Cobalt ferrite nanoparticles aggregated schwertmannite: A novel adsorbent for the efficient removal of arsenic

Arsenic poisoning is causing a serious threat to the environment. The application of nanoparticles in the abatement of arsenic is becoming an intense area of research nowadays. In the present study the adsorption behavior of arsenic was studied in detail by synthesizing a novel adsorbent by aggregating cobalt ferrite nanoparticles during the formation of iron oxide hydroxide, i.e. schwertmannite. Cobalt ferrite nanoparticle enhances the magnetic properties of schwertmannite and makes it a better candidate for arsenic removal. The various structural as well as morphological properties were investigated by VSM, XRD, FTIR, BET and FESEM analysis. Batch adsorption experiments were carried out by varying different process parameters such as contact time, adsorbent dose, pH, temperature and presence of other co-ions. Arsenic adsorption by cobalt ferrite nanoparticle aggregated schwertmannite (CNSh) was found to be highly pH sensitive. Maximum arsenic was adsorbed at around pH 5.3. Study of temperature effect on arsenic adsorption confirmed the endothermic nature of the process. Other thermodynamic properties were also calculated and found that physical adsorption was dominant with activation energy of 5.1 kJ/mol. Kinetic study revealed that the pseudo second order model was followed by the adsorption process having regression coefficient (R2) 0.99. The equilibrium study showed that the adsorption system followed the Langmuir isotherm model with maximum adsorption capacity of 1011 μg/g which was comparably efficient than several other adsorbents.