CN103896356A - Adsorption of novel tourmaline material on cadmium in acid solution - Google Patents

Abstract

The invention aims at the problems existing in the heavy metal pollution treatment technology, especially the problem of low adsorption capacity when the adsorbent is used to treat heavy metals in acidic water, and establishes a novel material tourmaline which has better adsorption technology for cadmium ions in acidic solution. The adsorption of tourmaline on Cd ²⁺ ions is affected by adsorption time, temperature and initial concentration. Tourmaline has two stages of fast and slow adsorption of Cd ²⁺ ions. Before 6 hours, tourmaline adsorbs Cd ²⁺ ions rapidly, and after 24 hours, it basically reaches equilibrium. After 48 hours, the removal rate of tourmaline for Cd ²⁺ ions can reach Reached 59.10%; Tourmaline has a good removal effect on Cd ²⁺ under acidic, neutral and alkaline conditions, and tourmaline has a good removal effect on Cd ²⁺ ions when the pH of the solution is 4.0 and the temperature is 15, 25 and 35 °C The saturated adsorption capacity of 31.77, 33.11 and 40.16mg/g respectively. Under the same temperature conditions, when the pH of the solution is 4.0, the higher the initial concentration of the solution, the greater the adsorption amount of tourmaline to Cd ²⁺ . With the increase of temperature, the adsorption amount of tourmaline to Cd ²⁺ increases. Tourmaline can be used for the adsorption of heavy metals in acidic solutions, and the invention provides new materials and theoretical basis for wastewater treatment, especially the treatment of heavy metal pollution in acidic wastewater.

Description

Adsorption of Cadmium in Acidic Solution by A New Material Tourmaline

technical field

The invention belongs to the field of environmental heavy metal pollution control, and in particular relates to the application of a novel material tourmaline in the treatment of heavy metal pollution in waste water, especially acid waste water.

technical background

With the advancement of industrialization and urbanization, electroplating, printing and dyeing, mining, metallurgy and chemical industry produce a large amount of wastewater containing heavy metal ions every year, resulting in increasingly serious heavy metal pollution. Heavy metals are difficult to degrade and can be bioaccumulated through the food chain, posing a serious threat to organisms and human health, especially cadmium (Cd) entering the human body and mainly accumulating in the liver, kidney, pancreas, thyroid and bones, causing anemia and high blood pressure , Neuralgia, osteoporosis, nephritis and secretion disorders and other diseases. How to effectively control heavy metal pollution in wastewater has become a common concern.

Common methods for treating heavy metal wastewater mainly include adsorption, chemical precipitation, ion exchange, and membrane separation. Among them, chemical precipitation, ion exchange, and membrane separation have the problem of high cost for the treatment of heavy metal pollution in wastewater, and adsorption method has become a very effective and common method. In recent years, many natural mineral adsorbents such as zeolite, quartz, apatite, goethite, calcite, dolomite, etc. have been applied in the research of heavy metal adsorption in water. However, these adsorbents have low adsorption capacity when used to treat acidic water for heavy metal adsorption. Therefore, seeking new materials that can treat heavy metal pollution in acidic wastewater is a hot issue in environmental science.

Tourmaline is a good eco-intelligence and functional material, and also a good green environmental protection material. It is a typical high-temperature gas-forming mineral, and its chemical composition is very complex. It was not until the crystal structure of tourmaline was determined that a more reasonable compositional formula was proposed. The general formula is XYZSi ₆ O ₁₈ (BO ₃ ) ₃ W ₄ , where X=Na ⁺ , Ca ²⁺ , K ⁺ or vacancies; Y= Mg ²⁺ , Fe ²⁺ , Mn ²⁺ , Al ³⁺ , Fe ³⁺ , Mn ³⁺ , Cr ³⁺ , Ti ⁴⁺ , Li ⁺ ; Z=Al ³⁺ , Fe ³⁺ , Cr ³⁺ , Mg ²⁺ ; W=OH ^- , F, O ^2- , X, Y, and Z are different types of atoms and ions, resulting in different components and colors of tourmaline. Tourmaline has the characteristics of spontaneous polarization of permanent spontaneous electrostatic field, radiation of far infrared rays, release of negative ions, continuous occurrence of DC static electricity, release of minerals and trace elements.

