Mercury pollutant, especially ionic mercury (Hg2+), has been ranked by the World Health Organization as one of the top ten chemicals that threatens the major public health. Absorption of Hg2+ on the solid phase is one of the effective ways for water remediation. In view of the disadvantages of most existing absorbents such as laborious preparation, secondary pollution, or time-consuming regeneration process, herein, we developed an aerogel absorbent based on poly(vinyl alcohol) and the auxiliary crosslinker of phytic acid, both of which can readily react through a self-assembly process in the hydrothermal condition. With good mechanical strength, tunable pore size and surface area, the aerogel is adequate in absorbing Hg2+ and organic mercury compound (MeHg+), and can be renewed in a super-fast process (~ 40 s). High removal rate of Hg2+ can be maintained even in presence of the competing ions (Mn2+, Cd2+, Cr2+, Cu2+ and Pb2+). The features of low-cost raw materials, straightforward synthesis, and the easy manipulation in remediation/regeneration process create a promising absorbent material to be used in the real scene.
Research Article
Function Led Design of Aerogels: One-pot Self-assembly of 3D Macroscope Poly(vinyl alcohol) Aerogel for Mercury Species Removal in Aqueous Solution with Super-Fast Regeneration
https://doi.org/10.21203/rs.3.rs-786342/v1
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Poly(vinyl alcohol) aerogel
Porous absorbent
Self-assembly
Mercury species removal
Super-fast regeneration
Water remediation
As ranked by the World Health Organization, mercury is one of the top ten chemicals that threatens the major public health. The Minamata disease is believed to be caused by Hg2+ pollution (Atwood &Zaman 2006, Benhammou et al. 2005, Blanchard et al. 1984, Huang &Blankenship 1984, McNutt 2013, Xu et al. 2013). Such background intensifies the development of the methods on removal of Hg2+ in a cost-effective manner. Compared to the conventional methods based on chemical reactions like chemical precipitation (Blue et al. 2010), electrodeposition (Tunsu &Wickman 2018) etc., absorption technique using porous materials is regarded to be a proper way to treat the mercury-containing water (Aguila et al. 2017, Huang et al. 2018, Ramezani et al. 2020, Shen et al. 2019a, Shen et al. 2019b). Recently, aerogel-based materials are playing more and more important roles in water remediation due to their advantages of cost-effectiveness, high porosity, large specific surface area, ultra-lightness thus are regarded as adequate alternatives to the traditional ones (Fan et al. 2015, Hu et al. 2018, Huang &Yan 2018, Lamy-Mendes et al. 2018, Wang et al. 2019). In fact, not limited to Hg2+, the removal of the metal ions on the porous materials may rely on the surface, pores and even complexation effect between the ions and absorbent. Thus, the purpose-oriented surface modification for the aerogels plays a crucial role in regulating the performance of the absorbent (Motahari et al. 2016). The research into carbon or silica aerogels have a long history, in spite of this, the engineering of the functional groups on silica aerogels surface is a surfeit of time-consuming task to be accomplished (Ramadan et al. 2010, Standeker et al. 2011) and the traditional carbon aerogels usually lack of flexibility in tuning the surface chemistry and pore size (Goel et al. 2005, Kadirvelu et al. 2008, Meena et al. 2005). The newly emerged carbon aerogels based on carbon nano tubes (CNTs) or graphene may have tunable pore size by altering components amount, and graphene can provide surface functional groups that can work as the binding sites for metal ions (Zhan et al. 2019, Zhang et al. 2019). However, people should be always aware of the deliberate production and the modification of high-quality graphene or CNTs, which are usually laborious. Moreover, few studies have focused on the quick regeneration of the absorbent, as well as the friendliness to the environment in case of the secondary pollution. Hence, using raw materials with excellent environmental-friendliness and a straightforward synthesis strategy are crucial to make the absorbent more suitable for real application.
