# US 11,112,367 B2 · Device and method for analyzing total cyanide in water samples

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- Number: US 11,112,367 B2
- Document ID: US11112367B2
- Status: Granted
- Kind: B2
- Application number: 16/574,534
- Filed: 2019-09-18
- Published: 2020-01-09
- Granted: 2021-09-07
- Earliest claimed: 2017-07-20
- Assignees: Fujian Kelungde Env. Tech. Co., Ltd
- Applicants: Fujian Kelungde Env. Tech. Co., Ltd
- Inventors: Shuiji Wang; Jianping Cui; Zhuobin Weng
- Web page: https://patentgrep.com/patent/US11112367B2

## CPC

- G01N 21/78: producing a change of colour
- B01L 3/502: {with fluid transport, e.g. in multi-compartment structures}
- B01L 3/5082: {Test tubes per se}
- G01N 31/22: using chemical indicators (G01N31/02 takes precedence)
- G01N 33/18: Water
- B01L 2300/0663: Whole sensors
- B01L 2300/18: Means for temperature control
- B01L 2400/0622: distribution valves, valves having multiple inlets and/or outlets, e.g. metering valves, multi-way valves
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE

## Abstract

A device and a method of analyzing total cyanide in water samples, including a mixing tube, a stripping tube, a sampling pipe, a reaction pipe, a peristaltic pump, an air pump, a UV digester, a heater, a condenser, a drain pipe and a water sample detector. The mixing tube, the stripping tube, the sampling pipe and the reaction pipe are respectively connected to the peristaltic pump. The mixing tube is connected to the reaction pipe. A bottom of the stripping tube, the air pump, the UV digester, the heater and the condenser and are sequentially connected. The condenser is connected to the mixing tube. An upper portion of the stripping tube, the sampling pipe and the reaction pipe are connected to the drain pipe. An absorbance of the water in the mixing tube is measured by the sample detector, and used to calculate the total cyanide content by spectrophotometry.

## Claims

### Claim 1

A device for analyzing total cyanide in a water sample, comprising: a mixing tube, a stripping tube, a sampling pipe, a reaction pipe, a peristaltic pump, an air pump, a UV digester, a heater, a condenser, a drain pipe and a water sample detector;
wherein the mixing tube, the stripping tube, the sampling pipe and the reaction pipe are respectively connected to the peristaltic pump; the mixing tube is connected to the reaction pipe; a bottom of the stripping tube, the air pump, the UV digester, the heater and the condenser are sequentially connected; the condenser is connected to the mixing tube; an upper portion of the stripping tube, the sampling pipe and the reaction pipe are respectively connected to the drain pipe; and the water sample detector is able to detect and analyze parameters of the water sample in the mixing tube.

### Claim 2 (depends on 1)

The device of claim 1, wherein the reaction pipe and the sampling pipe each comprise a plurality of three-way valves, and respective three-way valves comprise a normally closed end, a common end and a normally open end.

### Claim 3 (depends on 2)

The device of claim 2, wherein the reaction pipe comprises three-way valves Q0, Q1, Q2, Q3, Q4 and Q5;
wherein a normally closed end of Q0 is connected to a pure water pipe; a common end of Q0 is connected to a normally closed end of Q1; a common end of Q1 is connected to a normally open end of Q3; a normally open end of Q1 is connected to a normally open end of Q2; a normally closed end of Q2 is connected to the drain pipe; a common end of Q2 is connected to the mixing tube; normally closed ends of Q3, Q4 and Q5 are respectively connected to chemical agent tubes R1, R2 and R3; a common end of Q3 is connected to a normally open end of Q4; a common end of Q4 is connected to a normally open end of Q5; and a common end of Q5 is connected to the peristaltic pump.

