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1.
J Hazard Mater ; 416: 125822, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492784

RESUMO

Biochar adsorbents for removing As(III) suffer from the problems of low adsorption capacity and ineffective removal. Herein, a granular MgO-embedded biochar (g-MgO-Bc) adsorbent is fabricated in the form of millimeter-sized particles through a simple gelation-calcination method using chitosan as biochar sources. High-density MgO nanoparticles are evenly dispersed throughout the biochar matrix and can be fully exposed to As(III) through the rich pores in g-MgO-Bc. These features endow the adsorbent with a high adsorption capacity of 249.1 mg/g for As(III). The g-MgO-Bc can efficiently remove As(III) over a wide pH of 3-10. The coexisting carbonate, nitrate, sulfate, silicate, and humic acid exert a negligible influence on As(III) removal. 300 µg/L of As(III) can be purified to far below 10 µg/L using only 0.3 g/L g-MgO-Bc. The spent g-MgO-Bc could be well regenerated by simple calcination. In fixed-bed column experiments, the effective treatment volume of As(III)-spiked groundwater achieves 1500 BV (30 L) (3 g of adsorbent, solution flow rate of 2.0 mL/min, C0 = 50 µg/L). The Mg(OH)2 generated in situ in g-MgO-Bc is responsible for the adsorption of As(III) through the inner-sphere complex mechanism. The work would extend the potential applicability of biochar adsorbent for As(III) removal to a great extent.


Assuntos
Óxido de Magnésio , Poluentes Químicos da Água , Adsorção , Carvão Vegetal , Cinética , Porosidade , Água , Poluentes Químicos da Água/análise
2.
J Hazard Mater ; 416: 125825, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492787

RESUMO

The adsorbents with high adsorption capacity for simultaneously removing Cr(VI) and Hg(II) from aqueous solutions under broad working pH range are highly desirable but still extremely scarce. Here, a novel adsorbent with multidentate ligands was facilely fabricated by covalently bonding 4-amino-3-hydrazino-5-mercapto- 1,2,4-triazole on graphene oxide via the Schiff's base reaction. The maximum adsorption capacities of Cr(VI) and Hg(II) on the current adsorbent were 734.2 and 1091.1 mg/g, which were 14.36 and 5.61 times higher than that of the pure graphene oxide, respectively, exceeding those of most adsorbents previously reported. More interestingly, Cr(VI) and Hg(II) concentrations were decreased from 2 mg/L to 0.0001 mg/L for Hg(II) and 0.004 mg/L for Cr(VI), far below the WHO recommended threshold for drinking water. Moreover, the adsorbent shows an excellent performance for simultaneous removal of Cr(VI) and Hg(II) with more than 99.9% and 98.6% removal efficiencies in aqueous solutions. Finally, the adsorbent was successfully applied in dealing with the real industrial effluent, implying huge potential in industrial application. This work offers a new possibility for the removal of the metallic contaminants by rational designing target groups and ligands.


Assuntos
Mercúrio , Poluentes Químicos da Água , Adsorção , Cromo/análise , Grafite , Concentração de Íons de Hidrogênio , Cinética , Compostos de Sulfidrila , Poluentes Químicos da Água/análise
3.
J Hazard Mater ; 416: 125829, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492790

RESUMO

Enhancing the performance of adsorbents to the utmost extent is an objective but challenging in applying adsorption technology to wastewater treatment. In this work, novel quaternary ammonium polymers (QAPs) with high density adsorption site (i.e., quaternized N, confirmed by FT-IR results) were designed and prepared for rapid selective removal of Cr(VI) from water. The results of EDS analysis indicated the maximum exposure rate of N on the surface of QAPs was as high as 86.1%, which almost doubled comparing to that of Cr(VI) ions imprinted polymers (Cr(VI)-IIP) (46.2%). Interestingly, the maximum adsorption capacity (211.8 mg/g) and initial adsorption rate (h0, 66.6 mg/ (g·min)) of QAPs (i.e., 5:1(TRIM)) for Cr(VI) are about 3.6 times and 4.9 times those of Cr(VI)-IIP (63.0 mg/g and 13.5 mg/(g·min)), respectively. Impressively, flow-through adsorption experiments demonstrated 5:1(TRIM) can completely remove 5 mg/L of Cr(VI) within five seconds. Additionally, 5:1(TRIM) exhibited a remarkable selectivity for Cr(VI) adsorption, and high purity (100%) of chromium can be readily obtained. The proposed idea of high exposure effect of the adsorption site can provide a valuable guidance for designing rapid selective adsorbents to remove and reclaim Cr(VI) from wastewater.


