As the global freshwater crisis intensifies, desalination has emerged as a reliable method for water supply worldwide. However, the high energy consumption and operating costs associated with conventional steam-driven seawater desalination remain significant challenges. This study proposes a low-temperature multi-effect distillation (LT-MED) model driven by waste heat to replace conventional steam and reduce the cost of distillation. A case study was conducted on the 15,000 m³/day Hengli Petrochemical hybrid system in Dalian, China, which integrates distillation desalination with hot-water flashing. The thermodynamic model of the hybrid system, based on energy and mass balance equations, demonstrates that a seven-effect evaporator setup offers the most cost-effective and energy-efficient solution. The study explores four methods to enhance the Gain Output Ratio (GOR) and identifies optimal parameters and configurations for improved overall system performance. The findings provide valuable insights for designing innovative hybrid distillation systems powered by low-grade waste heat.
Bioleaching is regarded as an environmentally sustainable process for recycling spent lithium-ion batteries (LIBs). However, at high pulp densities, its application becomes challenging due to reduced microbial activity caused by the toxic metal components in the LIB black mass. Accordingly, the applicability of bioleaching under high pulp density conditions requires systematic evaluation. In this study, Acidithiobacillus ferriphilus 9-P1 was utilized, and leaching parameters, including inoculation rate, temperature, agitation speed, pulp density, and initial Fe2+ concentration, were tested in both 2 L and 10 L laboratory-scale reactors. Among the bioleaching factors, the bioleaching efficiency was enhanced by increasing the inoculation ratio to 50% and the iron concentration from 8.8 to 33 g/L. Elevating the temperature to 37.5°C significantly improved the leaching efficiencies to 99.2% for Li, 96.1% for Al, 96.8% for Mn, 98.7% for Co, 98.6% for Ni, and 95.8% for Cu within 168 h. Furthermore, at the 10 L reactor scale, leaching efficiencies exceeding 90% for Li, Al, Mn, Co, and Ni, and 81.6% for Cu were achieved within 168 h. These results demonstrate that bioleaching can serve as a practical and environmentally friendly alternative to traditional LIB recycling processes even under high pulp density conditions.
Currently, manganese-based catalysts suffer from insufficient low-temperature activity and a tendency to chlorine poisoning-induced deactivation during the catalytic combustion of chlorobenzene. This study successfully developed Nb-Ca/MnO2 catalysts, with the Nb(2)-Ca(2)/MnO2 catalyst exhibiting superior performance: A T90 of 340°C for CB conversion at 15,000 mL·g⁻¹·h⁻¹, over 85% conversion retention during a 30-hour test, and a significant reduction in polychlorinated by-products. Catalyst characterization results indicated that Nb existed in the form of Nb2O5. A small amount of Nb substantially increased the Mn3⁺/Mn4⁺ ratio and markedly raised the proportion of surface adsorbed oxygen. Furthermore, Nb loading enhanced the low-temperature redox capability of the catalyst. The introduction of Nb significantly altered the distribution of acidic sites, promoted the desorption of chlorine species, and effectively suppressed the formation of polychlorinated by-products. In situ DRIFTS results revealed the generation of abundant bidentate carbonates and maleates during the reaction, along with a significant reduction in chlorine species on the spent catalyst. The Nb-Ca/MnO2 catalyst exhibited advantages in both catalytic activity and resistance to chlorine poisoning.
Recently, there have been increasing challenges in handling surplus biomass such as barley straw, and technologies that utilize these materials to create high value-added resources, such as electrode materials, are gaining considerable attention. In this study, a barley straw biochar-based activated carbon was synthesized from an agricultural by-product and evaluated for membrane capacitive deionization (MCDI). The electrochemical properties and hardness removal performance of the fabricated electrode were systematically investigated and compared with those of six commercial activated carbon electrodes. The biochar-based electrode exhibited a morphology comparable to commercial electrodes and showed typical electric double-layer capacitive behavior. The MCDI system achieved a deionization capacity of approximately 14 mg/g and a deionization rate of 0.035 mg/g/s. Although the deionization rate was slightly lower than that of some commercial electrodes, the biochar-based electrode demonstrated comparable deionization capacity and energy consumption (approximately 0.98 Wh/g-CaCl2). In addition, excellent cycling stability was observed, with 94.6% of the initial charge capacity retained after 180 cycles and Coulombic efficiency exceeding 99%. These results demonstrate that barley straw biochar-based activated carbon is an alternative to commercial activated carbon electrodes for CDI-based hardness control.
Perfluorooctanoic acid (PFOA), a representative "forever chemical," poses significant threats to ecosystems and human health due to its persistence and bioaccumulation. While molecularly imprinted polymers (MIPs) offer selectivity for PFOA removal, their practical application is often hindered by low adsorption capacity and difficulties in separation. To address these limitations, this study developed a novel magnetic chitosan-based molecularly imprinted polymer (MMIP) via a surface molecular imprinting strategy. The synthesized MMIP utilized magnetic chitosan as a support and employed a dual-functional monomer system (methacrylic acid and chitosan) to enhance adsorption sites. Characterization confirmed the material's superparamagnetism, uniform porous structure, and crystalline stability. The adsorption process followed a Pseudo-second-order kinetic model and the Langmuir isotherm model, suggesting monolayer chemisorption as the primary adsorption mechanism with the synergy of electrostatic interactions and hydrogen bonding. The MMIP exhibited a high saturation adsorption capacity of 51.28 mg g-1 and a significant imprinting factor of 2.65, demonstrating excellent selectivity for PFOA even in the presence of structural analogs. Furthermore, the material retained over 90% of its adsorption capacity after five cycles, proving its robust reusability. This work highlights the potential of the designed MMIP as a highly efficient, selective, and easily separable adsorbent for the remediation of PFOA-contaminated water.
