Aquatic Media Research Articles

Structural properties of a biotechnological capsule confined by a 3D‐cellulose acetate membrane

Small bioreactor platform (SBP) capsules are designed to implement selective bacterial cultures within aquatic media, mainly wastewaters, in a bioaugmentation process. Such capsules, coated with cellulose acetate (CA) membranes to form three‐dimensional (3D) structural barriers, are intended to provide a long‐term protected and confined environment for the introduced bacterial cultures. These state‐of‐the‐art 3D membranes allow the tailored design of the encapsulated bacteria and adjustment to several environmental properties, such as organics and nutrients, pressure, and the natural flora. Our study characterizes, for the first time, the mechanical and thermal properties of the SBPCA structural membrane and the effects of water molecules on these properties. High‐resolution scanning electron microscopy images of the CA membranes show mesh‐like porous structures, crucial for mass transport both inside and outside the capsule. Thermal gravimetric analysis shows a reduction of ~115°C in the thermal decomposition temperature of wet capsules compared to that of dry capsules. Mechanical testing shows that the modulus and maximum stress of wet samples are each decreased by an order of magnitude compared to those of dry samples at similar maximum strain. The permeability of the CA membrane to phenol, a model water organic pollutant, was found to be 3 × 10−8 cm2 s−1. It is concluded that water molecules soften CA structural membranes, yielding soft amorphous structures, which are needed for the optimized processing of the SBP capsule. The plasticizing effect is important in the membrane architecture formation and fiber elasticity when used in an aqueous environment.

Transpicuous-Cum-Fouling Resistant Copolymers of 3-Sulfopropyl Methacrylate and Methyl Methacrylate for Optronics Applications in Aquatic Medium and Healthcare

The scope of optical sensors and scanners in aquatic media, fluids, and medical diagnostics has been limited by paucity of transparent shielding materials with antifouling potential. In this research endeavor, facile synthesis, characterization, and bioassay of antifouling transparent functional copolymers are reported. Copolymers of 3-sulfopropyl methacrylate (SPMA) and methyl methacrylate (MMA) were synthesized by free radical polymerization in various proportions. Samples PSM20, PSM30, PSM40, PSM50, and PSM60 contain 20%, 30%, 40%, 50%, and 60% SPMA by weight, respectively. Resultant products were characterized by FTIR and 1H-NMR spectroscopy. The synthesized copolymers have exhibited excellent transparency, i.e., 75% to 88%, as determined by the UV-Vis spectroscopic analysis. Transmittance was decreased from 6% to 2% in these copolymers upon changing the concentration of 3-sulfopropyl methacrylate from 20% to 50% owing to bacterial and algal biofilm formation. Water contact angle values were ranged from 18° to 63° and decreased with the increase in the polarity of copolymers. The surface energy lowest value 58 mJ/m2 and highest value 72 mJ/m2 were calculated for PSM20 and PSM50, respectively, by the Chibowski approach and Young equation. Sample PSM50 has exhibited the highest antibacterial activities, i.e., 18 mm and 19 mm, against Escherichia coli and Staphylococcus aureus, respectively, by the disk diffusion method. Copolymer PSM50 has shown minimum algal adhesion for Dictyosphaerium algae as observed by optical microscopy. This lower bacterial and algal adhesion is attributed to higher concentrations of anionic SPMA monomer that cause electrostatic repulsion between functional groups of the polymer and microorganisms. Thus, the resultant PSM50 product has exhibited good potential for optronics shielding application in aquatic medium and medical diagnostics.