Assuntos
Compostos de Amônio , Poluentes Químicos da Água , Adsorção , Cromo/análise , Concentração de Íons de Hidrogênio , Cinética , Polímeros , Espectroscopia de Infravermelho com Transformada de Fourier , Poluentes Químicos da Água/análise
4.
J Hazard Mater ; 416: 125863, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492811

RESUMO

Arsenic (As) adsorbed on Fe oxyhydroxides (adsorbent) is widely occurring in many environmental settings such as in acid mine drainage systems or in the hydrometallurgical operations to form Fe-As coprecipitates. However, the influence of the reaction media and the drying treatment on the microstructure of the directly formed adsorbents at various pHs was still not fully understood. In this work, As adsorption behaviors on various forms of Fe oxyhydroxides were systematically investigated by using XRD, FTIR, Raman, XANES, and HRTEM. The results revealed that at weak acidic pH, more As could adsorbed on the suspension adsorbent formed in sulfate and chloride media than that in nitrate media, possibly due to the microstructure alteration of the adsorbent in the presence of sulfate and chloride. Besides, the increasing crystallinity of the Fe oxyhydroxides and the aggregation effect after drying were the major reasons why less As could be hold by the dried adsorbents than that of the corresponding suspension adsorbents. These findings could shed more light on the nature of the Fe oxyhydroxides which may be helpful for more precisely predicting the fate of some toxic metal(loid)s in the environment.


Assuntos
Arsênio , Adsorção , Arsênio/análise , Mineração , Nitratos
5.
J Hazard Mater ; 416: 125884, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492822

RESUMO

The acid-extractable fraction Cd(II) in soil accumulates easily in organisms, migrates and transforms in the ecological environment, which has posed potential health risks to human. This study found that the acid-extractable fraction Cd(II) in soil could be released rapidly into water at very low Cd2+ concentration. Carboxylated polypropylene (PP-g-AA) fibers-ball with high selectivity as adsorbent was used in the Cd(II) contaminated soil-water system. It could remove promptly trace Cd2+ from water even in the presence of interfering metal ions. Moreover, Cd(II) desorbed from soil to water could be continuously adsorbed by PP-g-AA fibers-ball, which kept the Cd2+ concentration always at a low level. This forms a dynamic equilibrium of rapid release- selective adsorption toward the acid-extractable fraction Cd(II) in the soil-water system. Here, the migratory pathway for the acid-extractable fraction Cd(II) to be released from contaminated soil to water and adsorbed simultaneously on the surface of PP-g-AA fibers-ball was established. This work offers a novel protocol that can remove more than 90% of the acid-extractable fraction Cd(II) from contaminated soil within 12 h, thereby contributes better to mitigate the risk of Cd(II) from soil to the food chain without changing the physical and chemical properties of soil.