Phytic acid (PA), as a natural and non-toxic phosphonic acid, has been found to have impressive chelating capacity with Mg2+, Ca2+ and Fe3+ ions (Crea et al. 2008, Dost &Tokul 2006, Kumar et al. 2010, Ravichandran et al. 2013). Directly grafting PA on aerogel surface in a straightforward manner requires a high reaction efficiency between PA and the aerogel backbones. Benefitting from our recent reports on poly(vinyl alcohol) (PVA) based aerogel (Ma et al. 2017, Ma et al. 2018, Ma et al. 2020, Zhang et al. 2020), the products can be yielded, with variable concentration of PVA precursor, shifting ratio of PVA and the auxiliary crosslinkers. The pore size of the products ranges from nanometer- to micron-scale with the surface state adjustable. Hence, in this work, we developed an aerogel absorbent based on PVA and PA. The one-step reaction between them can readily occur under variable ratio, relying on a self-assembly process. The intimate relationship between the modifiers (PA) and aerogel backbones (PVA) is reached, which is evidenced by the tunability of pore sizes (from nanometer- to micron-scale), structure, density and surface area of the products. What is worth noting is the extreme ease in regeneration (duration of ~ 40 s), together with the ability in removing methylmercury compound (MeHg+) manifests the great potential of the absorbent for real application.
2.1 Materials and methods
PVA (Mw ~ 195,000; 98% purity), HgCl2 (99.5% purity), phytic acid (50%, in H2O) were purchased from Aladdin Reagent Company. Multi-wall carbon nanotubes (MWCNTs) aqueous dispersion (2%, weight percent (wt%)) was purchased from Shenzhen nanotech Port Co., Ltd. A standard solution of Hg2+ (1000 ppm) was supplied by Guobiao (Beijing) Testing & Certification Co. Ltd. A standard methylmercury (MeHg+) solution with a certified concentration of 10 µg mL-1 (with expanded uncertainty of 5%) was purchased from the Institute for Environmental Reference Materials Ministry of Environmental Protection. Deionized (DI) water used for all experiments and was obtained from a Millipore water purification system. All chemicals and reagents were used without further purification. Lake water was obtained from the Chagan Lake in Jilin Province, China. The municipal tap water in Changchun was directly used as the tap water in the experiments.
2.2 Apparatus and characterizations
Freeze-drying process was completed in Alpha 1-2LD plus instrument. SEM was performed on XL-30 ESEM FEG instrument (FEI Company). FT-IR spectra were obtained on VERTEX 70 (Bruker, Germany). SEM and FT-IR samples were prepared by freeze-drying the aerogels after purification. Compressive tests were carried out on Instron 1121 with two flat platforms. The BET specific surface area was acquired via nitrogen absorption on Autosorb iQ Gas Sorption (Quantachrome, USA). The analysis proceeded depending on the nitrogen amount absorbed by the aerogels, ignoring the relative vapor pressure (P/P0) below 0.35 at -195.8°C.
2.3 Adsorbent synthesis
In decision for dosage of PA solution, we assumed that one PA molecule can react with six hydroxyl groups in the PVA chain. According to this principle, certain amount of PA solution was added into 11 mL 7% (wt%) PVA solution to synthesize PA/PVA-n (n represents the hydroxyl groups in PVA chain reacting with the phosphate groups in PA molecule theoretically). 1 mL MWCNTs solution was added in the above solution. After the homogeneous mixture was formed, the mixture was transferred to Teflon lined autoclave and was kept in 200 oC oven for 24 h. The aerogel absorbent was obtained after being immersed in H2O to removal the residual ions.
2.4 Density, porosity, water content calculation of the aerogels:
The freeze-dried aerogels were cut into several regular cuboids, the volume of which was calculated by measuring its length, width, and height. Each cuboid was weighed by a balance with 0.1 mg resolution. The density of aerogel (ρ) was calculated by Eq. (1)
where m and V are the mass and volume of each piece, respectively. We did five parallel measurements to get the mean as the final value.
Porosity of the aerogels was calculated by Eq. (2):
where ρp is the density of PVA precursor that can be obtained from the product information provided by the manufacturer. Here, the value of ρp is 1190 kg m− 3.
The purified aerogel products (under wet state) were cut into some regular cuboids and weighed separately (mw), followed by the freeze-dry process and weighed again (md). The water content value was calculated by Eq. (3):
2.5 Strain-stress tests:
Aerogels with cylindrical shape (height: 28 mm, diameter: 28 mm) immersed in water. During the tests, the compressing rates for loading and unloading were set to be 10 mm min− 1.
