Hybrid Sorbent Research Articles

Recoverable and reusable light-induced multi-arm azobenzenes-Fe3O4 hybrid sorbent for enrichment of phthalate plasticizer and utilized as a SALDI substrate for the detection of 2-naphthol

The construction, structural identifications along with compositional properties, using TEM, FT-IR, and XPS spectroscopies, of an innovative light-induced multi-arm azobenzenes based Fe3O4 magnetic nanoparticles (Azo-Fe3O4 MNPs) are being reported. Such organic (light-sensitive dendrimers-like structure), inorganic (magnet core), hybrid material has been applied as an efficient recoverable/reusable extractive sorbent for the detection of phthalate plasticizers from acetate buffer solution. The extraction study was controlled within consecutive procedures via UV-light exposure to achieve pore-size control which then further subjected for the evaluation of the analytes’ retention, separation, and release as well as the detection of the phthalate pollutants using GCMS–. Various experimental conditions, such as time of extraction, salt concentration, pH, and desorption time, were studied and adjusted. Additionally, the extraction repeatability (RSD from 0.46 % to 6.12%, n = 5) of the studied sorbent was comparable to other published work. The linear range extended from 6.25 to 100 μg L-¹ and detection limits (LOD) within the range of 41- 150 ng L-1 were achieved, demonstrating good linearity with values ranging from 0.9992 to 0.9892. The inter-batch and intra-batch RSD ranged from 0.46 % to 6.12 %, respectively. Additionally, it provides effective detection of 2-naphthol when used as a SALDI substrate.

Intra-lanthanide separation performance of DOTP: Solid-phase extraction and selective precipitation studies

The applicability of 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetra(methylene phosphonic acid) (DOTP) for intra-lanthanide (Ln) separation was investigated through two approaches: the synthesis of inorganic–organic hybrid sorbents and selective precipitation in an aqueous solution. Hybrid sorbents combining zirconium oxide and DOTP were fabricated through post-synthetic grafting and hydrothermal synthesis. The successful syntheses were verified by FTIR and 31P magic-angle spinning (MAS) NMR spectroscopies. All the hybrid sorbents showed a lanthanide uptake of approximately 10–20 μmol/g at pH 3 and displayed only moderate selectivity, with the highest separation factor (SF) of about 10 for Lu3+ over La3+. In contrast, the selective precipitation of lanthanides by DOTP in an aqueous solution was successful in the presence of Cu2+. When a Cu-DOTP complex was introduced into a La/Lu equimolar solution, lanthanide ions were selectively precipitated with an SF of approximately 30–190. When the initial stoichiometry was set to Ln:Cu-DOTP = 8:1, roughly 95 % of the lanthanides in the precipitate were Lu3+, regardless of the pH ranging from 3 to 5. This precipitation process demonstrated selectivity even for adjacent lanthanide pairs. The selectivity is assumed to be a result of structural variations in the precipitates of Ln-Cu-DOTP, which is supported by the characterization results obtained from X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and UV–Vis spectroscopy. The findings presented in this study indicate that DOTP has the potential for use in the selective extraction of lanthanides, which may offer promising advancements in intra-lanthanide separation.

Enhancing solid-phase extraction of tetracyclines with a hybrid biochar sorbent: A comparative study of chlorella and bamboo biochars

Biochar, a sustainable sorbent derived from pyrolyzed biomass, has garnered attention for its efficacy in solid-phase extraction (SPE) of antibiotics, with a particular focus on tetracyclines (TCs). Despite its recognized potential, the intricate separation mechanisms operative in biochar-based SPE systems have not been fully deciphered. This investigation contrasts chlorella biochar against commercial bamboo biochar, harnessing an array of analytical methodologies-microstructure characterization, adsorption thermodynamics, competitive adsorption kinetics, H+ back titration, and selectivity adsorption studies-complemented by a Box-Behnken design for the optimization of chlorella/bamboo-SPE and subsequent application in the analysis of animal-derived foodstuffs. The study unveils that a hybrid sorbent, integrating nitrogen-doped microporous chlorella biochar with mesoporous bamboo biochar in a 95/5 mass ratio, markedly diminishes irreversible adsorption while enhancing selectivity, surpassing the performance of single biochar SPE systems. The elucidated separation mechanisms implicate a partition model, propelled by oxygen-rich functional groups on chlorella biochar and the rapid adsorption kinetics of bamboo biochar, all orchestrated by electrostatic interactions within the mixed biochar framework. Moreover, the synergy of mixed biochar-SPE with high-performance liquid chromatography (HPLC) demonstrates exceptional proficiency in detecting TCs in animal viscera, evidenced by recovery rates spanning 80.80 % to 106.98 % and RSDs ranging from 0.24 % to 14.69 %. In essence, this research not only sheds light on the multifaceted factors influencing SPE efficiency but also propels the use of biochar towards new horizons in environmental monitoring and food safety assurance.