Assuntos
Cádmio , Poluentes do Solo , Adsorção , Cádmio/análise , Humanos , Solo , Poluentes do Solo/análise , Água
6.
J Hazard Mater ; 416: 125888, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492826

RESUMO

Fabrication of simple and efficient adsorbents is greatly vital to satisfy the requirements of removal of tellurium in wastewater treatment, yet remains challenging. Here, a facile and cost-effective strategy to develop ZIF-L coated self-crosslinking cellulose membrane (ZIF-L/SC membrane) for tellurium adsorption was presented. In-situ vertical growth of ZIF-L nanoplates with functional properties on membrane substrate is an available strategy, effectively remedying deficiency of pure nanosized sorbent in agglomeration problem and unhandy recovery. The SC membrane formed by strong hydrogen bonding among cellulose fibers is an excellent substrate, due to the favorable mechanical strength and abundant hydroxyl groups. The as-prepared ZIF-L/SC membrane shows advantageous morphology of large contact surface, fine thermal stability and eligible mechanical strength. The adsorption performance and possible mechanism of ZIF-L/SC membrane for Te (IV) were investigated by diverse characterization methods, showing admirable adsorption effect. Furthermore, the ZIF-L/SC membrane has excellent antibacterial properties, thus it is expected to deal with membrane fouling caused by microorganism breeding. Therefore, the bifunctional ZIF-L/SC membrane with excellent antibacterial activity is anticipated to be a promising candidate for efficient tellurium adsorbents, and simultaneously have potential in various fields in the future.


Assuntos
Zeolitas , Adsorção , Antibacterianos/farmacologia , Celulose , Telúrio
7.
J Hazard Mater ; 416: 125896, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492834

RESUMO

Cork, a porous biomass material, is consist of thin-walled hollow prismatic cells arranged into a compact and orderly honeycomb-like structure and could be applied as an adsorption material. Here, cork-activated carbons (CACs) with a fluffy honeycomb-like structure were synthesized by two-step pyrolysis with solid KOH chemical activation to rapidly and efficiently adsorb methylene blue (MB) (maximum wavelength: 664 nm). The structure, morphology and surface functional groups of the CACs were characterized using BET, SEM, and FTIR analysis. The results show that the CACs have a well-developed hierarchical porous structure and an ultra-high specific surface area of 2864.9 m2/g, which would facilitate the efficient diffusion and adsorption of MB molecules onto CACs. MB adsorption performance results show that the CACs have an outstanding maximum MB adsorption capacity (1103.68 mg/g) and fast adsorption kinetics (800 mg/L, 99.8% in 10 min), indicating that CACs possess significant advantages compared with most other adsorbents previously reported. The adsorption mechanism was studied by various kinetic models, isothermal models and thermodynamic models. Langmuir model is the most adapted to describe the adsorption process, indicating that the MB molecules are uniformly adsorbed on CAC's surface in a single layer. Moreover, MB adsorption by the CACs was an endothermic, spontaneous and randomly increasing adsorption. The regeneration test showed that the uptake of MB onto CACs can still reached 580 mg/g after three adsorption-desorption cycles, demonstrating the excellent reusability of CACs. The continuous adsorption performance of MB onto CACs was evaluated by a packed column test, which further confirmed its potential as an adsorbent for dye wastewater purification.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Adsorção , Biomassa , Carvão Vegetal , Cinética , Azul de Metileno
8.
J Hazard Mater ; 416: 125897, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492835

RESUMO

Interconnected macro-porous cryogels with robust and pore-tunable structures have been fabricated using chemically crosslinked microfibrillated cellulose (MFC). Periodate oxidation was initially conducted to introduce aldehyde groups into the MFC surface, followed by the freeze-induced chemical crosslinking via the formation of hemiacetal bonds between aldehyde and hydroxyl at -12 °C. The cryogels with pore-tunable structures and sharply enhanced mechanical strengths were finally achieved by re-assembly of MFCs through soaking in NaIO4 solution. Furthermore, the MFC cryogels were post-crosslinked by polyethyleneimine (PEI), bestowing the cryogels with the capability of adsorbing anionic dyes. The stress of the PEI-MFC cryogel at the 80% strain was determined to be 304.5 kPa, which is the maximum value for the nanocellulose-based cryogels reported so far. Finally, the adsorption performances of PEI-MFC cryogels for methyl orange (MO) were evaluated. Maximum adsorption capacity of 500 mg/g could be obtained by the Langmuir model, outperforming that of previous absorbent materials. Reuse experiments indicated that over 90% of adsorption capacity was retained after 6 cycles. Continuous clean-up experiments demonstrated excellent MO removal abilities of the PEI-MFC cryogel. This study shows that the novel, green strategy to fabricate the robust cryogel extends the practical applications of nanocellulose adsorbents for environmental remediation.


