Removal of fluoride ions from aqueous solution at low pH using schwertmannite

Defluoridation with Locally Produced Thai Bone Char

“…Thus, the amount of fluoride sorbed onto bone char tends to increase with the increasing initial fluoride concentration (see Figure 2(d)). This agrees with results by Eskandarpour et al [20]. On the other hand, the correlation coefficients between chloride, nitrate, and sulfate to either Thai or Indian bone char approach zero (except for the case of sulfate and Thai bone char) implying that there is less of the relationship or an uncorrelated relationship between ion concentrations and the sorbed fluoride per weight of bone char.…”

“…In these tests, 200 mL of a synthetic fluoride aqueous solution with a concentration of 3.9 mg/L was mixed with 10 g of the homemade bone char in a plastic bottle and then shaken in a water bath at room temperature. Samples were collected and analyzed at 2,4,6,8,10,12,16,20, and 24 hours. Sorption kinetics and isotherms for each size of bone char were then analyzed.…”

“…Activated alumina sorbed less fluoride in high pH (>8) conditions [27]. Fluoride adsorption by granular ceramic [18], activated alumina [27], granular ferric hydroxide [26], and schwertmannite [20] was found to decrease in the presence 2 Advances in Environmental Chemistry of phosphate. Competing ions were found to have no effect on fluoride adsorption by other absorbents such as hydrous iron (III)-tin (IV) mixed oxide [19], polymer composites [28], and disposed earthenware [29].…”

“…Recently, many attempts have been made to use waste or low cost materials as the absorbent. The materials studied include bauxite [13], montmorillonite [14], activated water treatment sludge [15], waste mud [16], red mud [17], granular ceramic [18], hydrous iron (III)-tin (IV) mixed oxide [19], and schwertmannite [20].…”

Removal Characteristics of Fluoride Ions by PSf-Al(OH)3Beads Immobilized Al(OH)3with Polysulfone

“…폐수 중에 함유되어 있는 불소를 처리하는 방법은 칼슘화 합물을 사용하는 응집․침전법 [4]이 가장 보편적으로 사용되 고 있으나, 많은 양의 응집제를 사용해야 한다는 단점이 있다 [5]. 또한 막여과 [6], 전기응집 [7], 부상 [8], 이온교환수지 [9] 그 리고 흡착 [10] …”