Study on Leaching of Heavy Metal Lead from Unplasticized Poly(vinyl chloride) Drainpipes

doi:10.19491/j.issn.1001-9278.2020.07.011

Abstract

Abstract:

This paper reported a study on the total lead leaching and relevant mechanisms of three PVC?U drainpipes products with a lead stabilizer at different time, temperature and pH value. The results indicated that the leaching law was consistent for these three types of products, which presented an increase trend in the leaching amount of lead at first and then a decrease trend with the time. The leaching amount of lead reached a maximum value at the time of 4 h. The temperature also influenced the leaching amount of lead significantly. Moreover, the leaching amount of lead in the strong acid environment is greater than that in the strong alkaline environment, the products showed a minimum leaching amount in the partial alkaline environment.

Key words: unplasticized poly(vinyl chloride), drainpipes, lead, heavy metal, leaching

CLC Number:

TQ322.4

Sha LI, Jiayu ZHAN, Yanjun LI, Zhenxin LIU, Feihua YANG. Study on Leaching of Heavy Metal Lead from Unplasticized Poly(vinyl chloride) Drainpipes[J]. China Plastics, 2020, 34(7): 69-73.

Figures/Tables 10

Fig.1. PVC?U drainpipes

Fig.2. The main process flowchart of PVC?U drainpipes

管道样品编号	铅总量/μg·g^-1
1	49.5
2	6 577.3
3	5 512.8

Tab.1. Total lead in PVC?U drainpipes

Fig.3. Leaching amount of lead at different time

Fig.4. Leaching rates of lead at different times

Fig.5. Effect of time on pH of the solution

Fig.6. Effect of temperature on lead leaching

Fig.7. Effect of pH on lead leaching

Fig.8. Logarithmic map of concentrations of different components in Pb?O?H2O systemc(Pb2+)=10.00 mmol/L

序号	酸碱反应式	平衡常数
1	H₂O $?$ H⁺+OH^-	logK=-14.00
2	2Pb²⁺+6H₂O $?$ 2Pb(OH)₃^-+6H⁺	logK=-28.6
3	Pb²⁺+4H₂O $?$ Pb(OH)₄^2-+4H⁺	logK=-39.7
4	2Pb²⁺+H₂O $?$ Pb₂(OH)³⁺+H⁺	logK=-6.63
5	Pb²⁺+H₂O $?$ Pb(OH)⁺+H⁺	logK=-7.71

序号	酸碱反应式	平衡常数
1	H₂O $?$ H⁺+OH^-	logK=-14.00
2	2Pb²⁺+6H₂O $?$ 2Pb(OH)₃^-+6H⁺	logK=-28.6
3	Pb²⁺+4H₂O $?$ Pb(OH)₄^2-+4H⁺	logK=-39.7
4	2Pb²⁺+H₂O $?$ Pb₂(OH)³⁺+H⁺	logK=-6.63
5	Pb²⁺+H₂O $?$ Pb(OH)⁺+H⁺	logK=-7.71

Tab .2. Acid?base chemical reaction in Pb?O?H2O system

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