Colloids and Surfaces C: Environmental Aspects最新文献

Incorporation of amphoteric gemini surfactants into vermiculite (Vt) is a valuable task in developing clay application. Hereby amphoteric gemini surfactants with hydrophobic alkyl chains, dual N⁺ head groups and anionic functional groups are introduced to prepare organo-Vts as dye adsorbents. The adsorbents are labeled as TAES-Vt with sulfonic acid group and TABS-Vt with benzenesulfonic acid groups, respectively. Both single and binary adsorption towards azo blue (AB) and mordant black 17 (MB17) have been investigated. The max uptake amounts in single dye system are 189/177 mg/g for AB and 278/406 mg/g for MB17 by TAES-Vt/TABS-Vt, respectively. Furthermore, the presence of AB is favorable for the removal of MB17 in binary dye system, with adsorption capacities increasing to 449/469 mg/g by TAES-Vt/TABS-Vt. However, MB17 exhibits an antagonistic effect on adsorption of AB, thus resulting lower AB removal capacities in binary dye system. The adsorption mechanisms are elucidated via adsorption, characterization and calculation. (i) Hydrophobic interaction, electrostatic interaction, H-bond, and electron donor effect all support the adsorption for AB/MB17. (ii) Compared to TABS-Vt, TAES-Vt has a slightly higher adsorption capacity for large-sized AB due to its larger interlayer spacing. However, TABS-Vt is better at adsorbing small-sized MB17 than TAES-Vt by vitue of additional benzene ring that can provide π-π interaction. (iii) In view of adsorbates, the difference of molecular size and structural property in AB and MB17 also affect adsorption. This work provides ideas for the multi functionalization of Vt, reviving the adsorption advantages of clay based materials.

Life cycle assessments of home and personal care consumer products, carried out in the last 20 years, have provided insights and disclosed blind spots that prompted product developers to make significant changes in product format, formulation, and packaging, leading to more sustainable consumer products. However, fragrances are often overlooked in terms of interconnectedness with key environmental footprint parameters of consumer products. In this article we show that fragrance ingredients could be relevant for reducing the climate change impact of the full consumer product, defined as Global Warming Potential at 100 years (GWP100), and at the same time drive olfactory differentiation. To illustrate this, a comparison was drawn between the GWP100 for typical surfactants commonly used in the European market and the GWP100 for fragrance ingredient proxies, using in both cases GWP100 data extracted from the literature. Fragrance proxies were synthesized using two methods: a continuous flow process (scenario 1) and batch-type processes (scenario 2), representing optimal and non-optimal synthesis approaches, respectively. The findings revealed that fragrance ingredients synthesized through less efficient processes could approach the environmental impact of surfactants. The article delves as well into the complexities posed by fragrance concentration, solubilization, and fragrance delivery in the development of novel sustainable formulations.

This study explores the potential of some soil bacteria in the synthesis of iron oxide nanoparticles (IONPs), highlighting their advantages in terms of iron uptake and tolerance capacity. Soil samples collected from a metal fabricating workshop were successively screened in nutrient broth containing 1% iron salts (Fe₂O₃, FeCl_3, and FeSO₄) following a standard microbiological sampling technique. The recovered bacterial isolates (persister cells) were identified using polymerase chain reaction (PCR) and 16S rRNA sequencing. Ten bacterial isolates identified as Sporosarcina luteola, Bacillus badius (2), Bacillus subtilis (2), Bacillus tropicus, Bacillus cereus, Klebsiella pneumoniae, Klebsiella quasipneumoniae and Klebsiella africana were recovered. The method reports that six of the bacterial isolates extracellularly synthesize IONPs and the result from the energy dispersion x-ray (EDX) spectral analysis indicated varying weight percentages of bio-reduced iron by Bacillus subtilis-A12 (48.59%), Klebsiella quasipneumoniae (39.99%), Bacillus subtilis-B1 (39.97%), Bacillus cereus (38.62%), Bacillus badius (33.79%) and Klebsiella africana (32.61%). The IONPs exhibited absorbance peaks in the range of 250–350 nm, with a mean area size estimated between 31–72 nm using ImageJ software. Additionally, the presence of iron reductase (fhu) and cysteine desulfurase (suf) genes were detected in the recovered Bacillus and Klebsiella species through PCR analysis. This study has provided valuable insights into the physiology and genomic functions essential for microbial synthesis of IONPs and their relevance to nano-bioremediation.

