Electroplating heavy metal wastewater detection method?

Common heavy metal detection methods
Qualitative analysis (Shanghai Yishuang Water Treatment)
Detecting ions
Qualitative reagent
phenomenon
Reagent configuration
Copper ions
ammonia
After the addition, there is copper hydroxide precipitation, and the precipitate disappears after the excess.
Nickel ion
Dimethylglyoxime + ammonia
Red wine
Hexavalent chromium ion
Diphenylcarbazide
Red
Dissolve 0.1 g of diphenylcarbazide in 50 ml of 95% ethanol, and add 200 ml of cooled 1:9 sulfuric acid solution (with solution showing no color, colored is invalid)
Cyanide ion
Picric acid + ethanol
Rose red
Quantitative analysis
Detecting ions
Indicator
Use pH range
Discoloration
Buffer solution
Preparation method
Standard solution
Remarks
From
end
Total metal ion
Chrome black T
8-11
red
blue
ammonia
Weigh 1g of chrome black T and 100g of sodium chloride to evenly
EDTA
Copper ions
PAN
2-12
red
Yellow green
ammonia
0.0017g of PAN is dissolved in 70ml of ethanol
EDTA
Need to be heated and titrated
Nickel ion
Purple uric acid amine
10
Orange
purple
ammonia
Mixed with sodium chloride 1:100 mass
EDTA
Need to be heated and titrated
Hexavalent chromium ion
Sodium diphenyl sulfonate
red
Bright green
Sodium diphenyl sulfonate 0.2g dissolved in 100g water
Ammonium ferrous sulfate 0.1/L
Ferric ion
Sulfosalicylic acid
1.5-2.5
Purple red
Yellow/colorless
0.02g/L aqueous solution
EDTA
Zinc ions
Zinc reagent
8-10
blue
yellow
ammonia
EDTA
Cyanide ion
Test silver spirit
yellow
Orange red
AgNO ₃
0.01mol/L
Silver ion
Ferric ammonia
<7
White
red
NH ₄ SCN
0.05mol/L
Excess Fe ³⁺ and SC N ^- color development
Note: According to the water quality of electroplating wastewater, the reference concentration of EDTA is 0.05mol/L. Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
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Detecting ions	Qualitative reagent	phenomenon	Reagent configuration
Copper ions	ammonia	After the addition, there is copper hydroxide precipitation, and the precipitate disappears after the excess.
Nickel ion	Dimethylglyoxime + ammonia	Red wine
Hexavalent chromium ion	Diphenylcarbazide	Red	Dissolve 0.1 g of diphenylcarbazide in 50 ml of 95% ethanol, and add 200 ml of cooled 1:9 sulfuric acid solution (with solution showing no color, colored is invalid)
Cyanide ion	Picric acid + ethanol	Rose red

Detecting ions	Indicator	Use pH range	Discoloration		Buffer solution	Preparation method	Standard solution	Remarks
Detecting ions	Indicator	Use pH range	From	end	Buffer solution	Preparation method	Standard solution	Remarks
Total metal ion	Chrome black T	8-11	red	blue	ammonia	Weigh 1g of chrome black T and 100g of sodium chloride to evenly	EDTA
Copper ions	PAN	2-12	red	Yellow green	ammonia	0.0017g of PAN is dissolved in 70ml of ethanol	EDTA	Need to be heated and titrated
Nickel ion	Purple uric acid amine	10	Orange	purple	ammonia	Mixed with sodium chloride 1:100 mass	EDTA	Need to be heated and titrated
Hexavalent chromium ion	Sodium diphenyl sulfonate		red	Bright green		Sodium diphenyl sulfonate 0.2g dissolved in 100g water	Ammonium ferrous sulfate 0.1/L
Ferric ion	Sulfosalicylic acid	1.5-2.5	Purple red	Yellow/colorless		0.02g/L aqueous solution	EDTA
Zinc ions	Zinc reagent	8-10	blue	yellow	ammonia		EDTA
Cyanide ion	Test silver spirit		yellow	Orange red			AgNO ₃ 0.01mol/L
Silver ion	Ferric ammonia	<7	White	red			NH ₄ SCN 0.05mol/L	Excess Fe ³⁺ and SC N ^- color development