2.6 Hg2+ absorption test:
All the solutions to be remediated were made by the dilution of the Hg2+ standard solution. All the absorbing process proceeded under 37 oC. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to determine the Hg2+ concentration except the very low concentrations (p.p.b. level or below) were detected by ICP-mass spectrometry (ICP-MS). The distribution coefficient (Kd) was calculated via Eq. (4):
where C0 and Ci are Hg2+ concentration at equilibrium state and initial phase respectively. V is the volume of the treated solution (mL) and M is the mass of the freeze-dried aerogel (g). In our experiments, all the aerogel adsorbents were stored in H2O before use and were directly employed to adsorb the pollutant in the wet state. The mass of the dry gel was calculated through Eq. (3). The purification process proceeded under shaking (250 rpm) for 24 h. The absorption capacity (qe, mg g-1) was obtained via Eq. (5):
where Cb and Ce represent the Hg2+ concentration at the beginning and at equilibrium (p.p.m.), respectively. V is the volume of the treated solution (L). M is the mass of dry adsorbent (g). The adsorbents were added into a certain volume of aqueous solutions with different concentrations of Hg2+ with absorbent to solution ratio (A/S, g L-1) of 2.7 g L-1, and then shaken for 24 h. The final Hg2+ concentration was analyzed by ICP.
2.7 Absorbent regeneration:
The used aerogel absorbent was immersed in 1 M HCl solution, which was then vertically compressed downward for 20 times. The absorbent was taken out by a tweezer and thoroughly washed with H2O for the subsequent purification process. In order to affirm the high elution rate, the absorbent was freeze-dried, then the absorbed mercury was analyzed with ICP.
2.8 Hg2+ absorption under pH = 3 and 10:
The standard Hg2+ solution was diluted with HNO3 and KOH solution to prepare the pH = 3 and 10 solutions, whose Hg2+ concentration is ~ 10 p.p.m. (determined by ICP). Certain amount of absorbents was added into the above solutions with the A/S ratio of 3.7 g L-1, afterwards the mixture was shaken for 24 h. The final Hg2+ concentration was analyzed by ICP.
2.9 Hg2+ absorption in presence of the competing ions:
Certain amount of CuCl2·2H2O, CrCl3·6H2O, CdCl2·H2O, Pb(NO3)2 and MnCl2·4H2O was dissolved in the standard Hg2+ solution, which was then diluted to make the concentrations are ~ 10 p.p.m. (determined by ICP). Certain amount of absorbents was added into the above solutions with the A/S ratio of 4.1 g L-1, afterwards the mixture was shaken for 24 h. The final concentrations of the ions were analyzed by ICP.
2.10 Lake and tap water purification test:
Certain amount of HgCl2 was dissolved in lake and tap water to obtain the Hg2+ solution (~ 10 p.p.m., determined by ICP). Certain amount of absorbents was added into the above solutions with the A/S ratio of 4.3 g L-1, afterwards the mixture was shaken for 24 h. The final Hg2+ concentration was analyzed by ICP.
2.11 Methylmercury compound removal:
The standard methylmercury solution was firstly diluted by 100-fold. 3 µL of the above solution was added into 300 mL of H2O, which was then shaken with the absorbent (A/S ratio of 2.7 g L-1) at 37 oC for 24 h. The final mercury level was analyzed with ICP-MS. Three parallel measurements were performed to obtain the final data.
The straightforward synthesis process of the aerogel absorbent is simply illustrated in Scheme 1a. The whole synthesis mechanism relies on the self-assembling effect of PVA in the hydrothermal process, which is a manufacturer-friendly method because it is exempt from any professional manipulation or special equipment. The absorbent absorbs Hg2+ ion in a quick process and also has high removal efficiency for MeHg+, which is more toxic than its inorganic form. Notably, benefitting from the highly crosslinked aerogel matrix, the aerogel absorbent exhibits excellent mechanical property that it can bear dozens of compressive deformations meanwhile maintaining the integrity of itself. As a consequence of this, the absorbent shows super-fast regeneration that the absorbed Hg2+ can be fully eluted by compressing the aerogel in diluted HCl solution (Scheme 1b). No attenuation in absorbing capacity occurred for the renewed absorbent during the several reincarnation cycles. The manageable water remediation process as well as the simplicity in absorbent regeneration constitute a user-friendly characteristic of our absorbent. Cytotoxicity test suggested the absorbent has no toxicity which is another supportive evidence for being applied in real environment.