Vitamin D3‐loaded nanophytosomes for enrichment purposes: Formulation, structure optimization, and controlled release

AbstractThis study was aimed at using the nanophytosome delivery system to increase stability and controlled release of vitamin D3 due to the low stability of vitamin D3 during storage and digestion conditions. Response surface methodology was utilized to optimize the effect of reaction temperature, and ratios of vitamin D3/lecithin and complex/solvent on the responses. The optimum phytosome was characterized for differential scanning calorimetry, morphology, stability, Fourier transform infrared spectra (FTIR), antioxidant activity, moisture content, solubility, and in vitro release kinetics. FTIR spectra indicated the complex between vitamin D3 and lecithin was formed by hydrogen bonds. The optimum phytosome had a protective effect on the antioxidant activity of vitamin D3 and also had a significant increase in the solubility of vitamin D3 into aquatic media. The release of vitamin D3 in the intestine medium followed the Fickian diffusion mechanism. The optimization of variables to produce optimum phytosome increased their stability during storage.Practical applicationsA main part of the people nowadays are suffering with the lack of vitamin D3 majorly related to the loss of 7‐hydrocholesterol resources available in the skin over the years, due to the lack of contact with ultraviolet (UV) light. Several benefits reported for vitamin D3 intake including the increase of calcium and phosphorus absorption in the small intestine and the homeostasis of these minerals in the bloodstream, which prevent diseases as osteoporosis among others. Fat‐soluble vitamins such as vitamin D3 are sensitive compounds that should be protected from oxidation agents. Entrapment of vitamin D3 in phytosomes is an effective way to protect the main properties of vitamin D3 during the storage, production of an enriched food supplement with vitamin D3, and creates a physicochemical barrier against oxidation agents such as free radicals, oxygen, or UV light.

Evidence of the impact of noise pollution on biodiversity: a systematic map

BackgroundEcological research now deals increasingly with the effects of noise pollution on biodiversity. Indeed, many studies have shown the impacts of anthropogenic noise and concluded that it is potentially a threat to the persistence of many species. The present work is a systematic map of the evidence of the impacts of all anthropogenic noises (industrial, urban, transportation, etc.) on biodiversity. This report describes the mapping process and the evidence base with summary figures and tables presenting the characteristics of the selected articles.MethodsThe method used was published in an a priori protocol. Searches included peer-reviewed and grey literature published in English and French. Two online databases were searched using English terms and search consistency was assessed with a test list. Supplementary searches were also performed (using search engines, a call for literature and searching relevant reviews). Articles were screened through three stages (titles, abstracts, full-texts). No geographical restrictions were applied. The subject population included all wild species (plants and animals excluding humans) and ecosystems. Exposures comprised all types of man-made sounds in terrestrial and aquatic media, including all contexts and sound origins (spontaneous or recorded sounds, in situ or laboratory studies, etc.). All relevant outcomes were considered (space use, reproduction, communication, etc.). Then, for each article selected after full-text screening, metadata were extracted on key variables of interest (species, types of sound, outcomes, etc.).Review findingsOur main result is a database that includes all retrieved literature on the impacts of anthropogenic noise on species and ecosystems, coded with several markers (sources of noise, species concerned, types of impacts, etc.). Our search produced more than 29,000 articles and 1794 were selected after the three screening stages (1340 studies (i.e. primary research), 379 reviews, 16 meta-analyses). Some articles (n = 19) are written in French and all others are in English. This database is available as an additional file of this report. It provides an overview of the current state of knowledge. It can be used for primary research by identifying knowledge gaps or in view of further analysis, such as systematic reviews. It can also be helpful for scientists and researchers as well as for practitioners, such as managers of transportation infrastructure.ConclusionThe systematic map reveals that the impacts of anthropogenic noises on species and ecosystems have been researched for many years. In particular, some taxonomic groups (mammals, birds, fishes), types of noise (transportation, industrial, abstract) and outcomes (behavioural, biophysiological, communication) have been studied more than others. Conversely, less knowledge is available on certain species (amphibians, reptiles, invertebrates), noises (recreational, military, urban) and impacts (space use, reproduction, ecosystems). The map does not assess the impacts of anthropogenic noise, but it can be the starting point for more thorough synthesis of evidence. After a critical appraisal, the included reviews and meta-analyses could be exploited, if reliable, to transfer the already synthesized knowledge into operational decisions to reduce noise pollution and protect biodiversity.

