Chitosan, chitooligosaccharides and their derivatives’ production and use in many fields may result in their release to the environment, possibly affecting aquatic organisms. Both an experimental and ...a computational approach were considered for evaluating the effects of these compounds on Lemna minor. Based on the determined EC50 values against L. minor, only D-glucosamine hydrochloride (EC50 = 11.55 mg/L) was considered as “slightly toxic” for aquatic environments, while all the other investigated compounds, having EC50 > 100 mg/L, were considered as “practically non-toxic”. The results obtained in the experimental approach were in good agreement with the predictions obtained using the admetSAR2.0 computational tool, revealing that the investigated compounds were not considered toxic for crustacean, fish and Tetrahymena pyriformis aquatic microorganisms. The ADMETLab2.0 computational tool predicted the values of IGC50 for Tetrahymena pyriformis and the LC50 for fathead minnow and Daphnia magna, with the lowest values of these parameters being revealed by totally acetylated chitooligosaccharides in correlation with their lowest solubility. The effects of the chitooligosaccharides and chitosan on L. minor decreased with increased molecular weight, increased with the degree of deacetylation and were reliant on acetylation patterns. Furthermore, the solubility mainly influenced the effects on the aqueous environment, with a higher solubility conducted to lower toxicity.
In this study, zeta potentials of graphitic carbon nitride (g-C
3
N
4
) nanoparticles were detailedly investigated under various electrolytes, solution pH, and humic acid (HA) concentration ...conditions. The hydrodynamic radius of g-C
3
N
4
nanoparticles was measured to be 388.9 ± 24 nm, and the specific surface area of the g-C
3
N
4
nanoparticles was measured to be 46.2 m
2
g
−1
. The absolute values of g-C
3
N
4
zeta potentials significantly decreased with the increasing ionic strength (IS) due to the charge screening. Compared to the monovalent cation, the zeta potentials of g-C
3
N
4
were less negative with the presence of divalent cations. In addition, K
+
was more effective than Na
+
in decreasing the absolute values of g-C
3
N
4
zeta potentials, and Ca
2+
was more effective than Mg
2+
in decreasing the absolute values of g-C
3
N
4
zeta potentials. When NaCl and CaCl
2
were used as the electrolytes, the zeta potentials of g-C
3
N
4
became less negative with the decreasing pH conditions. When FeCl
3
and AlCl
3
were used as the electrolytes, the zeta potentials of g-C
3
N
4
became more positive with increasing solution pH due to the changing species of Fe
3+
and Al
3+
. The zeta potentials of g-C
3
N
4
were significantly more negative with the presence of HA. The results from this work indicated electrolytes, solution pH, and HA concentration conditions play a complex role in zeta potentials of g-C
3
N
4
nanoparticles in aqueous environment.
Chemiluminescent labelling, which is one of the promising procedures of modern immunodiagnostics, is increasingly carried out using acridinium derivatives, an oxidant, and an alkaline aqueous ...environment. However, the efficiency of the chemiluminescence of luminol or acridinium esters is higher in non‐aqueous solvents such as dimethyl sulfoxide or acetonitrile. Therefore, the search for a new environment for the chemiluminescence reaction, especially the one characterized by a higher quantum yield of chemiluminescence, is one of the aims of current research. Using computational methods (DFT and TD DFT with PCM model of solvent), we examined thermodynamic and kinetic data concerning the chemiluminescence and competitive dark pathways. Our results suggest that better characteristics of the chemiluminescence reaction of acridinium thioester are observed in nonpolar solvents, such as methylcyclohexane, n‐hexane and n‐pentane, than in aqueous media used so far. Further experimental verification is necessary to confirm the possible application of proposed nonpolar solvents in chemiluminescent labelling and hence in immunodiagnostics.
The efficiency of the chemiluminescence of luminol or acridinium esters is higher in nonaqueous solvents such as dimethyl sulfoxide or acetonitrile. Therefore, the search for new environments for the chemiluminescence reaction is one of the aims of current research. Using computational methods, the authors examine thermodynamic and kinetic data related to the chemiluminescence and competitive dark pathways.