Assuntos
Criogéis , Nanofibras , Adsorção , Compostos Azo , Celulose , Corantes , Porosidade
9.
Soft Matter ; 17(35): 8185-8194, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34525168

RESUMO

Because bacterial adhesion to surfaces is associated with infections and biofilm growth, it has been a longstanding goal to develop coatings that minimize biomolecular adsorption and eliminate bacteria adhesion. We demonstrate that, even on carefully-engineered non-bioadhesive coatings such as polyethylene glycol (PEG) layers that prevent biomolecule adsorption and cell adhesion, depletion interactions from non-adsorbing polymer in solution (such as 10 K PEG or 100 K PEO) can cause adhesion and retention of Escherichia coli cells, defeating the antifouling functionality of the coating. The cells are immobilized and remain viable on the timescale of the study, at least up to 45 minutes. When the polymer solution is replaced by buffer, cells rapidly escape from the surface, consistent with expectations for the reversibility of depletion attractions. The dissolved polymer additionally causes cells to aggregate in solution and aggregates rapidly dissociate to singlets upon tenfold dilution in buffer, also consistent with depletion. Hydrodynamic forces can substantially reduce the adhesion of aggregates on surfaces in conditions where single cells adhere via depletion. The findings reported here suggest that because bacteria thrive in polymer-rich environments both in vivo and in situ, depletion interactions may make it impossible to avoid bacterial retention on surfaces.


Assuntos
Aderência Bacteriana , Biofilmes , Adsorção , Bactérias , Polietilenoglicóis , Propriedades de Superfície
10.
Analyst ; 146(18): 5732-5739, 2021 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-34515698

RESUMO

Developing a functional affinity monolithic column towards in-tube solid-phase microextraction (IT-SPME) for selective sample pretreatment is critical. Herein, a high-performance capillary affinity monolithic column with an ultra-high aptamer coverage density was rapidly fabricated via a simple adsorption strategy, in which aptamers with natural sequences were directly immobilized on an ammonium-based strongly cationic matrix. Limitations of the traditional biological or covalent methods such as time-consuming modification reactions, special requirement of active groups (e.g. -NH2 and -SH) on the aptamer, and low aptamer coverage density levels were avoided. An ultra-high coverage density of 8616 pmol µL-1 was achieved with excellent stability, and the highest aptamer-modification level among all the current methods was reached. Selective recognition and high recovery yields of the model mycotoxin ochratoxin A (OTA) were achieved in 95.9 ± 0.98%-97.9 ± 0.28% (n = 3). In particular, there was little cross-reactivity towards the OTB analogue of only 0.5% even in the case of 250 fold of the analogue OTB, which was not reported in previous affinity monoliths. Upon sample analysis, satisfactory discriminations of trace OTA were obtained at 93.7 ± 1.4%-95.5 ± 2.5% (n = 3) in beer and wheat. A facile and direct method for efficiently fabricating an aptamer-based affinity monolith towards online selective IT-SPME was proposed.


Assuntos
Aptâmeros de Nucleotídeos , Micotoxinas , Adsorção , Cerveja/análise , Microextração em Fase Sólida
11.
Talanta ; 235: 122709, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517582

