Desorption Studies Research Articles

Photocatalytic degradation of acid violet dye by sunlight exposure using green synthesized magnesium oxide nanoparticles

An aqueous extract of Phyllanthus Emblica fruit extract was used as a precursor in the effective synthesis of Magnesium Oxide Nanoparticles (MgONP) and the same was calcined at different temperatures. The thermal study demonstrated that MgO nanoparticles evolved from Mg(OH)2 by the identification of characteristic weight loss curves and endothermic peaks in TGA and DTA, respectively. UV-visible analysis showed that the peak shifts to a longer wavelength at 350 nm when the calcination temperature rises from 200 to 600 °C, indicating a decrease in the size of MgONP particles. On the other hand, Tauc plot analysis showed that the band gaps between the precursor and calcined MgO samples varied from 5.84 to 3.70 eV. FTIR and XRD analysis confirmed the synthesis of MgONPs from Mg(OH)2 exhibiting spherical shapes of around 20 nm in size.Twenty minutes of exposure to sunshine caused the dye's colour to entirely vanish, demonstrating the remarkable photocatalytic effectiveness of MgONP calcined at 600 °C. The effective breakdown of Acid Violet was confirmed by the rate constant of the photocatalytic behaviour increasing proportionately with the catalyst dose. Furthermore, it was suggested by the Langmuir and Freundlich isotherm models that Acid Violet efficiently adheres to the photocatalyst surface when R2 values are nearer to 1. There are several potential applications for MgO nano adsorbents in dye removal processes, as evidenced by desorption studies that showed their reusability.

Study of frictional wear and desorption of nanoparticle‐rubber blend modified UHMWPE composites

AbstractTo address the issues of abrasive wear, impact wear, and soil adhesion that can lead to wear failure and excessive operational resistance in agricultural soil touching parts during farming. This study focuses on UHMWPE composites, modified by filling Nano‐SiC as a hard phase filler and XNBR as an elastic filler. These fillers were dispersed into the UHMWPE matrix through melt blending technology to create a high‐performance composite material for the surface protective material of soil touching parts. The study discovered that by adding hard and elastic fillers to the UHMWPE matrix, the density, hardness, flexural modulus and thermal stability of the materials were all increased. Specifically, the density increased by 5.67% and the flexural modulus increased by 107%. In the block on ring wear test the volumetric wear rate decreased by 98%, while in the mortar wear test the mass wear rate decreased by 64.64%. Additionally, the contact angle on the surface of the specimen after mortar erosion and wear increased to 102.76°, 18% higher than that of pure UHMWPE. These results demonstrate that the modified fillers can improve the abrasion and plastic deformation resistance and hydrophobic desorption of UHMWPE. UHMWPE composite material, serving as the surface protection for soil touching parts, resolves the issues of abrasion of soil abrasive particles and excessive soil adhesion resistance on these parts. This significantly prolongs the service life of soil touching parts of agricultural machinery and improves the operational efficiency and economy.Highlights Research on nanoparticles and elastomer‐modified composite materials. Research has shown the enhancement of UHMWPE composite materials by Nano‐SiC. XNBR improves the plastic deformation resistance of UHMWPE composites. Effects of Nano‐SiC and XNBR on the desorption behavior of composite materials. UHMWPE composites reduce soil contact wear and soil adhesion.

Efficient removal of heavy metal ions by modified cellulose prepared from rice husk: Equilibrium isotherms, Kinetics and desorption studies

The cellulose acetate was prepared from the naturally occurring cellulose extracted from rice husk. It was then characterized using FTIR, XRD, SEM/EDS, TEM and BET and the results were connected to their potential applications in the elimination of heavy metal ions. Differential pulse voltammetry was used for quantitative study of heavy metal ions. An adsorption experiment was conducted to study the effect of temperature, initial concentration, adsorbent dosage, pH and contact time on the adsorption capacity of cellulose acetate. The results of the adsorption experiment showed that the removal of metal ions from adsorbent was a pH-dependent, reaching its maximum adsorption capability at pH of 5-6. Adsorption process was effective with adsorbent dosage was 10±0.1 mg/mL and the temperature was kept at 303K. The adsorption properties of cellulose acetate can be effectively described by pseudo-second-order kinetic with lower error function value and adsorption isotherm such as Freundlich and Temkin adsorption model at 50 min contact time and 50±0.1 mg/L initial concentration. The thermodynamic parameters were investigated, they shows adsorption is favorable at low temperatures. Desorption and re-adsorption of the heavy metals were also studied. Cellulose acetate still retains its adsorption efficiency up to 6th cycles of adsorption.

