Dyestuff adsorption from aqueous solutions with activated bioadsorbents

One of the most serious problems in the world, water pollution caused by dyestuffs can be removed from water by various methods, especially adsorption method. This forces the scientific world to search for ways to use adsorption more effectively. Particularly, adsorbent, which performs the adsorption process on the surface, is the most important factor affecting the adsorption process. This work was carried out in order to reach an adsorbent that can be used in an environmentally friendly, economical, effective and efficient way. The seeds of the hawthorn, which was collected from the Erdoğan Akdağ Campus of our University and which can be found abundantly in our region and which have not previously been used for this purpose in the adsorption studies, was chosen as the adsorbent. Methylene blue (MB), one of the staining materials, was used as the target contaminant. Due to the low adsorption capacity of the unprocessed hawthorn kernel, a new bioadsorbent was prepared by activating the hawthorn kernel with sulfuric acid (H2SO4). Optimum conditions were determined by performing the activation process at different time, temperature, acid concentration and acid/sample ratio values. Optimum conditions for the activation of the hawthorn kernel were: 6 hours duration, 85 oC temperature, acid concentration of 18,20 M and acid/sample ratio of 5: 1. Characterization of bioadsorbent prepared under optimum conditions was performed using FTIR, SEM, BET, Boehm titration and surface pH (pHpzc) techniques. MB removal from aqueous solutions was investigated using the developed bioadsorbent. Adsorption experiments were carried out by a cut-off method and the effect of pH, initial dye concentration, contact time, temperature and adsorbent dosage on adsorption was investigated. In addition, adsorption isotherms and kinetics were studied and appropriate isotherm and kinetic models were determined. Desorption experiments (regeneration) were carried out to investigate the reusability of the developed bioadsorbent. As a result of the studies, behavior of MB adsorption onto hawthorn kernel was fit to Langmuir isotherm and the maximum adsorption capacities of AÇ and SAÇ are 49.50, 151.52 respectively. The kinetics of adsorption is found to be appropriate for both pseudo second-order kinetic models for both AÇ and SAÇ. It has been observed that the adsorption percentage decreased from 99.87 to 98.81 as a result of five repetitive studies in SHK's reusability studies. It has been observed that the developed bioadsorbent (SAÇ) can be used as an effective adsorbent for removal of MM from aqueous solutions.