Use of Ultrasound and Ultraviolet Radiation in Hybrid Methods for Water Disinfection

Hybrid photochemical methods are considered for water disinfection in which treatment with ultraviolet (UV) and ultrasonic (US) radiations are combined (US/UV) and applied consecutively or simultaneously; the use of catalysts is also included. The literature survey shows that inactivation of pathogenic microorganisms in aquatic media by high-frequency US (>100 kHz) has not been studied adequately, whereas only low-frequency (<100 kHz) US and low-pressure mercury vapor lamps (254 nm) were used in hybrid US/UV methods. Irradiation with high-frequency US generates reactive oxygen species (primarily hydroxyl radicals) in greater proportions, and a synergistic effect is observed when UV irradiation is included in treatment. Therefore, the use of high-frequency US and mercury-free UV sources in hybrid oxidizing systems, including those based on Fenton-like processes, is promising for intensifying disinfection processes and improving their effectiveness.

Synthesis, characterization and evaluation of carbon nanofiber modified-polymer for ultra-removal of thorium ions from aquatic media

Removal of thorium ions from aquatic media using high effective adsorbents is a very convenient viewpoint for the management of environmental pollutants. With this respect, this study is aimed to facile synthesize carbon nanofiber modified-(ethylene triamine- trimesoyl chloride) polymer (CNF-ETA-TMC) as a novel material for ultra-adsorption of thorium (Th(IV)) from aquatic media. The prepared CNF-ETA-TMC composite polymer adsorbent was characterized by FTIR and SEM/EDX techniques. The effective experimental parameters on the adsorption performance were optimized with factorial design analysis. The Langmuir modeling results showed that the CNF-ETA-TMC ultra-removal adsorption capacity of 867.9 mg g−1 at optimized batch conditions; pH 5, 30 min contact time, and 20 °C. Thermodynamic evaluations exhibited that the ΔG° function was decreased from -18.96 to -14.84 kJ/mol as the ΔH° parameter was calculated as -47.88 kJ.mol−1, confirming the spontaneous and exothermic nature of Th(IV) adsorption with increasing temperature from 303 to 333 K. The kinetic findings indicated that the adsorption mechanism was in an agreement with the pseudo-second-order model. Additionally, the regeneration performance of the adsorbent was increased in the range of 55-98% using HCl solvent at different concentrations, 0.25–1.0 mol.L−1. The cycling results that the composite polymer adsorbent revealed about 80% regeneration performance after five replications while the adsorption/desorption efficiencies decreased to 20/25% after 10th cycle. This research suggested that the synthesized CNF-ETA-TMC could be evaluated as a beneficial adsorbent for the infiltration of thorium from aquatic media due to its ultra-removal capacity.

Geochemistry of Engineered Nanoparticles (CdSe/ZnS Quantum Dots) in Surface Waters

The difficulties when studying the behavior of engineered nanoparticles (ENPs), and the subsequent metal speciation in aquatic ecosystems, at concentrations relevant of environment (i.e. ppt level) are often related to the occurrence of ENPs constitutive elements at high concentrations as a background in aquatic media (i.e.). In this study, the physico-chemical behavior of CdSe/ZnS quantum dots (QDs) when spread at very low concentration in surface waters was investigated. The above-mentioned issues were overcome with the use of isotopically labeled QDs, separated by centrifugal ultrafiltration (CU) and measured by HR-ICP-MS, combined with the detection of free and labile metal ions by Scanned Stripping ChronoPotentiometry (SSCP). They firmly provided a thorough comprehension regarding the transformation of QDs in surface waters. The physicochemical conditions of the medium including the presence of an analogue of natural organic matter and a mineral (i.e. fulvic acid, goethite), the manufactured coating of the QDs (here thioglycolic acid), and the occurrence of added Zn in the medium, were considered in the study. The overall results show that, in the absence of mineral/organic matter, the TGA ligands in solution detached from the QDs surface after dissolution control the metal ions speciation, especially for Cd. Conversely in a more representative aquatic ecosystem conditions (i.e. with Zn in the background media together with fulvic acid and goethite), almost no Zn nor Cd dissolution from the QDs is detected. SSCP measurements reveal that the Zn complexes formed with the organic/mineral material in the system are inert, whereas the speciation model calculations indicated that Cd2+ is bound to TGA ligands in solution and organic/inorganic matter – therefore suggesting that, under the studied conditions, aquatic organisms will be exposed to a very low concentration of free and labile metal ions issued from the QDs.

