Sinteza i karakterizacija polimernih hidrogelova na bazi akrilata za uklanjanje teških metala iz vodenih rastvora

Abstract

U prvom delu ovog rada su polimerizacijom preko slobodnih radikala sintetisani hidrogelovi na bazi 2-hidroksietil akrilata i itakonske kiseline (P(HEA/IK)). Tokom sinteze hidrogelova varirani su udeli itakonske kiseline (2,0, 5,0, 7,0 i 10,0 mol % IK) kako bi se ispitao uticaj sastava hidrogela na efikasnost sorpcije teških metala. Karakterizacija dobijenih uzoraka je izvedena ispitivanjem kinetike bubrenja u puferima razliţitih pH vrednosti kao i bubrenjem u destilovanoj vodi, primenom infracrvene spektroskopije sa Furijeovom transformacijom (FTIR), skenirajuše elektronske mikroskopije (SEM), dinamiţko-mehaniţke analize (DMA), mikroskopije atomskih sila (AFM) i diferencijalne skenirajuše kalorimetrije (DSC). U drugom delu ovog rada ispitana je mogušnost uklanjanja jona Pb2+, Cd2+ i Ni2+ iz vodenih rastvora pomošu P(HEA/IK) hidrogelova. Ispitan je uticaj pH sredine, mase sorbenta, uticaj soli, temperature i poţetne koncentracije metala na stepen uklanjanja. Ispitano je pet modela adsorpcionih izotermi (Langmuir-ov, Freundlich-ov, Redlich-Peterson-ov, Temkin-ov i Dubinin-Raduškeviţ-ev), a kinetika sorpcije metala je analizirana preko dva najţešše upotrebljavana modela (Lagergren-ovog kinetiţkog modela pseudo-prvog reda i Ho-ovog kinetiţkog modela pseudo-drugog reda). Obzirom da se u otpadnim vodama vrlo ţesto moţe naši veši broj metala, ispitan je i uticaj konkurentnih jona na proces sorpcije Pb2+, Cd2+ i Ni2+. Na kraju je ispitana mogušnost desorpcije metala sa sorbenata odgovarajušim desorpcionim sredstvima i ispitana mogušnost ponovne upotrebe hidrogelova kao sorbenata. Rezultati pokazuju da su P(HEA/IK) hidrogelovi pogodni kao sorbenti za uklanjanje jona Pb2+, Cd2+ i Ni2+ iz vodenih rastvora, pre svega zbog dobrog kapaciteta sorpcije, mogušnosti ponovne upotrebe i dobrih mehaniţkih svojstava, što je veoma vaţno za praktiţnu primenu

In the first part of this work hydrogels based on 2-hydroxyethyl acrylate and itaconic acid P(HEA/IA) were prepared by free radical cross-linking copolymerization. In order to investigate the influence of the hydrogel composition on heavy metal sorption efficiency, series of the hydrogels with different amount of the itaconic acid were prepared (2.0, 5.0, 7.0 i 10.0 mol %). The swelling kinetics was carried out in buffers of different pHs and in destiled water. Further, the samples were characterised by Fourier transform infrared spectroscopy (FTIR), dynamic-mechanical analysis (DMA), scanning electron microscopy (SEM), atomic force microscopy (AFM) and differential scanning calorimetry (DSC). In the second part of this work, the P(HEA/IA) hydrogels were investigated as potential sorbents for removal of Pb2+, Cd2+ i Ni2+ ions from aqueous solution. In order to evaluate sorption behavior of samples various factors affecting the uptake of heavy metal ions behavior, such as: contact time, temperature, pH, ionic strength, sorbent weight, competitive ions and initial concentration of the metal ions were investigated. Five adsorption isotherms (Langmuir, Freundlich, Redlich-Peterson, Temkin i Dubinin-Raduskevich) and two kinetic models were studied (Lagergren pseudo-first order and pseudo-second order kinetics). The sorption process in multicomponent heavy metal ion system was also investigated, since the natural and industrial effluents rarely contain a single heavy metal ion, and some of the ions in the effluent may reduce the sorption of others or may be co-adsorbed along with other ions. At the end, desorption and the potential reausability of P(HEA/IA) hydrogels was examined. All results indicate that the P(HEA/IA) hydrogels could be used as promising sorbents for the removal of Pb2+, Cd2+ i Ni2+ ions from aqueous solution due to their high sorption capacity, good mechanical properties and possibility of reuse.