CN1388256A - Method of recovering Pd from low-concentration waste Pd ion liquid with becteria thallus - Google Patents

Abstract

The invention relates to a method for recovering trace precious metals, and the bacteria used are bacillus licheniformis, strain number R08. First, mix the R08 bacterial cell solution with a bacterial cell concentration of 0.4-2.0 g/L and a Pd ²⁺ aqueous solution with a concentration of 30-300 mg/L. Oscillate at an oscillation frequency of 3-90min times/min, then filter the Pd ²⁺ cell action solution, place the filtered Pd ²⁺ -adsorbed cell at room temperature for 6-48 hours, and finally burn at 550-800°C for 1.5- After 3h, metal palladium was obtained. The method is simple and low in cost, and is especially suitable for recovering palladium from low-concentration Pd ²⁺ solution, and the adsorption rate of Pd ²⁺ can be as high as 99%.

Description

Method for recovering palladium from low-concentration palladium ion waste liquid with bacterial cells

(1) Technical field

The invention relates to a method for recovering trace precious metals.

(2) Background technology

Precious metals such as palladium are indispensable and important raw materials in industrial production such as national defense, chemical industry, petroleum refining and electronics. With the development of industrial technology, the application of precious metals is becoming more and more extensive. However, precious metal resources such as palladium are scarce and rare. Therefore, all countries attach great importance to the recycling of precious metals. Currently, methods for recovering precious metals such as palladium from solutions include activated carbon adsorption, ion exchange, chemical precipitation, electrolysis, and solvent extraction. The process of these methods is loaded down with trivial details and easily causes secondary pollution, especially when the noble metal ion content in the solution is low, it is uneconomical to use the above-mentioned recovery method. Brierly et al. (Biohydrometa, Proc Int Symp, 1988, 477) used dead bacteria to prepare granular metal remover to recover palladium from 10mgPd ²⁺ /L solution. Lloyd et al. (ApplEnviron Microbiol, 1998, 4607) reported that Desulfovibriodesulfuricanns quiescent cells were able to reduce soluble Pd ²⁺ to metallic palladium (Pd ⁰ ). It has been reported (Mreeoun et al J ApplMicrobiol, 1998, 84:63) that living or dead intact microbial cells and their metabolites can efficiently adsorb soluble and particulate metals, especially from low-soluble Recovery of precious metals from metal ions. Many studies have shown that the adsorption of dead microbial cells to metal ions has the characteristics of fast speed, high selectivity, and large adsorption capacity (Niu Hui et al., 1993, 33(6): 459).

(3) Contents of the invention

The purpose of the present invention aims to provide a kind of method that utilizes bacterial cell to reclaim palladium from the palladium ion waste liquid of low concentration.

The microbial adsorbent used in the present invention is a bacterial strain R08 with a strong ability to adsorb and reduce Pa ²⁺ isolated and screened from the environment of the metal mining area. It has been identified as Bacillus licheniformis. The Committee's General Microbiology Center, the registration number is 0503, and the strain number is RO8.

The present invention uses R08 bacterium to absorb Pd ²⁺ in the reduction solution, and its operation, analysis and determination methods are as follows:

First, mix the bacterial cell solution with the Pd ²⁺ aqueous solution, the bacterial concentration is 0.4-2.0g/L, preferably 0.8-1.6g/L, and the Pd ²⁺ concentration is 30-300mg/L. Under the conditions of pH 1.0-3.8, preferably pH 2.0-3.5, shake at an oscillation frequency of 130 times/min for 3-90 minutes, preferably 30-60 minutes, so that the bacteria can fully adsorb Pd ²⁺ . Then filter the Pd ²⁺ -bacteria action solution with a filter membrane with a pore size of 0.22um, so as to separate the adsorbed Pd ²⁺ bacteria from the residual Pd ²⁺ solution. Pd ²⁺ adsorbed bacteria obtained by filtration are placed at room temperature for 6-48 hours, preferably 18-36 hours, and then burned at 550-800°C for 1.5-3 hours to recover metal palladium. The residual Pd2 ⁺ concentration of the filtrate was measured with a WFX-IE2 atomic absorption spectrophotometer, and the adsorption rate and adsorption amount of the bacteria to Pd2 ⁺ were calculated according to the following formula:

Adsorption rate (%)=(C _i -C _f )/C _i ×100%

Adsorption capacity (mg/g dry cells) = (C _i -C _f )/C _b

In the formula, C _i and C _f are the initial and final concentrations of Pd ²⁺ (mg/L), respectively, and C _b is the bacterial concentration (g/L).

Observation with a transmission electron microscope (TEM) showed that there were Pd ⁰ particles on the cell wall after the R08 cells were in contact with the Pd ²⁺ solution for 6h to 48h. The method provided by the invention is simple and low in cost, and is particularly suitable for recovering palladium from a low-concentration Pd ²⁺ solution, and the adsorption rate of Pb ²⁺ can be as high as 99%.

(4) specific implementation

The present invention will be further described below by embodiment.

Example 1:

Mix the R08 dead bacterial cell solution with a cell concentration of 1.2g/L and the Pd ²⁺ solution with an initial concentration of 200mg/L, adjust the pH value to 3.5, and at 30°C, press the oscillation frequency of 130 times/min Shake the mixed solution for 45 minutes, then filter the Pd ²⁺ - cell action solution with a filter membrane with a pore size of 0.22mm, place the cell adsorbed by Pd ²⁺ at room temperature for 24 hours, and finally recover metal palladium after burning at 600°C. After determination and analysis, the adsorption capacity of R08 bacteria to Pd ²⁺ can reach 149.0 mg/g bacteria, and the adsorption rate is 89.4%.

Embodiment 2～9:

Under the conditions of initial Pd ²⁺ concentration of 200 mg/L, cell concentration of 0.8 g/L, pH 3.0 and 25°C, the adsorption was carried out for different times, and the effect of adsorption time on the adsorption of Pd ²⁺ by cells was determined. Other operations are with embodiment 1, and result is as follows:

Example Time (min) Adsorption capacity (mg/g) Adsorption rate (%)

2 3 139.4 58.1

3 8 147.4 61.4

4 11 152.2 63.4

5 15 156.3 65.1

6 30 164.1 68.4

7 45 177.1 70.8

8 60 175.2 70.1

9 90 176.5 70.6

Examples 10-13

Adjust the PdCl ₂ solution to different pH values, ^and under the conditions of the initial Pd ²⁺ concentration of 100 mg/L, the bacterial concentration of 0.8 g/L and 25°C, adsorb for 45 minutes, and measure the adsorption rate and Adsorption capacity. Others are the same as in Example 1, the bacterial cells adsorbing Pb ²⁺ are filtered, placed for 18 hours, and burned at 550° C. for 3 hours to recover metal palladium. The result is as follows:

Example pH value Adsorption capacity (mg/g) Adsorption rate (%)

10 1.0 58.8 47.0

11 2.0 87.9 70.3

12 3.0 107.3 85.8

13 3.5 116.5 93.2

Examples 14-19

Change the temperature of adsorption, under the conditions of initial Pd ²⁺ concentration of 200mg/L, bacterial concentration of 0.8g/L and pH3.5, adsorption was carried out for 45min, and the effect of temperature on the adsorption of Pd ²⁺ by bacteria was determined. The rest are the same as in Example 1. After the bacteria cells are left for 36 hours, they are burned at 800° C. for 1.5 hours to recover metal palladium. The result is as follows:

Example Temperature (°C) Adsorption capacity (mg/g) Adsorption rate (%)

14 5 190.4 76.2

15 20 196.0 78.4

16 30 196.7 78.7

17 40 197.6 79.0

18 50 201.3 81.3

19 60 202.2 81.3

Examples 20-23

Change the concentration of bacteria for adsorption, under the conditions of initial Pd ²⁺ concentration of 200 mg/L, pH 3.5 and 30°C, adsorb for 45 minutes, and determine the effect of bacteria concentration on the adsorption of Pd ²⁺ by bacteria. The result is as follows:

Example Cell concentration (g/L) C _i : C _b (mg/g) Adsorption amount (mg/g) Adsorption rate (%)

20 0.4 500 224.8 45.0

21 0.8 250 175.2 70.1

22 1.6 125 115.5 92.4

23 2.0 100 94.4 94.4

C _i : C _{b :} ratio of initial Pd ²⁺ concentration to cell concentration.

Examples 24-33

Change the initial concentration of Pd ²⁺ for adsorption, under the conditions of cell concentration 0.8g/L, pH 3.5 and 30°C, adsorb for 45min, and determine the effect of the initial concentration of Pd ²⁺ on cell adsorption of Pd ²⁺ . The result is as follows:

Example Pd ²⁺ Concentration (mg/L) Adsorption Amount (mg/g) Adsorption Rate (%)

24 30 37.1 99.0

25 60 74.1 98.7

26 90 107.2 95.3

27 120 128.4 85.6

28 150 149.8 79.9

29 180 165.4 73.5

30 210 84.8 70.4

31 240 192.2 64.1

32 270 198.8 59.3

33 300 202.9 55.1

Examples 34-38

Adjust the initial concentration of Pd ²⁺ in the waste palladium catalyst treatment solution to about 200mg/L, and adsorb for 60min under the conditions of bacterial cell concentration of 2-10g/L and 30°C, the results are as follows:

Example Bacteria Concentration (g/L) Adsorption Rate (%)

34 2 11.7

35 4 36.9

36 6 56.1

37 8 68.3

38 10 78.4Pd ²⁺ initial concentration: 206mg/L

Claims (8)

1. the method for reclaiming palladium from the palladium ion waste liquid of low concentration with bacterial thalline, it is characterized in that said bacterium is bacillus licheniformis (Bacillus lichemiformis), strain number R08, and recovery method is as follows: first thalline concentration is Mix 0.4-2.0g/L bacterial cell solution with Pd ²⁺ aqueous solution with a concentration of 30-300mg/L, and oscillate at a frequency of 130 times/min at a temperature of 5-60°C and a pH value of 2.0-3.5 3 to 90 minutes, then filter the Pd ²⁺ -bacteria action solution, place the filtered Pd ²⁺ adsorbed bacteria at room temperature for 6 to 48 hours, and finally burn at 550 to 800°C for 1.5 to 3 hours to obtain metal palladium. 2. the method for reclaiming palladium from low-concentration palladium ion waste liquid with bacterial cell as claimed in claim 1, it is characterized in that the bacterial cell concentration is 0.8～1.6g/L. 3. the method for reclaiming palladium from low-concentration palladium ion waste liquid with bacterial cell as claimed in claim 1, it is characterized in that the adsorption temperature is 20～50 ℃. 4. the method for reclaiming palladium from low-concentration palladium ion waste liquid with bacterial cell as claimed in claim 1, it is characterized in that the adsorption pH value is 2.0～3.5. 5. the method for reclaiming palladium from low-concentration palladium ion waste liquid with bacterial cell as claimed in claim 1, it is characterized in that the adsorption oscillation time is 30～60min. 6. the method for reclaiming palladium from low-concentration palladium ion waste liquid with bacterial cell as claimed in claim 1, it is characterized in that the thalline after adsorption is placed at room temperature for 18～36h. 7. the method for reclaiming palladium from low-concentration palladium ion waste liquid with bacterial thalline as claimed in claim 1, it is characterized in that being that the filter membrane of 0.22mm filters Pd with aperture ²⁺ thalline action liquid. 8. the method for reclaiming palladium from the palladium ion waste liquid of low concentration with bacterial cell as claimed in claim 1, it is characterized in that the R08 thalline that adopts is the dead bacterium cell of doing.