CN100448524C - A kind of manufacture method of inorganic modified bentonite chromium removal agent - Google Patents

Abstract

A method for manufacturing an inorganic modified bentonite chromium removal agent, relating to a method for manufacturing an inorganic adsorbent, the method comprising the following steps: 1) washing, purifying, drying, and pulverizing calcium-based bentonite raw ore to obtain refined calcium-based bentonite; 2) Prepare a soluble salt solution with a mass concentration of 5-30%; 3) Mix activated carbon, soluble salt solution and calcium-based bentonite through a 100-200 mesh sieve, stir for 5-15 minutes, and let stand for 10-30 minutes; 4) Mix the Put the aged mixture into a muffle furnace, raise it to 360-420°C at a rate of 10-30°C/min, and roast at this temperature for 1-2 hours; Diameter chrome remover products. The removal of Cr(VI) by the chromium removing agent of the present invention is mainly based on surface complexation and electrostatic adsorption, and the adsorbed Cr(VI) pollutants are very stable and are not easy to form secondary pollution.

Description

A kind of manufacture method of inorganic modified bentonite chromium removal agent

technical field

The invention relates to a method for manufacturing an inorganic adsorbent, in particular to a method for modifying calcium-based bentonite by adding carbon and roasting with inorganic salt as a modifying agent.

Background technique

At present, the known inorganic modification methods of bentonite mainly include acid modification, salt modification, roasting modification and the like. Inorganically modified bentonite can be used as an adsorbent in water and soil polluted by inorganic or organic matter. Its cost is low and it has a greater price advantage than activated carbon adsorbents. However, bentonite adsorbents prepared by the above inorganic modification methods will Suspended solids that are difficult to settle are generated, which increases the difficulty of solid-liquid separation after water treatment. At the same time, the removal effect of pollutants such as Cr(VI) which is hundreds of times more toxic than Cr(III) is not good, and there are problems such as secondary pollution.

Contents of the invention

The object of the present invention is to provide a kind of method that inorganic salt is modified calcium-based bentonite by adding carbon and roasting and modifying. In this method, the raw ore of bentonite is washed, purified, dried and pulverized to obtain refined calcium-based bentonite. Calcium-based bentonite and an inorganic salt are modified by adding carbon and roasting at a certain temperature and a certain time, and the chromium removal agent prepared by the invention has good adsorption performance.

The purpose of the present invention is achieved through the following technical solutions:

A method for manufacturing an inorganic modified bentonite chromium removal agent, the method comprising the following steps: 1) washing, purifying, drying, and pulverizing calcium-based bentonite raw ore to obtain refined calcium-based bentonite; 2) preparing a mass concentration of 5-30% ₃ ) Mix activated carbon, inorganic salt solution _{Al 2 (} SO ₄ ) ₃ and refined calcium-based bentonite through _a 100-200 mesh sieve, stir for 5-15 minutes, and let stand for 10-20 minutes 30min; 4) Put the mixture after standing in a muffle furnace, raise it to 360-420°C at a rate of 10-30°C/min, and roast at this temperature for 1-2h; 5) Use a pulverizer to pulverize, that is Chromium remover products with desired particle size can be obtained.

According to the above-mentioned manufacturing method of an inorganic modified bentonite chromium remover, the drying is carried out at a temperature of 85-105°C.

Advantage and effect of the present invention are:

1. The chromium-removing agent of the present invention has higher removal rate to chromium (VI), easy solid-liquid separation, and no secondary pollution; its reaction raw materials are cheap and easy to obtain, the preparation method has few steps, safe operation, low energy consumption, and short cycle .

2. The removal of Cr(VI) by the chromium remover of the present invention is mainly based on surface complexation and electrostatic adsorption, and the adsorbed Cr(VI) pollutants will be very stable and difficult to reactivate to form secondary pollution.

Detailed ways

First, wash, purify, dry and pulverize the bentonite raw ore to obtain refined calcium-based bentonite. Mix activated carbon, soluble salt solution and refined calcium-based bentonite through a 100-200 mesh sieve according to the corresponding proportion, stir for 5-15 minutes, and let stand for 10-200 minutes. After 30 minutes, put the mixture after standing still into a muffle furnace and gradually increase the temperature to 360-420°C for 1-2 hours, and then pulverize it with a pulverizer to obtain the chromium remover product of the present invention with the required particle size.

The determination of the roasting time of the present invention is based on the principle of removing calcium-based bentonite surface water, bound water and impurities in the voids. If the roasting time is too long, the bentonite sheet-like structure will be sintered and piled up, which will reduce the porosity and pore size. The performance is reduced and the processing cost is increased, so the roasting time is determined to be 1 to 2 hours.

