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Quantity of water is a major concern, but the quality is of more urgent concern due to heavy metal pollution. In this study, the focus was to develop adsorbents (tannin resin (TR) and iron-doped tannin resin (Fe-TR)) from invasive Acacia mearnsii for Pb2+ and Ni2+ in solution. The developed TR and Fe-TR were prepared directly by crosslinking and iron-grafting; respectively with thermal stable at ≤ 350 °C. Surface functionality analysis revealed the presence of chelating groups at ≈ 1688 and 3661 cm−1. The crystallite sizes of the adsorbents were smaller compared to tannin; however, the % carbon and nitrogen were significantly higher. Also, the Brunauer–Emmet–Teller study revealed that iron-grafting of tannin after crosslinking increases the surface area, pore volume and pore size. Furthermore, the surface morphology of adsorbents indicated a well-defined structure with the formation of a whitish deposit and rough lump-like after ion uptake. Both adsorbents showed a type II isotherm with adsorption capacities of 40.650 mg/g and 13.763 mg/g for Pb2+and 120.63 mg/g and 110.74 for Ni2+ ion by TR and Fe-TR; respectively. The absorbate-adsorbent interactions were observed to be endothermic with negative and positive Gibb's free energy values for the adsorption of Pb2+ and Ni2+; respectively. The adsorption kinetics of Ni2+ is governed by several models; however, Pb2+ interaction is regulated by Pseudo-second-order model. Furthermore, the data generated offered the possibility of both chemisorption and physisorption processes; highlighting the flexibility and multifunctionality of tannin traps for the erasure of ion impurities in wastewater.

International audience; By using biosourced raw materials such as condensed tannins and furfuryl alcohol a biosourced thermoset resin was developed and used and tested for a new application: as a resin matrix of solid grinding wheels for angle grinders. The manufacturing procedure developed is particularly easy. Cutting and grinding discs based on this green resin were used for bonding different sizes of abrasive particles of aluminium trioxide. These discs were characterized and showed excellent abrasiveness and cutting properties. Their mechanical resistance was found to be comparable to that of commercial grinding discs bonded with synthetic phenolic resins. They tolerated well the severe stresses induced on them at 11,000 revolutions per minute (rpm) by operation in an angle grinder when grinding or cutting steel.