Adsorption of anionic wood dyes on KOH-activated carbons from Pinus radiata sawdust

AbstractChemically activated carbons synthesized from pine sawdust were applied efficiently for the elimination of wood dyes from aqueous solutions. Different proportions (1:2 and 1:4) of activating agent (KOH) and activation temperatures (600 and 850 °C) were used. Carbon surface morphology was characterized. The effect of pH (2–12), initial adsorbate concentration (5–500 mg L−1), and carbon dosage (0.1–0.5 g L−1) on dye adsorption were studied in batch mode. Langmuir model described well the adsorption equilibrium. The maximum found adsorption capacities were 1221.58, 1673.03, and 240.38 mg g−1 for blue and red at 500 mg L−1 and black at 100 mg L−1, respectively, using activated carbon at 850 °C and 1:4 (ACPS-4–850); at 25 °C, adsorbent dose 0.4 g L−1 for blue and black and 0.3 g L−1 for red dye and without change the pH for blue and red and at pH = 2 for black dye. The pseudo-second-order model explained the kinetics of adsorption except for the black dye at 100 mg L−1 using ACPS-4–850 for which it was the pseudo-first-order model. Desorption studies performed with ACPS-4–850 revealed that the adsorption was irreversible by chemical regeneration, whereas for the black dye, regeneration was efficient using H2O2 as desorbing agent.

Effect of porosity on deuterium retention in titanium thin film

Abstract The absorption process of deuterium in titanium was studied in titanium film produced in two different types of copper substrate, one was a polished copper substrate and the other one was chemically etched copper substrate. Titanium film was produced by thermal evaporation method. It was activated at a temperature of 500 0C followed by deuteration at room temperature. Titanium film was characterized by XRD for crystallographic information, SEM for surface morphology, RGA for deuterium desorption studies and weight measurement for D/Ti ratio. The difference in porosity of both the samples is confirmed from XRD analysis and SEM images. Different diffusion process is observed in two different substrates from the RGA spectra. Presence of multiple trap sites in the thin film of both the substrates is observed from the RGA spectra. From the weight measurement, D/Ti ratio in polished substrate is found to be 1.03 whereas in case of chemically etched substrate it is 1.54.

Accessible Eco-Friendly Method for Wastewater Removal of the Azo Dye Reactive Black 5 by Reusable Protonated Chitosan-Deep Eutectic Solvent Beads.

A novel approach to enhance the utilization of low-cost and sustainable chitosan for wastewater remediation is presented in this investigation. The study centers around the modification of chitosan beads using a deep eutectic solvent composed of choline chloride and urea at a molar ratio of 1:2, followed by treatment with sulfuric acid using an impregnation accessible methodology. The effectiveness of the modified chitosan beads as an adsorbent was evaluated by studying the removal of the azo dye Reactive Black 5 (RB5) from aqueous solutions. Remarkably, the modified chitosan beads demonstrated a substantial increase in adsorption efficiency, achieving excellent removal of RB5 within the concentration range of 25-250 mg/L, ultimately leading to complete elimination. Several key parameters influencing the adsorption process were investigated, including initial RB5 concentration, adsorbent dosage, contact time, temperature, and pH. Quantitative analysis revealed that the pseudo-second-order kinetic model provided the best fit for the experimental data at lower dye concentrations, while the intraparticle diffusion model showed superior performance at higher RB5 concentration ranges (150-250 mg/L). The experimental data were successfully explained by the Langmuir isotherm model, and the maximum adsorption capacities were found to be 116.78 mg/g at 298 K and 379.90 mg/g at 318 K. Desorption studies demonstrated that approximately 41.7% of the dye could be successfully desorbed in a single cycle. Moreover, the regenerated adsorbent exhibited highly efficient RB5 removal (80.0-87.6%) for at least five consecutive uses. The outstanding adsorption properties of the modified chitosan beads can be attributed to the increased porosity, surface area, and swelling behavior resulting from the acidic treatment in combination with the DES modification. These findings establish the modified chitosan beads as a stable, versatile, and reusable eco-friendly adsorbent with high potential for industrial implementation.

