阅读说明：本技术 一种含硫酸根电镀废水的凝胶化处理及所得凝胶制备泡沫微晶玻璃的方法及产品 (Method for performing gelation treatment on sulfate-containing electroplating wastewater and preparing foam glass ceramics from obtained gel and product ) 是由 刘世权 李云豪 张维娟 于 2019-09-17 设计创作，主要内容包括：本发明公开了一种凝胶化处理含硫酸根的电镀废水及所得凝胶制备泡沫微晶玻璃的方法及产品。该方法先向含硫酸根的电镀废水加入硝酸钡除去硫,再分别加入氧化钙和水玻璃,使废水全部凝胶化。废水中硫酸根转化为可回收的硫酸钡,所得的凝胶经干燥、研磨后直接制备泡沫微晶玻璃。本发明方法的优点是废水全部凝胶化,废水处理过程不产生新的污水排放,产生的凝胶可以完全再利用,无二次污染。凝胶主体为无定型相,含水率高,泡沫微晶玻璃制备过程发泡温度低,无需添加发泡剂和稳泡剂,发泡微晶玻璃制备过程简单,成本低,性能好。(the invention discloses a method for preparing foam glass ceramics by using gelation treatment of sulfate radical-containing electroplating wastewater and obtained gel, and a product. The method comprises the steps of firstly adding barium nitrate into the electroplating wastewater containing sulfate radicals to remove sulfur, and then respectively adding calcium oxide and water glass to completely gelatinize the wastewater. Sulfate radical in the waste water is converted into recoverable barium sulfate, and the obtained gel is dried and ground to directly prepare the foam glass ceramics. The method has the advantages that the waste water is completely gelatinized, no new sewage is generated in the waste water treatment process, the generated gel can be completely reused, and no secondary pollution is caused. The gel main body is an amorphous phase, the water content is high, the foaming temperature in the preparation process of the foam glass ceramics is low, a foaming agent and a foam stabilizer do not need to be added, the preparation process of the foam glass ceramics is simple, the cost is low, and the performance is good.)

1. a method for treating electroplating wastewater containing sulfate radicals is characterized by comprising the following steps:

(1) Adding barium nitrate into the electroplating wastewater, and stirring for reaction to remove sulfate radicals in the wastewater;

(2) Filtering to obtain the primary treated wastewater; drying the filter residue to recover barium sulfate;

(3) adding calcium oxide into the primarily treated wastewater, and uniformly stirring;

(4) Adding water glass into the mixed solution obtained in the step (3), and uniformly stirring;

(5) Standing until the mixed solution in the step (4) is completely gelatinized to form wet gel;

(6) And (5) aging the wet gel, and drying to obtain dry gel.

2. The process of claim 1, further comprising: the barium nitrate is added into the wastewater in the step (1) until no turbidity is generated after the stirring reaction after the barium nitrate is added into the wastewater.

3. The process of claim 1, further comprising: in the step (3), 20 g of calcium oxide is added into each liter of treated wastewater.

4. the process of claim 1, further comprising: the volume ratio of the wastewater to the water glass in the step (4) is 3: 2.

5. the process of claim 1, further comprising: the stirring time in the step (1) is 0.5; and (6) aging for 1 h.

6. The process of claim 1, further comprising: and (4) drying at 100 ℃ for 6 h in the step (6).

7. A xerogel obtained by the method for treating sulfate-containing electroplating wastewater according to any one of claims 1 to 6.

8. A method for preparing foam glass ceramics from xerogel obtained by the method for treating the sulfate-containing electroplating wastewater according to any one of claims 1 to 7, which is characterized by comprising the following steps:

(1) Grinding the xerogel, and sieving with a 100-mesh sieve to obtain gel powder;

(2) The gel powder is pressed and molded in a mould or directly stacked on a refractory plate;

(3) heating to 710-790 ℃ at the rate of 5 ℃/min in a muffle furnace, and preserving heat for a period of time;

(4) And cooling the sample along with the furnace to obtain the foam glass ceramics.

9. the method for preparing foam glass-ceramic according to claim 8, characterized in that: the foaming temperature in the step (3) is 710-790 ℃, and the heat preservation time is 15-60 min.

10. The foamed glass ceramic obtained by the method for preparing foamed glass ceramic according to any one of claims 8 to 9.

Technical Field

the invention relates to a gelation treatment method of electroplating wastewater, a method for preparing a foaming material from obtained gel and a product.