Synthesis of an organic-inorganic hybrid absorbent for in-tube solid-phase microextraction of bisphenol A.

This research is an application of fiber-in-tube solid-phase microextraction followed by high-performance liquid chromatography with UV detection for the extraction and determination of trace amounts of bisphenol A. Nanomagnetic Fe3 O4 was formed on the surface of polypropylene porous hollow fibers to increase the surface area and then it was coated with polystyrene. The introduction of polystyrene improves the surface hydrophobicity and is an appropriate extractive phase because it is highly stable in aquatic media. The extraction was carried out in a short capillary packed longitudinally with the fine fibers as the extraction medium. Extraction conditions, including extraction and desorption flow rates, extraction time, pH, and ionic strength of the sample solution, were investigated and optimized. Under optimal conditions, the limit of detection was 0.01µg/L. This method showed good linearity for bisphenol A in the range of 0.033-1000µg/L, with the coefficient of determination of 0.9984. The inter- and intraday precisions (RSD%, n=3) were 7.9 and 6.3%, respectively. Finally, the method was applied to analysis of the analyte in thermal papers, disposable plastic cups, and soft drink bottles.

Integrated polyaniline with graphene oxide-iron tungsten nitride nanoflakes as ultrasensitive electrochemical sensor for precise detection of 4-nitrophenol within aquatic media

Extensive release of highly toxic pollutants within the ecosystem resulting from industrial/human activities has adversely affected the life of living species and raised the requirement for development of sensitive/accurate detection systems for monitoring the level of hazardous pollutants within the ecosystem. Among these toxic pollutants, 4-nitrophenol (4-NP) and its derived compounds applied serious damages to the nature that require practical protocols to remove them from the environment. To address this demand, we boosted the polymeric structure and sensitivity of polyaniline (PANi) through its reinforcement with decorated graphene oxide (GO) nanoflakes with interconnected, porous and highly dense pattern of iron tungsten nitride (GO-ITN) toward modification of glassy carbon electrode (GCE) for precise and real-time detection of 4-NP within the aqueous media. The developed nanocomposite showed superior sensitivity along with improved protonation that exhibited detection limit/quantification limit/sensitivity of 5.2 nM/18.2 nM/253.08 μA.μM.cm−2 and 2.4 nM/7.1 nM/354.92 μA.μM.cm−2 for oxidation and reduction peak currents, respectively. The developed sensor also showed superior sensitivity toward detection of 4-NP within real samples which highlighting the capability and functionality of the developed sensor toward the real-time detection of 4-NP within different aqueous media.

Surface functionalization of recycled polyacrylonitrile fibers with ethylenediamine for highly effective adsorption of Hg(II) from contaminated waters

