Removal of micropollutants by fresh and colonized magnetic powdered activated carbon.

This study evaluated the adsorption capacity and rate constants for 9 micropollutants (MP) on fresh and aged magnetic powdered activated carbon (MPAC) as a magnetically separable alternative to conventional PAC for drinking water treatment. MPAC with mass fractions of 10%, 38% and 54% maghemite nanoparticles were compared to bare PAC and pure maghemite in batch adsorption experiments. Pure maghemite alone did not adsorb significant amounts of MP and when normalized to PAC content, no significant differences of MP adsorption between MPAC and PAC were observed. Freundlich constants K (normalized to PAC content) ranged between 2.3-37 μg/mg (L/μg) for all MP and adsorbents. Pseudo-second order rate constants for MP decreased with increasing maghemite content ranging between 0.2-2.7 mg/μg/min for bare PAC and 0.02-2.19 mg/μg/min for MPAC. Residual adsorption capacities of 90-days old colonized adsorbents were 10 times lower than for fresh adsorbent. At typical concentrations of 3.5 g colonized adsorbent/L found inside reactors, kinetics were still fast and removals of all MP except sulfamethoxazole exceeded 90% within 5 min.