Melanin-Based Coatings as Lead-Binding Agents

Table 1

Lead-binding parameters.

	Synthetic-eumelanin-coated discs
pH^a	𝐾𝐿 (M^−1)^b	Capacity; 𝜇g/disc^b
Uncorrected	1.74(±0.12)⋅10^4	137.8±10.1
5.50	2.21(±0.22)⋅10^4	133.0±4.2
4.75	1.83(±0.02)⋅10^4	130.3±5.5
4.00	1.40(±0.15)⋅10^4	119.1±6.5
	Hair-extract-coated discs
pH^a	𝐾𝐿 (M^−1)^b	Capacity; 𝜇g/disc^b
Uncorrected	7.58(±0.39)⋅10^3	126.1±9.5
5.50	7.04(±0.56)⋅10^3	139.1±14.7
4.75	6.74(±1.04)⋅10^3	115.6±5.4
4.00^c	3.40(±0.20)⋅10^3	110.5±9.3

^aUncorrected titrations are Pb(NO₃)₂ in H₂O, other titrations are Pb(NO₃)₂ in 50 mM NaNO₃ with the initial pH adjusted as shown.
^bValues calculated from linearized Langmuir isotherms from at least three independent titrations with different discs; standard deviations shown.
^cLinearized Langmuir isotherm 𝑅²≥0.96, all others 𝑅²≥0.98.