Karakterizacija kemijskih svojstava biosorbensa

master's thesis

• Author: Ira Senji
• Mentor: Mirela Rožić (mentor)
• Committee member: Mirela Rožić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Graphic Arts; Zagreb
• Defense date and country: 2011-3-21, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Graphic Technology

Abstract

U ovom radu prouĉavana su kemijska svojstva kationskih biosorbensa; kore naranĉe i limuna. ATR spektri pokazuju da su funkcijske skupine ispitivanih uzoraka biosorbensa protonirane i deprotonirane karboksilne skupine te hidroksilne skupine. U otopini NaOH pH vrijednosti 13 dolazi do neutralizacije kiselih –COOH skupina ali i do hidrolize esterskih skupina ugljikohidrata. Zbog toga se ta inaĉe u literaturi široko preporuĉavana neutralizacijska metoda odreĊivanja karboksilnih skupina nije pokazala toĉnom. Pošto baznom hidrolizom sorbensa nastaju dodatne koliĉine deprotoniranih karboksilnih skupina (–COO-), koliĉina sorbiranog kationskog bojila metilenskog modrila na biosorbensima je veća nakon obrade biosorbensa s otopinom NaOH. Potenciometrijskom i konduktometrijskom titracijom s otopinom NaOH suspenzija uzoraka biosorbensa u destiliranoj vodi dobiveno je da se povećanjem mase biosorbensa u otopini smanjuje i stupanj disocijacije –COOH skupina pa je i manji udio H+ iona koji se mogu izmjeniti s kationima u otopini. U otopini HCl pH vrijednosti 1 dolazi do neutralizacije baziĉnih –COO- skupina i ta neutralizacijska metoda odreĊivanja –COO- skupina pokazala se toĉnom. Izoterme sorpcije metilenskog modrila na uzorke biosorbensa imaju S oblik koji se može pripisati sorpciji metilenskog modrila na protonirane i deprotonirane karboksilne skupine u otopinama koncentracija bojila manjih od 800 mg/dm3, te na –OH skupine u otopinama većih koncentracija bojila. Sorpcija metilenskog modrila može se upotrijebiti kao metoda odreĊivanja ukupne koliĉine –COO- i –COOH skupina.

Abstract (english)

This study examines chemical properties of cationic biosorbents; orange and lemon peel. ATR spectra show the functional groups of tested biosorbent samples are protonated and deprotonated carboxyl and hidroxyl groups. In the NaOH solution with pH value 13, acidic –COOH groups are neutralized while the ester groups of carbohydrates are hydrolised. Because of the latter, this neutralization method of detection of carboxyl groups, otherwise widely recomended in literature, has not been accurate. Since the alkaline hydrolysis of sorbent produces extra deprotonated carboxyl groups (–COO-), the amount of cationic dye methylene blue sorbed by biosorbents is greater after the biosorbents have been processed with the NaOH solution. Potentiometric and conductometric titration of biosorbent suspensions in distilled water, with varying masses of biosorbent, shows a reduction in the degree of dissociation of –COOH groups with the growth of the biosorbent mass, so the portion of H+ ions that can be exchanged with cations in the solution diminishes. In the HCl solution with pH value 1 the alkaline –COO- groups are neutralized and this neutralization method of detection of –COO- groups turned out to be correct. The isotherms of methylene blue sorption by the biosorbent samples are S-shaped, and this can be ascribed to the sorption of methylene blue by protonated and deprotonated carboxyl groups in solutions with dye concentrations lesser than 800 mg/dm³, and by –OH groups in solutions with dye concentrations greater than that. Sorption of methylene blue can be used as a method of determination of total quantites of –COO- and –COOH groups.

• Keywords: biosorbens; kora naranĉe i limuna; karakterizacija; metilensko modrilo; izoterme
• Keywords (english): biosorbent; orange and lemon peel; characterisation; methylene blue; isotherms
• Language: croatian
• URN:NBN: urn:nbn:hr:216:814206
• Study programme: Title: Graphic technology; specializations in: Graphic technology, Design of graphic products; Course: Graphic technology; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra inženjer/inženjerka grafičke tehnologije (sveučilišni/a magistar/magistra inženjer/inženjerka grafičke tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2024-04-17 09:30:47