8 research outputs found
Using Magnetically Responsive Tea Waste to Remove Lead in Waters under Environmentally Relevant Conditions
We report the use of a simple yet highly effective magnetite-waste tea composite to remove lead(II) (Pb[superscript 2+]) ions from water. Magnetite-waste tea composites were dispersed in four different types of water–deionized (DI), artificial rainwater, artificial groundwater and artificial freshwater–that mimic actual environmental conditions. The water samples had varying initial concentrations (0.16–5.55 ppm) of Pb[superscript 2+] ions and were mixed with the magnetite-waste tea composite for at least 24 hours to allow adsorption of the Pb[superscript 2+] ions to reach equilibrium. The magnetite-waste tea composites were stable in all the water samples for at least 3 months and could be easily removed from the aqueous media via the use of permanent magnets. We detected no significant leaching of iron (Fe) ions into the water from the magnetite-waste tea composites. The percentage of Pb adsorbed onto the magnetite-waste tea composite ranged from ~70% to 100%; the composites were as effective as activated carbon (AC) in removing the Pb[superscript 2+] ions from water, depending on the initial Pb concentration. Our prepared magnetite-waste tea composites show promise as a green, inexpensive and highly effective sorbent for removal of Pb in water under environmentally realistic conditions.SUTD-MIT International Design Center (Research Grant IDG11200105/IDD11200109)Singapore-MIT Allianc
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
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
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
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
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