Synthesis of polymeric ferrite composites (Ni-CoFe2O4/Chitosan, Zn-NiFe2O4/Starch, Co-NiZnFe2O4/Polyaniline, Ni doped CrZnFe2O4/Alginate, and Cr doped ZnCoFe2O4/PVA) for the removal of reactive golden yellow-160 dye from wastewater

One of the most significant environmental problems facing the entire planet today is water contamination, which is caused by the increasing industry and urbanization. The present study involves the synthesis of polymeric ferrite composites Ni-CoFe2O4/Chitosan, Zn-NiFe2O4/Starch, Co-NiZnFe2O4/Polyaniline, Ni doped CrZnFe2O4/Alginate, and Cr doped ZnCoFe2O4/PVA for the removal of Golden Yellow-160 dye. The polymeric ferrite composites were characterized using Scanning electron microscopy (SEM), X-ray Diffraction (XRD), and Fourier transmission infrared spectroscopy (FT-IR) which showed the surface morphology, crystallinity, chemical structure and thermal stability of the composites. To get the optimal removal, different parameters like pH, composite dose, contact time, temperature and initial dye concentration were optimized. Different equilibrium and kinetic models were used to check the nature of process and reaction rate of sorption. Thermodynamic were studied to check the feasibility of reaction. The effect of presence of various electrolytes NaCl, CaCl2.2 H2O and AlCl3.6 H2O was also studied. Effect of presence of different metals and surfactants was also studied which cause reduction in adsorption of dyes. For large scale, the effects of bed height, flow rate, and initial dye concentration were examined in column study. Different eluents were used for the desorption study of reactive dyes to check the reusability of process.

Green synthesis of carbon nanotubes functionalized with iron nanoparticles and coffee husk biomass for efficient removal of losartan and diclofenac: Adsorption kinetics and ANN modeling studies

The presence of emerging contaminants in wastewater poses a global environmental challenge, requiring the development of innovative materials or methods for their treatment. This study focused on the production of green functionalized carbon nanotubes (CNTs) and using them in the adsorption of the pharmaceuticals Losartan (LOS) and Diclofenac (DIC). The efficiency of the methodology was verified by characterization techniques. Elemental composition analysis indicated a significant increase in the iron content after the green functionalization, proving the effectiveness of the method. Thermogravimetric analysis showed similar thermal degradation profiles for pristine CNTs and functionalized CNTs, indicating better post-functionalization thermal stability. BET analysis revealed mesoporous characteristics of CNTs, with increased surface area and pore volumes after functionalization. X-Ray diffraction confirmed the preservation of the lattice structure of the CNTs post-functionalization and post-adsorption, with changes in peak broadening suggesting surface modifications. LOS and DIC adsorption were evaluated via kinetic studies at four different concentrations (0.1–0.4 mmol/L) that were best represented by the pseudo-second order model, suggesting chemisorption mechanisms, with faster and higher uptakes for DIC (0.084–0.261 mmol/g; teq = 5 min) when compared to LOS (0.058–0.235 mmol/g; teq = 20 min). The curves were also studied via artificial neural networks (ANN) and revealed that the best ANN architecture for representing the experimental data is a network with [3 5 5 2] neurons trained using the Bayesian-Regularization algorithm and the Log-sigmoid (hidden layers) and Linear (output layer) transfer functions. The desorption study showed that CaCl2 had better performance in CNT regeneration, reaching its removal capacity above 50% up to 3 cycles, for both pharmaceuticals. These findings reveal the potential of the developed material as a promising adsorbent for targeted removal of pollutants, contributing to advances in the remediation of emerging contaminants and the application of artificial intelligence in adsorption research.

