Char/Magnesium Iron LDO.

The process of the invention is simple and easy, and the bagasse is used as the main raw material, which greatly reduces the production cost and improves various performance indexes of the product; the prepared product can be widely used in the process of advanced treatment of arsenic-containing wastewater in industrial and mining enterprises.

Description of drawings

Fig. 1 is the scanning electron micrograph of bagasse carbon/magnesium iron LDH, bagasse carbon/magnesium iron LDO and the bagasse carbon/magnesium iron LDO after absorbing arsenic that the embodiment of the present invention makes, a: bagasse carbon/magnesium iron LDH; b: Bagasse charcoal/magnesium iron LDO; c: bagasse charcoal/magnesium iron LDO after arsenic adsorption.

Fig. 2 is the X-ray diffraction patterns of bagasse char/magnesium iron LDH, bagasse charcoal/magnesium iron LDO and bagasse charcoal/magnesium iron LDO after arsenic adsorption prepared in the embodiment of the present invention.

Figure 3 shows the adsorption rate of arsenic by bagasse charcoal/magnesium-iron LDO at different initial pH in the examples of the present invention.

detailed description

Example:

(1) Dry the bagasse in an oven at 80°C, crush it with a universal crusher, pass it through a 20-mesh sieve, and carbonize it in a muffle furnace at 450°C for 2 hours to obtain bagasse charcoal for later use.

(2) Add 200 mL of magnesium chloride solution with a concentration of 0.5 mol/L to a 2000 mL beaker, then add 200 mL of ferrous chloride solution with a concentration of 0.125 mol/L with stirring and dropwise, and then add 100 mL of a solution with a concentration of 0.005 mol/L with stirring and dropwise Hexadecyltrimethylammonium bromide, mix well, add 15 g of bagasse charcoal obtained in step (1), ultrasonically sonicate for 30 minutes, and let stand for 24 hours.

(3) Add dropwise a mixed solution of 1 mol/L sodium hydroxide and 0.5 mol/L sodium carbonate to the product of step (2) under stirring to adjust the pH at the end of the reaction to 10.5.

(4) The product obtained in step (3) was placed on a full-temperature biological shaker at 200 rpm for 60 minutes, and then placed in a digital display constant temperature water bath at 80 °C for 6 hours.

(5) Cool the product obtained in step (4) naturally, filter it with suction, wash the solid phase precipitate with ultrapure water for 3 times, when the pH of the washing filtrate=7.0±0.1, end the washing, and put the solid phase precipitate filter cake Dry in a porcelain dish at 80°C for 10 hours to obtain a bagasse carbon/magnesium-iron hydrotalcite composite, namely bagasse carbon/magnesium-iron LDH.

(6) Roast the bagasse carbon/magnesium-iron hydrotalcite composite obtained in step (5) at 450°C for 2 hours, then grind and pass through a 100-mesh sieve to obtain the bagasse carbon/magnesium-iron hydrotalcite composite adsorbent, namely bagasse carbon/magnesium-iron LDO.

The prepared bagasse carbon/magnesium-iron LDH, bagasse carbon/magnesium-iron LDO, and bagasse carbon/magnesium-iron LDO after adsorbing arsenic were observed with JSM-5610LV scanning electron microscope at 5000 times magnification, as shown in Figure 1 shown. The German D8ADVANCE X-ray diffractometer was used for XRD analysis of bagasse carbon/magnesium iron LDH, bagasse carbon/magnesium iron LDO and bagasse carbon/magnesium iron LDO after arsenic adsorption, and the results are shown in Figure 2.

Application example: Experiment on the influence of pH on adsorption

Weigh 0.1 g bagasse carbon/magnesium-iron LDO composite adsorbent into a series of 100mL plastic centrifuge tubes, add 0.1mol/L hydrochloric acid or sodium hydroxide solution to adjust the pH to the set value (2~11), the concentration is 50 mL of 20 mg/L arsenic-containing solution. Each centrifuge tube was then shaken for 24 hours in a full-temperature biological shaker shaker at 25°C. Finally, the centrifuge tube was centrifuged at a speed of 4000 rpm for 5 minutes in a low-speed centrifuge, and then filtered with a 0.45 μm filter membrane. The concentration of arsenic in the solution after adsorption was measured, and the adsorption rate of arsenic by bagasse carbon/magnesium-iron LDO at different initial pHs was obtained. The experimental results are shown in Figure 3.

Claims (1)

1. the preparation method of bagasse charcoal/Mg-Fe ball compound adsorbent, it is characterised in that concretely comprise the following steps:

(1) bagasse is placed in baking oven at 60 DEG C ~ 80 DEG C drying, with crossing 20 ~ 40 mesh sieves after omnipotent crusher in crushing, In Muffle furnace after 400 DEG C ~ 650 DEG C carbonizations 2 ~ 4 hours, it is thus achieved that bagasse charcoal, standby；

(2) in 1000 mL beakers, add the magnesium chloride solution that 200 ml concentration are 0.1 mol/L ~ 1.0 mol/L, be stirred for Dripping 200 mL concentration is 0.025 mol/L ~ 0.25 mol/L solution of ferrous chloride, is stirred for dripping 100 mL concentration and is 0.005 mol/L cetyl trimethylammonium bromide, mix homogeneously, add 10 g ~ 25 g step (1) gained bagasse charcoals, with super Sonication 20 ~ 40 minutes, stands 24 ~ 48 hours；

(3) in step (2) product, under agitation it is added dropwise to 1 mol/L sodium hydroxide and the mixing of 0.5 mol/L sodium carbonate is molten The pH to 9.0 ~ 11 of liquid regulation reaction end；

(4) by step (3) products therefrom, it is placed in after 200 rpm were with vibration 30 ~ 60 minutes on the biological shaking table of full temperature, is subsequently placed in Digital display thermostat water bath is aged 4 ~ 8 hours in 60 DEG C ~ 90 DEG C water-baths；

(5) by step (4) products therefrom natural cooling, sucking filtration, with milli-Q water solid phase precipitation thing 3 ~ 5 times, work as wash filtrate PH=7.0 ± 0.1 time, by solid phase precipitation thing after ultra-pure water cyclic washing to neutrality, filter cake be placed in porcelain dish 80 DEG C ~ It is dried 10 hours at 110 DEG C, obtains bagasse charcoal/Mg-Fe ball complex, i.e. bagasse charcoal/magnesium ferrum LDH；

(6) by step (5) gained bagasse charcoal/Mg-Fe ball complex roasting 2 ~ 5 hours at 400 DEG C ~ 550 DEG C, then Grind, cross 100 mesh sieves, obtain bagasse charcoal/Mg-Fe ball compound adsorbent, i.e. bagasse charcoal/magnesium ferrum LDO.