Recovery of antimony using biological waste and stepwise resourcization as catalysts for both polyesterification and transfer hydrogenation

Unlocking a Sustainable Future for Plastics: A Chemical-Enzymatic Pathway for Efficient Conversion of Mixed Waste to MHET and Energy-Saving PET Recycling

The heterogeneous monomers obtained from plastic waste degradation are unfavorable for PET recondensation and high-value derivative synthesis. Herein, we developed an efficient chemical-enzymatic approach to convert mixed plastic wastes into homogeneous mono-2-hydroxyethyl terephthalate (MHET) without downstream purification, benefiting from three discovered BHETases (KbEst, KbHyd, and BrevEst) in nature. Towards the mixed plastic waste, integrating the chemical K2CO3-driven glycolysis process with the BHETase depolymerization technique resulted in an MHET yield of up to 98.26 % in 40 h. Remarkably, BrevEst accomplished the highest BHET hydrolysis (~87 % efficiency in 12 h) for yielding analytical-grade MHET compared to seven state-of-the-art PET hydrolases (18 %-40 %). In an investigation combining quantum theoretical computations and experimental validations, we established a MHET-initiated PET repolymerization pathway. This shortcut approach with MHET promises to strengthen the valorization of mixed plastics, offering a substantially more efficient and energy-saving route for PET recycling.

Managing antimony pollution: Insights into Soil-Plant system dynamics and remediation Strategies

Researchers are increasingly concerned about antimony (Sb) in ecosystems and the environment. Sb primarily enters the environment through anthropogenic (urbanization, industries, coal mining, cars, and biosolid wastes) and geological (natural and chemical weathering of parent material, leaching, and wet deposition) processes. Sb is a hazardous metal that can potentially harm human health. However, no comprehensive information is available on its sources, how it behaves in soil, and its bioaccumulation. Thus, this study reviews more than 160 peer-reviewed studies examining Sb's origins, geochemical distribution and speciation in soil, biogeochemical mechanisms regulating Sb mobilization, bioavailability, and plant phytotoxicity. In addition, Sb exposure effects plant physio-morphological and biochemical attributes were investigated. The toxicity of Sb has a pronounced impact on various aspects of plant life, including a reduction in seed germination and impeding plant growth and development, resulting from restricted essential nutrient uptake, oxidative damages, disruption of photosynthetic system, and amino acid and protein synthesis. Various widely employed methods for Sb remediation, such as organic manure and compost, coal fly ash, biochar, phytoremediation, microbial-based bioremediation, micronutrients, clay minerals, and nanoremediation, are reviewed with a critical assessment of their effectiveness, cost-efficiency, and suitability for use in agricultural soils. This review shows how plants deal with Sb stress, providing insights into lowering Sb levels in the environment and lessening risks to ecosystems and human health along the food chain. Examining different methods like bioaccumulation, bio-sorption, electrostatic attraction, and complexation actively works to reduce toxicity in contaminated agricultural soil caused by Sb. In the end, the exploration of recent advancements in genetics and molecular biology techniques are highlighted, which offers valuable insights into combating Sb toxicity. In conclusion, the findings of this comprehensive review should help develop innovative and useful strategies for minimizing Sb absorption and contamination and thus successfully managing Sb-polluted soil and plants to reduce environmental and public health risks.

Arsenic and antimony desorption in water treatment processes: Scaling up challenges with emerging adsorbents

The metalloids arsenic (As) and antimony (Sb) belong to the pnictogen group of the periodic table; they share many characteristics, including their toxic and carcinogenic properties; and rank as high-priority pollutants in the United States and the European Union. Adsorption is one of the most effective techniques for removing both elements and desorption, for further reuse, is a part of the process to make adsorption more sustainable and feasible. This review presents the current state of knowledge on arsenic and antimony desorption from exhausted adsorbents previously used in water treatment, that has been reported in the literature. The application of different types of eluents to desorb As and Sb and their desorption performance are described. The regeneration of saturated adsorbents and adsorbate recovery techniques are outlined, including the fate of spent media and possible alternatives for waste disposal of exhausted materials. Future research directions are discussed, as well as current issues including the lack of environmental impact analysis of emerging adsorbents.

High capacity adsorption of antimony in biomass-based composite and its consequential utilization as battery anode

Antimony is more than an emerging pollutant in water but a scare resource. In this study, we report an adsorbent with the record capacity so far from the balanced view of Sb(III) and Sb(V). The composite adsorbent was fabricated by encapsulating hollow Fe₃O₄ nanosphere with the EDTA grafted chitosan, and it has superhigh adsorption capacity of for 657.1 mg/g for Sb(III) and 467.3 mg/g for Sb(V), respectively. The mechanism study reveals that the adsorption of Sb initializes from the Fe₃O₄, propagates along the chitosan with hydrogen bond, and terminates at the inner sphere complex with the EDTA moiety in the adsorbent. In view of the ultra-high adsorption capacity of the adsorbent, the recovered adsorbent that contains abundant (>36.4%) highly dispersed antimony nanoparticles (600-FCSE-Sb) is applied to Li-ion battery anode after reduction. This article provides a new idea for connecting water treatment and electric energy storage.

Antimony (Sb) pollution control by coagulation and membrane filtration in water/wastewater treatment: A comprehensive review

Antimony (Sb) pollution in the water environment caused by the large-scale mining of Sb ore and the wide use of Sb-containing products seriously endangers human health and poses a great threat to the ecological environment. Coagulation is one of the most cost-effective technologies for Sb pollution control in water/wastewater treatment and has been widely used. However, a comprehensive understanding of Sb pollution control by coagulation, from fundamental research to practical applications, is lacking. In this work, based on the current status of Sb pollution in the water environment, a critical review of the Sb removal performance and mechanism by coagulation and related combined processes was carried out. The influencing factors of Sb removal performance by coagulation are introduced in detail. The internal mechanisms and improvement strategies of Sb removal by oxidation/reduction-coagulation and coagulation-membrane filtration technologies are emphasized. Moreover, given the development of Sb-removing coagulants and the resource utilization of Sb-containing sludge, future perspectives of coagulation for Sb removal are discussed. As the first review in this field, this work will illuminate avenues of basic research and practical applications for Sb and Sb-like pollution control in water/wastewater treatment.

Biochar microtube interconnected hydrotalcite nanosheets for the adsorption of aqueous Sb(III)

Actuated by the non-ionic heavy metal of antimony (Sb) contaminants with undesired toxicity to the environment and human health, capturing Sb is urgent to remedy contaminated water. Herein, the lamellar MnCo hydrotalcite was grown on catkin-derived biochar through the in situ etching of ZIF-L to construct a hierarchical microtube@nanosheet hybrid (CLMH) for Sb immobilization. The adsorption behaviour and mechanism of trivalent antimony (Sb (III)) on the CLMH were investigated. The CLMH shows good pH applicability for capturing Sb(III) at pH from 2 to 9. The excellent adsorption capacity of CLMH for Sb(III) is 247.62 mg g^-1at 303 K, and the endothermic process is proved by the positive value of ΔH0(10.54 kJ mol^-1). The adsorption process is fitted with the intra-particle diffusion model, which can be described with external mass transfer, intraparticle diffusion in pores, and equilibrium stage. The adsorption mechanism is proved, which includes the bind of Metal-O-Sb bonds by inner-sphere complex, the embedding of Sb in the intercalation of hydrotalcite, redox between Mn and Sb, and functional groups dependent anchoring effect. The work benefits the understanding of the antimony removal behaviour over the hierarchical microtube@nanosheet hybrids.