A Kinetic Study of Microwave‐Assisted Desorption of Co2 from Zeolite 13x

CO2 is the main contributor of the greenhouse gas emission which considerably accelerates climate change. The capture of CO2 requires the development of sustainable adsorption‐desorption processes, which can be upscaled to satisfy the industrial demands. It is well‐known that sustainable microwave (MW) heating leads to fast desorption of CO2 compared to conventional, but there is a lack of study on how to upscale this process. Here it is investigated a concept for the upscaled multi‐mode MW heating of zeolite 13X. The proposed concept is based on the non‐isothermal kinetic study of CO2 desorption, revealing a complex multi‐step process: activation of zeolite 13X below 40 °C and CO2 desorption at T > 40 °C with Eact = 0 kJ mol−1. It was found that MW‐assisted CO2 desorption happens simultaneously with H2O desorption after zeolite MW‐activation. The mechanism of MW‐assisted desorption of CO2 has been proposed. Based on this mechanism, the parameters important for optimizing CO2 desorption process at a larger scale are offered together with an upscaled concept.

Sorption of Sulfur in Highly Leached Humid Soils of North East India

ABSTRACT High rainfall areas suffer from severe leaching loss of sulfate owing to their negatively charged nature. Sorption of sulfur (S) onto soil particles protect it from leaching out of the system. The S-sorption characteristics in humid soils from north-eastern India was studied with the objective to identify factors controlling S-sorption behavior in these acidic soils. Soils were collected from six different locations of north-eastern India. The soils were equilibrated with increasing concentrations of S for the sorption study, and later equilibrated with 0.01 N CaCl2 for desorption study. Results were fitted to three different isotherm models (Freundlich, Langmuir and Tempkin). The data fitted well to all three isotherm models. However, Freundlich adsorption isotherm yielded the best fit. Sorption parameters like S-sorption maxima (k), bonding energy (b), adsorption capacity (K), bonding energy constant (A) were positively correlated with the clay and, crystalline iron (Fe) and aluminum (Al) content in soil. Supply parameter increased with the increasing concentration of sulfate, while equilibrium buffering capacity was found decreasing. Soils from Nongpoh and Mustem with higher clay and crystalline Fe and Al content exhibited higher S-sorption capacity, whereas those of Padu having lowest clay content reported least S-sorption. It is recommended that in a soil having low S-sorption capacity, the minimal amount of S should be applied at a time.

Application of TiO2-loaded fly ash-based geopolymer in adsorption of methylene blue from water: Waste-to-value approach

This paper aims to explore the removal of methylene blue from wastewater using fly ash-based geopolymer (FAG) modified with titanium dioxide (TiO2) nanoparticles referred to as FAG-TiO2. Using several analytical techniques, the modified geopolymer was physically and chemically characterized. Additionally, it was investigated how pH, MB concentration, and temperature affected the MB adsorption process utilizing FAG-TiO2. Scanning electron microscopy images exhibited a porous morphology. Furthermore, transmission electron microscopy images revealed a nanostructured shape, with nanoparticles clumping together to form small channels suitable for MB adsorption. The stretching vibration of the alumina silicate was seen using the Fourier transform infrared, indicating that geopolymerization was successfully conducted. The developed FAG-TiO2 showed a remarkable capacity for MB adsorption from the aqueous phase. The Langmuir isotherm model was the best-fitting adsorption model, with a maximum adsorption capacity of 103.19 mg/g at pH 6 and 35 °C. The thermodynamics investigations revealed negative values for Gibbs free energy (ΔGo), emphasizing the spontaneous nature of the processes. While the positive entropy (ΔSo) indicated a significant affinity between the two phases, the positive enthalpy (ΔHo) implies an endothermic reaction. Additionally, hydrogen bonds, n-π, and electrostatic interactions between MB and FAG-TiO2 facilitated the adsorption process. Furthermore, desorption studies with two different chemicals were used to investigate MB retention onto FAG-TiO2. The adsorbents were desorbed using an HCl (0.5 M) reagent where the maximum MB desorption reached 41.95%. Real wastewater samples were also tested, and promising results were found, indicating the possible use of the prepared adsorbent in industrial applications.

