Removal of arsenic ions by using different adsorbents in aqueous solutions

Arsenic can be present in more than one oxidation state, but is usually found in inorganic form of As (III) and As (V) in natural waters. As for biological systems, As (III) is more toxic than As (V). The main methods for arsenic removal; coagulation, flocculation and precipitation, membrane filtration, ion exchange and adsorption. Generally, adsorption is considered a promising method. In addition, adsorption has been shown as an economical method for the removal of arsenic from water sources. In this study, arsenic removal from aqueous media was measured by using adsorption method by using adsorption method using atomic absorption spectrophotometer. Adsorbents which were more successful in removing arsenic were selected. These adsorbents are pumice stone, pumice stone modified with FeCl3 and pumice stone modified with FeCl3 and NaOH. The adsorption method was carried out in batch and then the arsenic ions in the medium were measured by hydride formation technique using flame atomic absorption spectrophotometer. In this study, the effect of parameters such as contact time, ambient pH, temperature and concentration on adsorption was investigated. Then, adsorption isotherm graphs were drawn and the adsorption type was determined and the capacities of the adsorbents used were calculated and the most suitable adsorbent for arsenic ions was determined. As a result of these studies; optimum contact time was 60 min for pumice, 60 min for pumice modified with FeCl3, and 120 min for pumice modified with NaOH and FeCl3. The optimum temperature was 35 ºC for pumice, 35 ºC for pumice modified with FeCl3 and 30 ºC for pumice modified with NaOH and FeCl3. It gives an endothermic reaction for pumice modified with pumice and FeCl3, while it exothermic for pumice modified with NaOH and FeCl3. The optimum pH was 6.0 for pumice, 9.0 for pumice modified with FeCl3, and 5.0 for pumice modified with NaOH and FeCl3. The concentration with the highest adsorption capacity was 1500 µg / L for pumice, 1500 µg / L for pumice modified with FeCl3 and 1500 µg / L for pumice modified with NaOH and FeCl3. All three adsorbents are compatible with Freundlich isotherm.