Concentrations of main electrolytes and dissolved organic content in the artificial waters used in the experiments.

<p>Concentrations of main electrolytes and dissolved organic content in the artificial waters used in the experiments.</p

Testing the magnetic stability of magnetite-waste tea composite after 8 days in water.

<p>Testing the magnetic stability of magnetite-waste tea composite after 8 days in water.</p

TGA analyses of the uncoated and magnetite-waste tea composite showing that the magnetite coating accounts for about 22% of the total mass of the composite.

<p>TGA analyses of the uncoated and magnetite-waste tea composite showing that the magnetite coating accounts for about 22% of the total mass of the composite.</p

Amount of Fe leached out into the four waters from uncoated tea (A) and magnetite-waste tea composite (B).

<p>Amount of Fe leached out into the four waters from uncoated tea (A) and magnetite-waste tea composite (B).</p

SEM images of waste tea powder (A) without and (B) with magnetite coating.

<p>SEM images of waste tea powder (A) without and (B) with magnetite coating.</p

Percentage of Pb adsorbed onto the four sorbents for each of the four different waters: (A) deionized water, (B) rainwater, (C) groundwater and (D) freshwater.

<p>Percentage of Pb adsorbed onto the four sorbents for each of the four different waters: (A) deionized water, (B) rainwater, (C) groundwater and (D) freshwater.</p

Key parameters of the tea powders (unmagnetized tea and magnetite-waste tea composite) measured using the nitrogen physisorption isotherms.

<p>Key parameters of the tea powders (unmagnetized tea and magnetite-waste tea composite) measured using the nitrogen physisorption isotherms.</p