Indigo as a Low‐Cost Redox‐Active Sorbent for Electrochemically Mediated Carbon Capture

AbstractClimate change has driven the need for carbon capture to mitigate anthropogenic greenhouse gas emissions, yet current thermochemical methods are hampered by high energy intensities. Electrochemically mediated carbon capture (EMCC) utilizing redox‐active carbon dioxide (CO2) carriers is an attractive alternative for carbon capture. Here, an economical vat dye compound, indigo, is presented, which can reversibly capture and release CO2 upon electrochemical reduction and oxidation, respectively. Electrode and electrolyte engineering strategies are utilized to improve the reversibility and stability of indigo for EMCC. A bench‐scale prototypical fixed‐bed carbon capture device is constructed to demonstrate indigo's EMCC performance under various practically relevant conditions, such as simulated flue gas and extremely dilute sources pertinent to direct air capture. A hybrid sorbent electrode‐gas diffusion layer approach is revealed to alleviate CO2 mass transport limitations, achieving ≈80% CO2 capacity utilization under a 15% CO2 feed stream. Furthermore, a reactive‐diffusive mass transport model is developed to illustrate engineering approaches that can be universally applied to optimize fixed‐bed EMCC systems. This work advances the potential for a class of low‐cost sorbents for EMCC while underscoring the importance of molecular, electrolyte, materials, and device engineering strategies to enable high‐performance carbon capture.

Synthesis and application of dual-functional sorbent SBA-15-Fe3O4-PDA-ODA for removing both water soluble and insoluble pollutants

In this study, inorganic-organic hybrid sorbent SBA-15-Fe3O4-PDA-ODA with functional groups having affinity for both water-soluble and insoluble pollutants was synthesized for treatment of wastewater where Malachite Green (MG) dye and motor oil coexist. In order to enhance the specific interactions between the sorbent and dye via functional groups of polydopamine (PDA), Fe3O4 nanoparticles were encapsulated with SBA-15 and surface functionalization with PDA was accomplished and then the surface of Fe3O4-SBA-15-PDA was modified with octadecylamine (ODA) to remove the oil present in the same environment with dye. While the SBA-15-Fe3O4-PDA-ODA directed to the aqueous phase by magnet provided MG removal thanks to the hydrophilic groups of PDA, it provided motor oil removal thanks to hydrophobicity of ODA when directed to the oil phase. 99.20 % dye removal and 9.24 g/g oil adsorption capacity were achieved from the environment where oil and dye were present together. Besides, the adsorption of MG on Fe3O4-SBA-15-PDA was searched at various pH, dye concentration, adsorbent dosage, and temperature in order to propose optimum experimental conditions for removal of dye and maximum adsorption capacity was determined as 95.83 mg g−1 at optimum conditions (10 mg adsorbent, 10 mg L−1 MG concentration, pH 9). Interaction mechanism between dye and Fe3O4-SBA-15-PDA was explained by studying the adsorption behavior of sorbent derived from the isotherm and kinetic results. The sorbents were characterized by FT-IR, XRD, SEM, N2-adsorption/desorption, water-contact-angle, and VSM measurements. SBA-15-Fe3O4-PDA-ODA sorbent was tested for three successive adsorption cycles for both dye and oil and eventuated insignificant loss in activity when they were recycled. Easy and low-cost fabrication protocol, controllable removal ability of dye and oil will facilitate its versatility in environmental cleanup process for water soluble and insoluble pollutants.

