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Nanofluids are complex fluids, mainly proposed to improve the efficiency of thermal systems. However, their poor stability, caused by the agglomeration and sedimentation of ...nanoparticles over time, has limited their practical application. A common technique to increase the stability of nanofluids is to add surfactants, which produce electrostatic or steric repulsion between nanoparticles, thus avoiding their agglomeration. This work evaluated the effects of surfactants and their concentration on the zeta potential and hydrodynamic diameter at different pH values as an indicator of nanofluids stability. Commercial alumina nanoparticles (0.1 wt.%) were dispersed in deionized water using two surfactants (cetyltrimethylammonium bromide, CTAB and sodium dodecylbenzenesulfonate, SDBS) at different concentrations, and the pH values were varied (2–12) by adding hydrochloric acid and sodium hydroxide. The results show the importance of the critical micelle concentration value in the nanofluids stabilization by electrostatic repulsion between nanoparticles and indicate that SDBS at a concentration of 0.064 wt.% (critical micelle concentration) offers the best dispersion conditions according with their zeta potential values, allowing high stability regardless of the pH value of the suspension.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
There is increasing pressure on global agricultural systems due to higher food demand, climate change, and environmental concerns. The design of nanostructures is proposed as one of the economically ...viable technological solutions that can make agrochemical use (fertilizers and pesticides) more efficient through reduced runoff, increased foliar uptake and bioavailability, and decreased environmental impacts. However, gaps in knowledge about the transport of nanoparticles across the leaf surface and their behavior in planta limit the rational design of nanoparticles for foliar delivery with controlled fate and limited risk. Here, the current literature on nano-objects deposited on leaves is reviewed. The different possible foliar routes of uptake (stomata, cuticle, trichomes, hydathodes, necrotic spots) are discussed, along with the paths of translocation, via the phloem, from the leaf to the end sinks (mature and developing tissues, roots, rhizosphere). This review details the interplays between morphological constraints, environmental stimuli, and physical-chemical properties of nanoparticles influencing their fate, transformation, and transport after foliar deposition. A metadata analysis from the existing literature highlighted that plant used for testing nanoparticle fate are most often dicotyledon plants (75%), while monocotyledons (as cereals) are less considered. Correlations on parameters calculated from the literature indicated that nanoparticle dose, size, zeta potential, and affinity to organic phases correlated with leaf-to-sink translocation, demonstrating that targeting nanoparticles to specific plant compartments by design should be achievable. Correlations also showed that time and plant growth seemed to be drivers for in planta mobility, parameters that are largely overlooked in the literature. This review thus highlights the material design opportunities and the knowledge gaps for targeted, stimuli driven deliveries of safe nanomaterials for agriculture.
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IJS, KILJ, NUK, PNG, UL, UM
New multi-featured adsorbent beads were fabricated through impregnation of sulfonated graphene (SGO) oxide into cellulose acetate (CA) beads for fast adsorption of cationic methylene blue (MB) dye. ...The formulated SGO@CA composite beads were thoroughly characterized by several tools including FTIR, TGA, SEM, XRD, XPS and zeta potential. The optimal levels of the most significant identified variables affecting the adsorption process were sequential determined by the response surface methodology (RSM) using Plackett-Burman and Box-Behnken designs. The gained results denoted that the surface of SGO@CA beads displayed the higher negative charges (- 42.2 mV) compared to - 35.7 and - 38.7 mV for pristine CA and SGO, respectively. In addition, the floated SGO@CA beads demonstrated excellent floating property, fast adsorption and easy separation. The adsorption performance was accomplished rapidly, since the adsorption equilibrium was closely gotten within 30 min. Furthermore, the adsorption capacity was greatly improved with increasing SGO content from 10 to 30%. The obtained data were followed the pseudo-second order kinetic model and agreed with Langmuir adsorption isotherm model with a maximum adsorption capacity reached 234.74 mg g
. The thermodynamic studies designated the spontaneity and endothermic nature of MB dye adsorption. Besides, the floated beads exposed acceptable adsorption characteristics for six successive reuse cycles, in addition to their better adsorption selectivity towards MB dye compared to cationic crystal violet and anionic Congo red dyes. These findings assume that the formulated SGO@CA floated beads could be used effectively as highly efficient, easy separable and reusable adsorbents for the fast removal of toxic cationic dyes.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
A new adsorbent composite Mn-doped UiO-66/Aminated-graphene oxide (Mn-UiO-66@GO-NH2) was synthesized via solvothermal method and well-characterized by XRD, SEM, EDX, TGA, FT-IR, N2 ...adsorption/desorption analysis and zeta potential. The as-synthesized Mn-UiO-66@GO-NH2 composite showed excellent performance toward Congo red dye adsorption with ultra-high capacity of 1265.82 mg/g. Adsorption performance of Mn-UiO-66@GO-NH2 composite and effect of pH on its adsorption capacity were investigated. The adsorption process fitted well with pseudo-second order and both Langmuir and Freundlich models. Thermodynamic of the process showed that the adsorption of CR on Mn-UiO-66@GO-NH2 composite is an endothermic process. In addition, Mn-UiO-66@GO-NH2 composite displays a good adsorption selectivity toward CR among two other dyes cationic methylene blue (MB) and anionic methyl orange (MO). The mechanism of the removal is proposed to be a combination of electrostatic attraction, π-π stacking, hydrogen bonding, and pore filling mechanism. The good reusability indicates that Mn-UiO-66@GO-NH2 composite can be applied for practical wastewater treatment.