Fly ash as a cost-effective catalyst to promote sorbent regeneration for energy efficient CO2 capture

The use of catalysts to promote sorbent regeneration is currently considered an effective method to reduce the energy required in CO2 capture processes. Aiming at identifying stable and cost-effective catalysts with high CO2 desorption efficiency, here we investigated the performance of fly ash (FA) during thermal regeneration of aqueous amine solutions. The desorption rate, cyclic capacity and heat duty of a CO2-saturated aqueous ethanolamine with the addition of FA were experimentally measured, and the results were compared with those obtained for the same solution without and with eight different catalysts. Experimental results showed that catalysts significantly improved the regeneration compared to the non-catalyzed system, and FA was the most efficient of these. Further studies of CO2 desorption at different temperatures showed that FA provided desorption performance comparable to that of the non-catalyzed system at temperatures at least 5 °C higher and always significantly reduced the heat duty at the same temperature, especially at the beginning of the process. Finally, recycling tests demonstrated that FA had good stability and its catalytic efficiency remained high even after 20 cycles. In conclusion, FA could be considered a cost-effective catalyst for energy-efficient CO2 capture, deserving further investigation to promote its application in industrial-scale plants.

Theoretical study of hydrogen desorption on the Ni(100) surface through simulated temperature programmed desorption spectra

Nickel has been widely used as heterogeneous catalysts in important reactions such as dehydrogenation and steam reforming, where the desorption of H2 molecules is one of the key steps. Herein, based on density functional theory calculations, we have simulated the temperature programmed desorption (TPD) spectra of hydrogen (H) on the Ni(100) surface using the mean-field approximation and a new HH dimer desorption method. Zero-point energy corrections are also considered. It is found that the centered-peaks of TPD obtained from simulations are in good agreement with the previous experimental results. However, the centered-peak position moves in an opposite direction to the experiments as atomic hydrogen coverage increases. We have systematically investigated the effects of the interaction between adsorbed H atoms and the diffusion of H atoms on the peak shifts, and found that they are not responsible for the experimentally observed leftward shift of the TPD peak. We then propose and confirm that the presence of subsurface H atoms plays a key role in the leftward peak shift. This work refines the interpretation of H2 TPD spectra and contributes to the understanding of microscopic behaviors of H atoms on the Ni(100) surface.

Magnetic Fe3O4 /Al2O3 /MnO2 ternary nanocomposite: Synthesis and characterization for phosphorus desorption from acidic soils using dialysis membrane tube

Monitoring phosphorus fertilization is crucial for controlling the concentration of biologically available soil P. Over the years, several methodologies have been used, including successive cropping in a greenhouse or field, as well as extractions employing P sink procedures. The latter procedures are ideal laboratory experiments to show the soil's ability to supply P and to explore the P-residual release kinetics. Following these methodologies, long-term P desorption studies have been developed using dialysis membrane tubes filled with nanomaterial solutions. In this study, a magnetic nanocomposite (Fe3O4/Al2O3/MnO2) was synthesized and characterized utilizing cutting-edge instruments such as XRD, FTIR, FAAS, BET, SEM, and EDX. The resulting material had a crystalline size and surface area of 22.75 nm and 203.69 m2/g, respectively, and was employed for long-term P-desorption and kinetics experiments while filled in dialysis membrane tubes. The P-desorption experiment was conducted on four separate acidic soil samples that were cultured for 122 days with four different P concentrations. The findings demonstrated a direct relationship between P-desorbed and P-treatment, as well as with desorption time. The minimum desorption was obtained from the control of Boji Dirmaji soil P0 (1.16–9.36) and the highest desorption from Nedjo soil with P3 (5.23–30.35 mg/kg) treatment over 1–28 days. The rate of P release from soil to solution or diffusion through the membrane was determined by pseudo-first-order kinetics with a rate constant (0.021–0.028 hr−1). This method has the potential to measure fixed-P availability by mimicking it as a plant would, with high P-desorption efficiency and quick P-release capacity.

Multicoverage Study of Femtosecond Laser-Induced Desorption of CO from Pd(111).