Scaling up 3D printed hybrid sorbents towards (cost) effective post-combustion CO2 capture: A multiscale study

A 3D-printed sorbent containing polyethylene-imine and multi-walled carbon nanotubes (PEI-MWCNT) was studied for post-combustion carbon capture. In this work, the adsorbent was printed on a kg scale and characterized for CO2 adsorption through lab experiments. A 6-step VSA process was simulated using the lab data to capture CO2 from a representative 800 MW power plant. The adsorbent captured >70 % of the CO2 and 95 % CO2 purity was achieved. The levelized cost of electricity (LCOE) was 130.2 $/MWh and the costs of CO2 captured and avoided were 80 and 100.12 $/tonne. However, a zeolite 13X-activated carbon (13X-AC) monolith achieved a lower LCOE of 118.1 $/MWh, with the captured and avoided costs being 63 and 78.4 $/tonne, respectively. The LCOE value for the 13X-AC monolith was 5.1 % lower than a reference-packed bed system with Zeolite 13X pellets. The corresponding cost values were lower by 9.1 % and 13.9 %, respectively for the costs of CO2 captured and avoided. The lab experiments on the PEI-MWCNT sorbent revealed that further work is necessary to improve the thermal stability and stability with long-term storage of the precursor paste.

Cu-BDC MOF/CNFs hybrids for rapid CO2 capture in a circulating fluidized bed via temperature swing adsorption process

The research aimed to evaluate the effectiveness of Cu-BDC MOF/CNFs hybrid sorbents in capturing CO2 in post-combustion processes. Various analytical techniques were used to analyze the adsorption materials, including XRD, FTIR, TGA, FE-SEM, EDS, BET, and elemental mapping. Capture performance evaluations were conducted using a fluidized-bed system and temperature swing adsorption on a laboratory scale. The Cu-BDC MOF/CNFs hybrids demonstrated their highest sorption capacity at 90 °C. Working capacity evaluations at a regeneration temperature of 120 °C consistently measured an average of 1.34 mol/kg, with a negligible standard deviation of 0.01 mol/kg. Cyclic tests were performed to assess the sorbents' performance, revealing efficient and rapid desorption of adsorbed CO2 within a short duration. Furthermore, 90 % of the sorption capacity was achieved within 5 min. These findings highlight the potential of Cu-BDC MOF/CNFs hybrid sorbents for CO2 capture in post-combustion processes.

A novel sustainable and eco-friendly biosourced hybrid sorbent for toxic Pb2+decontamination: Nano metal oxide functionalized salt-tolerant plant biomass

A novel biomaterial was designed by functionalizing halophytic salt-tolerant Salicornia europa biomass with nano-metal oxide (MnO2) for Pb2+ removal from aqueous environments. To assess the impact of key variables on the sorption behavior of the new biomaterial, a series of batch and column assays were executed. The optimum solution pH and sorbent dosage were 4.5 and 20 mg, respectively. The maximum experimental uptake capacity of the modified sorbent in batch mode was 164.87 mg/g at 25 °C. The findings demonstrated that the modification procedure could greatly enhance the sorbent's performance. The sorption reached an equilibrium after 30 min and obeyed the pseudo-second-order rate equation. Compared to the Langmuir and Dubinin–Radushkevich models, the Freundlich model (r2 = 0.980−0.991) was better for predicting equilibrium data, which indicates the multilayer coverage of the sorbent surface by metal ions. The sorption performance of the suggested material in batch and dynamic flow treatment systems was higher than 94% and 99%, respectively. The removal of Pb2+ by the proposed sorbent was not greatly affected by aqueous disturbances like the coexistence of competing ions. The breakthrough capacities were 251.16 and 55.64 mg/g in synthetic metal ion solution and simulated wastewater, respectively. SEM-EDX and FTIR analysis revealed the biomaterial surface was successfully modified by MnO2 particles. The improved Pb2+ sorption can be linked to the biosorbent's altered surface structure, which endorses electrostatic interactions and complexation. Eventually, this study offers an easy approach for creating lignocellulosic biomass modified with a nano metal oxide that may effectively eliminate toxic Pb2+ ions from aqueous solutions.

Aluminum Montmorillonite/Polyaniline Hybrid Composite-Based Organogels for the Expurgation of Carcinogenic Chlorophenols and Congo Red Dye from Defiled Water Sources.

