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The aim of this study was to investigate the influence of bovine serum albumin (BSA) on the Lactobacillus-strain-mediated removal of benzo[a]pyrene (BaP). A combination of 0.5 mg/mL of BSA with 1.0 × 1010 CFU/mL bacterial cells had a removal of 49.61% BaP for strain 121, while a combination of 0.4 mg/mL of BSA with 1.0 × 1010 CFU/mL bacterial cells had a removal of 66.09% BaP for strain ML32. The results indicated that the binding of BaP to Lactobacillus-BSA was stable. BSA maintains Lactobacillus activity and BaP removal in the gastrointestinal environment. Heat and ultrasonic treatment of BSA reduced the BaP-binding ability of Lactobacillus–BSA. With the addition of BSA, the surface properties of the two strains affected BaP binding. The Fourier-transform infrared (FTIR) data demonstrated that O-H, N-H, C=O, and P=O groups were involved in the binding of BaP to Lactobacillus–BSA. Scanning electron microscopy (SEM) results revealed that the morphology of Lactobacillus–BSA bound to BaP was maintained. The adsorption of BaP by Lactobacillus–BSA was appropriately described by the pseudo-second-order kinetic model and Freundlich isotherm model. BSA enhances the affinity between the bacterial cells and BaP. [ABSTRACT FROM AUTHOR]

Azo dyes are well known recalcitrant and hazardous pollutants from dyeing industries which are essentially needed to be removed from the industrial effluents before discharged in the environment. Among many dye removal techniques, biosorption has gained attraction due to eco -friendliness and cost effectiveness. Biosorption of pollutant is surface phenomena which is resultant of the physicochemical interactions between biologically originated surfaces and the pollutant molecules. On the other hand, biomass from agro-industrial activities (e.g., rice straw, rice husk, wheat straw etc.) poses significant adversity on the environment, if traditional management practices are adopted. This study integrates the use of biomass for azo dye removal. It focusses on the utilization of rice straw biomass for removal of azo dye in the purview of sustainable environmental management. Biosorption of methylene blue dye (MB) by the use of rice straw and surface modified rice straw was studied. Rice straw powder (RSP) was treated with autoclaved sea water (RSP-ASW) and Sodium dithionite (RSP-SDT) and their characteristics was studied. Proximate analysis suggests the improvement in chemical composition by the treatments. The surface characterization with FTIR, PZC and SEM inferred the effect of modifying agents on RSP. Batch biosorption experiments were conducted to check the effect of operating parameters, viz., solution pH (pH3 -- pH11), temperature (298K-318K), initial dye concentration (50 mg/L-200 mg/L), contact time (0 -- 360 minutes), and adsorbent dosage (0.25 gm -1 gm) on MB removal. The preliminary investigations on sorption equilibrium of MB on pre-treated and untreated rice straw biomass showed the highest congruity with the Langmuir isotherm model, among the four adsorption isotherm models, viz., Freundlich, Langmuir, Temkin and DubininRadushkevich (D-R) isotherm models. The adsorption process follows the pseudo second order kinetics. The MB removal achieved was in the order RSPSDT> RSP-ASW>RSP in all the adsorption experiments conducted. The maximum dye removal efficiency was 181.8 mg of MB / gm of RSP-SDT at neutral pH and room temperature. [ABSTRACT FROM AUTHOR]

As new pollutants, microplastics has been proved to can adsorb the traditional heavy metal pollutants in in the aqueous environment. While microplastics will age continuously in the environment, and their physicochemical properties will change accordingly, but the impact of aging process on adsorption behavior of microplastics are not fully understood. Herein, to explore the aging process of microplastics on the adsorption of heavy metal, the adsorption behavior of Cu2+ on polylactic acid (PLA) microplastics with four treatments of unaged (L0), aged 10 days (L10), 20 days (L20) and 30 days (L30) were investigated. Results showed that the optimal PLA microplastics dosage was 0.025 g/L. The adsorption capacity increased with increasing pH and the optimal pH was 7. The adsorption kinetics of Cu2+ onto aged PLA microplastics was explained well by the pseudo-second order kinetic model and the Langmuir model, respectively, suggesting that chemisorption was possibly the adsorption mechanism. On the other hand, the adsorption capacity of four kinds of aged PLA microplastics for Cu2+ under optimal condition was as follow: L30 > L20 > L10 > L0, indicating that would increase their adsorption affinity towards heavy metals, resulting in potential harm to the environment. The results of this study provide valuable information for studying the environmental behavior of aged microplastics and interaction between microplastics and heavy metals in the real environment. [ABSTRACT FROM AUTHOR]

