Contribution of tertiary amino groups to Re(VII) biosorption on modified corn stalk: Competitiveness and regularity

[Display omitted] ► A low corn stalk gel modified by di-n-octylamine was developed. ► The novel gel exhibited a high affinity for Re(VII). ► Re(VII) adsorption capacity and selectivity depend on basic strength and steric hindrance of the modified gels. ► The recovery of Re(VII) in the presence of excess of other metal ions was possible. The effects of basic strength and steric hindrance of gels modified by dimethylamine, diethylamine, di-n-octylamine and di-2-ethylhexylamine, respectively, on rhenium (Re(VII)) adsorption capacity and selectivity were discussed. By comparing with the adsorption of other coexisting metals, such as Mo(VI), Cu(II), Pb(II), Fe(III), Zn(II), Mn(VII) and Ni(II), the gel modified by di-n-octylamine (DNOA-OCS) showed a high affinity for Re(VII) at higher hydrochloric acid concentration (CH+⩾1.0molL−1), and the maximum adsorption capacity was 98.69mgg−1. This article not only described the adsorption behavior but also suggested isotherms, kinetics and thermodynamics of Re(VII) onto the DNOA-OCS gel in an aqueous medium using several models. Further study on adsorption of rhenium in a fixed-bed column packed with the DNOA-OCS gel under continuous and recirculating modes could confirm that the corn stalk gel modified by di-n-octylamine could be used as the adsorbent of Re(VII) from Mo-containing wastewater.