Lignitic Humic Acids as Environmentally-Friendly Adsorbent for Heavy Metals

Table 5

Average contents of mobile phase, ion-exchangeable phase, strongly bound phase, and residual phase of single Cu²⁺ ions and Cd²⁺, Cu²⁺, Pb²⁺, and Zn²⁺ ions adsorbed from their mixture.

	Cu^2+ (single)	Cd^2+	Cu^2+	Pb^2+	Zn^2+
Mobile phase	9.8%	14.4%	11.2%	12.4%	17.8%
Ion-exchangeable phase	17.0%	25.7%	18.0%	19.3%	21.8%
Strongly bound phase	22.2%	29.2%	23.6%	23.1%	26.7%
Residual phase	51.0%	30.7%	47.2%	45.2%	33.7%