Enhanced Heterogeneous Fenton Degradation of Organic Pollutants by CRC/Fe3O4 Catalyst at Neutral pH

Fe3O4-based heterogeneous Fenton catalysts have been widely employed for degrading organic pollutants, however it is challenging to use them in highly efficient and recyclable application in wastewater treatment. In this work, carboxylate-rich carbon (CRC)-modified Fe3O4 magnetic particles are prepared by the sol-gel self-combustion method, where CRC is obtained from the carbonization of sodium gluconate. The CRC/Fe3O4 catalyst exhibits high heterogeneous Fenton degradation performance. The complete 10 mg L−1 methylene blue (MB) removal is achieved in 180 min under conditions of 10 mM H2O2 and 1.00 g of L−1 CRC/Fe3O4 at neutral pH. After five cycles, the structure and morphology of CRC/Fe3O4 composites remained unchanged and the catalytic activity also remained unaltered. Moreover, phenol, benzoic acid (BA), sulfamethazine (SMT), and tetracycline (TC) were also degraded in the heterogeneous Fenton reaction using CRC/Fe3O4 as a catalyst. The strong coordinating ability of –COOH/ –COO– functionalities of CRC formed strong bonds with Fe(II/III) ions on the surfaces of Fe3O4 particles, which was conducive to adsorption of organic matter on the surface of the catalyst and promoted the occurrence of heterogeneous Fenton reactions. It was found that CRC/Fe3O4 had higher removal rates for the adsorptive exclusions of pollutants, such as TC and MB, whereas there were lower removal rates for phenol, BA, and SMT. This work brings potential insights for development of a novel adsorption-enhanced heterogeneous Fenton reaction for wastewater treatment.

Synthesis of core-shell magnetic metal organic frameworks composite for efficient uranium (VI) removal

The combination of magnetic nanoparticles and metal-organic frameworks (MOFs) has demonstrated their prospective for pollutant sequestration. In this work, Fe3O4@SiO2@UiO-66 core-shell magnetic microspheres were synthesized and used for the removal...

Heterogeneous copper-catalyzed synthesis of diaryl sulfones

A carbon-supported copper nanoparticle (Cu-NP) with high catalytic activity for the synthesis of diaryl sulfones is reported. For the first time, this Cu-NP is proved to be able to effectively promote the reaction of arylboronic acids and arylsulfonyl hydrazides to generate diaryl sulfones at room temperature. The reaction shows excellent substrate universality, and substrates with different substituents can undergo the reaction smoothly, leading to the desired products in good yields. The Cu-NP is found to be made of low valence Cu based on XRD. Hence, the reaction catalyzed by the Cu-NP is believed to involve a Cu-mediated organometallic cycle.

Superadsorbent Fe3O4-coated carbon black nanocomposite for separation of light rare earth elements from aqueous solution: GMDH-based Neural Network and sensitivity analysis

A series of nanocomposites adsorbents with different magnetite/carbon black ratios were synthesized by using the co-precipitation method and used for separation of LREEs (Ce, La, and Nd) from aqueous solution. The adsorption efficiency of nanocomposites is strongly dependent on both pH and the loading carbon on nanocomposite. The maximum adsorption capacity (370 mg/g) was reported by nanocomposite with 20% Fe3O4 and 80% carbon in pH 7 for LREE initial concentration of 250 ppm. Results revealed that the LREEs adsorption behavior of the optimal adsorbent fits well with Langmuir isotherm and pseudo-first-order kinetic model. Moreover, the average values of thermodynamic parameters suggest the endothermic and irreversible chemisorption mechanism. An empirical correlation was obtained by using GMDH (Group Method of Data Handling)-based Neural Network to predict the adsorption kinetics of LREEs as a function of ion's electronegativity, molecular weight, and initial concentration. The results showed that the correlation can predict the experimental data mostly lower than 12.5% and it can predict the results of other researches with similar conditions with up to 25% from the experimental values. Finally, the results of sensitivity analysis revealed that the adsorption of LREEs is more sensitive to ions electronegativity and molecular weight at equilibrium conditions.

Single-Step Synthesis of Magnesium-Doped Lithium Manganese Oxide Nanosorbent and Their Polymer Composite Beads for Selective Heavy Metal Removal

Magnesium-doped lithium manganese oxide nanosorbent is prepared by a single-step solid-state method and characterized with appropriate analytical techniques, adsorption kinetic model, and isotherms. Competitive and noncompetitive adsorption studies are performed for a range of heavy metal ions. Prepared nanosorbent has shown explicit selectivity for various heavy metal ions and no remarkable influence of coexisting common interfering ions (Na⁺, K⁺, Mg²⁺, and Ca²⁺), which generally coexist with all natural sources of water, contaminated water, and industrial waste. To achieve easy handling of an adsorbent, polysulfone-nanosorbent (PS-nanosorbent) composite beads are prepared, and their competitive heavy metal removal performance is determined. Competitive adsorption and regeneration studies have shown that PS-nanosorbent beads can be employed for selective heavy metal removal and reuse for multiple cycles.

Synergistic effects of ion exchange and complexation processes in cysteine-modified clinoptilolite nanoparticles for removal of Cu(ii) from aqueous solutions in batch and continuous flow systems

In this work, clinoptilolite tuff was pre-treated and converted to microparticles (CMP) and nanoparticles (CNP) by a mechanical method.