Selective Separation of Pd(II) on Pyridine-Functionalized Graphene Oxide Prepared by Radiation-Induced Simultaneous Grafting Polymerization and Reduction

Abstract

The recovery of precious metals like palladium (Pd) from secondary resources has enormous economic benefits and is in favor of resource reuse. In this work, we prepared a high efficiency pyridine-functionalized reduced graphene oxide (rGO) adsorbent for selective separation of Pd­(II) from simulated electronic waste leachate, by one-pot γ-ray radiation-induced simultaneous grafting polymerization (RIGP) of 4-vinylpyridine (4VP) from graphene oxide (GO) and reduction of GO. The poly­(4-vinylpyridine)-grafted reduced graphene oxide (rGO-g-P4VP) exhibits fast adsorption kinetics and high maximum adsorption capacity. The adsorption capacity is 105 mg g–1 in the first minute and reaches equilibrium within 120 min. The adsorption process follows the Langmuir model, from which the maximum adsorption capacity of Pd­(II) is estimated to be 177 mg g–1. We also proved that the adsorption mechanism of Pd­(II) on rGO-g-P4VP involves both ion exchange and coordination adsorption by XPS analysis. Most importantly, the loss of oxygen-containing groups due to reduction of GO not only facilitates the separation of adsorbent from aqueous solution but also reduces the electrostatic repulsion toward Pd­(II)­Cl4 2– in hydrochloric acid solution, leading to a higher adsorption selectivity of Pd­(II) over some common metal cations in electronic waste including Fe­(III), Cu­(II), and Al­(III) compared with poly­(4-vinylpyridine)-grafted graphene oxide (GO-g-P4VP) prepared by atom transfer radical polymerization. Other precious metals like Pt­(IV) and Au­(III) can also be recovered easily and selectively by rGO-g-P4VP. This work demonstrates that rGO-g-P4VP prepared by the facile RIGP is a promising adsorbent for recovery of precious metals from secondary resources like electronic waste leachate.

Polymerization Reactions and Modifications of Polymers by Ionizing Radiation

“…This allows for a variety of applications [144]. Over the last 5 years, the major applications remain in accordance to societal needs with the development of: adsorbents for depollution (removal of toxic metals [144][145][146][147][148][149][150][151][152], ammonia/ammonium species [153,154], atmospheric CO 2 [155]); exchange membranes for fuel cell (anion [156,157] and proton [158,159], batteries or super capacitors [116]; functional fibers other than adsorbent applications (flame-retardant [160], antistatic and antibacterial [161] properties); and numerous applications are emerging in the field of renewable energies [162].…”

Pd- and Au-Induced Circular and Fibrous Polymer Gelation via Thiocarbonyl Groups and High Pd Catalyst Activity

“…Hybrid materials have also been used to recover precious metals (e.g., Pd, Au, Pt). − Previous studies have reported a high-recovery material based on a polymer consisting of thiocarbonyl groups for metal coordination and amino groups for hydrophilicity . Gelation occurred through self-assembly between the thiocarbonyl groups and metal ions, precipitating the self-assembled polymer–metal complexes, which were then separated by filtration (Figure ).…”

Radiation Controllable Synthesis of Robust Covalent Organic Framework Conjugates for Efficient Dynamic Column Extraction of 99TcO4−

“…58 Post-synthesis COF functionalization by grafting is an appealing alternative synthetic strategy, 52,[59][60][61] among which radiation-induced grafting polymerization represents a typical and mature method of post-synthesis with a long history. [62][63][64][65][66][67][68][69] Compared with chemical initiation methods, g-ray radiation-induced grafting possesses advantages of environmentally green, effective, energy-efficient, and operationally simple for functional modification of substrates. grays are also penetrative enough to ensure the homogeneity of the grafting reaction and, thus, the excellent mechanical properties of the COFs allow continuous and stable operation of the column experiments by maintaining the intrinsic structure of the…”