We study the strong coverage dependence of the femtosecond laser-induced desorption of CO from Pd(111) using molecular dynamics simulations that consistently include the effect of the laser-induced hot electrons on both the adsorbates and surface atoms. Adiabatic forces are obtained from a multicoverage neural network potential energy surface that we construct using data from density functional theory calculations for 0.33 and 0.75 monolayer (ML). Our molecular dynamics simulations performed for these two trained coverages and an additional intermediate coverage of 0.60 ML reproduce well the peculiarities of the experimental findings. The performed simulations also permit us to disentangle the relative role played by the excited electrons and phonons on the desorption process and discover interesting properties of the reaction dynamics as the relevance that the precursor physisorption well acquires during the dynamics as coverage increases.

Tetraethylenepentamine-modified Cu2(OH)PO4 for efficient CO2 capture

This study focused on creating tetraethylenepentamine (TEPA) modified copper hydroxyl phosphate (Cu2(OH)PO4) adsorbents via physical impregnation. The TEPA-modified Cu2(OH)PO4 adsorbents were analyzed for structure and characteristics through SEM, XPS, TGA, N2 adsorption–desorption studies. The effects of different parameters (TEPA contents, temperatures, flow rates and CO2 concentrations) and cyclic stability were evaluated. Kinetics, thermodynamics and density functional theory (DFT) calculations were employed to understand the impact of TEPA modification on Cu2(OH)PO4 for CO2 adsorption. Experimental results showed that a 50 wt% loading yielded optimal results, with a maximum surface area of 65.12 m2/g, a pore volume of 0.29 cm3/g, and a maximum adsorption capacity of 6.54 mmol/g. The amine efficiency is extraordinary which reached 67 %. The best performance occurred at 60 °C, 30 ml/min gas flow, and 15 vol% CO2 concentration. The pseudo-second-order kinetic model better described the CO2 adsorption process. The adsorption process was found to be exothermic at 20–60 °C and endothermic at 60–80 °C, suggesting physical–chemical co-adsorption and chemical adsorption, respectively. The adsorption activation energy is 34.322 kJ/mol. The DFT shows the adsorption energy ranged from −0.565 eV to −5.584 eV, indicating coexistence of physical and chemical adsorption. The d-band theoretical calculation shows that TEPA doping is beneficial to the adsorption of CO2 by Cu2(OH)PO4. Minimal structural modification of the adsorbate was observed, with bond lengths changing by less than 1 %. The density of states (DOS) curve shifted toward lower-energy states after adsorption, suggesting a more stable structural configuration post-adsorption. We have proved that TEPA-Cu2(OH)PO4 has good adsorption for CO2 and is an efficient green adsorption material.

Ultrasound-assisted removal of Imidacloprid from aqueous solutions using carboxymethyl cellulose-based bionanocomposite hydrogel beads (CMC/Fe3O4-Zeolite): Emphasis on effects Fe3O4-Zeolite nanoparticles and ultrasound

In the present work, carboxymethyl cellulose-based bionanocomposite hydrogel beads with diverse concentration ratios of Fe3O4-Zeolite were produced and used for the removal of Imidacloprid from an aqueous solution. Optimization of various factors such as Imidacloprid initial concentration, adsorbent dosage, pH solution, and sonicating time (42 kHz) affecting Imidacloprid removal was evaluated by response surface methodology (RSM). The optimum values for these parameters were obtained at 38 mg L−1, 1.9 g L−1, 7, and 19 min, respectively. The adsorption process of Imidacloprid by CMC/Fe3O4-Zeolite20 is multilayer adsorption (Jossens model) and was controlled by internal and external diffusion (double-exponential model). Additionally, the study of the ultrasonic effect on Imidacloprid removal performance showed that the ultrasound combined with adsorption significantly reduces the equilibration time. Also, the adsorption and desorption study showed that the adsorbent with high stability in adsorption performance was recycled in 6 cycles without a significant reduction in adsorption efficiency. And finally, the removal performance of CMC/Fe3O4-Zeolite20 was studied on the real wastewater samples and confirmed the feasibility of adsorbent for practical applications in industrial purposes.