The water pollutant diisopropylamine (DIPA) creates surfactantless emulsions in water. DIPA droplets bear a negative electrostatic charge, as demonstrated by electrophoretic measurements. Sodium salts (NaCl and Na₂SO₄) decrease their charge, leading to droplet coalescence and separation into bulk layers, depending on the salt and DIPA percentages. Attenuated total reflectance – Fourier transform infrared spectroscopy (ATR-FTIR) show that the DIPA concentration in the water rich phase is below 10 wt% DIPA when adding 2 wt% Na₂SO₄ (relative to the mixture) to mixtures of 20 wt%, 40 wt% and 50 wt% DIPA (relative to water). The same occurs when adding 2% NaCl to mixtures of 30 wt%, 50 wt% and 70 wt% DIPA (relative to water). DIPA-water mixtures are electrically conductive and can be separated by subjecting them to an electric field (electrokinetic separation). Without salts, the concentration of DIPA in 30 wt% DIPA could be reduced by ≈ 20 wt% after 60 mins treatment using a differential voltage = 12 V. NaCl (0.25 wt% relative to water) improved efficiency. After 15 mins, the percent decrease in DIPA was ≈ 50 wt%. Electrokinetic treatment targets exclusively contaminants dispersed in water. DIPA sorbs onto clay, alumina and iron oxide minerals, whereas it does not sorb onto gypsum and limestone. Therefore, the in situ electrokinetic separation of DIPA can be most successfully applied in aquifers where the dominant minerals are gypsum and limestone.

Cs₃Bi₂Br₉ perovskite has attracted tremendous research attention in the field of photocatalysis due to its promising light-harvesting properties. However, its practical applications are hindered by water-induced degradation, limiting stability and photocatalytic activity. In this study, we address this challenge by synthesizing stable 2D Cs₃Bi₂Br₉ nanosheets through a modified anti-solvent reprecipitation method. Optimizing the isopropanol amount enabled unprecedented synthesis of 2D Cs₃Bi₂Br₉ nanosheets. SEM and HRTEM images show 2D stacked nanosheets of the sample prepared using 250 mL of isopropanol, while bulks and agglomerations were noticed in the samples prepared using different amounts of isopropanol. The Cs₃Bi₂Br₉ nanosheets exhibits the lowest charge recombination rate, hence achieving the highest degradation ratio of methylene blue, removing ∼80 % of the dye within 90 min under visible light attributed to their stability, facilitating efficient charge separation. Our study sheds light on the pivotal role of 2D morphology in enhancing the stability and photocatalytic performance of Cs₃Bi₂Br₉.

The separation of uranium oxide (UO₂) particles from soil-surrogate particles in aqueous suspensions was achieved using filtration enhanced by a magnetic field. Enhanced attraction of paramagnetic UO₂ colloids to a ferromagnetic stainless-steel filter placed in a strong magnetic field arises because of the positive magnetic susceptibility of the particles and the high-gradient field generated near ferromagnetic fibers. Enhanced uptake of smaller particles over larger ones occurs through Brownian motion that promotes the collision of particles with the ferromagnetic fibers of the filter. Hence, this work focused on UO₂ particles in the colloidal size range. Experiments used a water-cooled electromagnet and an array of permanent magnets. Chemical analysis showed that the magnetic field increased the capture efficiency of uranium particles from a range of 27–53% with the magnet off up to 98% with the magnet on after a single pass of the suspension through the filter. The recovery of the UO₂ particles from the filter, however, was more difficult to achieve. Small amounts of UO₂, together with significant amounts of background SiO₂ particles, were removed from the filter during a first flush with the magnetic field on. A much larger recovery of UO₂ was not observed until a second out-of-field flush was performed, which also released some SiO₂. The degree to which particle separation was enhanced through the use of multi-stage filtration compared to single pass-through filtration was also examined. A design was suggested that could be used to optimize the separation efficiency for a continuous process.

Biochar often undergoes multiple thermal processes. Thermal evolution is described in this study as the process by which biochar in the environment changes again in a thermal environment. In this study, the thermal evolution process of biochar was studied by characterization test. The results showed that the oxygen content in biochar increased after thermal evolution, mainly due to functional groups such as O-H and C-O, while the functional groups of CO did not change significantly. Micro-pores will be generated in biochar after thermal evolution, which will increase the surface area and significantly enhance the adsorption capacity. The biochar was added to natural water to observe how biochar enhanced the removal of dissolved organic carbon (DOC). The concentration of DOC was reduced by about 6.68 mg/L by SB 800, and most of the components were humus, which indicated that the thermal evolution of biochar promoted the removal of DOC. The Electron spin resonance (ESR) test shows that after thermal evolution, biochar has more oxygen-containing carbon center persistent free radicals due to the increase of C-O functional groups in biochar. Under visible light, persistent free radicals in oxygen center are formed by electron transition, which can undergo a variety of reactions with water to form reactive oxygen species.

