Cu(II) removal and recovery with biopolymer-clay nanocomposite adsorbent

The wastewater may contain many pollutants such as pathogenic microorganisms, organic and inorganic compounds and heavy metals. Heavy metals from these pollutants are dangerous for humans, animals and plants. Cost-effective solutions are required to treat wastewater, remove heavy metals from wastewater and recyle water. The development of environmentally friendly, biocompatible and biodegradable adsorbent materials with controllable properties is an important research topic. Bentonite is a preferred material for removing unwanted substances from aqueous solutions due to its high adsorption capacity. Chitosan is a preferred material in adsorption applications due to its biodegradability and biocompatibility. Chitosan-modified bentonites are an important adsorbent candidate to prevent heavy metal contamination and improve water quality. In this thesis study, nanocomposite adsorbent was synthesized using chitosan and bentonite and the removal of Cu(II) heavy metal was carried out with this synthesized adsorbent. For this, the effects of these parameters were optimized so that the pH values were between 1 and 6, the contact time between 5 minutes and 1440 minutes, the amount of adsorbent between 0.5 and 3 g/L and temperature between 25 °C and 35 °C . Under optimum conditions of pH=3, contact time of 1440 minutes, amount of adsorbent 1 g/L and 25 °C, adsorption became the most efficient and 99.74% removal of Copper(II) from aqueous solution was obtained. In addition, these adsorption data were modeled with Langmuir, Freundlich and Temkin Isotherms. It was determined that Langmuir Adsorption Isotherm is the most suitable adsorption isotherm model for Cu(II). The maximum adsorption capacity (qm) of Chitosan-Bentonite Nanocomposite adsorbent was found to be 214.28 mg/g for Cu(II). In addition, the pseudo-second-order reaction kinetic model is the most suitable kinetic model for Cu(II) adsorption. Then, desorption experiments were applied to recover the adsorbent molecule and the desorption efficiency from the KBNK surface was 99.36% by using 2 mol/L HNO3. These results revealed that KBNK can be considered as a highly effective, economical and important alternative adsorbent for Cu(II) removal based on both 99.74% removal efficiency and 214.28 mg/g adsorption capacity.