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Black soldier fly larvae (BSFL) are gaining attention as an alternative protein source in food and feed, promoting a circular economy, particularly in their dried form. In the literature, monitoring the behavior of larvae in a humid environment has not been established under different conditions of temperature and relative humidity as well as the quality of dried larvae is not always correlated to the conditions of drying. Therefore, this study comprehensively analyses the adsorption–desorption isotherms, drying kinetics, and subsequent quality changes of dried BSFL. Sorption isotherms were assessed at 40, 50, 60, and 70 °C using the gravimetric method, followed by mathematical modelling and determination of thermodynamic variables. Thin-layer drying kinetics were studied in a forced-air oven at the same temperatures, with a subsequent proximate analysis of the dried larvae. Among eight sorption isotherm models evaluated, the Peleg model provided the best fit, revealing type II sorption isotherms with an optimal storage water activity of 0.38. The Page model accurately described the drying kinetics of BSFL across all temperatures. Moisture diffusion coefficients ranged from 6.15 × 10–11 to 2.63 × 10–10 m2/s, with an activation energy of 48.66 kJ/mol. The dried larvae displayed impressive protein levels, varying from 39.67 ± 0.28% to 45.29 ± 0.07%, exceeding the minimum requirements set in the global insect production industry. Higher drying temperatures significantly impacted the proximate composition, reducing larvae quality. These findings underscore the potential of BSFL as a valuable protein source and enhance the understanding of their sorption behavior and quality attributes during drying. This study contributes to the optimization of drying conditions for improving the quality of BSFL as a sustainable protein alternative. [ABSTRACT FROM AUTHOR]

The contribution of organic matter content to the hydrosorption properties of soils is demonstrated. Hydrosorption properties were studied for soils of different genesis and with different degrees of technogenic load. Among technogenic soils, urban and arable soils are considered. Natural soils are represented by soddy eluvial metamorphic on varved clays (Albic Stagnic Retisol (Siltic)), gray metamorphic (Luvic Greyzemic Phaeozem (Clayic, Humic)) and clayey illuvial chernozem (Luvic Chernozem (Clayic, Humic)) on brown clays. Sorption isotherms constructed using the BET method and the specific surface areas of the initial samples and samples after organic matter destruction were compared. Organic matter was destroyed in a laboratory experiment using hydrogen peroxide. It has been revealed that treatment with H2O2 led to a significant decrease in the sorption capacity of soils and a change in hysteresis phenomena. At the same time, the sorption capacity of the soils decreased differently. The specific surface area decreased from 1.9 to 2.8 times. Statistical analysis has shown no correlation between the degree of reduction in specific surface area and the degree of reduction in organic matter content. However, a close correlation has been found between the degree of reduction in specific surface area and the initial organic matter content. The higher the initial organic matter content of the soil, the greater the reduction in specific surface area as a result of the treatment. It has been revealed that treatment with H2O2 has the most significant effect on equilibrium water contents in the capillary condensation interval. The sorption capacity of the urban soils was lower than that of their natural and arable counterparts. At a relatively high organic carbon content in urban soils, its destruction had a lower effect on the specific surface than that in other soils, which suggests that it is related to the qualitative composition of the organic matter. [ABSTRACT FROM AUTHOR]

In this study, four types of "Juá" stem barks (Ziziphus joazeiro) were investigated for the removal of Cu(II) from aqueous solutions. The tested samples included natural coarse barks, and barks washed with water, ethanol–water, and NaOH solutions. The solvent-modified materials simulated the waste of the industrial extraction of saponins from bark. The valorization of these processing residues as sorbents was evaluated. The NaOH-washed sorbent exhibited the highest sorption capacity for Cu(II) (maximum sorption capacity ≈ 32 mg g−1). Ion exchange process between copper and exchangeable surface cations and electrostatic attraction of copper with carboxylate and phenolate groups were identified as the primary sorption mechanisms. Desorption tests revealed that a large portion of the metal sorbed (80%) was easily released from the sorbent thus suggesting, in line with the proposed mechanisms, the existence of weak sorbate-sorbent interactions. The sorptive process was found to be exothermic (∆H° = − 48.1 ± 13.5 kJ.mol−1) and thermodynamically favorable at lower temperatures. [ABSTRACT FROM AUTHOR]

