Novel carbon microsphere-supported metallic copper nanoparticles (Cu-NP/C) were synthesized using a low-cost and facile method based on carbonising a styrene-based, chelate-forming cation exchange resin loaded with Cu²⁺ ions. The metal–organic framework served as both copper and carbon source. Cu-NP/C microspheres were characterized by XRD, Raman, SEM, TGA, EDAX, and BET surface area analyser and were employed as heterogeneous catalysts for the reduction of 4-nitrophenol to 4-aminophenol by NaBH₄ and for the synthesis of medicinally significant hexahydroquinoline derivatives based on the one-pot, multi-component reaction of aldehydes, dimedone, ethyl acetoacetate, and ammonium acetate. The sustainable and cheap starting material, the relatively easy synthetic procedure, the catalytic efficiency, and the easy separation and reusability of Cu-NP/C microspheres open the door for their wide-scale application.

Molecular iodine contributes significantly to organic transformations in synthetic organic chemistry. It works effectively due to its mild Lewis acidic character, ability as an oxidizing agent, good moisture stability, and easy availability.

Copper manganese oxides (CMO) with CuMn₂O₄ composition are well-known catalysts, which are widely used for the oxidative removal of dangerous chemicals, e.g., enhancing the CO to CO₂ conversion. Their catalytic activity is the highest, close to those of the pre-crystalline and amorphous states. Here we show an easy way to prepare a stable CMO material at the borderline of the amorphous and crystalline state (BAC-CMO) at low temperatures (<100 °C) followed annealing at 300 °C and point out its excellent catalytic activity in CO oxidation reactions. We demonstrate that the temperature-controlled decomposition of [Cu(NH₃)₄](MnO₄)₂ in CHCl₃ and CCl₄ at 61 and 77 °C, respectively, gives rise to the formation of amorphous CMO and NH₄NO₃, which greatly influences the composition as well as the Cu valence state of the annealed CMOs. Washing with water and annealing at 300 °C result in a BAC-CMO material, whereas the direct annealing of the as-prepared product at 300 °C gives rise to crystalline CuMn₂O₄ (sCMO, 15–40 nm) and ((Cu,Mn)₂O₃, bCMO, 35–40 nm) mixture. The annealing temperature influences both the quantity and crystallite size of sCMO and bCMO products. In 0.5% CO/0.5% O₂/He mixture the best CO to CO₂ conversion rates were achieved at 200 °C with the BAC-CMO sample (0.011 mol CO₂/(m² h)) prepared in CCl₄. The activity of this BAC-CMO at 125 °C decreases to half of its original value within 3 h and this activity is almost unchanged during another 20 h. The BAC-CMO catalyst can be regenerated without any loss in its catalytic activity, which provides the possibility for its long-term industrial application.

A new and simple method is developed to synthesize carbon microspheres decorated with iron sulfide nanoparticles for mercury ion removal from water. The synthesis is based on carbonizing polystyrene–divinylbenzene-based and iron(III) sulfate-loaded cation exchange resins between 500 and 1000 °C. The phase composition, surface area, and morphology of these materials are characterized by various spectroscopic and diffraction techniques, including Mössbauer spectroscopy, powder X-ray diffraction, Raman and scanning electron microscopy, and BET analysis. Pyrrhotite is found to be the dominant iron-containing phase. The adsorption performance of microspheres for mercury ion removal from water is studied as a function of adsorbent load and contact time at pH 6.5 using a solution of 40 mg dm⁻³mercury ion. Pyrrhotite nanoparticles played a key role in mercury ion removal amounting to 70–90% of the extracted amount. A high adsorption capacity of 104 mg of mercury/g of adsorbent at an adsorbent load of 0.33 g dm⁻³is achieved, and the removal kinetics could be well fitted with a pseudo-second-order kinetic model, indicating chemical sorption. The synthetic method is easy to scale up for large-scale production and materials are easy to handle, which is significant for large-scale environmental applications.