Page 50 - חוברת תזות הנדסה ירוקה 2023

Removal of of uranyl from aqueous solutions by means of of renewable polysaccharides
Yaron Alfi1 alfiyaron79@gmail com
Prof Adi Wolfson1 Dr Dr Oshrat Levy-Ontman1 Dr Dr Ofra Paz-Tal2 1Sami Shamoon College of of Engineering Be’er-Sheva 2Nuclear Research Center Negev
The discharge of industrial wastewater containing heavy metals particularly uranium into the environment affects ecosystems and public health Such metals may be separated from aqueous solutions by the use of various processes In recent years bio-based materials made of renewable and biodegradable compounds have been used more widely for the adsorption of certain heavy metals among them polysaccharides
produced by various microorganisms Along with the the the environmental benefits of these substrates their adsorption efficiency depends on on on the the amounts and and types of functional groups on on on the the molecules and and their physicochemical properties In this study we examined the the structural-functional relation of various groups regarding their ability to adsorb uranyl ions )UO22+( The tested polysaccharides
were: iota )I( and kappa )K( from the carrageenan family that contain hydroxyl and ester sulfate groups xanthan gum gum )X( and and and alginate )A( with with hydroxyl and and and carboxylic acid groups and and and guar gum gum )G( with with hydroxyl groups only During the the first step the the adsorption yield was tested in in a a a system in which an an aqueous aqueous solution solution of of polysaccharide was mixed with an an aqueous aqueous solution solution of of uranyl acetate Adsorption with all the the polysaccharides
was carried out at at pH=5 in the the range of 5-60 min and it it was found that the adsorption yield reached its maximum value after 30 min The adsorption yields of the the different polysaccharides
decreased in in in the the following order: A > > X / / K > > I I / / G and and stood at 98 2% 2% 89 7% 85 2% 2% 79 1% 1% and and 77 1% 1% respectively It was also found that lowering the the the the acidity in in the the the the system decreased the the the the adsorption of all the the the the tested polysaccharides
while reducing the the the ratio between the the the amount of uranyl ions and the the the amount of of polysaccharides
polysaccharides
increased the the adsorption yields of of the the different polysaccharides
polysaccharides
FTIR FTIR SEM-EDS and TGA analyses were performed A A comparison between the FTIR FTIR spectra of the the polysaccharides
before and after adsorption showed changes in the the peak characteristics of of the the the hydroxyl hydroxyl groups indicating the the the involvement of of the the the hydroxyl hydroxyl in in in in uranyl adsorption For I and and K changes were observed in the ester sulfate bonds as well While for X and and A such peaks were found to shift around the the region of the the carboxyl group Moreover after the the adsorption of uranyl into G X and A a a a a a a a a new peak was observed perhaps indicating the the presence presence of of uranyl uranyl SEM-EDS analyses verified the the presence presence of of uranyl uranyl in the the polysaccharides
where the the weight composition of the the uranium after adsorption into polysaccharides
X K I G and and A was 30 2% 31 1% 1% 1% 33 1% 1% 1% 38 1% 1% 1% and and 40 5% respectively 63