### Claim 4 (depends on 2)

The device of claim 2, wherein the sampling pipe comprises three-way valves Q6, Q7, Q8, Q9 and Q10;
wherein normally closed ends of Q6, Q7, Q8, Q9 and Q10 are respectively connected to a pure water pipe, a water sample-monitoring tube, a standard sample tube, the drain pipe and a chemical agent tube R4; a normally open end of Q6 is connected to an air inlet pipe; common ends of Q6, Q7, Q8 and Q9 are respectively connected to normally open ends of Q7, Q8, Q9 and Q10; and a common end of Q10 is connected to the peristaltic pump.

### Claim 5 (depends on 1)

The device of claim 1, wherein the peristaltic pump is provided with two connecting ports, which are respectively connected to common ends of two simultaneously-operated three-way valves QA1 and QA2; normally open ends of QA1 and QA2 are respectively connected to the reaction pipe and the mixing tube; and normally closed ends of QA1 and QA2 are respectively connected to the sampling pipe and the stripping tube.

### Claim 6 (depends on 1)

The device of claim 1, wherein the mixing tube is connected to the condenser through three-way valves QB and QC; and the air pump is connected to the bottom of the stripping tube through a three-way valve QD.

### Claim 7 (depends on 1)

A method for analyzing total cyanide in a water sample using the device of claim 1, comprising:
(1) emptying a stripping tube and a mixing tube in a thermostatic water bath; and performing a heating process to obtain a constant temperature inside a heater;
(2) pumping pure water into the mixing tube followed by a standing to obtain an initial absorbance of the water sample;
(3) pumping chemical agents R1 and R2, as well as a small amount of pure water from a reaction pipe to the mixing tube through a peristaltic pump to produce a mixed chemical agent solution; wherein R1 is a mixed solution of a 18-22 g/L potassium Hydrogen phthalate solution and a 2-4 g/L sodium hydroxide solution, and R2 is a 3-5 g/L chloramine T solution;
(4) pumping a sample to be detected from a sampling pipe to the stripping tube through the peristaltic pump;
(5) adding a chemical agent R4 to the stripping tube for catalytic elimination; wherein R4 is a mixed solution of a 3-5 g/L sodium hydroxide solution with a concentration of and a 18-22 g/L citric acid solution;
(6) pumping the sample to be detected in the stripping tube by an air pump to a UV digester and then to the heater; instantaneously vaporizing the sample to be detected by distillation in the heater to release a cyanide gas; cooling the cyanide gas into a cyanide liquid by a condenser; allowing the cyanide liquid to flow into the mixing tube to react with the mixed chemical agent solution obtained in step (3); and repeating the distillation until the sample to be detected is completely vaporized;
(7) adding a chemical agent R3 to the mixing tube for color development, wherein R3 is a mixed solution of pyridine with a volume fraction of 99% or more, barbituric acid with a mass concentration of 28-32 g/L and concentrated hydrochloric acid; subjecting the reaction mixture to standing for a certain period after the color development; measuring a final absorbance of the reaction mixture; and calculating the total cyanide content in the sample to be detected according to spectrophotometry; and
(8) pumping pure water to empty and clean the mixing tube, the stripping tube, the UV digester, the heater and the condenser.

### Claim 8 (depends on 7)

The method of claim 7, wherein the sample to be detected in step (4) is a water sample to be monitored or a standard sample; the water sample to be monitored is collected to the sampling pipe through a water sample-monitoring tube, and then pumped into the stripping tube through the peristaltic pump; and the standard sample is collected to the sampling pipe through a standard sample tube, and then pumped into the stripping tube through the peristaltic pump.

### Claim 9 (depends on 7)

The method of claim 7, wherein in step (3), air is pumped into the mixing tube to completely mix the chemical agents R3 and R4 with pure water; and in step (4), the excess sample to be detected in the stripping tube is discharged from a drain pipe which is provided at an upper portion of the stripping tube.

### Claim 10 (depends on 7)

The method of claim 7, wherein in step (1), the heater has an internal temperature of 80° C., a pulse-heating temperature of 162° C. and a maximum temperature of 165° C.