In 2011, Wang Cuiping and others used tourmaline to adsorb heavy metal ions close to industrial strong acid wastewater for the first time, basically overcoming the problem of difficult adsorption of heavy metals in acid wastewater by adsorption method, and providing a new adsorption material and treatment technology for acid wastewater treatment

Contents of the invention

Aiming at the problem of difficult treatment of acidic heavy metal pollution and low adsorption capacity, the present invention proposes a new type of material - tourmaline, which can quickly and effectively remove Cd ²⁺ in strongly acidic wastewater.

Detailed description of the invention:

In the strongly acidic solution polluted by heavy metals, a small amount of tourmaline is added to evaluate the adsorption characteristics and adsorption capacity of heavy metals. The tourmaline particle size used in the present invention is the tourmaline of 800nm, purchased from Tianjin Hongyan Mineral Products Co., Ltd., the tourmaline produced in Xinjiang. The main chemical composition is: SiO ₂ 36.75%, Al ₂ O ₃ 33.62%, Fe ₂ O ₃ 12.19%, TiO ₂ 0.57%, B ₂ O ₃ 9.78%, FeO 1.7%, CaO 0.4%, MgO 4.76%, K ₂ O 0.14%, _Na2O 0.74%, _{P2O5 0.19} %, _H3O ⁺ 1.0%, and MnO 0.21%.

Specific process parameters:

1. The effect of adsorption time on the removal of Cd ²⁺ by tourmaline

The dosage of tourmaline is 6g/L, the concentration of cadmium ion solution is 100mg/L, the pH of the solution is 4.0, and the adsorption time is 5min-48h.

2. The effect of pH value on the removal of Cd ²⁺ by tourmaline

In order to investigate the adsorption capacity of tourmaline to heavy metals in different pH solutions, adjust the Cd ²⁺ solution by 2-8, the adsorption time is 24h, the dosage of tourmaline is 2g/L, and the concentration of cadmium ion solution is 100mg/L.

3. The effect of temperature on the removal of Cd ²⁺ by tourmaline

In order to be close to the actual temperature of the environment, the temperature of this experiment is 15, 25 and 35 degrees respectively, the pH of the solution is 4, the adsorption time is 24h, the dosage of tourmaline is 2g/L, and the concentration of cadmium ion solution is 100mg/L.

4. Evaluation of the adsorption performance of tourmaline on Cd ²⁺ in acidic solution

The normal temperature is 25 degrees, the pH of the solution is 4, the adsorption time is 24 hours, and the amount of tourmaline is 2 g/L.

Description of drawings

Fig.1 Adsorption kinetics of tourmaline in strongly acidic solution for Cd ²⁺

Fig.2 Adsorption of tourmaline on Cd ²⁺ in different pH solutions

Fig.3 Effect of initial concentration and temperature on the adsorption effect of Cd ²⁺ ions

Fig.4 The adsorption isotherms of tourmaline on Cd ²⁺ ions at different temperatures

In order to better understand the contents of the present invention, the present invention will be further described below through examples, but the examples given do not limit the protection scope of the present invention.

Detailed ways

(1) Solution preparation: Accurately weigh 2.745g of cadmium nitrate (analytically pure, Tianjin Beike Chemicals Co., Ltd.), add 10mL1mol/L HNO ₃ , and dilute it in a 1L volumetric flask with distilled water to prepare 1g/L Ion stock solution of L. Take 25, 50, 75, 100, 125, 150, 175, and 200mL of ion stock solution respectively, and use distilled water to fix the volume in a 500mL volumetric flask to prepare 50, 100, 150, 200, 250, 300, 350, and 400mg/L The heavy metal ion solution was stored in a 4°C refrigerator away from light.

(2) Explain the adsorption effect of different adsorption time from the kinetic point of view

In order to obtain the adsorption kinetics characteristics of tourmaline on Cd ²⁺ ions in acidic solution, adjust the pH of Cd(NO ₃ ) ₂ solution to 4.0, and adjust the amount of tourmaline to 6 g/L when the adsorption temperature is 25°C, and the cadmium ions The concentration of the solution was 100mg/L, and the kinetic adsorption test of heavy metal ions was carried out. It can be seen from Figure 1 that tourmaline has two stages of fast and slow adsorption on Cd ²⁺ ions. Before 6h, tourmaline adsorbs Cd ²⁺ ions rapidly, and after 24h it basically reaches equilibrium. The removal rate of Cd ²⁺ ions can reach 59.10%.

