pH-Responsive Semi-Interpenetrated Polymer Networks of pHEMA/PAA for the Capture of Copper Ions and Corrosion Removal

Abstract

Bronze artifacts constitute a fundamental portion of Cultural Heritage, but effective methodologies for the removal of corrosion layers, such as those produced by the “bronze disease”, are currently missing. We propose the formulation and application of novel poly­(2-hydroxyethyl methacrylate) (pHEMA) networks semi-interpenetrated (SIPN) with poly­(acrylic acid) (PAA) to achieve enhanced capture of copper ions and removal of corrosion products. The pHEMA/PAA SIPNs were designed to improve previous pHEMA/poly­(vinylpyrrolidone) (PVP) networks, taking advantage of the chelating ability of pH-responsive carboxylic groups in PAA. Increasing the pH ionizes carboxyls, increases the porosity in pHEMA/PAA, and leads to the co-presence of enol and enolate forms of vinylpyrrolidone (VP), changing the macroporosity and decreasing the mesh size in pHEMA/PVP. The ion–matrix interaction is stronger in pHEMA/PAA, where the process occurs through an initial diffusion-limited step followed by diffusion in smaller pores or adsorption by less available sites. In pHEMA/PVP, the uptake is probably controlled by adsorption as expected, considering the porogen role of PVP in the network. Upon application of the SIPNs loaded with tetraethylenpentamine (TEPA) onto corroded bronze, copper oxychlorides dissolve and migrate inside the gels, where Cu­(II) ions form ternary complexes with TEPA and carboxylates in PAA or carbonyls in PVP. The removal of oxychlorides is more effective and faster for pHEMA/PAA than its /PVP counterpart. The selective action of the gels preserved the cuprite layers that are needed to passivate bronze against corrosion, and the pH-responsive behavior of pHEMA/PAA allows full control of the uptake and release of the Cu­(II)–TEPA complex, making these systems appealing in several fields even beyond Cultural Heritage conservation (e.g., drug delivery, wastewater treatment, agricultural industry, and food chemistry).

Ultrahigh Selective Hydrogenation of Furfural Enabled by Modularizing Hydrogen Dissociation and Substrate Activation

“…Finally, Cu species was complexed with poly­(vinyl polyamine) (TEPA), followed by its introduction into the mesopores of the shell by means of wet impregnation, namely, Cu–Pt@TMS . The as-formed Cu–TEPA complexes could prevent Cu species from entering the pores of zeolites during impregnation, thus positioning Cu species in the mesopores . For comparison, the Pt/TMS and Cu/TMS catalysts were synthesized via the wet impregnation method, in which Pt or Cu was localized in the mesopores of TMS.…”

Removal of Brilliant Green Dye from Water Using Ficus benghalensis Tree Leaves as an Efficient Biosorbent

“…To evaluate the best linear fit and the order of the adsorption process for BG removal, the pseudo-first-order [ 41 ] and pseudo-second-order [ 42 ] linear equations were examined. The reaction pathway, dye adsorption mass transfer method, and diffusion rate are all vitally revealed by the process’ kinetics [ 43 , 44 , 45 ].…”

Adsorption of Cu(II) in aqueous solution by sodium dodecyl benzene sulfonate‐modified montmorillonite

“…[4] In the case of severe contamination of water with Cu(II), excess Cu(II) can be ingested through drinking water and the food chain to enrich the human bodies, causing damage to organs and the digestive system, and so forth. [5,6] Therefore, it is essential to reduce the concentration of Cu(II) in water.…”