In this research, recycled polyacrylonitrile fibers (PANFs) acquired from the textile recycling process were amino-functionalized in one simple step by means of ethylenediamine (EDA). The amino-functionalized polyacrylonitrile fibers (AF-PANFs) were utilized for adsorption of Hg(II) ions from aquatic media. Temperature and contact time during the synthesis were optimized by the Central Composite Design (CCD) method. FE-SEM, EDS, BET, and FT-IR analysis, and pHZPC measurement were conducted to characterize the features of the AF-PANFs. The average diameter of raw fiber was 20 μm, which increased 20 percent after functionalizing. The impact of independent parameters on the adsorption process was investigated using the Box-Behnken Design (BBD) method during the batch experiments. The column tests were conducted in a semi-continuous system with the removal efficiency of over 99% for various initial concentrations after specific cycles. Freundlich, Langmuir, UT, Redlich-Peterson, and Temkin isotherm models were employed to analyze the relation between the final concentration of Hg(II) (Co) and the equilibrium adsorption capacity (qe) of the AF-PANFs. According to the isotherm models and experimental results, the maximum qe of the AF-PANFs was 1116 mg g−1 at initial Hg(II) concentration of 850 mg L−1, contact time of 120 min, solution pH of 6, and at 40 °C. Kinetic and thermodynamic studies illustrated the approximate equilibrium time and endothermicity or exothermicity of the process. Regeneration of the AF-PANFs was accomplished for seven times without efficiency drop. The superb performance of the AF-PANFs in the presence of co-existing ions did not decline.

Effect of biogenic jarosite on the bio-immobilization of toxic elements from sulfide tailings

The discharge of toxic elements from tailings soils in the aquatic environments occurs chiefly in the presence of indigenous bacteria. The biotic components may interact in the opposite direction, leading to the formation of a passivation layer, which can inhibit the solubility of the elements. In this work, the influence of jarosite on the bio-immobilization of toxic elements was studied by native bacteria. In batch experiments, the bio-immobilization of heavy metals by an inhibitory layer was examined in the different aquatic media using pure cultures of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. A variety of analyses also investigated the mechanisms of metals bio-immobilization. Among different tests, the highest metal solubility yielded 99% Mn, 91% Cr, 95% Fe, and 78% Cu using A. ferrooxidans in 9KFe medium after ten days. After 22 days, these percentages decreased down to 30% Mn and about 20% Cr, Fe, and Cu, likely due to metal immobilization by biogenic jarosite. The formation of jarosite was confirmed by an electron probe micro-analyzer (EPMA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The mechanisms of metal bio-immobilization by biogenic jarosite from tailings soil confirmed three main steps: 1) the dissolution of metal sulfides in the presence of Acidithiobacillus bacteria; 2) the nucleation of jarosite on the surface of sulfide minerals; 3) the co-precipitation of dissolved elements with jarosite during the bio-immobilization process, demonstrated by a structural study for jarosite. Covering the surface of soils by the jarosite provided a stable compound in the acidic environment of mine-waste.

Enhanced Hg Removal from Aqueous Streams by Sulfurized Activated Carbon Products: Equilibrium and Kinetic Studies

The removal of Hg from contaminated aquatic media is of major importance, taking into consideration the highly toxic character of the element. One of the most promising water treatment technologies is adsorption by low cost adsorbents, such as activated carbon produced by agricultural byproducts. In this study, activated carbon in granular form (GAC) was produced using pistachio shells from Aegina Island (Greece). Two main GAC products have been synthesized. The first one was chemically activated using ZnCl2. The second one was further treated with Na2S in order to introduce S atoms on the functional groups. The effectiveness of synthesized GAC products for Hg removal was evaluated by conducting batch equilibrium and kinetic experiments. It was found that sulfurization was able to increase by a factor of more than 2 the adsorptive capacity of activated carbon. Namely the maximum adsorption capacity was 73 mg/g for the simple GAC and increased up to 166 mg/g for the S-modified product. The kinetics of adsorption was described with almost equivalent precision using the pseudo-first and the pseudo-second order models, a behavior which is often observed in adsorption experiments, depending on the experimental conditions. The value of activation energy EA was found to be negative (− 18.8 kJ/mol) in the case of simple GAC and positive (8.27 kJ/mol), in the case of S-modified GAC, suggesting that Hg adsorption on the modified carbon follows a different mechanism, closer to chemisorption processes.