The effluent from the rubber processing industry usually contains a high concentration of organic compounds, suspended solids, color, nitrogen, and other pollutants. If an excessive amount of ammonia nitrogen is discharged into bodies of water, it may cause eutrophication and the death of various aquatic creatures. The goal of this experimental design was to investigate the effectiveness of zeolite for ammoniacal nitrogen, chemical oxygen demand (COD), and color removal from rubber processing industry effluent. The samples of rubber processing industry effluent for this study were acquired directly from the discharging point of a manufacturer in Kluang, Malaysia. The effects of optimal adsorbent dose, shaken speed, contact time, and pH were determined for ammoniacal nitrogen, COD and color removal. The obtained result reveals that the best batch adsorption experiment of ammoniacal nitrogen, COD, and color removal was attained at pH 7, ZEO dosage 4.0 g, contact time 120 min, and shaken speed 200 rpm respectively. The best efficiency removal of ammoniacal nitrogen, COD, and color was achieved based on dosage generally in the range of 75% for ammoniacal nitrogen, 69% for COD, and 79% for the color of all batch experiments conducted. The kinetic equilibrium model data fitted well with the pseudo-first and second model. The pseudo-second-order better fitted the equilibrium data over the entire concentration range studied. The pseudo-second-order described the best coefficient of determination compared to the pseudo-first-order. The coefficient of determination for pseudo-second-order was generally in the range of 0.9958 for ammoniacal nitrogen, 0.9978 for COD, and 0.9984 for the color of all kinetics studies conducted. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the influence of bovine serum albumin (BSA) on the Lactobacillus-strain-mediated removal of benzo[a]pyrene (BaP). A combination of 0.5 mg/mL of BSA with 1.0 × 1010 CFU/mL bacterial cells had a removal of 49.61% BaP for strain 121, while a combination of 0.4 mg/mL of BSA with 1.0 × 1010 CFU/mL bacterial cells had a removal of 66.09% BaP for strain ML32. The results indicated that the binding of BaP to Lactobacillus-BSA was stable. BSA maintains Lactobacillus activity and BaP removal in the gastrointestinal environment. Heat and ultrasonic treatment of BSA reduced the BaP-binding ability of Lactobacillus–BSA. With the addition of BSA, the surface properties of the two strains affected BaP binding. The Fourier-transform infrared (FTIR) data demonstrated that O-H, N-H, C=O, and P=O groups were involved in the binding of BaP to Lactobacillus–BSA. Scanning electron microscopy (SEM) results revealed that the morphology of Lactobacillus–BSA bound to BaP was maintained. The adsorption of BaP by Lactobacillus–BSA was appropriately described by the pseudo-second-order kinetic model and Freundlich isotherm model. BSA enhances the affinity between the bacterial cells and BaP.

• MEA, DEA, and TEA are successfully loaded onto UiO-66 by impregnation method to obtain MOFs-based materials modified with different spatial site resistance amines. • Under the coordination of physical and chemical adsorption forces, UiO-66-T has a good adsorption capacity for low concentration H 2 S at room temperature and pressure. • The larger spatial dimension of the TEA in UiO-66-T allows ideal gas mass transfer kinetics for interaction with H 2 S. • The conformation of UiO-66-T interacting with H 2 S is demonstrated to be stable at the molecular level by DFT calculation. In order to treat hydrogen sulfide(H 2 S), a series of amine-modified MOFs with high sulfur capacity are prepared by impregnating UiO-66 with different steric hindrance amines (MEA, DEA, TEA). Among them, the UiO-66-T material modified by TEA not only well maintains the high specific surface area and micropore structure of the raw material, showing the specific surface area of 257 m2/g and the pore volume of 0.18 cm3/g, but also shows the high hydrogen sulfide adsorption capacity of 2.79 mmol/g. This is because the action of steric hindrance makes the TEA molecules suitable for the 9 × 9 × 9 Å space box fail to enter the micropore depth when entering UiO-66 with 8 Å and 11 Å double-pore cage structure. Therefore, it is difficult for amine molecules to interact with the metal center of the MOFs structure, so that the modified UiO-66-T not only maintains the porosity and stability of the raw material, but also increases the acid-base interaction force with hydrogen sulfide by introducing amine molecules. The binding energy of both is 352.84 kJ/mol, and it has a stable adsorption binding configuration. The penetration experiment results show that the adsorption capacity of hydrogen sulfide is determined by the amine load on the surface of the adsorbent. The mass transfer kinetics of UiO-66 series materials is analyzed by using the quasi-first-order kinetic model, quasi-second-order kinetic model and internal diffusion model. The correlation coefficients R2 fitted between the model and the experimental results are all above 0.9. Therefore, the effect of van der Waals force on the adsorption process of UiO-66 series materials and hydrogen sulfide is greater than that of chemical bond force, and intra-particle diffusion is the actual key step and main diffusion mechanism in the adsorption process of H 2 S. [ABSTRACT FROM AUTHOR]

