Low-cost adsorbents for the removal of nitrophenols from waste waters

The adsorption behaviour of three substituted nitrophenols, 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP), on different type natural materials, yellow/white bentonite, expanded perlite, perlite insulation filter, zeolite, and on the biosorbent Rhizopus oryzae was studied. The experimental results were analyzed on the basis of the effect of nitrophenol removal, E, calculated from the kinetic curves, as well as on the basis of the values of the equilibrium adsorption capacity, q(max). According to the equilibrium and kinetic data, the adsorption capacity of the studied materials follows the order: yellow bentonite > Rhizopus oryzae > perlite insulation filter > white bentonite > zeolite, while the uptake of the mono- and disubstituted nitrophenols increases in the order 2-NP < 2,4-DNP < 4-NP.