The present invention relates to calcining calcium-based bentonite at different temperatures, which can successively lose surface water, hydration water and bound water in the skeleton, increase the specific surface area, and reduce the adsorption resistance of the water film to Cr(VI). Calcium-based bentonite is calcined at 360-420 °C to drive away the surface water in the structural channel without destroying the skeleton structure, and the adsorption performance is improved; when it exceeds 360-420 °C, the bound water will be gradually lost, and the OH-structure skeleton will be broken, which is beneficial Structural destruction of adsorption. Therefore, the best firing temperature is 360-420°C.

Inorganic salt involved in the present invention is as a kind of modifying agent, and the Al that provides has exchanged the low-valent cation in the calcium-based bentonite, has reduced the negative charge between montmorillonite lattice, thereby has reduced bentonite to Cr( ^VI ) Anionic electrostatic repulsion. At the same time, the inorganic salt acts as an electrolyte and acts as a bridge between the modified bentonite and the Cr(VI) anion. Considering factors such as removal effect and cost, the best dosage of inorganic salt is 5-30g per 100g of calcium-based bentonite.

The activated carbon involved in the present invention is oxidized by water vapor and oxygen at high temperature, and a series of reactions occur to produce CO, CO ₂ , H ₂ and other gases. When these gases expand and escape at high temperature, small pores are formed in the bentonite, further The specific surface area of bentonite is increased, and the adsorption performance is improved. At the same time, the adsorbent prepared by roasting activated carbon can realize solid-liquid separation after water treatment after a short period of standing, which solves the difficult problem of solid-liquid separation after water treatment by traditional modification methods. However, when the content of activated carbon is too high, the pore size of bentonite will become larger, the structure will be loose and brittle, and the adsorption performance of Cr(VI) will be reduced. The best dosage of activated carbon is 1-5g per 100g of calcium-based bentonite.

The present invention is further illustrated by the following examples.

Take 6.5L of deionized water and put it into a 12L round plastic bucket, slowly add 1000g of bentonite raw ore under stirring, stir to form a slurry, and soak for 24 hours. After stirring for 15 minutes, add 3.5L of water, continue beating for 10 minutes, and let stand for 4 hours to remove impurities at the bottom. Suck out the upper suspension slurry of impurities, stir for 15 minutes, let stand for 8 hours, and separate the coarse soil. The upper suspension slurry after sucking out the coarse soil was stirred for 15 minutes, left to stand for 12 hours, and the middle soil was separated, and finally the upper suspension slurry (fine soil) after the middle soil was sucked out was left standing, after the supernatant was sucked out, the remaining mud was placed Put it in a tray and dry it in a drying oven at 95°C, pulverize it with a pulverizer, and pass through an 80-mesh sieve to obtain refined calcium-based bentonite with a yield of 56%. Mix 3g of activated carbon passed through a 200 mesh sieve, 100ml of a 25% Al ₂ (SO ₄ ) ₃ solution, and 100g of refined calcium-based bentonite according to the corresponding ratio, stir for 10 minutes, let stand for 30 minutes, and then put it into a muffle furnace , raised to 420°C at a rate of 30°C/min, roasted at this temperature for 2 hours, and pulverized by a pulverizer to obtain the chromium remover product of the present invention with the required particle size.

Adopting 10g80 order chromium removing agent product of the present invention is that temperature is 13.5 ℃, pH is 1L water concentration of 7.5 and is 1mg/L Cr (VI) removal effect is better, and removal rate reaches 98.21%, and Cr (VI) concentration reaches after treatment. The water quality of groundwater is Class III standard, and it has the advantages of easy solid-liquid separation and no secondary pollution. It will have a good application prospect in the restoration of contaminated soil and groundwater.

Claims (2)

1. the manufacture method of an inorganic modified bentonite chromium remover is characterized in that this method comprises the steps: 1) the raw ore of calcium base bentonite washing is purified, dries, pulverized, get the redistilled calcium base bentonite; 2) the preparation mass concentration is 5～30% inorganic salt solution Al ₂(SO ₄) ₃3) will cross active carbon, the inorganic salt solution Al of 100～200 mesh sieves ₂(SO ₄) ₃Mix with the redistilled calcium base bentonite, stir 5～15min, leave standstill 10～30min; 4) mixture after will leaving standstill is put into Muffle furnace, is elevated to 360～420 ℃ with 10～30 ℃/min speed, at this roasting temperature 1～2h; 5) utilize pulverizer to pulverize, can obtain the chromium remover product of required particle diameter.

2. the manufacture method of a kind of inorganic modified bentonite chromium remover according to claim 1 is characterized in that described oven dry is is to carry out under 85～105 ℃ in temperature.