3.1 Absorbents characterizations
PA, as the crosslinker, the amount of which affects the characteristics (e.g. aerogel density, porosity etc.) of the aerogel, assists the aerogel formation. Since PA has six strong acid groups that can make complete dissociation in solution, we roughly consider 1 mol PA molecules can react with six mol -OH in the PVA chain. The aerogel products with different amount of PA engaged in their synthesis are named PA/PVA-n (n represents the dosage of PA according to the ratio of -OH groups theoretically occupied by the acid groups of PA, and in this case, n = 5%, 15%, 25%, 35% and 50%). The prepared products were firstly characterized by Fourier transform infrared spectroscopy (FT-IR) to ensure PA molecules indeed participated in the aerogel synthesis (Fig. 1a). For comparison purposes, the aerogel derived from the same precursor concentration but without PA incorporation (PA/PVA-0%) was also prepared (black curve in Fig. 1a), for which the absorption band at 650 − 540 cm − 1 (deformation vibration of PO4 (Gao et al. 2009)) is absent. For those samples synthesized with PA, the existence of P = O in phosphate ester group can be verified by the broad band at 1200 − 940 cm − 1 (stretching vibration of P = O (Gao et al. 2009)). In order to quantify how the dosage of PA affects the properties of the aerogels, the density and the porosity were calculated and compared (Fig. 1b). A low-dosage of PA can decrease the density by ~ 40% (Fig. 1b, n = 0% and 5%), meanwhile the porosity reaches the peak value for n = 5%. When n ≥ 15%, the density increases. For such a phenomenon, we speculate that the “self-crosslinking” and “PA-engaged-crosslinking” are concomitant, of which the former one is induced by the ionized H + and the latter by the intercalated PA molecules. At low-dosage of PA, the acidity is weaker than the high-level and the self-crosslinking is suppressed. As the PA concentration increases, large amount of H + promotes the activation of -OH thus boosting the self-crosslinking of PVA. In the surface area comparison, PA/PVA-5% has the largest surface area (193 m2 g-1) among the 6 samples (Fig. 1c). It also explains the more loosened structure of PA/PVA-5% in the scanned electron microscopy (SEM) images (Fig. 2a) than the other four samples (Fig. 2b-e), and also verifies the regulation effect of PA in the gradually varied micro-structure and pore size.
3.2 Absorbing performance
The user-friendliness lies in the easy manipulation in the batch absorption tests. The absorbents imbedded in the Hg2+-containing solutions can be simply separated after the absorption process. The absorbing kinetics for Hg2+ was firstly investigated (Fig. 3a). All the absorbents show fast absorbing process that a total concentration of 1,0000 p.p.b. can be decreased by 95% or more within 1.5 h with the absorbent to solution ratio (A/S) of 2.7 g L-1. These results affirm the good affinity between Hg2+ and the absorbent surface. All the data follow the pseudo-second-order kinetic model with the correlation coefficient R2 = 0.9999 for all of them (Fig. 3b). The PA/PVA-5% exhibits the fastest absorption, and more than 98% of Hg2+ can be held (Fig. 2a, the black curve). The capability of the five samples was examined by placing the same mass of absorbents in equivalent volume of Hg2+-containing solutions. The Hg2+ concentration was compared after the absorbing process reached the equilibrium (Fig. 3c). The highest removal efficiency (~ 94.7%) corresponds to the PA/PVA-5% sample with the distribution coefficient value (Kd) of 1.03×105 mL g-1, which can be generally regarded as excellent (Li et al. 2014). The high removal rate is followed closely by the PA/PVA-15% sample (~ 93.4%). Such performance of the two samples is originated from the highest porosity (PA/PVA-5%) and lowest density (PA/PVA-15%) among the five samples (Fig. 1b). Having positive correlation with the porosity, the water content in the aerogel matrices is generally interrelated to the absorption capacity (Fig. S1 in Supporting Information (SI)). Owing to the high porosity and low density, the PA/PVA-5% sample can hold more water than the other four. Based on the above, PA/PVA-5% was selected to examine the maximum absorption competence for Hg2+, with the isotherm presented in Fig. 3d. The maximum absorption is estimated to be 40.5 mg g-1, higher than that of some absorbents reported in recent years (Mora Alvarez et al. 2018, Saleh 2015, Solisio et al. 2019, Tan et al. 2016).