Chlorophenol and Congo Red dye being highly toxic are well known for their carcinogenic activity. This work focuses on preparing an organogel for the removal of both chlorophenol and Congo Red. PAni molecules were grafted in situ between the layers of montmorillonite (MMT) to form a PAni/MMT composite, which was further modified to form a gel structure. The composite was thoroughly characterized by high-resolution X-ray diffraction (HR-XRD), Fourier transform infrared (FT-IR) analysis, Brunauer-Emmett-Teller (BET) analysis, and thermogravimetric analysis (TGA). The gel was further analyzed by scanning electron microscopy (SEM) and by studying the rheological properties. The resulting gel exhibited an impressive solvent uptake, with a maximum of 2084% (20 times) for chlorophenol, while the dye adsorption capacity was 349.72 mg/g with 99.44% removal efficiency. The adsorption proceeded with the pseudo-second-order model followed by the Langmuir monolayer adsorption model and Weber's intraparticle diffusion model. The sorbent was found to be selective among cationic dyes while retaining 83% of dye even in the fifth cycle. The hybrid sorbent shows great promise for sustainable purposes, and the results of this study are certainly encouraging.

Novel method for synthesizing high S-bearing hybrid sorbent for efficient silver binding – Characterization, testing, and application to metal recovery from X-ray films

The reaction of thiocarbazide with pentaerythritol tetrakis(3-mercaptopropionate) in the presence of mesoporous silica beads allows producing a composite sorbent (PTMF-SiO2) with high affinity for silver. The high density of both N- and S-based reactive groups (about 5 mmol g−1) explains sorption capacities as high as 3 mmol Ag g−1 at pH 6. The sorption mechanisms are correlated to the pH effect, and to FTIR and XPS spectroscopic analyses. The sorption is endothermic and spontaneous, and the sorption isotherms are successfully modeled using the Temkin equation. Uptake kinetics are fitted by the pseudo-first order rate equation: the equilibrium is reached in 20–30 min. Ultrasonic treatment allows slightly increasing both kinetics (apparent rate coefficient k1 is almost doubled) and sorption capacities (by less than 7 %). Silver (being a soft acid) preferentially reacts with soft bases; this may explain the selective removal of Ag(I) by PTMF-SiO2 against base metals and alkali or alkaline earth metals (in multicomponent equimolar solutions). The sorbent shows remarkable recycling stability (for at least 5 cycles): complete desorption is achieved in ≈20 min with 0.3 M HNO3 solution and the loss in sorption does not exceed 2.5 % at the fifth recycling. Finally, the sorbent is successfully applied to silver recovery from acidic leachates of spent X-ray films (from different hospitals from Hengyang, China), as a case study. Silver is selectively recovered with high efficiency (>96 %) (together with Cu(II), to a lesser extent).

ZIF-8-90 @ graphene oxide reinforced porous hollow fiber coupled with deep eutectic solvent for hollow fiber solid-phase microextraction of selected phthalate esters followed by quantification through high-performance liquid chromatography-ultraviolet detection

The present study was conducted to synthesize hybrid MOFs with a high effective surface area consisting of ZIF-8 and ZIF-90 on the surface of Graphene Oxide (GO). The hybrid ZIF-8-90@GO was finally placed inside the Hollow Fiber (HF) pores to use the substrate filtration properties. Then, the extraction device was used to extract three selected phthalate esters including DiMethyl Phthalate (DMP), DiEthyl Phthalate (DEP) and DiButyl Phthalate (DBP) (as the model analytes) followed by back extraction using Deep Eutectic Solvent (DES). Herein, the DES was utilized as a suitable and effective alternative to common toxic desorption solvents, and it led to the greening of the method. In order to achieve maximum efficiency and sensitivity, the parameters influencing on extraction and desorption processes were optimized. In the obtained optimum situation, the method linearity, Limits Of Detection (LODs), Limits Of Quantification (LOQs), Relative Standard Deviations (RSDs%), Enrichment Factors (EFs) were equal to 0.1–500 µg/L, 0.026–0.058 µg/L, 0.089–0.194 µg/L, 1.8 to 4.7% and 45.4–47.1, respectively. The obtained coefficients of determination (r2) were also higher than 0.9990. The Extraction Recovery (%ER) values were also 90, 87 and 91%, respectively for DMP, DEP and DBP. The above-mentioned method was used for the analysis of water and juice samples and acceptable results were obtained. The obtained relative recoveries in the real samples were in the range of 90–103%. Moreover, due to the presence of aldehyde and methyl groups with hydrophilic and hydrophobic properties in the structure of the synthesized hybrid sorbent, the possibility of interaction increased between sorbent and the studied species, and it per se, led to the increase of extraction efficiency.

