Proposed models were fitted to the experimental

Table 2 contains the calculated values of breakthrough times, retardation factors, bed adsorption capacities and bed utilization percentages for all dynamic adsorption experiments in the micro-columns. It is clear that these characteristics of fluoride breakthrough curves are determined by both Q and [F−]feed. In particular, tb values ranged from 5.67 to 9.50 h and from 3.33 to 4.83 h for Q = 0.18 and 0.36 L/h, respectively. These breakthrough times decreased with both feed flow and column inlet concentration. The location of breakthrough point depends on the adsorbate–solute system and its values are relevant for the application of packed-bed columns in water treatment where high tb values are desirable. On the other hand, the retardation factors (rf) are determined by the characteristics of the column feed and they Atractyloside ranged from 319.4 to 704.1, see Table 2. As expected, rf decreased with feed fluoride concentration independently of the feed flow used. Note organ systems high values of retardation factor indicated a better removal performance of the packed-bed column. The estimated values of bed capacities for fluoride adsorption ranged from 3.3 to 18.5 mg/g at tested experimental conditions. These bed capacities correspond to a degree of bed utilization of 10.7–59.7%. Results of these calculations are consistent with the dynamic performance reported for water defluoridation using commercial bone chars in micro-columns where the bed utilization may range from 35 to 50% [6]. Bed capacities for fluoride adsorption and, consequently the degree of bed utilization, increased with both feed fluoride concentration and flow. It is convenient to remark that the fluoride uptakes of the novel aluminum-doped bone char are higher (up to 500%) than those values reported for packed-bed micro-columns using commercial bone chars, i.e., 1.0–3.0 mg/g [6].