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•Presenting a new aminated-GO/Mn-doped UiO-66 composite adsorbent for CR removal.•The prepared MOF composite shows ultra-high adsorption capacity of 1265.82 mg/g.•The prepared MOF composite showed excellent reusability and good selectivity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Abstract
The article presents an innovative approach to the analysis of nanofluids using a nonlinear multifractal algorithm. The conducted research concerned nanofluids prepared from SiO
2
...nanoparticles (~ 0.01 g) suspended in 100 ml of demineralized water and in 100 ml of 99.5% isopropanol. Subsequently, the nanofluids were subjected to conventional characterization methods such as: determination of the contact angle, determination of zeta potential, pH, and particle size analysis. The obtained results show that the prepared nanofluid is stable in terms of agglomeration over time (nanofluid suspension) and properly prepared in terms of dissolving and dispersing powder particles. The authors, analyzing the results of the presented methods for characterizing nanofluids, proposed a multifractal analysis, which allows detailed local descriptions of complex scaling behaviour, using a spectrum of singularity exponents. Nonlinear analyzes show that the use of multifractal algorithm for nanofluids can improve the process of fluid quality analysis and its preparation based on the multifractal spectrum.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Optimization of chitosan nanoparticles (ChNs) production process employing a 2(5–2) fractional factorial design was performed to analyze the influence of viscosity average molecular weight (40–120 ...kDa), the initial concentration of chitosan (2–5 g/L), the initial tripolyphosphate (TPP) concentration (0.8–1.2 g/L), the ratio chitosan/TPP (4/1–10/1) (V/V), and the stirring speed (300–700 rpm), on final nanoparticles size and zeta potential. The measured responses of average particle size and surface charge were determined on Zetasizer Nano ZS. ChNs were prepared using ionotropic cross‐linking of chitosan and TPP and were characterized by Fourier‐transform infrared spectroscopy (FTIR), X‐ray powder diffraction (XRD), and differential scanning calorimetry (DSC). The experiments showed that the size of synthesized nanoparticles depended on initial concentration and molecular weight of chitosan, TPP concentration and stirring speed within the chosen levels. However, the zeta potential was significantly influenced by chitosan molecular weight, chitosan concentration and stirring speed. The FTIR analysis confirmed the interaction between negative charge of TPP with positive charge of chitosan through the appearance of new peaks at 1222 and 895 cm−1 in produced ChNs. XRD and DSC analysis were used to evaluate the effect of crosslinking of chitosan on crystal structure of ChNs.
The ability of controlling mean particle size and zeta potential is highly desired for most applications of chitosan nanoparticles. Determination of parameters that govern the control of nanoparticles properties.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Activated carbon (AC) was modified by FeCl
. Batch experiments were carried out to evaluate the characteristics of equilibrium, kinetics and thermodynamics of Sulfamethazine adsorption onto original ...and modified AC. The results showed that Fe
treatment changed the surface area, pore volume and surface zeta potential and increased the number of surface oxygenic functional groups. The adsorption of Sulfamethazine on modified activated carbon (MAC) was significantly improved. Isotherm test results revealed that the adsorption isotherms of Sulfamethazine on MAC fit the Freundlich, Langmuir and Temkin equations well. The maximum adsorption quantity of Sulfamethazine on MAC was 17.2414 mg/g at 25 °C. The adsorption kinetics of Sulfamethazine on AC and MAC can be characterized by the pseudo-second-order model. The adsorption process was affected by membrane diffusion, surface adsorption and internal diffusion. The adsorption quantities of Sulfamethazine first increased and then decreased for pH between 3 and 10. The removal efficiencies decreased with increasing temperature, which is favorable for adsorption at low temperature. It was also found that the mechanisms of adsorption included micropore capture and electrostatic, hydrogen bonding, π-π electron donor-acceptor (EDA) and coordination interactions as well as other interactions.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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•Monomeric carbamoylcarboxylic ligands have great capacity to heavy metal ions removal.•Carbamoylcarboxylic ligands exhibit a good six-heavy metal ions simultaneous removal.•Chemical ...structure of carbamoylcarboxylic ligands influences their removal efficiency.•Instability phenomena in flocs evolution are the sedimentation and clarification.•Carbamoylcarboxylic ligands are biodegradable materials.