The influence of magnetic particle incorporation on bisphenol A removal by β-cyclodextrin-derived sorbent

A novel, biomass-derived hybrid sorbent Ban-CD-EPI-Fe was successfully synthesized in a coprecipitation method, in which β-cyclodextrin copolymerized with banana peel extract and epichlorohydrin was grafted onto an iron oxide surface. The composition, presence of functional groups, morphology, thermal stability, and magnetic properties of the obtained material were characterized by Powder X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy (SEM-EDS), Thermogravimetric Analysis (TGA), and Physical Properties Measurement System (PPMS). The material bearing around 28% of β-cyclodextrin units has mesoporous structure with plate-like morphology and active surface area determined by BET and Langmuir models equal to 38.35 and 53.59 m2 g−1, respectively. The sorption studies aimed to remove an endocrine disruptor – bisphenol A (BPA), from water. The results showed that the time evolution could be fitted with pseudo-second kinetic order with a rate constant k equal to 0.05 g mg−1 min−1. According to the Langmuir isotherm, a monolayer is created during BPA sorption, and the maximum sorption capacity was estimated as 93.5 mg g−1. After BPA sorption, the hybrid material could be easily separated by an external magnet and regenerated under mild conditions keeping its recyclability in at least eight cycles.

Detailed study on the regeneration of CoS2 loaded porous carbon for elemental mercury removal from flue gas

Metal sulfides are promising sorbents in elemental mercury (Hg0) removal from flue gas, but they need to be regenerated during Hg0 removal cycle. Developing an effective regeneration method and elucidating the associated mechanisms hold significant importance in reducing operating costs for Hg0 removal by metal sulfides. This paper reported a CoS2 loaded porous carbon for Hg0 capture and investigated the regeneration of the deactivated sorbent using elemental sulfur for the first time. The elemental sulfur can fully recover the Hg0 capture ability of the hybrid sorbent, and display the same regeneration stability during five Hg0 removal cycle in comparison with toxic H2S. The regained activity of the sorbent in Hg0 capture depends mainly on the regeneration of S22− sites. The regenerated sorbent contains higher amount of S22− sites than the fresh sample, but less Co3+ and Sn2−(n >2) sites. Particularly, elemental sulfur is more effective in recovering S22− sites than H2S. The particle size of CoS2 on carbon decreases obviously during the Hg0 adsorption and regeneration, but cannot be restored by elemental sulfur and H2S. This work provides a detailed insight into the deactivation of metal sulfides for Hg0 removal, and will help the design of sorbent regeneration method for practical gaseous Hg0 capture.

Guest Editorial: Is CO2 Removal Technology Key to a Sustainable Future?

_ The urgent need to address climate change has unleashed a wave of innovative ideas on how to mitigate the greenhouse gas (GHG) emissions that are driving the problem. Among the approaches considered to hold great promise is carbon dioxide removal, or what some call negative emissions technologies. These strategies have attracted significant attention in recent years and involve removing carbon dioxide (CO2) from the atmosphere and storing it in long-term sinks such as oceans, forests, and underground geological formations. What follows is a closer look at how these strategies work, their potential to address the global climate crisis, and the challenges they currently face. Direct Air Capture (DAC) This technology captures CO2 directly from the air using chemical reactions and/or physical processes. The captured CO2 can then be stored in a long-term sink, used for food processing and cement manufacturing, or combined with hydrogen to create synthetic fuel. There are currently about 20 direct air capture plants operating worldwide. Climeworks’ Orca plant in Iceland, the largest operating DAC plant in the world, has the capacity to remove 4,000 tons of CO2 per year and store it deep underground. The majority of commercial direct air carbon capture techniques utilize large fans to force ambient air through a filter, with a liquid solvent, often amine-based or caustic, being used to absorb CO2 from the gas. There are three chemical processes that are being studied extensively for purposes of DAC: causticization using alkali and alkali-earth hydroxides, carbonation, and organic-inorganic hybrid sorbents consisting of amines supported in porous adsorbents. Additionally, others are exploring membrane separation methods based on semipermeable membranes to capture CO2, which require less water and a smaller footprint. Perhaps the biggest challenge facing this technology’s ability to scale up lies in its ability to be economically successful given current carbon credit pricing regimes balanced with the unknown amount of energy DAC units will need to achieve meaningful capture volumes. Ocean Fertilization The aim of ocean fertilization (OF) strategies is to enhance certain biological processes in the oceans that will lead to increased uptake of atmospheric CO2 followed by permanent storage in deep oceanic layers. The technique involves the addition of nutrients such as iron, phosphorus, and nitrogen to the ocean for stimulating the growth of phytoplankton that absorb CO2 from the atmosphere. When the marine species die, they sink to the ocean floor, taking the absorbed CO2 with them, where it is stored permanently. However, the implementation of OF has not been thoroughly studied and there are limited long-term experiments. Additionally, certain OF storage approaches are subject to reversibility. In other words, the stored carbon may not remain sequestered permanently and could be released back into the atmosphere due to the constant changes in ocean conditions such as temperature or nutrient availability. This issue highlights the need for caution and thorough study before implementing OF as a carbon dioxide removal strategy. The Convention on Biological Diversity and the London Protocol have called for appropriate regulations and assessments of risks and impacts related to climate-related geoengineering and OF.