Using smartphones as hydrophones: two experiments in underwater acoustics

The use of smartphone microphones in aquatic media is explored by means of two experiments. The first experiment consists of a simple time-of-flight measurement of the sound speed in water, while the second deals with the acoustic location—or ranging—of a distant object. As the underwater noise is considerable, the experimental details and the uncertainties are worth discussing.

Channel catfish ovarian fluid differentially enhances blue catfish sperm performance

For externally fertilizing fishes, interactions between male and female gametes have been shown to have remarkable impacts on sperm performance. Ovarian fluid (OF) and its ability to alter the swimming behavior of fish sperm makes it a determining factor of fertility. With the expansion of channel catfish (Ictalurus punctatus) ♀ × blue catfish (Ictalurus furcatus) ♂ hybrid aquaculture, it is essential to understand the impacts during fertilization and the magnitude such gametic interactions have on sperm performance and subsequent male fertility potential. This study was conducted to address the following: 1) activate blue catfish sperm with/without channel catfish OF to determine impacts on sperm performance and 2) assess if sperm behave differently when activated in the OF from individual females. Sperm (n = 4 males) were activated without OF (control) and with diluted OF from unique females (n = 6), creating 24 experimental crosses. Sperm motility (%), velocity (VCL), and longevity were analyzed using computer assisted sperm analyses software. With OF incorporated in the activation media, sperm velocity was significantly higher than the control at 10, 20, and 30 s post-activation. OF did not have an impact on motility for any females at 10 s and 20 s post-activation but became significantly higher than the control at 30 s. In all cases, OF treatments greatly increased longevity. Male × female interactions were highly significant, such that motility, velocity, and longevity were dependent on specific male-female pairs. This information shows that OF should be incorporated in aquatic media to simulate natural spawning conditions and accurately assess the fluid mechanics of sperm propulsion for each male. Additionally, there are mechanisms that drive gamete interactions that need to be explored further, which may improve selection of male-female pairs for in-vitro fertilization. On a broad scale, our results also help to shed light on the complexities of fertilization and fish reproduction overall, which may have implications for recruitment variability and recovery strategies of threatened and/or endangered freshwater species.

Diacetylmonoxine modified chitosan derived ion-imprinted polymer for selective solid-phase extraction of nickel (II) ions

An ion-imprinted sorbent (Ni-CDMO) derived from diacetylmonoxime (DMO)-chitosan Schiff base has been prepared by incorporating Ni(II) ion matching sites, which can selectively coordinate and recover Ni(II) ions from aquatic media. The chitosan was first modified by DMO to improve the targeted Ni(II) ion coordination and then the polymeric Ni-complex was treated with glyoxal to cross-link the polysaccharide chains and maintain the coordination sites rigid and inflexible after eluting the Ni(II) ions from the sorbent matrix. The maximum Ni(II) ion capacities of the Ni-CDMO and the control adsorbent C-CDMO were determined by performing the isotherm studies under different Ni(II) initial concentrations and treating the obtained experimental results using Langmuir and Freundlich models. The maximum capacity was around 135 mg/g, which is considered a high competing value. Furthermore, the competitive extraction of Ni(II) ions among various similar ions including Pb(II), Cu(II), Co(II), and Cd(II) was carried out using Ni-CDMO and C-CDMO and the results confirmed the distinct role of the utilized imprinting procedure in creating a considerable Ni(II) ion selectivity within the structure of the Ni-CDMO. Also, the regeneration and reusability experiments indicated the preservation of approximately 98% of the initial efficiency after the performance of five consecutive cycles.

Fate and ecotoxicological effects of pyriproxyfen in aquatic ecosystems.

