Synthesis of biochar/silicagel hybrid sorbent material and investigation of Ni(II) removal potential from aqueous solutions

The development of effective and alternative adsorbents for the removal of various pollutants, especially heavy metals, that have contaminated water resources is an important research area of today. In this context, biochars are among the prominent adsorbent materials. In our study, biochar prepared from Borrago officinalis herbal biomass was modified with silica gel and used to remove Ni(II) ions from the solution medium. In this direction, adsorption studies were carried out for Ni(II) ions in batch and continuous systems. In the batch system, pH, adsorbent amount, mixing speed, ambient temperature, mixing time and initial Ni(II) concentration parameters were optimized by examining, adsorption equilibrium data were evaluated with kinetic and isotherm models. In the continuous system, the amount of adsorbent, flow rate, break throught and desorption parameters were investigated. In the characterization of the developed material, zeta potential measurement, IR analysis, SEM-EDS analyzes were used. After optimization studies in the continuous system, 95.85% Ni(II) removal efficiency was achieved. It was determined that the kinetic data of the Ni(II) removal process with modified biochar were consistent with the pseudo-second-order kinetic model. It was noted that the adsorption equilibrium data could be described mostly with the Langmuir isotherm model. The results obtained from both batch and continuous system studies reveal the potential of the proposed modified biochar as an economical and effective alternative for removing Ni(II) ions from aqueous media.