RESUMO

Herein, a high-performance screening tool for the selective and sensitive monitoring of aflatoxins is reported based on their great quenching effect on the blue emission of graphene quantum dots (GQDs). To make a specific determination, a pre-extraction method was also developed using a new nano-sorbent based on the surface-imprinted Zr metal-organic framework on the magnetic graphene oxide (MGO/MOF-808@MIP). The adsorbing efficiency of the prepared composite was remarkably higher than the pristine MOF-808 or bare GO. The presence of GO nanosheets, as well as nanoporous MOF-808 provided a high accessible surface area to form the MIP layer. It provided a great number of MIP sites for high efficient and rapid extraction of aflatoxins. The presence of magnetic nanoparticles in the structure of nanocomposite also facilitated the extraction process using a magnetic solid-phase extraction (MSPE) system. The combination of this specific and high-performance extraction with simple fluorometric detection caused a potent screening tool for aflatoxins. The method was able to monitor the total aflatoxins content of food samples with a linear range of 0.05-8 ng mL-1, which was more sensitive than the fluorometric system without extraction (5-500 ng mL-1). More developments were made by the application of a high-performance liquid chromatography (HPLC) method for the discrimination of the extracted aflatoxins. The system showed high sensitivity and selectivity and was able to detect different aflatoxins with an acceptable resolution.


Assuntos
Aflatoxinas , Grafite , Adsorção , Aflatoxinas/análise , Cromatografia Líquida de Alta Pressão , Limite de Detecção , Fenômenos Magnéticos , Extração em Fase Sólida
12.
Talanta ; 235: 122791, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517649

RESUMO

A new type of temperature-sensitive imprinted composite membranes(ICMs) was developed. Poly N,N-diethylacrylamide (DEA) blocks, as temperature-sensitive polymer, were grafted onto the substrate of the imprinted polymer separation layer to endow membranes with better adsorption effect. The comprehensive properties of the imprinted composite membranes were adequately tested and evaluated in detail. Results showed that ReO4- -ICMs (Re-ICMs) with temperature-sensitive recognition sites could adjust the structure of the imprinted holes at different temperatures, which presented excellent performance in the selective separation and purification of ReO4-. The prepared Re-ICMs exhibit the maximum adsorption capacity of 0.1639 mmol/g at 35 °C with the equilibrium adsorption time of 2 h. After ten adsorption/desorption cycles, Re-ICMs could still maintain 73.5% of the original adsorption capacity, the separation degree of ReO4-/MnO4- was only reduced from the initial 24.5 to 15.9, and the desorption ratio dropped from 80.4% to 68.4%, indicating that Re-ICMs have excellent adsorption and separation performance and reusability.


Assuntos
Impressão Molecular , Adsorção , Biomimética , Polímeros , Temperatura
13.
Talanta ; 235: 122818, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517674

RESUMO

As a type of environmental endocrine disrupting chemicals, bisphenols (BPs) have a certain embryonic toxicity and teratogenicity, which can significantly increase the risks of breast cancer, prostate cancer, leukemia and other cancers. In this work, stable multivariate metal-organic frameworks (UiO-66-NH2/TCPPx) were synthesized via in situ one-pot method and used as miniaturized dispersive solid-phase extraction (dµSPE) sorbents for extraction of trace BPs from environmental samples. The phase purity, crystal morphology and physical properties of UiO-66-NH2/TCPPx samples were varied by adjusting the mass ratio of TCPP. The extraction performance of UiO-66-NH2/TCPPx samples were investigated and UiO-66-NH2/TCPP1.0 exhibited the highest adsorption efficiency. Besides, UiO-66-NH2/TCPP1.0 possessed excellent recycling stability for the adsorption and desorption of BPs more than 20 cycles. The experimental parameters including amount of adsorbent, adsorption time, sample solution pH, temperature, desorption time and desorption solvents which affecting the efficiency of dµSPE were studied, respectively. Good linearity (R2 > 0.9992) in range of 0.1-200 ng mL-1 was obtained. The detection limits (S/N = 3) and quantification limits (S/N = 10) were achieved at 0.03-0.08 ng mL-1 and 0.1-0.5 ng mL-1, respectively. The relative standard deviations (RSDs) of intra-day and inter-day ranged from 2.5 to 5.5% and 1.1-6.8%. Enrichment factors were calculated in the range of 303-338. The obtained recoveries of bisphenol F (BPF), bisphenol A (BPA), bisphenol B (BPB) and bisphenol AF (BPAF) were 81.26-91.03% (RSDs = 0.96-6.47%), 82.2-97.27% (RSDs = 0.45-6.15%), 87.56-97.26% (RSDs = 1.1-6.22%) and 82.2-100.8% (RSDs = 0.46-4.07%). The UiO-66-NH2/TCPP1.0 can be employed as potential dµSPE sorbents for the enrichment of trace BPs in the environmental samples.


