Nitrate removal from aqueous solution by activated carbon prepared from shrimp shell

In this study, activated carbon was prepared after pyrolysis and activation of shrimp shells. The effects of different impregnation ratios and temperatures on the physical and chemical properties of activated carbon were investigated. The physical and chemical properties of different activated carbons were characterized by N2 adsorption–desorption, scanning electron microscopy, and X-ray diffraction. The results show that at a pyrolysis temperature of 400°C, the activated carbon with a C/ZnCl2 ratio of 1/2 has the maximum specific surface area and pore volume of 1,536.3 m2/g and 0.83 cm3/g, respectively. The experimental results show that with the increase of pH value, the adsorption capacity of activated carbon will gradually decrease, indicating that acidic conditions are more favorable for nitrate adsorption. The maximum adsorption capacity was of the carbon achieved at about 5.58 mg/g at such conditions. The pseudo-first-order kinetic model fits well with the nitrate adsorption kinetics date with a high determination coefficient (R2 > 0.95), while both the Freundlich and Langmuir isothermal model fit the experimental data well (R2 > 0.95). Also, the influence of the coexisting anions on the adsorption performance of activated carbon has also been studied, the inhibitory effect of coexisting anions on the adsorption of nitrate on activated carbon is from high to low: CO32– > SO42– > Cl–.