Guo Lin

In zinc electrodeposition, deposit morphology and thickness uniformity are governed by the coupling of current distribution, ion transport, and interfacial reactions. In this study, a three-dimensional transient finite-element model was established using COMSOL Multiphysics based on the tertiary current distribution framework. The model coupled ionic transport, charge conservation, interfacial electrochemical reactions, and deposition-thickness evolution to analyze Zn2+ and H+ concentration fields, current distribution, and deposition behavior. Simulations were performed under different flow rates, anode–cathode spacings, acid–zinc ratios, and current densities. The results showed that 250 ml min−1, 20 mm spacing, an acid–zinc ratio of 3.4, and 600 A m−2 provided a preferred operating window by balancing Zn2+ supply, H+ accumulation, and zinc growth. Experimental observations agreed well with the simulation trends.

Heavy metal contamination in water bodies poses a persistent threat to aquatic ecosystems and public health. Metal–organic frameworks (MOFs) have emerged as promising adsorbents due to their exceptional surface areas, tunable pore structures, and chemically versatile frameworks. However, despite extensive laboratory-scale success, the practical deployment of MOFs for heavy metal removal remains limited. This review argues that progress requires moving beyond isolated material optimization toward a system-level assessment. We evaluate MOF-based heavy metal adsorption through five interdependent dimensions that collectively determine real-world viability: water stability, selectivity in multi-ion matrices, regenerability over multiple cycles, scalability from gram to kilogram production, and real-water validation under authentic wastewater conditions. A critical observation is that while most studies report the number of cycles, very few investigate the root causes of performance decline during regeneration. We also highlight the gap between idealized laboratory conditions and complex real wastewater, where competing cations, natural organic matter, and suspended solids can severely compromise performance. Building on recent advances in adaptive MOFs, closed-loop resource recovery, and AI-driven material design, we propose a n integrated framework uniting responsive materials, smart regeneration, and process engineering. This review offers a practical roadmap for transitioning MOF-based heavy metal remediation from laboratory promise to deployable technology, emphasizing that progress depends on system integration rather than incremental material refinement.

Owing to the superior reduction kinetics of limonite and goethite relative to silicates, coupled with the poor beneficiation performance of saprolite-type laterite, the direct carbothermal reduction of saprolite-type laterite exhibits limited nickel selectivity. This study leverages the selective oxidation effect of CO-CO₂ atmosphere on the metallic iron of pre-reduced minerals, as well as its suppression of Fe²⁺ reduction, to promote iron migration from oxides to the silicate phase, achieving homogenization and thereby negating its kinetic advantage in reduction. Parameter optimization experiments revealed that treating pre-reduced minerals with a 30 vol% CO atmosphere at 1200 °C for 20 min achieves complete iron homogenization within the silicate phase. Compared with the nickel–iron alloy (containing less than 10 wt% Ni) obtained via the RKEF process, the combination of pre-reduction, CO-CO₂ treatment, and the melting reduction process yielded nickel–iron alloys with nickel contents of 52.1 wt% (FeNi50 alloy) and 64.2 wt% at carbon consumptions of 4.0 wt% and 3.83 wt%, respectively, accompanied by nickel recovery rates of 95.5% and 91.2%. Furthermore, the enrichment of Fe²⁺ in the slag significantly reduces its melting point to approximately 1450 °C, enabling complete slag–metal separation after smelting at 1550 °C for 10 min.

Owing to the superior reduction kinetics of limonite and goethite relative to silicates, coupled with the poor beneficiation performance of saprolite-type laterite, the direct carbothermal reduction of saprolite-type laterite exhibits limited nickel selectivity. This study leverages the selective oxidation effect of CO-CO2 atmosphere on metallic iron and its suppression of Fe2+ reduction to promote iron migration from oxides into the silicate phase, achieving homogenization and thereby negating its kinetic advantage in reduction. Parameter optimization experiments revealed that treating pre-reduced minerals with a 30 vol% CO atmosphere at 1200 °C for 20 minutes achieves complete iron homogenization within the silicate phase. Compared with the nickel-iron alloy (containing less than 10 wt% Ni) obtained via RKEF process, the combination of pre-reduction, CO-CO2 treatment, and melting reduction process yielded nickel-iron alloys with nickel contents of 52.1 wt% (FeNi50 alloy) and 64.2 wt% at carbon consumptions of 4.0 wt% and 3.83 wt%, respectively, accompanied by nickel recovery rates of 95.5% and 91.2%. Furthermore, the enrichment of Fe2+ in the slag significantly reduces its melting point to approximately 1450 °C, enabling complete slag-metal separation after smelting at 1550 °C for 10 minutes.

This investigation addressed the challenge of lead-containing wastewater treatment. We successfully synthesized a novel bimetallic magnetic adsorbent, MOF@Fe₃O₄-PAA, for Pb(II) removal by incorporating Ti ions via hydrothermal/chemical modification. Combined SEM, XRD, BET, FTIR, and XPS characterization elucidated its structure-property relationships. Results demonstrated optimal adsorption at pH 5.0 with a maximum capacity of 295.8 mg/g. Kinetics followed the pseudo-second-order model (R²=0.999), indicating chemisorption dominance. Isotherm analysis favored the Temkin equation (R²=0.979), suggesting combined physicochemical interactions. Thermodynamics revealed spontaneous exothermic adsorption (ΔG < 0, ΔH < 0) with enhanced efficacy at low temperatures. Selectivity tests showed significantly higher affinity for Pb(II) over competing ions (e.g., Cu²⁺, Zn²⁺). Amino (-NH₂) and sulfhydryl (-SH) functional groups enabled Pb(II) binding via coordination, yielding high adsorption capacity, rapid equilibrium attainment, and facile magnetic recovery. This work provides an innovative strategy for efficient wastewater Pb(II) removal.

Ultrasonic and stirring technologies are widely applied due to their strengthening effects in hydrometallurgical processes. However, practical applications often face challenges arising from the randomness in equipment layout and the absence of standardized technical criteria, which result in inconsistencies in process parameters and fluctuations in production efficiency. Therefore, COMSOL finite element software is utilized to establish a multiphysics numerical model coupling ultrasonic and mechanical stirring temperature fields. Through simulation experiments, the study investigates the effects of the distance between the ultrasonic probe and reactor wall, ultrasonic frequency, number of horns, and positioning on the absolute average sound pressure, uniformity of the sound field, and sound speed. The results indicated that the distance between the probe and the container wall, frequency, and probe quantity significantly influence the uniformity of the sound field. The optimal parameter combination achieves maximum efficiency and optimal uniformity. The sound pressure in the reaction tank was measured using a hydrophone. The experimental results align closely with the simulation findings, confirming the numerical model's validity. This model predicts the influence of process parameters on mixing and provides valuable theoretical support for future experimental designs and process optimization.