3.3 Super-fast regeneration of the absorbent
Another outstanding feature of the absorbents is the good mechanical strength that makes the absorbents adequate for cycles of compressive deformation, endowing them with super-fast regeneration ability. In our test, the absorbents maintain the perfect integrity after 20 counts of compressive deformation cycles beneath water (Fig. 4a). Based on the same crosslinking mechanism, the stress of aerogels under concordant deformation ratio usually increases linearly with the aerogel density (Ma et al. 2017, Pekala et al. 1990). However, in this study, the crosslinking is mainly dominated by PA molecules when n < 15%, but largely follows the self-crosslinking mechanism between -OH in the PVA chain when n ≥ 15% since more PA molecules induce more H+ engaged in the synthesis process. For the four samples whose n ≥ 15%, the stress value at 50% deformation is roughly proportionally increased with the aerogel density (Fig. S2, in SI), which is another evidence for altering the crosslinking mechanism. The excellent compressive resilient property of the foam-like absorbent encourages the super-fast regeneration ability after absorbing Hg2+. The whole process can be finished within 40 seconds (Video S1) by immersing the absorbent in 1 M HCl solution that is vertically compressed downward for 20 cycles. Almost all the absorbed Hg2+ could be eluted. PA/PVA-5% was typically tested in three absorption-elution cycles with absorbing capacity and elution rate maintained at high level (absorbing capacity > 97%, elution rate > 92%) (Fig. 4b). It is the good mechanical property of the aerogel and the renewability of the phytic acid that create the valuable feature of the absorbent, which is superior to other mercury absorbent (Table 1). Although the absorbing capacity is lower than those of many absorbents, the easy synthesis process together with the super-fast regeneration makes the aerogel favorable for water remediation in real application. The pH value is also considered to be a factor that affects the absorbing performance. The PA/PVA-5% absorbent remains high removal efficiency towards Hg2+ under acidic and alkaline conditions (Table 2), but with higher A/S ratio of 3.7 g L-1. In general, the polymer absorbent usually substantially consists of the chelating moiety and the polymeric matrix part, of which the former is equipped with donor atoms able to form complexes with metal ions. The most commonly used donor atoms include N, S and O and the groups containing them involve (for N) azoic compound, amines, acidamide, azo groups or nitriles, (for S) thioalcohols, sulfoethers, or thiocarbamic acid esters, (for O) carboxyls, hydroxyls, phenols, ethers, carbonyls or phosphoryl groups. Previous studies have already illustrated the high specificity of phytate in sequestering Hg2+ ions (De Stefano et al. 2006), and the combination between carbonyls and Hg2+ has high idiosyncrasy (Ermakova et al. 2013, Shen et al. 2017). In our study, despite the absorbent is nitrogen- and sulfur-free, the PA molecules provide sufficient phosphoryl groups that can efficiently bind with Hg2+, even in the presence of some competing heavy metal ions (Mn2+, Cd2+, Cr2+, Cu2+ and Pb2+) (A/S ratio of 4.1 g L-1) (Table 3). Therefore, the absorbing mechanism may be chiefly concluded as the chelating between the donor atom of O and the soft metal ion of Hg2+, and secondarily the hydrogen bonding between the phosphoester/hydroxyls and the Hg(OH)+ species derived from the hydrolysis of Hg2+ (Fig. S3, in SI). Such a speculated mechanism may interpret the higher A/S ratio required in acidic, alkaline, or multi-ions containing solutions to reach high removal efficiency, probably due to the weakened hydrogen bonding under higher ionic strength. The formed complex would have complete dissociation in acidic environment (Ermakova et al. 2013), which may be the reason why the absorbent can be regenerated in a fast process in HCl solution.