Pyriproxyfen is an insect growth regulator acting as larvicide against a large spectrum of public health insect pests, especially dipterans. It is also widely used in agriculture and horticulture for the control of many insect species. Disrupting the endocrine system by mimicking the activity of the juvenile hormone, pyriproxyfen interferes with metamorphosis in insects and prevents them from reaching maturity and reproducing. Because the aquatic ecosystems can be directly or indirectly contaminated by pyriproxyfen, the goal of this study was to establish the aquatic ecotoxicological profile of pyriproxyfen and to identify the gaps that need to be filled. Pyriproxyfen is photodegraded quickly in water. In the absence of organic matter, its persistence in aerobic water media is also limited especially with high temperature and sunlight. Analysis of the laboratory and in situ results for more than 60 aquatic algae, plants, invertebrates, and vertebrates shows that the toxicity of pyriproxyfen is highly variable including within a same taxonomical group. Abiotic and biotic factors can highly influence the toxicity of the molecule. Pyriproxyfen disrupts the development of numerous species and adversely impacts various physiological events. It can also disturb the behavior of the organisms such as their predatory and swimming performances. Although some experimental studies focus on the environmental fate of pyriproxyfen metabolites, those dealing with their aquatic ecotoxicity assessment are scarce. In the same way, the limited number of studies dealing with the search of pyriproxyfen residues in lake, river, and other natural aquatic media does not include the identification of the metabolites.

Comparing the Adsorption Performance of Multiwalled Carbon Nanotubes Oxidized by Varying Degrees for Removal of Low Levels of Copper, Nickel and Chromium(VI) from Aqueous Solutions

Functionalized multiwalled carbon nanotubes (MWCNTs) have drawn wide attention in recent years as novel materials for the removal of heavy metals from the aquatic media. This paper investigates the effect that the functionalization (oxidation) process duration time (3 h or 6 h) has on the ability of MWCNTs to treat water contaminated with low levels of Cu(II), Ni(II) and Cr(VI) (initial concentrations 0.5–5 mg L−1) and elucidates the adsorption mechanisms involved. Adsorbent characterization showed that the molar ratio of C and O in these materials was slightly lower for the oxMWCNT6h, due to the higher degree of oxidation, but the specific surface areas and mesopore volumes of these materials were very similar, suggesting that prolonging the functionalization duration had an insignificant effect on the physical characteristics of oxidized multiwalled carbon nanotubes (oxMWCNTs). Increasing the Ph of the solutions from Ph 2 to Ph 8 had a large positive impact on the removal of Cu(II) and Ni(II) by oxMWCNT, but reduced the adsorption of Cr(VI). However, the ionic strength of the solutions had far less pronounced effects. Coupled with the results of fitting the kinetics data to the Elowich and Weber–Morris models, we conclude that adsorption of Cu(II) and Ni(II) is largely driven by electrostatic interactions and surface complexation at the interface of the adsorbate/adsorbent system, whereas the slower adsorption of Cr(VI) on the oxMWCNTs investigated is controlled by an additional chemisorption step where Cr(VI) is reduced to Cr(III). Both oxMWCNT3h and oxMWCNT6h have high adsorption affinities for the heavy metals investigated, with adsorption capacities (expressed by the Freundlich coefficient KF) ranging from 1.24 to 13.2 (mg g−1)/(mg l−1)n, highlighting the great potential such adsorbents have in the removal of heavy metals from aqueous solutions.

A Systematic Investigation on the Properties of Silica Nanoparticles "Multipoint"-Grafted with Poly(2-acrylamido-2-methylpropanesulfonate-co-acrylic Acid) in Extreme Salinity Brines and Brine-Oil Interfaces.

