Modified barley straw as a potential biosorbent for removal of copper ions from aqueous solution

► The aim is to develop a new adsorbent by modifying barley straws (MBS) and to utilize them for copper ions removal. ► Results indicate that the number of functional groups on the BS increased after it was modified with citric acid solution. ► The adsorbent was originated from the central Anatolia and this modified adsorbent is abundantly available and biodegradable. ► The capacity of MBS is high for the removal of copper and can be applicable for the removal of other toxic trace elements.