Assuntos
Estruturas Metalorgânicas , Adsorção , Compostos Benzidrílicos , Humanos , Masculino , Fenóis , Extração em Fase Sólida , Solventes
14.
Environ Monit Assess ; 193(10): 642, 2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34508274

RESUMO

The present research describes the successful preparation of melon peel biochar modified with CoFe2O4 (MPBC/CoFe2O4) followed by its usage as a new sorbent to separate, preconcentrate, and determine the toxic heavy metal ions by magnetic solid-phase extraction. The metal ion desorption was performed by 0.1 M HCl solution with a volume of 5.0 mL. Flame atomic absorption spectrometry (FAAS) was utilized for detection of the analyte levels. SEM-EDX, TEM, XRD, and FTIR techniques were carried out to illuminate the structure of MPBC/CoFe2O4. The fundamental variables affecting the adsorption and elution efficiencies of the analyte ions including solution pH, MPBC/CoFe2O4 amount, type and concentration of eluent, adsorption and desorption equilibrium time, and sample volume were optimized. The detection limits were calculated as 0.41, 1.82, and 3.16 µg L-1 for Cu2+, Cd2+, and Pb2+ ions, respectively, with the relative standard deviation of lower than 4.2%. There were no substantial interference effects on the analyte ion recovery due to the presence of foreign ions at high levels. Five minutes of contact time was adequate to attain the adsorption equilibrium. The adsorption capacity of MPBC/CoFe2O4 was obtained as 106.4, 65.4, and 188.7 mg g-1 for Cu2+, Cd2+, and Pb2+ ions, respectively, by utilizing Langmuir isotherm model. The pseudo-second order model is favorable to identify the adsorption kinetics. The method was validated by spike/recovery test, and then, it was successfully implemented to determine the aforementioned analyte levels in sea and stream water, pepper, black cabbage, eggplant, and tomato samples.


Assuntos
Cucurbitaceae , Poluentes Químicos da Água , Adsorção , Cádmio/análise , Carvão Vegetal , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , Chumbo , Extração em Fase Sólida , Espectrofotometria Atômica , Verduras , Água , Poluentes Químicos da Água/análise
15.
Chemosphere ; 282: 131110, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470162

RESUMO

Fibrous activated carbon has attracted emerging research interests due to its remarkable adsorption performance for volatile organic compounds (VOCs). Though this adsorption behavior for VOCs is closely related to the pore structure on the surface of activated carbon fiber (ACF), few researchers paid attentions to the influence of textural properties of this adsorption process. Especially, cotton-based activated carbon fiber (CACF) for adsorbing benzene pollutant is rarely reported. Herein, in order to develop a high-performance adsorbent for the removal of VOCs pollutants, this work studied the influence of textural properties of CACF on the adsorption of benzene. The results showed that the increase of carbonization temperature would lead to the reduction of mesopores but the increase of micropores for CACF; the embedment of phosphoric acid and its derivatives into the carbon layers contributed to the formation of pore structure for CACF; furthermore, specific surface area of CACF can also be enlarged by increasing the concentration of phosphoric acid. More importantly, it was found that the adsorption capacity of CACF for benzene was strongly dependent on the specific surface area and volume of micropores within CACF because micropores can provide more favorable binding sites. This adsorption process preferred to occur on the wall of micropores, then the accumulated benzene would slowly fill the pores. Interestingly, the decrease of pore size of micropores can unexpectedly improve the affinity of CACF to benzene on the contrary. This work provides a new strategy to develop porous structured ACF materials for the high-performance adsorption of VOCs.


