Adsorbent Method /type of water Optimum pH Contamination concentration (mg/L) Capacity (mg/g) References As (III) As (V) Bentonite (modified) Batch 6.0/9.0 0.2-1 0.82 1.48 [44] Montmorillonite Batch 6-May 20 µM ~0.2 mmol/g ~0.4 mmol/g [42] Illite Batch 9 20 µM ~0.2 mmol/g ~0.5 mmol/g [42] Kaolinite Batch 8-Mar 20 µM ~0.3 mmol/g ~0.5 mmol/g [42] Kaolinite, surfactant modified Batch/column 5.0-6.5 0.2-14 4.3 mmol/kg 9.0 mmol/kg [45] Gibbsite Wastewater 5.5 10-1000 3.3 4.6 [46] Soil, Sharkey Soil 5-6 5-100   0.74 [47] Zeolite, surfactant modified Batch/ column 7.2-7.5 0.2-14 1.6 mmol/kg 7.2 mmol/kg [48,49] Zeolites Batch 4 0.1-4.0 0.017 0.1 [50] Malachite Batch 4 5   57.1 mg/g [51] Feldspar Water/ wastewater 4.2 133.49 μmol/L   0.18 [52] Siderite Batch and column 7 250-2000 1040 μg/g 516 μg/g [53,54] Fe–Mn mineral material Batch/column 3/3,5.5 0.47 mmol/L 14.7 6.7 [55] Al2O3/Fe(OH)3  Batch 6.1 ± 0.3/8.0 ± 0.3 0.1-0.4 0.12 mmol/g 36.7 [56] Fe–Mn binary oxide Batch 4.8 0.20 mmol/L 1.77 mmol/g 0.93 mmol/g [57,58] Goethite Batch wastewater 5.5 10-1000 7.5 12.5 [57,59] Ferrihydrite Batch/natural   325 μg/L   0.25 [60]  Ferric hydroxide, granular Column drinking water 8-9 5-100 2.3   [61]  TiO2 Batch 8.5/7.3 0.4-80 32.4 41.4 [62,63] Synthetic hydrotalcite Ground water 7 400   105 [64] Layered double hydroxides, calcined Wastewater 4.2-5.4 20-200   5.61 [65] FePO4(amorphous) Drinking water 7-9/6-6.7 0.5-100 21 10 [66] FePO4 (cryst.) Drinking water 7-9/6-6.7 0.5-100 16 9 [66] Fe/NN-MCM-41 Drinking water 6 ~0-1500   119.8 [67] Cu/NN-MCM-48 Drinking water 7 ~0-1500   37.46 [67]

Table 3: Constituents used for arsenic remediation purposes; adopted and modified from [43].