Nanoparticles (NPs) may have great potential for various subsurface applications, including oil and gas recovery, reservoir imaging, and environmental remediation. One of the important challenges for these downhole applications is to achieve colloidal stability in subsurface media at high salinity and high temperature. It has been previously shown that several functional NPs "multipoint"-grafted with anionic poly(2-acrylamido-2-methyl-1-propanesulfonate-co-acrylic acid; AMPS-co-AA) exhibited remarkable colloidal stabilities in specific environments mimicking the harsh subsurface aquatic media, such as the American Petroleum Institute (API) brine. However, many important properties of such particles, other than the colloidal stabilities, must be studied in a more systematic fashion for a wide range of salt concentrations (Cs). Herein, we investigate various properties of the silica (SiO2) NPs multipoint-grafted with poly(AMPS-co-AA), SiO2-g-poly(AMPS-co-AA), in NaCl and CaCl2 solutions across a range of salinities. The brush behavior of the grafted random copolymers was investigated in both salt solutions from salt-free conditions up to extreme salinities. The particles displayed brine-oil interfacial activity with increasing Cs, stabilizing oil-in-brine emulsions as Pickering emulsifiers. A high internal phase emulsion (HIPE) with an internal oil phase of up to 80 vol % could be formed in CaCl2 solutions at high Cs, which exhibited gel-like behaviors.

Common sea urchin (Paracentrotus lividus) and sea cucumber of the genus Holothuria as bioindicators of pollution in the study of chemical contaminants in aquatic media. A revision

Abstract Currently many pollutants enter the seas and oceans as a result of anthropogenic activities such as agriculture, fishing, shipping, etc. Many of these chemical compounds cause serious damage to marine and terrestrial ecosystems because they tend to accumulate and begin their activity as pollutants once their useful cycle has ended. Therefore, there is growing concern about how to act to stop the increase in environmental pollution. Some of these compounds that began to accumulate in the environment since the last century are well known by the scientific community and are widely called persistent pollutants. This group includes polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and heavy metals, among others. However, other compounds that have not been considered as contaminants have appeared recently. These are the so-called emerging pollutants, which involve a long list of compounds including drugs, hormones, antimicrobials, plasticizers, UV filters, etc. Through the study of different organisms, the presence of these pollutants in natural environments as well as the harmful effects they cause to the biota present in said media are being deeply investigated. Two of the aquatic model organisms used as bioindicators in the different studies for this purpose are reviewed here: the sea cucumber of the genus Holothuria and the common sea urchin Paracentrotus lividus that share the fact of being, both, edible echinoderms. This review could be used to make people aware of the damage it is causing through the irresponsible management of natural resources, so that they serve to launch a series of measures that allow recovering the original conditions of the different ecosystems.

Sequestration of a non-steroidal anti-inflammatory drug from aquatic media by lignocellulosic material (Luffa cylindrica) reinforced with polypyrrole: Study of parameters, kinetics, and equilibrium

Luffa cylindrica (LF) is a plant that has been utilized for water treatment, particularly cationic species; however, in terms of anionic compounds, it owns low applicability. Accordingly, in the current study for the first time, LF was reinforced with polypyrrole (ppy) for the elimination of an emerging contaminant named ibuprofen from aquatic media. The prepared LF/ppy adsorbents were characterized by SEM, BET, FTIR, and XRD. LF/ppy was successfully prepared. The equilibrium time was achieved at 90 min. Lower equilibrium time was found at higher LF/ppy dosages. The agitation speed of 100 rpm revealed the highest removal percentage of 97 %. The initial pH of 5 was the optimum value. By enhancing the temperature from 298 to 323 K, the removal percentage decreased from 97 % to 16 %, revealing the exothermic nature of the adsorption processes. The equilibrium and kinetics data were best described by Langmuir (R2 = 0.9879) and pseudo-second-order (R2 = 0.9987) models, respectively, with the maximum monolayer adsorption capacity of 19.157 mg/g. In the case of Dubinin-Radushkevich model, the activation energy was calculated to be 2.5 kJ/mol, and so the removal process followed physical sorption. The results revealed that the removal percentage of LF/ppy was 7.72 times higher than raw LF. Herein, the present investigation clearly proved that the novel low-cost LF/ppy composite is an efficient, promising, and cost-effective choice for the elimination of ibuprofen from aqueous media.