Removal of Cr(VI) from liquid by iron-loaded composite resin was studied. The isothermal adsorption model and the adsorption kinetic model were established. The adsorption thermodynamic parameters were solved. The iron-loaded composite resins before and after adsorption were characterized by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). It was found that the adsorption capacity of iron-loaded composite resin was higher than others. The results showed that the optimum adsorption condition was performed at 318 K, the pH of 2, and the time of 6 h. Freundlich model and pseudo-first-order kinetic model fitted the experimental data. The main control step of the adsorption was liquid film diffusion process. The value of ΔH was 2–16 kJ mol–1, which showed that the adsorption was an endothermic process. The adsorption of ΔG was less than zero which indicated the adsorption was spontaneous. The value of ΔS was constant positive that revealed the adsorption was the total entropy-increasing process. SEM and EDS analyses indicated that Cr(VI) can adsorb by iron-loaded composite resin effectively. The eluent of 6% NaOH + 5% NaCl had an excellent desorbing performance. [ABSTRACT FROM AUTHOR]

Taking uranium tailings treated to hazard-free as the main raw material, a new type of environment functional material-uranium tailings-based porous ceramisite was prepared. The adsorption capacity of uranium tailings porous ceramisite for hydroquinone were investigated. The results indicated that, the removal rate and adsorption capacity of uranium tailings-based porous ceramisite for hydroquinone uranium tailings were 91.2% and 4.56 mg/g respectively with a pH value of 7. During the adsorption of the uranium tailing-based porous ceramsite for hydroquinone, the liquid film diffusion dominated and was more accurately described by the pseudo-first-order kinetic equation. Data fitting degree of Langmuir equation and Koble-Corrigan equation of adsorption isotherm was higher. The adsorption properties of uranium tailings-based porous ceramsite were fixed at a fixed site by a single layer molecular layer, and it was a non-uniform composite adsorption system. The adsorption process of uranium tailings porous ceramisite for hydroquinone was a high fitting for the liquid film diiffusion model. The R² and k value were 0.847 8 and 0.041 7 respectively. [ABSTRACT FROM AUTHOR]

The surface tension of aqueous solution drops of ß-casein, ß-lactoglobulin, and human serum albumin at the interface to air and hexane saturated air are measured by drop profile analysis tensiometry. The results indicate that the dynamic and equilibrium surface tension for a hexane vapor atmosphere are considerably lower as compared to the values at the interface with pure air. The experiments are performed with the initial adsorption of protein followed by hexane adsorption, and with subsequent removal of hexane from the measuring cell after equilibrium is attained. Two models are proposed, both of which assume the diffusion of protein in the solution and either diffusion-governed or barrier-governed hexane coadsorption. The new developed theoretical equilibrium model assumes a double layer adsorption in these systems, with the first layer composed of protein mixed with hexane and the second layer formed by hexane molecules only. The experimental and calculated equilibrium surface tension data are in a perfect agreement. Note the model parameters are exactly the same as those found for the individual compounds. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) was prepared from eucalyptus sawdust by microwave-assisted activation with ZnCl2and utilized for removing chromium(VI) from an aqueous solution with a concentration of 10–80 mg L−1and a temperature of 30–60°C. The effects of pH, contact time, initial concentration of Cr(VI) and temperature on adsorption, as well as the thermodynamics and kinetics were investigated. The results were as follows: (1) The adsorption capacity of Cr(VI) was dependent on pH and initial concentration as the equilibrium time increased, but the Cr(VI) removal percentage decreased with an increase in the initial Cr(VI) concentration; (2) The adsorption process was in good agreement with the Langmuir adsorption isotherm model at 30°C and the Freundlich adsorption isotherm model at 45 and 60°C; (3) Adsorption thermodynamic parameters ΔH°, ΔS°, and ΔG°indicated that Cr(VI) adsorption on AC was a spontaneous and endothermic process with increased randomness at the solid–solution interface; (4) Cr(VI) adsorption on AC followed a pseudo-second-order equation at 30, 45, and 60°C fitted into an intraparticle diffusion model at 30 and 45°C, and it followed a pseudo-first-order equation only at 60°C and at Cr(VI) concentrations of 10 and 20 mg L−1. [ABSTRACT FROM PUBLISHER]