Background

Electroplating wastewater in industrial wastewater becomes one of the main factors for polluting soil and water systems. The electroplating wastewater contains a large amount of heavy metal ions (copper, zinc, chromium, nickel, lead, cadmium and the like), organic compounds, inorganic compounds and other harmful substances, and finally accumulates in organisms under the action of a food chain to destroy the normal physiological metabolic activity of the organisms, thereby having great influence on human health and environment.

the current electroplating wastewater treatment methods comprise an electrolysis method, a precipitation method, an adsorption method, a membrane separation method and the like. Among them, the electrolysis method and the membrane separation method have high cost and are difficult to popularize and apply. The most common method is the combination of precipitation and adsorption, but the waste water after treatment generates a large amount of solid waste and secondary pollution, and the treated waste water still contains a small amount of toxic metal ions and needs to be treated again to be used or discharged into the natural environment.

The foam glass has the characteristics of high porosity, small apparent density, small heat conductivity coefficient, good heat insulation performance, chemical corrosion resistance and the like, and can be used in the fields of heat insulation materials of petrochemical industry, refrigeration houses, inner and outer wall surfaces of buildings and the like. The preparation method is characterized in that waste glass raw materials, carbon black or calcium carbonate and the like are used as foaming agents and are foamed at high temperature, and the foaming process of glass can be accompanied with the generation of microcrystalline phases to form the foamed microcrystalline glass. The foaming process can be roughly divided into several stages of preheating, sintering, foaming, foam stabilizing and annealing. The traditional foaming glass has the disadvantages of high cost of raw materials (glass powder), high foaming temperature and long time, so the price is high, the market competitiveness is weak, and the traditional foaming glass is difficult to be applied in large quantities.

Disclosure of Invention

In order to solve the technical defects, the invention provides a method for treating electroplating wastewater by gelation, which comprises the steps of completely gelatinizing the wastewater by a specific wastewater treatment process and reasonably adding an additive, and fixing all substances in the wastewater in gel; the obtained gel main body is a glass phase and contains a glass fluxing component sodium nitrate, so that the gel main body can be easily vitrified at low temperature and has proper viscosity and tension required by further foaming and foam stabilization; the gel is directly foamed at low temperature by the water solidified in the gel to form the foam glass ceramics with high porosity, low density and low thermal conductivity coefficient.

the invention is realized by the following measures:

Firstly, adding barium nitrate into the electroplating wastewater to remove sulfate ions in the electroplating wastewater, and recovering barium sulfate. The electroplating wastewater without sulfate provides an acid environment for the whole reaction system, the pH value of the system is adjusted by calcium oxide to promote the water glass to generate sol-gel reaction, and a gel material still containing a large amount of bound water or hydroxyl is obtained after the steps of aging and drying.

The method comprises the following specific operation steps:

(1) Adding barium nitrate into the electroplating wastewater, and stirring for reaction to remove sulfate radicals in the wastewater;

(2) Filtering to obtain the primary treated wastewater; drying the filter residue to recover barium sulfate;

(3) Adding calcium oxide into the primarily treated wastewater, and uniformly stirring;

(4) adding water glass into the mixed solution obtained in the step (3), and uniformly stirring;

(5) Standing until the mixed solution in the step (4) is completely gelatinized to form wet gel;

(6) And (5) aging the wet gel, and drying to obtain dry gel.

the barium nitrate is added into the wastewater in the step (1) until no turbidity is generated after the stirring reaction after the barium nitrate is added into the wastewater. Taking the copper electroplating wastewater as an example, wherein the sulfur content measured by ICP is 3583.9mg/L, and the addition amount of barium nitrate in each liter of wastewater is 52 g; the stirring time was 0.5 h.

the addition amount of the calcium oxide in the step (3) is 20 g per liter of wastewater.

The water glass in the step (4) is a commercial product, and the modulus of the water glass is 3.3; the volume ratio of the waste water to the water glass is 3: 2.

The stirring time in the steps (3) and (4) is only required to be uniformly distributed by the additives, and the stirring time is short, such as 10s and 30s in practice in experiments.

The aging time in the step (6) is 1h, the drying temperature is 100 ℃ and the drying time is 6 h.

The wet gel is generated in the step (5), and all water and metal ions in the wastewater exist in the wet gel. Iron, copper, sodium, calcium, magnesium ions and the like in the copper electroplating wastewater are all present in the wet gel; the obtained wet gel loses 59 percent of water in the drying process in the step (6), and the solidified water in the dried gel is 32.13 percent after drying.

through XRD analysis, the obtained gel presents a typical steamed bun peak in the range of 20-40 degrees, and the gel main body is an amorphous glass phase. In addition, diffraction peaks in the XRD pattern showed that the sample also contained NaNO3 and a crystalline phase of soda-lime-silicate (Na2Ca3Si6O 16); wherein the former is formed by the reaction of nitrate radical brought in by barium nitrate and sodium oxide brought in by water glass, and the latter is formed by the reaction of additives.