Assuntos
Benzeno , Carvão Vegetal , Adsorção , Fibra de Carbono , Porosidade
16.
Chemosphere ; 282: 131111, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470163

RESUMO

In an ever-growing attempt to reduce the excessive anthropogenic CO2 emissions, several CO2 capture technologies have been developed in recent years. Adsorption using solid carbonaceous materials is one of the many promising examples of these technologies. Carbon-based materials, notably activated carbons, are considered very attractive adsorbents for this purpose given their exceptional thermal stability and excellent adsorption capacities. More importantly, the ability to obtain activated carbons from agricultural wastes and other biomass that are readily available makes them good candidates for several industrial applications ranging from wastewater treatment to CO2 adsorption, among others. Activated carbons from biomass can be prepared using various techniques, resulting in a range of textual properties. They can also be functionalized by adding nitrogen-based groups to their structure that facilitates faster and more efficient CO2 capture. This review provides a detailed overview of the recent work reported in this field, highlighting the different preparation methods and their differences and effects on the textual properties such as pore size, surface area, and adsorption performance in terms of the CO2 adsorption capacity and isosteric heats. The prospect of activated carbon functionalization and its effect on CO2 capture performance is also included. Finally, the review covers some of the pilot-plant scale processes in which these materials have been tested. Some identified gaps in the field have been highlighted, leading to the perspectives for future work.


Assuntos
Dióxido de Carbono , Carvão Vegetal , Adsorção , Biomassa , Nitrogênio
17.
Chemosphere ; 282: 131128, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470167

RESUMO

We introduce a novel, efficient and fast method for the total and simultaneous removal of monomethylmercury, dimethylmercury, ethylmercury and Hg (II) from aquatic environments using magnetic core nanoparticles, coated with metallic nanomeric silver and functionalized with l-Cysteine. As far as the authors know, simultaneous removal has not been achieved previously. The experimental design was based on exploring a wide range of experimental conditions, including pH of the medium (2-12), contact time (up to 20 min), adsorbent dose (50-800 µL) and temperature (293-323 K), in order to achieve the highest adsorption efficiency. The results show that, for a pH equal to 6.2 at room temperature, 400 µL of nanoparticles is sufficient to achieve 100% adsorption efficiency for all the studied Hg species after a contact time of 30 s. The adsorbent was characterized by means of Scanning Electron Microscopy, Energy Dispersive X-ray Analysis, Fourier-Transform Infrared Spectroscopy and a BET test. Moreover, the procedure allows the total recovery and recycling of the nanoparticles using 50 µL of 0.01 M KI. As regards reuse, the adsorbent exhibits no loss of adsorption capacity during the first three adsorption cycles. Thermodynamics reveals that adsorption is of a physicochemical nature, the equilibrium isotherms being described by a Langmuir model for all the Hg species. The ability of the method to simultaneously adsorb all species of mercury present in water, achieving full adsorption in just a few seconds, along with the simple experimental conditions and its cost-effectiveness, strongly support the approach as an alternative to current procedures.


Assuntos
Nanopartículas de Magnetita , Mercúrio , Poluentes Químicos da Água , Adsorção , Cisteína , Concentração de Íons de Hidrogênio , Cinética , Projetos de Pesquisa , Prata , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Poluentes Químicos da Água/análise
18.
Nanoscale ; 13(31): 13353-13367, 2021 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-34477741