In this work, a library of new aniline and pyridyl functionalized carbamoylcarboxylic acids were synthesized, physicochemically analyzed and evaluated as ligands for the simultaneous removal of environmental interest cations. The effect of the structural characteristics of these functionalized ligands over the simultaneous removal performance of metal ions (Cr3+, Pb2+, Cd2+, Cu2+, Ni2+, Zn2+ and Ca2+) was established. The metal ion-ligand association constants calculated from zeta potential (102 to 104 M−1) and UV–vis (103 to 107 M−1) demonstrate a strong affinity of these ligands towards metal ions. The micro-Jar test for cation removal shows these new functionalized carbamoylcarboxylic acids L1-L12 show average removal efficiencies of 100 % Cr3+, 73 % Pb2+, 42 % Zn2+, 50 % Ni2+, 42 % Cd2+, 39 % Cu2+ and 30 % Ca2+. The quantification of destabilization phenomena through transmittance and backscattering measurements allowed to evaluate the mechanisms of colloidal instability to all ligands. Among the twelve ligands, L9 showed the best removal performance at pH = 4.0 with an overall removal capacity (19.28 mg Mn+ removed/mg of L9), clarification kinetics (55.99 T%/h) and sedimentation ratio (117.6 mm/h). The flocs recovered from the coagulation-flocculation tests were analyzed by scanning electron microscopy and dispersive energy spectroscopy with mapping finding the dispersion patterns of metals on the surface. A BOD5/COD = 0.44 indicates that L9 is a biodegradable compound. Based on the results, aniline and pyridyl functionalized carbamoylbenzoic acids have great potential to be applied in the wastewater treatment industry containing multiple cations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Iron oxide nanoparticles (IONs) have several applications in medical fields including magnetic resonance imaging (MRI), drug delivery, cancer treatment and cell splitting. Therefore, it is important ...to investigate their cellular toxicity. It is difficult to predict their cellular toxicity due to complexities associated with their cellular mechanisms. The present study was designed to collect data on the cell viability of IONs and obtain a mathematical modeling. For this purpose, particle size, concentration, incubation time and the surface charge of NPs were selected as the model inputs and the percentage of cell viability (%CV) as the model output. Using a version of the modeling called SA-LOOCV-GRBF, these issues can be resolved with favorable results. Since the behavior of positive zeta potential (PZP) is different from negative zeta potential (NZP), they were compared by separate modeling efforts. Kidney is a vital body organ that dispose of IONs in the body, but it is possible that these cells engage in unwanted interactions with IONs. Therefore, the kidney cell line was examined in this study.
•Data extraction of Kidney cell viability for iron oxide nanoparticle•Investigation of cell viability behavior by prediction of approximate model•Using new version of neural network modeling called: SA-LOOCV-GRBF
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
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•Ternary nanoparticles showed 8 times lower MIC than pure lactoferrin and chitosan.•The MIC of the ternary complexes was lower than that of the binary ...complexes.•Carboxymethylcellulose coating with nanoparticles increased fruit shelf life.•The nanoparticles inhibited the growth of mesophilic bacteria in strawberries.
Lactoferrin (L), chitosan (C) and gellan (G) nanoparticles were produced by electrostatic complexation, aiming to enhance the antimicrobial characteristics of these compounds. Binary complexes (lactoferrin-gellan and chitosan-gellan) and ternary complexes (lactoferrin-chitosan-gellan) were studied in eight different proportions of biopolymers. The antimicrobial activity of nanoparticles against S. aureus was compared with that of pure biopolymers and related to nanoparticle size, charge density and morphology. Those with a 4.5L:4.5C:1G ratio presented the highest positive charge density (+57.90 ± 1.50) mV and smaller hydrodynamic diameter (53.53 ± 2.06) nm, which resulted in the highest antimicrobial action (minimum inhibitory concentration of 0.0117 mg/ml). When applied to a coating of fresh strawberries, the nanoparticles were effective in preserving their physicochemical properties, especially in the presence of carboxymethylcellulose that enhanced the adhesion of particles to the fruits. In this study, the antimicrobial action of nanoparticles was better than that of lactoferrin and pure chitosan alone, proving that the antimicrobial properties of such biopolymers were enhanced due to aggregation at the nanoscale. The nanoparticles produced have outstanding application potential as natural food preservers.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
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