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In this study, the removal of nitrite from aqueous solution by adsorption was investigated. Sepiolite and powdered activated carbon (PAC) were used as adsorbents. In order to investigate the adsorption mechanisms, three simplified kinetic models, i.e., pseudo-first-order, pseudo-second-order and intraparticle diffusion were applied to fit the kinetic data obtained by using sepiolite and PAC. The rate constants for the three models were determined and the correlation coefficients were calculated. Adsorption followed pseudo-second-order rate kinetics for both sepiolite and PAC.

The suitability of the kinetic models for the adsorption of nitrite on the sepiolite and PAC were investigated. Adsorption kinetic data were analysed using the pseudo-first-order, pseudosecond-order and intraparticle diffusion model. The results showed the process can be described by a pseudo-second-order model. The advantage 1.21 0.65 Intraparticle diffusion model _ ki (mg/g min1/2) R2 D (m2/s) 0.999 0.064 0.999 0.012 0.679 4.7 × 10−14 0.049 3.8 × 10−13 of using this model is that the adsorption capacity, the rate constant of pseudo-second-order, and the initial adsorption rate at any given time t, can be predicted from the equation. Sepiolite has adsorption properties due to its channel structure, high surface area and sorption capacities. Since sepiolite is a waste material from hand carving, the treatment method seems to be economic.