Controlled release herbicide formulation for effective weed control efficacy

Controlled release formulation (CRF) of herbicide is an effective weed management technique with less eco-toxicity than other available commercial formulations. To maximise the effectiveness of CRFs however, it is crucial to understand the herbicide-releasing behaviour at play, which predominately depends on the interaction mechanisms between active ingredients and carrier materials during adsorption. In this study, we investigated and modelled the adsorption characteristics of model herbicide 2,4-D onto two organo-montmorillonites (octadecylamine- and aminopropyltriethoxysilane-modified) to synthesise polymer-based CRFs. Herbicide-releasing behaviour of the synthesised CRF microbeads was then analysed under various experimental conditions, and weed control efficacy determined under glasshouse conditions. Results revealed that adsorption of 2,4-D onto both organo-montmorillonites follows the pseudo-second-order kinetics model and is predominately controlled by the chemisorption process. However, multi-step mechanisms were detected in the adsorption on both organoclays, hence intra-particle diffusion is not the sole rate-limiting step for the adsorption process. Both organoclays followed the Elovich model, suggesting they have energetically heterogeneous surfaces. Herbicide-releasing behaviours of synthesised beads were investigated at various pH temperatures and ionic strengths under laboratory and glasshouse conditions. Furthermore, weed control efficacy of synthesised beads were investigated using pot studies under glasshouse condition. Desorption studies revealed that both synthesised microbeads have slow releasing behaviour at a wide range of pHs (5–9), temperatures (25–45 °C), and ionic strengths. The results also revealed that synthesised microbeads have excellent weed control efficacy on different broad-leaf weed species under glasshouse conditions.

Equilibrium and kinetic studies of sorption of Fe(III) ions on R-modified sorbent with CSMA

The sorbent was obtained based on a copolymer of styrene with maleic anhydride and 2-nitro-4- sulphoaniline (S) and subsequently modified with the reagent 4,4'-(ethane-1,2-diylbis(azanilidene))bis(pentan- 2-one) (S1). The sorption of the resulting product with respect to Fe(III) ions was studied. During the study, the influence of various factors on adsorption was studied, such as: pH, contact time, ionic strength, initial concentration of the metal ion, etc. The results were characterized using various adsorption isotherm and kinetic models. The results of the research showed that sorption is best described by the Langmuir model and the pseudo-second order kinetic model. The maximum sorption capacity was 348 mg/g for S and 479.2 mg/g for S1. For the adsorption studies, solutions of 5∙10-3 mol/dm3 Fe(III) were used. Static sorption studies were carried out at room temperature. For the desorption studies, acids of various concentrations were used, in particular solutions of 0.5 mol/dm3 HNO3, HCl, H2SO4 and HClO4. Studies have shown that the modification of the adsorbent with a reagent led to an increase in sorption capacity, which means that the efficiency of extraction of Fe(III) ions by the corresponding product also increased. Thus, we can continue research in this area and modify the adsorbent with other reagents. A comparison of maximum adsorption capacities qmax of various adsorbents for the removal of Fe(III) ions showed that the adsorbents used in this study have higher sorption abilities. The resulting products were used for the sorption-photometric de- termination of Fe(III) in apricot and provided positive results. These factors suggest that the synthesized prod- ucts can be considered as being effective materials for the extraction of Fe(III) ions.

Molecular Dynamics Study of Protein Aggregation at Moving Interfaces.

Repeated compression and dilation of a protein film adsorbed to an interface lead to aggregation and entry of film fragments into the bulk. This is a major mechanism for protein aggregate formation in drug products upon mechanical stress, such as shaking or pumping. To gain a better understanding of these events, we developed a molecular dynamics (MD) setup, which would, in a later stage, allow for in silico formulation optimization. In contrast to previous approaches, the molecules of our model protein human growth hormone displayed realistic shapes, surfaces, and interactions with each other and the interface. This enabled quantitative assessment of protein cluster formation. Simulation outcomes aligned with experimental data on subvisible particles and turbidity, thereby validating the model. Computational and experimental results indicated that compression speed does not affect the aggregation behavior of preformed protein films but rather their regeneration. Protein clusters that formed during compression disassembled upon relaxation, suggesting that the particles originate from a partly compressed state. Desorption studies via steered MD revealed that proteins from compressed systems are more likely to detach as clusters, implying that compression effects at the interface translate into aggregates present in the bulk solution. With the possibility of studying the impact of different variables upon compression and dilation at the interface on a molecular level, our model contributes to the understanding of the mechanisms of protein aggregation at moving interfaces. It also enables further studies to change formulation parameters, interfaces, or proteins.