Sulphonation of expanded polystyrene waste with commercial sulphuric acid for potential use in removal of heavy metals from contaminated waters

Polistiren je sulfoniran komercijalnom sumpornom kiselinom kako bi se dobio izmjenjivač iona primjenjiv za uklanjanje teških metala iz otopina. Istraživani su sljedeći reakcijski uvjeti koji utječu na konverziju sulfonacije: vrijeme reakcije, temperatura reakcije te molarni omjer stirena i sumporne kiseline. Prema očekivanjima, vrijeme reakcije povećava konverziju. Iskoristivost reakcije također raste s povišenjem temperature uljne kupke. Molarni omjer ima važnu ulogu i sulfonacija se javlja pri molarnom omjeru S:H2SO4 1:1, a konverzija reakcije raste s povećanjem molarnog omjera. Konverzija reakcije uz korištenje čiste sumporne kiseline bila je znatno jača u usporedbi s konverzijom s pomoću komercijalne sumporne kiseline. Osim toga uzorci polistirena ozračivani su gamazrakama prije sulfonacije. Zamijećeno je da ozračeni uzorci postižu viši stupanj sulfonacije. Sposobnost sulfoniranog polistirena da preuzima neke otrovne metalne ione procijenjena je prema omjeru sulfonacije: Cu2+, Co2+, Ni2+, Cr3+.Polystyrene has been sulphonated using commercial sulphuric acid in order to obtain ion exchangers, which could be used to uptake some heavy metals from solutions. Reaction conditions which affect the sulphonation conversion, have been investigated such as: reaction time, reaction temperature and molar ratio of styrene: sulphuric acid. As expected, the reaction time leads to higher conversion. The reaction yield is also increased with increasing the temperature of the oil bath. The molar ratio plays an important role, the sulphonation occurs with a molar ratio (1 : 1, St : H2SO4), and the reaction conversion increases with increasing the molar ratio. The reaction conversion using pure sulphuric acid was insignificantly higher compared with the conversion using commercial sulphuric acid. In addition, polystyrene samples were irradiated with gamma rays prior to sulphonation; a higher sulphonation degree was obtained for the irradiated samples. The ability of sulphonated PS to uptake some toxic metal ions has been evaluated with respect to the sulphonation ratio: Cu2+, Co2+, Ni2+, Cr3+