Table 3: Adsorption capacities of different adsorbents for the removal of Zn2+ from water.

AdsorbentZn+2 mg/LModifying agent(s) mg/gSource

Bagasse200Sulfuric acid31.11[19]
Moss100Distilled water14.7[20]
Bentonite30052.91[95]
Botrytis cinerea 100NaOH12.98[23]
Sea nodule residue200Hydrochloric acid32.46[24]
Powdered waste sludge200H2O2168[25]
Waste activated sludge1636.9[26]
Sugar beet pulp160Deionized water17.78[27]
Papaya woodDeionized water13.64[31]
Clarified sludge25Distilled water15.53 [32]
Rice husk ashDistilled water14.30
Neem barkDistilled water13.29
Activated alumina13.69
Saltbush leavesHCl32.7[33]
Natural zeolite1202.21[45]
Black gram husk10Distilled water33.81[47]
Carrot residues500HCl29.61[52]
Cassava wasteUntreated55.82 [54]
Thioglycollic acid + HNO3559.74
Caulerpa lentillifera 10Tab water2.66[56]
Dried marine green macroalga260CaCl2128.8[57]
Sawdust-oakUnmodified7.1 [58]
Sawdust-oakFormaldehyde6.1
Sawdust-oakFormaldehyde + NaOH9.3
Sawdust-oakNaOH8.3
Sawdust-black locustUnmodified5.2
Sawdust-black locustFormaldehyde5.3
Sawdust-black locustFormaldehyde + NaOH9
Sawdust-black locustNaOH6.7
Sawdust-poplar196Unmodified1 [59]
Sawdust-fir196Unmodified1
Sawdust-poplar130NaOH15.8
Sawdust-fir40NaOH13.4
Lignin6.5HCl + ether + benzene73.2[60]
Bagasse fly ash50Hydrogen peroxide2.34[72]
Bagasse850Activated carbon (10°C)24.06 [19]
800Activated carbon (25°C)31.11
775Activated carbon (40°C)54
Coal fly ashUnmodified (30–60°C) 6.5–13.3 [96]
Fe impregnated fly ashFe(Cl)3 (30–60°C)7.5–15.5
Al impregnated fly ashAl(NO3)3 (30–60°C) 7.0–15.4
Rice husk ash + coal fly ash + palm oil fuel ash15Sol gel method16.95[97]