Separation and purification of target flavonoids using covalently connected MOFs@boronic acid-functionalized-COFs magnetic hybrids: Precise identification and enhanced stability

The magnetic boronate based sorbents have been widely used to separation of cis-diol containing flavonoids. However, It's still challenging due to its chemical structural fragility and low grafting efficiency. The major obstacles are low concentration, the hydrophobicity of flavoniods, and complexity of crude extract solutions. For solving these problems, a new kind of covalently connect MOF@boronic acid-functionalized-COFs core–shell hybrid composites based on magnetic colloidal nanocrystal clusters (MCNCs), MCNCs@NH2-UiO-66@BTCA-BA-COFs, with high surface area, abundant binding sites and excellent chemical and structurally stability were synthesized for enhancing the structure stability and selective recognition efficiency. The alkynylation COFs were not only to be facilely grated on the surface of magnetic microsphere@NH2-UiO-66 via Schiff-based reaction but also beneficial to the further modification of azide phenylboronic acid group via click reaction. Such mentioned advantages and covalently connect click strategy could generate highly structure stable and strong binding sites for the template flavonoids (Naringin, NRG). Adsorption equilibrium experiments were reached rapidly within 120 min, and the maximum equilibrium binding capacities of MCNCs@PDA@NH2-UiO-66@BTCA-BA-COFs were 31.20 µmol g−1 for NRG. Moreover, MCNCs@PDA@NH2-UiO-66@BTCA-BA-COFs exhibited a stronger selectivity towards NRG than other competitive targets (i.e rutin, catechol, hesperetin, o-nitrophenol). The MCNCs@PDA@NH2-UiO-66@BTCA-BA-COFs have shown outstanding reusability of 91.99 % loss in enrichment performance towards NRG after seven times repeatedly. The obtained MCNCs@PDA@NH2-UiO-66@BTCA-BA-COFs-based mass spectrum (MS) methods were applied to analyze the purity of NRG products. As excepted, a commercially available NRG with purity (approximately 60 %) could be effectively extracted and concentrated to 93.15 % purity. More interestingly, the separation performance of the sorbents was influenced by hydrophilic and hydrophobic performance. This approach provided an idea for constructing a new kind of hybrid sorbents with both enhanced functionality, suitable hydrophobic performance and fast magnetic-response behavior, which is of great significance to the field of separation and purification of hydrophobic flavonoids.

Direct air capture (DAC) and sequestration of CO 2 : Dramatic effect of coordinated Cu(II) onto a chelating weak base ion exchanger

Direct air capture (DAC) is important for achieving net-zero greenhouse gas emissions by 2050. However, the ultradilute atmospheric CO2 concentration (~400 parts per million) poses a formidable hurdle for high CO2 capture capacities using sorption-desorption processes. Here, we present a Lewis acid-base interaction-derived hybrid sorbent with polyamine-Cu(II) complex enabling over 5.0 mol of CO2 capture/kg sorbent, nearly two to three times greater capacity than most of the DAC sorbents reported to date. The hybrid sorbent, such as other amine-based sorbents, is amenable to thermal desorption at less than 90°C. In addition, seawater was validated as a viable regenerant, and the desorbed CO2 is simultaneously sequestered as innocuous, chemically stable alkalinity (NaHCO3). The dual-mode regeneration offers unique flexibility and facilitates using oceans as decarbonizing sinks to widen DAC application opportunities.

