Heavy metals removal from aqueous solution by biosorbent based on apricot stones waste biomass.

U okviru ove doktorske disertacije ispitana je mogućnost upotrebe biosorbenta na bazi endokarpa koštica kajsije Prunus armeniaca L. u svrhu uklanjanja Cu(II), Zn(II) i Pb(II) jona iz vodenih rastvora. Koštice kajsija (KK) su poreklom iz fabrike za preradu sokova „Vino Župa” iz Aleksandrovca, gde su klasifikovane kao otpadni materijal iz procesa prerade voća. U cilju dobijanja biosorbenta sa što boljim sorpcionim karakteristikama KK je tretiran rastvorom NaOH. Serijom eksperimenata odabrani su optimalni parametri modifikacije (početna koncentracija NaOH 1 mol/L; odnos čvrsto/tečno 1:20; vreme kontakta 180 minuta) i dobijen je modifikovani materijal KKM. Izvršena je karakterizacija i upoređivanje KK i KKM. Rezulatati hemijskih analiza su potvrdili da je posledica baznog tretmana razlaganje hemiceluloze (19,23 i 3,52% kod KK i KKM, respektivno), što su i FT-IR spektri potvrdili (pik na 1730 cm-1, koji ukazuje na -C=O vezu koja potiče od estarske grupe u hemicelulozi, se kod KKM gubi). Takođe, bazni tretman je doveo do uklanjanja masti i voskova sa površine biomaterijala, što je potvrđeno hemijskom analizom i FT-IR i SEM analizama. Posledica baznog tretmana je i povećanje tačke nultog naelektrisanja i promena odnosa količine kiselih i baznih grupa na površini KKM. Kod KK sadržaj ukupnih kiselih grupa je veći u odnosu na KKM (1,619 mmol/g i 0,317 mmol/g, respektivno), dok je kod KKM obrnuto: sadržaj ukupnih baznih grupa je veći nego kod KK (0,309 mmol/g i 0,037 mmol/g, respektivno). Rezultati živine porozimetrije su potvrdili da je nakon baznog tretmana kod KKM došlo do povećanja zapremine pora (sa 218 na 270 mm3/g), povećanja prosečnog prečnika pora (sa 393 na 468 nm) i poroznosti (sa 25 na 30 %). KKM je ispitan kao biosorbent za uklanjanje Cu(II), Zn(II) i Pb(II) jona iz vodenih rastvora. Ispitani su osnovni parametri koji utiču na proces biosorpcije (pH, kontaktno vreme, koncentracija biosorbenta, granulacija)...In this doctoral thesis, use of apricot (Prunus armeniaca L.) stone endocarp as possible biosorbent for the removal of Cu(II), Zn(II) and Pb(II) ions from aqueous solution was examined. Apricot stones are from “Vino Župa” Inc. Aleksandrovac where it is classified as a waste product from fruit processing. In order to get biosorbent with highest sorption performances this waste material was treated with solution of NaOH. In a series of experiments optimal modification parameters were determined (initial concentration 1mol/L NaOH; solid/liquid ratio 1:20; contact time 180 minutes) and modified material was obtained (KKM). Characterization and comparison of both material, native (KK) and modified (KKM), was performed. Results of chemical analysis as well as FT-IR spectra, showed that disintegration of hemicellulose occurs as a result of alkaline treatment (decrease of hemicellulose content from 19.23% in KK to 3,52% in KKM; FT-IR spectrum shows loss of 1730 cm-1 peak in KKM, that shows -C=O group in hemicellulose). FT-IR and SEM analysis showed that with alkaline treatment wax and oils are removed from the surface of the biomatirial. Point of zero charge also rose as a consequence of alkaline treatment. Concentration of total acidic groups is higher in KK than in KKM (1.619 mmol/g and 0.317 mmol/g, respectively), while in KKM total concentration of basic groups is higher than in KK (0.309 mmol/g and 0.037 mmol/g, respectively). Results of porosimetry confirmed that after alkaline treatment pore volumes increased in KKM (from 218 to 270 mm3/g), as well as pore diameters (from 393 to 468 nm) and porosity (from 25 to 30%). KKM was examined as a biosorbent for removal of Cu(II), Zn(II) and Pb(II) ions from water solutions. Parameters that affect biosorption were triald (pH, contact time, concentration of biosorbent, granulation) and optimum values for each parameter were established: pH=5,0; contact time 120 minutes; solid/liquid ratio 0,1g/50mL; granulation