Pure water scarcity is an emerging, all-around problem that globally affects both the life quality and the world’s economy. Heterogeneous photocatalysis under solar irradiation is a promising ...technique for the organic pollutants (e.g., pesticides, drugs) removal from an aqueous environment. Furthermore, the drawbacks of commercially available photocatalysts can be successfully overcome by using innovative nanoparticles, such as ZrO2/Fe3O4. Four ZrO2/Fe3O4 nanopowders with a different mass ratio of ZrO2 and Fe3O4 were synthesized using the chemical co-precipitation method. XRD analysis showed the presence of magnetite and hematite Fe-oxide phases in all samples. The content of the magnetite phase increased with the addition of 19% ZrO2. The efficiency of the newly synthesized ZrO2/Fe3O4 nanoparticles was investigated in the rapid removal of selected pollutants under various experimental conditions. Nevertheless, the influence of the water matrix on photocatalytic degradation was also examined. The obtained data showed that using ZrO2/Fe3O4 nanosystems, an appropriate removal rate of the selected pesticides and pharmaceuticals can be reached after 120 min of solar irradiation. Further, the total organic carbon measurements proved the mineralization of the target emerging pollutants. ZrO2/Fe3O4 nanoparticles are economically feasible, as their removal from the suspension can be easily achieved using affordable, environmentally-friendly magnetic separation.
The simultaneous balance of electrode materials and electrode structures can energize the development of innovative electrochemical sensors. In this work, a 3D nanocarbon layer of hybrid heteroatoms ...and metal atoms (CN/Fe) with excellent electrical properties and abundant active sites was self-constructed on the surface of a quartz-based nanofiber by high-temperature pyrolysis. Further, the nanofiber tip was selected as the sensing region to develop an electrochemical sensing platform with high sensitivity, miniaturization, and portability. A common broad-spectrum antibiotic (Doxycycline hyclate, DOX) was used as a model to evaluate the designed miniaturized sensing platform, and the stability, reproducibility, and applicability of the microsensor were verified in a variety of real samples, including algal solution, milk, human serum, and cell culture media. The results show that the proposed sensing platform has a detection limit as low as 82 nM in aqueous environments. Furthermore, it is further shown that coupling the design of electrode materials and electrode structures facilitates the development of electrochemical sensors with more practical applications. This concept will open up new avenues for the development of electrochemical sensors that meet many application scenarios.
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•A method for preparing multi-doped carbon microelectrodes is presented.•The active sites on the microelectrodes play an important role in detecting DOX.•The miniaturized electrochemical sensor was integrated based on CN/Fe ME.•The miniaturized analytical platform was examined in a variety of real samples.
Natural inorganic colloids (NICs) are the most common and dominant existence in the ecosystem, with high concentration and wide variety. In spite of the low toxicity, they can alter activity and ...mobility of hazardous engineered nanoparticles (ENPs) through different interactions, which warrants the necessity to understand and predict the fate and transport of NICs in aquatic ecosystems. Here, this review summarized NICs properties and behaviors, interaction mechanisms and environmental factors at the first time. Various representative NICs and their physicochemical properties were introduced across the board. Then, the aggregation and sedimentation behaviors were discussed systematically, mainly concerning the heteroaggregation between NICs and ENPs. To speculate their fate and elucidate the corresponding mechanisms, the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) and extended DLVO (X-DLVO) theories were focused. Furthermore, a range of intrinsic and extrinsic factors was presented in different perspective. Last but not the least, this paper pointed out theoretical and analytical gaps in current researches, and put forward suggestions for further research, aiming to provide a more comprehensive and original perspective in the fields of natural occurring colloids.
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•The aggregation behaviors of NICs in water environment are systematically reviewed.•Typical NICs are introduced in terms of structure, morphology, charge proprieties.•The classical and extended DLVO interaction mechanisms are summarized elaborately.•Both the intrinsic and extrinsic factors affecting NICs fate are analyzed in detail.•The existing drawbacks and the future research directions are reasonably put forward.
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•Seven ferrocenyl-based unsymmetrical azines 3a–3f and 5a were synthesized under metal-free conditions in good yields.•The compounds 3f and 5a have shown to be excellent multichannel ...recognition receptors for Hg2+ and Cu2+.•1,1′-disubstituted ferrocene-based azines 3f has higher sensitivity than 1-disubstituted ferrocene-based azines 5a.•Different substituent groups on the phenyl have significant influence on the sensitivity.•The color of the solution containing chemosensor 3f changed from yellow to colorless, upon the addition of Hg2+ and Cu2+ ions.
