Technical faculty in Bor, University of Belgrade , Belgrade , Serbia
The changes in pH and conductivity during the rinsing of the pumpkin peel and the biosorption of Cu2+ ions were the subject of this work. The obtained data showed that the pH value of the solutions increased during the rinsing of the biosorbent, as a result of the transfer of H+ ions from the aqueous phase into the structure of the pumpkin peel. An increase in the conductivity value was observed in the initial period of rinsing the pumpkin peel, followed by a decrease. The increase in conductivity in the initial phase contributed to the self-leaching of the alkali and alkaline earth metal ions from the structure of the pumpkin peel, which were transferred into the aqueous phase. The further decrease in conductivity is a result of the dilution of the aqueous phase. The pH value decreased during the biosorption of Cu2+ ions, as hydrogen ions were transferred from the pumpkin peel structure into the solution, and then exchanged with Cu2+ ions. The conductivity value increased during the biosorption process, with a rapid increase in the initial period of 5 minutes, due to the transfer of alkali and alkaline earth metal ions into the solution.
The research presented in this paper was done with the financial support of the Ministry of Science, Technological Development and Innovation of the Republic of Serbia, within the funding of the scientific research work at the University of Belgrade - Technical Faculty in Bor, according to the contract with registration number 451-03-137/2025-03/200131.
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