RESUMO

Despite the significance of surface absorbed proteins in determining the biological identity of nanoparticles (NPs) entering the human body, little is known about the surface corona and factors that shape their formation on dietary particles used as food additives. In this study, food grade NPs of silica and titania and their food additive counterparts (E551 and E171) were interacted with milk proteins or with skimmed milk and the levels of protein adsorption were quantified. Characteristics of proteins correlating with their level of adsorption to NPs were determined using partial least squares regression analysis. Results from individual protein-particle interactions revealed the significance of factors such as zeta potential, hydrophobicity and hydrodynamic size of particles, and protein characteristics such as the number of beta strands, isoelectric points, the number of amino acid units (Ile, Tyr, Ala, Gly, Pro, Asp, and Arg), and phosphorylation sites on their adsorption to particles. Similar regression analysis was performed to identify the characteristics of twenty abundant and enriched proteins (identified using LC-MS/MS analysis) for their association with the surface corona of milk-interacted particles. Contrary to individual protein-particle interactions, protein characteristics such as helices, turns, protein structures, disulfide bonds, the number of amino acid units (Cys, Met, Leu, and Trp), and Fe binding sites were significant for their association with the surface corona of milk interacted particles. This difference in factors identified from individual proteins and milk interacted particles suggested possible interactions of proteins with surface adsorbed biomolecules as revealed by scanning transmission X-ray microscopy and other biochemical assays.


Assuntos
Nanopartículas , Coroa de Proteína , Adsorção , Sequência de Aminoácidos , Cromatografia Líquida , Humanos , Proteoma , Espectrometria de Massas em Tandem
19.
Anal Chim Acta ; 1178: 338849, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34482875

RESUMO

Various mesoporous adsorbents are of great promise for enriching small molecules from biological samples based on the size-exclusion effect. At present, the mesoporous adsorbents have adsorption sites distributed uniformly on the internal and external surfaces of mesopores. However, the adsorption sites on the external surface can adsorb proteins, interfering with the enrichment of small molecules. Herein, a novel immobilized-Ti4+ magnetic mesoporous adsorbent removing the adsorption sites on the external surface was facile prepared via the coupling chemistry of isocyanate with amine and consequent hydrolysis of urea linkage by urease. The adsorbent enables fast and selective enrichment of phosphopeptides and nucleotides from biological samples. In addition, sensitive detection methods for phosphopeptides and nucleotides in human serum are developed by coupling the magnetic solid-phase extraction with matrix-assisted laser desorption/ionization time of flight mass spectrometry and liquid chromatography-mass spectrometer, respectively. Under optimal conditions, response is linear (R2 ≥ 0.9923), limits of detection are low (0.41-9.48 ng mL-1), and reproducibility is acceptable (inter- and intra-day assay RSDs of≤15.0%) for six nucleotides. The developed strategy offers an effective method to eliminate the interference of proteins in the enrichment of small molecules from real biological samples.


Assuntos
Nucleotídeos , Fosfopeptídeos , Adsorção , Humanos , Reprodutibilidade dos Testes , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
20.
Anal Chim Acta ; 1178: 338789, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34482877

RESUMO

Electroosmotic flow (EOF) plays a pivotal role in optimization of capillary electrophoresis (CE) separations of (bio)molecules and (bio)particles. EOF velocity is directly related to analysis time, peak resolution and separation efficiency. Here, we report a concept of charged polymer coatings of the inner fused silica capillary wall, which allows anodic EOF with mobility ranging from 0 to ∼(30-40) × 10-9 m2V-1s-1. The capillary wall is modified by covalently bound cationic copolymer poly(acrylamide-co-(3-acrylamidopropyl)trimethylammonium chloride) (PAMAPTAC) containing variable ratio of the charged monomer in the 0-60 mol. % interval. The EOF mobility showed minor variability with composition of background electrolyte (BGE) and pH in the 2-10 interval. The coatings were evaluated by CE-UV and nanospray CE-MS in the counter-EOF arrangement for a series of basic drug molecules in acetic acid based acidic BGE. Tunable EOF velocity was demonstrated as a useful tool for optimization of peak resolution, separation efficiency and migration time of analytes. Electrostatic repulsion of positively charged capillary surface was shown as beneficial for suppression of analyte adsorption, notably for hydrophobic cationic analytes.


Assuntos
Eletro-Osmose , Eletroforese Capilar , Adsorção , Cátions , Polímeros
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