Seven ferrocenyl-based unsymmetrical azines 3a–3f and 5a were synthesized under metal-free conditions in good yields. Ferrocene-based unsymmetrical azines 3f and 5a have shown to be excellent multichannel chemosensors for Hg2+ and Cu2+ ions in aqueous environment. The color of the solution containing chemosensor 3f changed from yellow to colorless, upon the addition of Hg2+ and Cu2+ ions. Quantification of the absorption titration analysis shows that the detection limit was 6.77×10−7M for 3f-Cu2+ and 7.19×10−7M for 3f-Hg2+, respectively. For 5a, the detection limit can reach 1.29×10−7M and 2.40×10−7M for Cu2+ and Hg2+, respectively. Moreover, 1-substituted ferrocene-based unsymmetrical azines 3a–3e with electron-rich, electron-neutral, and electron-deficient aryl groups have significant influence on the sensitivity.
Carbon-centric adsorbents (CCA) are diverse forms, from simple biochar (BC) to graphene derivatives, carbon nanotubes (CNTs), and activated carbon (AC), which have been vastly explored for their ...removal of a plethora of pollutants, including heavy metals (HM). The prominent features of CCA are their operational attributes like extensive surface area, the occurrence of flexible surface functional groups, etc. This work offers a comprehensive examination of contemporary research on CCA for their superior metal removal aptitude and performances in simulated solutions and wastewater flows; via portraying the recent research advances as an outlook on the appliances of CACs for heavy metal adsorption for removal via distinct forms like AC, BC, Graphene oxide (GO), and CNTs. The bibliometric analysis tool was employed to highlight the number of documents, country-wise contribution, and co-occurrence mapping based on the Scopus database. The coverage of research works in this review is limited to the last 5 years (2017–2021) to highlight recent progress and prospects in using CCAs such as AC, BC, GO, and CNTs to remove HM from aqueous media, which makes the review unique. Besides an overview of the common mechanisms of CACs, the future scope of CAC, especially towards HM mitigation, is also discussed in this review. This review endorses that further efforts should be commenced to enhance the repertory of CCAs that effectively eliminate multiple targeted metals in both simulated and real wastewater.
Knowledge of electric charge and potential distributions at the nanoscale is of great interest in the fields of material science and biology. The required high measurement accuracy, spatial ...resolution, and applicability to aqueous environments are not always provided by conventional techniques such as Kelvin probe force microscopy (KPFM) due to averaging artifacts and the use of a dc bias. This article presents the development of an atomic force microscopy measurement mode, enabling quantitative surface potential measurements of nanoscale structures with high measurement accuracy in air and liquid (aqueous) environments. Averaging artifacts caused by the influence of the cantilever cone, cantilever beam and tip-sample distance in dc-bias-free KPFM (AC-KPFM) are eliminated by the implemented heterodyne detection and single-pass operation. The accuracy of the potential measurement as compared to amplitude-modulated KPFM (AM-KPFM) modes is greatly improved while keeping the advantages of closed-loop and dc-bias-free operation. Experiments on a gold-aluminum test sample and collagen fibrils show quantitative surface potential measurements on nanoscale structures and operability in an aqueous environment.
Microplastics (MPs) pollution has become a major environmental problem and poses a risk to a variety of organisms. In this study, the photoaging behavior of acrylonitrile butadiene styrene ...microplastics (ABS-MP) in aqueous environment was investigated under simulated solar irradiation. Results showed that the long chains of ABS-MP broke under the light irradiation, and its thermal stability was reduced. ABS-MP was oxidized during photoaging and produced a large number of oxygen-containing functional groups. Structure destruction of ABS-MP decreased the formation of environmentally persistent free radicals (EPFRs) and further photoirradiation generated secondary EPFRs. Nuclear magnetic resonance (NMR) analysis of the aged leachates confirmed that ABS-MP was oxidized and some small molecular fragments were dropped during photoaging. Meanwhile, C–Br bond broke of additive tetrabromobisphenol A (TBBPA) resulting in more bromine released into water and Sb(III) of additive Sb2O3 was oxidized to Sb(V) during photoaging. These findings illustrate the necessity of considering the aging of MPs in natural environment, expand the understanding of the potential harm and fate of MPs in aqueous environment, which is important for the management of MPs.
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•Photoaging of ABS-MP was investigated in water under simulated solar irradiation.•Long chains of ABS-MP broke and released into water.•ABS-MP was oxidized and surface oxygen-containing functional groups increased.•Additive TBBPA released Br− and Sb (III) of Sb2O3 was oxidized to Sb (V).•Structure destruction of ABS-MP decreased the formation of EPFRs and further photoirradiation generated secondary EPFRs.