The invention also provides a method for preparing the foam microcrystalline glass from the xerogel obtained in the wastewater treatment process and the obtained foam microcrystalline glass, and provides a new idea for recycling waste generated in the wastewater treatment process.

The method for preparing the foam glass ceramics from the xerogel generated by the wastewater treatment comprises the following specific steps:

(1) grinding the xerogel, and sieving with a 100-mesh sieve to obtain gel powder;

(2) The powder is pressed and molded in a die or directly stacked on a refractory plate;

(3) heating to 710-790 ℃ at the rate of 5 ℃ per min in a muffle furnace, and preserving heat for 15-60 min;

(4) And cooling the sample along with the furnace to obtain the foam glass ceramics.

xerogels contain a large amount of glass phase as well as moisture and hydroxyl groups, are easily vitrified and foamed at low temperatures, and are accompanied by crystallization. The foaming temperature in the step (3) is lower than that of the foaming temperature of the traditional foam glass prepared from waste glass by more than 200 ℃, and the energy-saving effect is remarkable; waste heat generated by foaming equipment can be used for drying wet gel, and the heat utilization rate is improved. Preferably, the foaming temperature is 710-790 ℃. The foaming temperature is too low, and the foaming effect is not obvious; the foaming temperature is too high, and a serious reverse shrinkage phenomenon is generated after foaming.

the obtained foam microcrystalline glass contains a crystal phase of sodium silicate (Na6Si2O7) and sodium calcium silicate (Na2Ca3Si6O16) and a residual glass phase through XRD detection. The strength of the crystalline phase gradually decreases with increasing processing temperature.

the properties of the resulting foamed glass-ceramic are influenced by the foaming temperature. When the foaming temperature is 710-790 ℃, the apparent density of the obtained sample is 0.2949-0.3467 g/cm3, the porosity is 81.7-82.84%, and the thermal conductivity is 0.0813-0.1178W/(m.K).

Has the advantages that: the wastewater treatment process is simple, and sulfate radicals in the wastewater are converted into recyclable barium sulfate; the wastewater is completely gelatinized, the gel main body is an amorphous phase, the water content is high, and the gel is easy to foam after being heated; the foaming temperature is low in the preparation process of the foam glass ceramics, and a foaming agent and a foam stabilizer do not need to be added; the preparation process of the foamed microcrystalline glass is simple, the cost is low, and the performance is good; no new sewage discharge is generated in the wastewater treatment process, and no solid waste generates secondary pollution.

drawings

Figure 1 is the XRD pattern of BaSO4 recovered in example 1.

FIG. 2 is an XRD pattern of the xerogel obtained in example 1.

Figure 3 is the XRD pattern of the foamed glass ceramic obtained in example 2.

Detailed Description

the present invention will be described in further detail with reference to the following specific embodiments, which are only used to more clearly illustrate the technical solutions of the present patent, but not to limit the scope of the present invention.

And analyzing the crystal structure of the sample by XRD, detecting the density and porosity of the foamed glass-ceramic sample prepared from the xerogel by a drainage method, and detecting the heat conductivity coefficient of the foamed glass-ceramic by a transient hot wire method.

The following are specific examples:

Example 1

(1) adding 52g of barium nitrate into 1L of copper electroplating wastewater, and stirring for reaction for 0.5 h;

(2) Filtering to obtain BaSO4 filter residue and primarily treated wastewater;

(3) Adding 20 g of calcium oxide into 1L of primarily treated wastewater, and stirring for 10 s;

(4) Adding 667 ml of water glass into the mixed solution and stirring for 30 s;

(5) Standing for 4 h to obtain wet gel;

(6) Aging for 1h, and drying in a 100 ℃ oven to obtain xerogel.

drying the filter residue obtained in the step (1), detecting the filter residue to be BaSO4 (shown in figure 1) by XRD, and recycling the filter residue.

The obtained wet gel loses 59 percent of water in the drying process in the step (5), and the solidified water in the dried gel is 32.13 percent after drying. The main crystalline phases of the xerogel samples were the sodium nitrate (NaNO3) and the sodium calcium silicate (Na2Ca3Si6O16) phases as analyzed by XRD diffraction (see FIG. 2).