It is well known that arsenic is a very harmful toxin to humans. Among arsenic species, arsenite is more toxic and more difficult to remove from water than arsenate. In this study, a nanostructured Zr-Mn binary hydrous oxide was synthesized using one-step simultaneous oxidation and coprecipitation method, aiming at removing both arsenate and arsenite effectively and simultaneously. The Zr-Mn binary hydrous oxide particles were aggregated with smaller nanosized particles, resulting in a rough surface. The hydrous oxide was very effective for both As(V) and As(III) removal from water. The maximal sorption capacities for As(V) and As(III) were 52 and 96 mg/g at neutral environment, respectively. The higher sorption capacity for As(III) may be attributed to the As(III) oxidation and reductive dissolution of manganese dioxide, which resulted in the formation of new sorptive sites for arsenic at the solid surface. The presence of sulfate and carbonate had no significantly influence in the arsenic removal. However, the presence of phosphate greatly decreased the removal, especially at high concentrations. Furthermore, the performance of Zr-Mn binary hydrous oxide was further confirmed by an adsorption study with a groundwater. Additionally, the leaching of arsenic from the used sorbent was less serious, indicating that it may not be hazard to the environment after the landfill disposal. Due to its excellent arsenic removal performance and the simple, low-cost synthesis process, the Zr-Mn binary hydrous oxide could be a promising alternate for both As(V) and As(II) simultaneous removal from water or groundwater without the oxidation pretreatment.

Understanding copper (Cu) dynamics in cocoa soils can help predict the fate, mobility, and toxicity, which is crucial for sustaining soil functionality, as well as the quality and health safety of cocoa products. Herein, the study investigated sorption-desorption characteristics of Cu(II) in six cocoa soils of varying weathering by kinetics, isothermal, and pH effect experiments in a batch system. Equilibrium sorption increased in the order of Fluvisol < Lixisol < Luvisol < Acrisol = Ferralsol = Nitisol. Kinetics data fitted well to pseudo-second-order and Elovich models. Cu(II) sorption was dominated by outer-sphere and inner-sphere complexations at low and high pH, respectively. The sorption data fitted well with Freundlich and Langmuir's models. Sorption maximum increased in the order of Nitisol (0.91 mg g⁻¹) < Ferralsol (1.21 mg g⁻¹) < Acrisol (1.29 mg g⁻¹) < Lixisol (1.61 mg g⁻¹) < Luvisol (1.68 mg g⁻¹) < Fluvisol (2.01 mg g⁻¹). The binding energy values obtained showed the highest interaction between Cu(II) and soil matrix in Fluvisol and the least in Ferralsol and Nitisol. The desorption studies consistent with the hysteresis index indicated high sorption irreversibility and less Cu(II) mobilization in Fluvisol, Lixisol, Luvisol, and Acrisol vis-à-vis Nitisol and Ferralsol. Nitisol and Ferralsol may promote the possible toxicity of Cu(II) to the soil ecosystem. The study contributes to the sensitivity of Cu(II) mobility and toxicity to the degree of soil weathering; thus, management of heavy metals in cocoa soils should be dependent on soil type.

In this study, phosphorylated starch (PS) was prepared and utilized to adsorb methylene blue (MB), safranin (SF) and copper Cu (II) ions from an aqueous solution. Scanning electron microscopy (SEM) and infrared spectroscopy (IR) were used to investigate the microstructure of phosphorylated starch. The effects of adsorption period, adsorbent dose, pH, the presence of replacement groups, starting concentrations, and temperature were all studied in batch adsorption experiments. According to the findings, 10 min of adsorption time is enough to attain the adsorption equilibrium. The adsorption kinetic model can be aptly represented as the pseudo-second order (PSO). The adsorption isotherm model, is appropriately described by Freundlich and Redlich Peterson, with maximum adsorption capacity of PS was 1036 mg/g, 14994 mg/g and 1535 mg/ g for MB, Cu and SF, respectively. With fast equilibrium time (10–20 min), high adsorption efficiency (97–99%) and the regeneration and reusability of PS that can achieved, more than 3 cycles. The PS powder was a promising remediation for polluted wastewater.