|
Absorbent |
Regeneration method |
Reference |
|---|---|---|
|
Graphene oxide/polyethyleneimine aerogel |
Placed in 40 mL of HNO3 for 6 h, freeze-dried for 24 h |
(Bessa et al. 2020) |
|
3D MoS2 composition aerogel |
Heated at 80 oC for volatilization of Hg0 |
(Zhi et al. 2016) |
|
Reduced-graphene oxide aerogel |
In 0.2 M HNO3, stirred by an electromagnetic agitator in a sealed plastic flask at 25 oC for 24 h |
(Wu et al. 2016) |
|
Nanocellulose aerogel |
Wash with H2O, put into 1 M HCl containing 5 wt% thiourea, agitated at 25 oC for 6 h |
(Geng et al. 2017) |
|
Silica–gelatin aerogels |
Agitated in EDTA solution for 30 min, centrifuged, re-suspended in diluted HNO3 solution, multi-centrifuge steps |
(Herman et al. 2020) |
|
Modified graphene composite |
Stirred in thiourea and 0.1 M HCl for 1 h and washed with H2O |
(Yap et al. 2019) |
|
Fe3O4 nanoparticles modified MoS2 nanosheets |
Sonication for 30 min in HCl solution and washed with H2O |
(Song et al. 2018) |
|
cellulose nanocrystal absorbent |
Eluted with 2 M HCl and 0.5 M thiourea for 30 min, centrifuged for 10 min |
(Li et al. 2019) |
|
MoS2 nanosheets |
Stirred with 0.1 M EDTA solution for 2 h, washed with H2O and ethanol |
(Pirarath et al. 2020) |
|
Gelatin-based mesoporous hybrid materials |
Treated with 0.5 M HCl solution for 30 min |
(Jamwal et al. 2020) |
|
PVA aerogel crosslinked by phytic acid |
Twenty compression-rebound cycles (within 40 s) |
This work |
|
pH = 3 |
pH = 10 |
|||||
|---|---|---|---|---|---|---|
|
Batch 1 |
Batch 2 |
Batch 3 |
Batch 1 |
Batch 2 |
Batch 3 |
|
|
Removal efficiency (%) |
97.2 |
96.5 |
98.1 |
95.9 |
96.5 |
97.1 |
|
Ions |
Removal efficiency in different batches (%) |
||
|---|---|---|---|
|
Batch 1 |
Batch 2 |
Batch 3 |
|
|
Mn2+ |
0 |
0 |
0 |
|
Cd2+ |
0 |
0 |
0 |
|
Cr2+ |
0 |
0 |
0 |
|
Cu2+ |
0 |
0 |
0 |
|
Pb2+ |
0 |
0 |
0 |
|
Hg2+ |
94.99 |
94.85 |
94.73 |
3.4 Lake & tap water remediation and MeHg+ absorption
Real application of the absorbent expects high removal efficiency in different water matrixes like lake water and tap water, as well as high removal rate for the organic form of mercury (e.g. methylmercury compound) that is more toxic. The PA/PVA-5% poses removal rate of 85.4% and 90.5% in the spiked lake and tap water with the A/S ratio of 4.3 g L-1 and 2.4 g L-1, respectively. 98.1% of 100 ng mL-1 methylmercury compound can also be removed by PA/PVA-5% in an A/S ratio of 2.7 g L-1 (Fig. 5a). The biocompatibility of the water remediation material is also important performance index in case that it poses secondary pollution for the water matrix (Ma et al. 2017, Ma et al. 2018). Typically, PA/PVA-5% absorbent exhibits excellent biocompatibility even in a high concentration of 104 µg mL-1 (Fig. 5b).
In summary, we have introduced an aerogel absorbent based on PVA with phytic acid as auxiliary crosslinker aiming for mercury species removal in water matrix. The synthesis process more straightforward than many other absorbents (Geng et al. 2017, Li et al. 2019, Ma et al. 2018, Yap et al. 2020), together with the regeneration faster and easier than most of the analogues (Bessa et al. 2020, Geng et al. 2017, Herman et al. 2020, Jamwal et al. 2020, Li et al. 2019, Pirarath et al. 2020, Song et al. 2018, Wu et al. 2016, Yap et al. 2019, Zhi et al. 2016) collectively makes it manufacturer- and user-friendly absorbent that can be adequate in removing both ionic (Hg2+) and organic mercury (MeHg+) pollutants. The absorbent also shows high specificity to mercury in presence of several common heavy metal ions, and works well for lake and tap water remediation. Based on the above merits as well as the remarkable biocompatibility, our absorbent is suitable for real application, producing no side effects for the water matrixes. Additionally, the design philosophy based on self-assembly of PVA and the alterable crosslinker lays the foundation for other functionalization of the aerogels.
Ethics approval and consent to participate: Not applicable
Consent for publication: All authors have read and approved to publish the final manuscript.
Data availability: All data analyzed in this study are included in this article.
Conflict of interest: The authors declare no competing interests.
Funding: This work was supported by the support from the National Natural Science Foundation of China (22004014) and the Fundamental Research Funds for the Central Universities (No. 2412020QD007), Human Resources and Social Security Department of Jilin Province, the Key Laboratory of Nanobiosensing and Nanobioanalysis at Universities of Jilin Province, and Analysis and Testing Center of Northeast Normal University.
Authors' contributions: JL and JB conducted the experiments. JJ and YS participated in the discussion and analysis of the results. CB conceived the study and revised the manuscript. The final version of the manuscript has been approved by all the authors.
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- scheme1.png
Scheme 1 (a) Synthesis of the aerogel crosslinked by phytic acid. (b) Super-fast regeneration process for the absorbent
- VideoS1.mp4
- si.docx
