Carbon
block filters, commonly employed as point-of-use (POU) water
treatment components, effectively eliminate pathogens and adsorb undesirable
tastes, odors, and organic contaminants, all while producing no water
waste. However, they lack the capability to remove arsenic. Enabling
the carbon block to remove arsenic could reduce its exposure risks
in tap water. Inspired by Sous vide cooking techniques, we developed
a low-energy, low-chemical method for impregnating commercially available
carbon block with titanium (hydr)oxide (THO) in four integrated steps:
(1) vacuum removal of air from the carbon block, (2) impregnation
with precursors in a flexible pouch, (3) sealing to prevent oxygen
intrusion, and (4) heating in a water bath at 80 °C for 20 h
to eliminate exposure and reactions with air. This process achieved
a uniform 13 wt % Ti loading in the carbon block. Our modified carbon
block POU filter efficiently removed both arsenate and arsenite from
tap water matrices containing 10 or 100 μg/L arsenic concentrations
in batch experiments or continuous flow operations. Surprisingly,
the THO-modified carbon block removed arsenite better than arsenate.
This innovative method, using 70% fewer chemicals than traditional
autoclave techniques, offers a cost-effective solution to reduce exposure
to arsenic and lower its overall risk in tap water.