The measured dynamic surface tension of a water drop in air saturated by heptane vapor shows a sharp decrease from about 60 mN m−1 to 40 mN m−1, and less after a certain adsorption time. The observed adsorption kinetics is analyzed by a theoretical model based on multilayer adsorption of alkanes from the vapor phase at the water surface. The model assumes a dependence of the kinetic coefficients of adsorption and desorption on the surface coverage and in equilibrium it reduces to the classical Brunauer–Emmett–Teller adsorption isotherm. The calculated time dependencies of adsorption and surface tension agree well with experimental data and predict a five-layer adsorption of heptane.

[Display omitted] • Laccase immobilization introduced enzymatic degradation for micropollutant removal. • Adsorption and enzymatic degradation had synergy effect for micropollutant removal. • Enzyme-enhanced adsorption improved the adsorption capacity and adsorption rate. • Laccase immobilization promoted the diffusion rate and reduced diffusion resistance. Laccase immobilization has been proven to improve the adsorption efficiency for promoting the micro-pollutant removal performance. However, the enzyme-enhanced adsorption mechanism remains poorly investigated. The main objective of this work is to examine the water purification performance of laccase immobilized graphene oxide (Lac-GO), to reveal the enzyme-enhanced adsorption mechanism and to explain the synergy of adsorption and enzymatic degradation, from the views of theory and experiment. Above all, by the appropriate laccase immobilization, the enzyme-enhanced adsorption process formed, and enzymatic degradation was introduced by the change of micromorphology. Then, the laccase immobilization did not affect the GO adsorption behavior, which was dominated by monolayer and homogeneous adsorption, based on the analysis of adsorption thermodynamics and adsorption kinetics theories. Nevertheless, the enzyme-enhanced adsorption showed higher adsorption capacity and greater adsorption rate, because the enzyme is able to degrade the micro-pollutant adsorbed on GO surface, releasing the occupied active sites and delaying the adsorption saturation. Moreover, the calculation of particle diffusion dynamic model clarified that the micro-pollutant diffusion process accelerated after laccase immobilization, since the enzymatic degradation eliminated the diffusion resistance. Afterwards, the GO adsorption and enzymatic degradation exhibited the clear synergy mechanism for micro-pollutant removal, because of the enzymatic degradation enhancement, diffusion resistance elimination and adsorption saturation reduction. In addition, at the optimal operating conditions (laccase concentration of 333.3 mg L−1, Malachite Green concentration of 100 mg L−1, adsorbent concentration of 200 mg L−1, rotation rate of 150 rpm, and temperature of 40 °C), the enzyme-enhanced adsorption process displayed a significant equilibrium adsorption capacity and high micro-pollutant diffusion rate. In final, this study provides an in-depth understanding to improve the adsorption processes for water purification by the unique advantages of enzyme-enhanced adsorption process. [ABSTRACT FROM AUTHOR]

In order to explore the characteristics and mechanisms of ammonia adsorption by both nitrifying sludge waterborne polyurethane (WPU)-immobilized pellets and nitrifying sludge polyvinyl alcohol-sodium alginate (PVA-SA)-immobilized pellets, the ammonia adsorption characteristics of immobilized pellets under different initial ammonia concentrations, and the influences of temperature, pH, and salinity on ammonia adsorption were studied respectively. Moreover, the adsorption isotherms, thermodynamics, and kinetics model analysis were employed to investigate the adsorption process. The adsorption capacity increased as the initial ammonia concentration increased. The optimal pH was 7.0, and salinity and temperature exhibited an inhibitory effect on adsorption. The adsorption capacity for nitrifying sludge-immobilized pellets was higher than the pellets with no sludge; the adsorption capacity of WPU pellets was higher than that of PVA-SA pellets. The thermodynamics demonstrated that the adsorption process was a spontaneous exothermic process and that low temperature favored ammonia adsorption. The process was fitted to the Langmuir and Freundlich isotherm. It exhibited multilevel adsorption at higher energy (Freundlich isotherm) and single adsorption at lower energy by electrostatic force (Langmuir isotherm). Additionally, the process was consistent with the pseudo-second-order kinetic model, as it explained that chemical adsorption was the primary mechanism of ammonia adsorption by immobilized pellets.