Coal-based sulfur hybrid sorbent for removal of Hg0 from flue gas. Part 2. High organic sulfur coal

It is a win–win strategy to prepare mercury sorbents from low-cost high-sulfur raw materials. In part 1, mercury sorbents with excellent performance were prepared from high inorganic sulfur coal through KOH activation. However, this method does not work for high organic sulfur coal. In this work, a two-step preparation method is developed to prepare mercury sorbents from high organic sulfur coal. The first step is the co-pyrolysis/carbonization of Fe2O3 and coal, during which organic sulfur in coal is converted into FeSx. XPS shows that the percentage of Sx2–/S on the surface of the carbonized samples gradually increases from 5.4% to 22.2% with the m(Fe):m(So) ratio from 0:4 to 5:4. The second step is KOH activation, and it converts FeSx into various S species, including C-S, S0, S22− and S2−. Among the prepared mercury sorbents, LF+3Fe/4S-A (m(Fe):m(So) = 3:4) shows the best mercury removal performance, and its mercury removal efficiency remains above 84% for 120 min under N2+O2 at 120 °C. The Hg-TPDD and XPS results indicate that S*, including C-S, S0 and S22−, are the major active sites for mercury removal rather than Fe element, and HgS is the main existing form of mercury on the used sorbents. Besides LF coal, this two-step process is also applicable to other high organic sulfur coals (such as LL coal, WJZ coal, and SY coal) and high-sulfur petroleum coke.

One-step fabrication of hydrophobic metal-organic framework@covalent organic framework hybrid as sorbent for high-performance solid-phase extraction of flavonoids

Metal-organic framework (MOF) and covalent organic framework (COF) exhibit excellent extraction performance in sample pretreatment, but their wider application is hindered by some inherent drawbacks. Herein, we successfully synthesized a novel MOF@COF hybrid material with large specific surface area, good chemical stability and reusability, which is suitable as a solid phase extraction (SPE) sorbent for the efficient extraction of flavonoids. Importantly, due to the synergistic effect, the obtained MOF@COF hybrid material showing a higher extraction efficiency than individual MOF and COF. This is mainly due to the obtained MOF@COF hybrid material combines the high specific surface area of MOF and multiple interactions (hydrophobic interaction, hydrogen bonding and π-π stacking interaction) with flavonoids conferred by the COF structure. Then, a sensitive analytical method for flavonoids with ideal linear range (1–500 ng mL−1), low detection limit (0.15–0.41 ng mL−1) and good repeatability (2.64–6.20%) was developed under optimized conditions. In addition, the MOF@COF hybrid sorbent has better selectivity for hydrophobic targets containing multiple hydrogen bond acceptors/donors. Finally, the established method was applied to the determination of flavonoids in different food samples, and satisfactory recoveries (81.4–102.1%) were obtained, which initially confirmed its applicability.

The effect of phosphonates on lanthanide separation for surface-grafted porous zirconia

Inorganic–organic hybrid sorbents were synthesized by grafting porous zirconia with a series of aminomethylenephosphonate ligands. Sorbents with a larger number of phosphonate groups showed higher selectivity for intra-lanthanide separation.

Reusable carbon dot/chitin nanocrystal hybrid sorbent for the selective detection and removal of Cr(VI) and Co(II) ions from wastewater

The last few decades have seen a dramatic increase in heavy metal ions in industrial wastewater, especially Cr6+ and Co2+ ions, which have been shown to adversely affect human health; thus, there is a great need for their removal. Existing removal methods are time-consuming, expensive, and require high technical skills; therefore, there exists a need for a quick, simple, and cost-effective method. Chitin was selected from natural materials (shrimp waste), and an inexpensive, biodegradable, fluorescent carbon dot/chitin nanocrystal (C-dot/ChNC) sorbent for the simultaneous detection and removal of heavy metal ions from wastewater was synthesized from it. C-dot/ChNC shows high selectivity and sensitivity to Cr6+ and Co2+ ions and has high chromium(VI) and cobalt(II) adsorption capacities. These ions are weakly adsorbed on the C-dot/ChNC surface and are easily removed during regeneration, showing high cyclability. Thus, C-dot/ChNC is a viable sorbent for the removal of heavy metal ions during wastewater treatment.