Calculated by the Langmuir model, the saturation adsorption capacity of tourmaline to Cd ²⁺ ions is 31.77, 33.11 and 40.16 mg/g at pH 4.0 and temperature 15, 25 and 35 ℃, respectively. Therefore, tourmaline has a good adsorption effect on Cd ²⁺ in acidic solution.

(3) Adsorption characteristics of tourmaline under different pH conditions

Adjust the initial pH of the Cd(NO ₃ ) ₂ solution with a concentration of 100 mg/L to 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, and 8.0, the amount of tourmaline is 4 g/L, and the adsorption temperature is 25°C. Time 24h.

As can be seen from accompanying drawing 2, when solution pH is lower than 4.0, tourmaline is lower than 12% to the adsorption rate of ^Cd ion; pH is between 4.0～6.0, and adsorption rate is 31%～49%; Neutral and Under alkaline conditions, the adsorption rate of tourmaline to Cd ²⁺ is 55%-59%. It shows that tourmaline has a good removal effect on Cd ²⁺ under acidic, neutral and alkaline conditions, especially under strong acidic conditions (relative to the acidity of industrial wastewater), tourmaline still has good adsorption on Cd ²⁺ Efficiency, which mainly comes down to the ability of tourmaline to automatically adjust the pH of acidic (except pH 2.0 and 3.0), neutral or alkaline solutions to around 6.4.

(4) Effect of initial concentration and temperature on the adsorption characteristics of tourmaline

The adsorption time is 24h, the initial pH of the Cd(NO ₃ ) ₂ solution is adjusted to 4.0, the amount of tourmaline is 2g/L, and the initial concentration of Cd(NO ₃ ) ₂ is 50, 100, 150, 200, 250, 300, 350, 400mg/L, the adsorption experiments were carried out at different temperatures. It can be seen from Figure 3 that under the same temperature conditions, the higher the initial concentration of the solution, the greater the adsorption capacity of tourmaline to Cd ²⁺ . With the increase of temperature, the adsorption amount of tourmaline to Cd ²⁺ increases.

(5) Evaluation of the adsorption performance of tourmaline on Cd ²⁺ in acidic solution

Using the adsorption Freundlich and Langmuir isotherm adsorption model to evaluate the adsorption performance of tourmaline at different temperatures and concentrations for Cd ²⁺ ions is shown in Figure 4, Table 2.

Tourmaline is superior to other mineral materials in adsorption of Cd ²⁺ ions in strongly acidic solution (Table 2).

Table 1 Isothermal adsorption parameters of Cd ²⁺ on tourmaline at different temperatures

Table 2 Comparison of different natural adsorbents for Cd(II) ion adsorption (Langmuir model, unit: mg/g)

The invention proves that the adsorption process of tourmaline to Cd ²⁺ ions in solution is affected by adsorption time, solution pH, system temperature and initial concentration of ions; tourmaline can be used for the adsorption of Cd ²⁺ ions in strong acid solution.

Claims (3)

1. Established a new material-tourmaline adsorption technology for cadmium ions in strong acid solution. 2. The adsorption characteristics of tourmaline in claim 1 to cadmium ions in strong acidic solution: The adsorption of tourmaline to Cd ²⁺ is rapid before 6h, and basically reaches equilibrium after 24h; The higher the initial concentration of Cd ²⁺ in the solution, the greater the adsorption capacity of tourmaline to Cd ²⁺ ; With the increase of temperature, the adsorption amount of tourmaline to Cd ²⁺ increases; When the pH of the solution is 4.0 and the temperature is 15, 25 and 35℃, the saturated adsorption capacity of tourmaline to Cd ²⁺ ions is 31.77, 33.11 and 40.16 mg/g, respectively. 3. The tourmaline described in claims 1 and 2 can be used for the adsorption of acidic single or coexisting heavy metal ions, or the treatment of actual acidic wastewater.

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