Polyethylene (PE) and other polymers are widely and successfully used as passive samplers for organic pollutants in the environment. This study provides high-resolution experimental data from batch shaking tests on the uptake, reversibility, and linear equilibrium partitioning of polycyclic aromatic hydrocarbons (PAHs) using two different PE sheets of 30 µm and 80 µm thickness. Kinetics for phenanthrene are well described by a mechanistic first-order model with mass transfer limited by an aqueous boundary layer (with a mean thickness of 170 µm). Equilibration in laboratory batch systems during uptake and desorption is very rapid with characteristic times of 1–2 h but this depends on the boundary condition, e.g., the ratio of PE mass to water volume. Therefore, equilibration of PE in other setups, e.g., in soil slurries or sediment suspensions, may take orders of magnitude longer because the boundary condition for PE changes from finite to infinite bath conditions (soil or sediment particles may keep the concentration in water almost constant). Solid precipitates for high molecular weight PAHs explain partition coefficients below expected values because of kinetic limitations in such a system. Nevertheless, passive sampling can be employed safely if such limitations are considered; furthermore, partition coefficients can be estimated accurately by empirical relationships (e.g., within 0.1 log unit) based on molecular weight, octanol/water partition coefficients, or subcooled liquid solubilities. [ABSTRACT FROM AUTHOR]

Background: The widely adopted use of charred biomass for agronomic and environmental purposes; and the reported positive and deleterious effects necessitated the need for this study to ascertain the potential causes of the erratic results surrounding the use of charred biomass in agriculture and the environment. A batch sorption experiment was carried out to determine the sorptive and desorptive capacity of bone char and biochar on nitrate, ammonium, phosphate and sulphate concentrations in a loamy sand soil. The potential agronomic and environmental implications of the sorption data were also discussed. Results: The results indicated that bone char is richer in nutrient composition than biochar, with 70% more ability to sorb nutrients. The bone char and biochar sorption isotherms conformed to the H-curve isotherm type. Bone char and biochar have multiple layers of adsorption sites. Nutrient adsorption maxima, binding energy, and maximum buffering capacities of the soil were increased with the addition of bone char and biochar. The unamended soil was observed to retain as low as 6% of added nitrate to as much as 58% of added phosphate, while bone char retained 56% of added sulphate, 47% of phosphate, 76% nitrate and 64% of ammonium. Generally, bone char retained 60.6% of the added nutrients, while biochar retained 40.7% of the nutrients. The addition of bone char led to a 45.8% increase in the nutrient retention ability of the soil and a 36.1% increase with the addition of biochar. Conclusion: The nutrient sorption characteristics of biochar should be studied prior to its use as a soil nutrient amendment. It was concluded that bone char or biochar is a potential soil nutrient immobilizer; hence, applications for agronomic purposes should take cognizance of the native soil fertility so as to appropriately add fertilizer input before use. [ABSTRACT FROM AUTHOR]

Chloride binding by the hydrate phases of cementitious materials influences the rate of chloride ingress into these materials and, thus, the time at which chloride reaches the steel reinforcement in concrete structures. Chloride binding isotherms of individual hydrate phases would be required to model chloride ingress but are only scarcely available and partly conflicting. The present study by RILEM TC 283-CAM 'Chloride transport in alkali-activated materials' significantly extends the available database and resolves some of the apparent contradictions by determining the chloride binding isotherms of layered double hydroxides (LDH), including AFm phases (monosulfate, strätlingite, hydrotalcite, and meixnerite), and of alkali-activated slags (AAS) produced with four different activators (Na2SiO3, Na2O·1.87SiO2, Na2CO3, and Na2SO4), in NaOH/NaCl solutions at various liquid/solid ratios. Selected solids after chloride binding were analysed by X-ray diffraction, and thermodynamic modelling was applied to simulate the phase changes occurring during chloride binding by the AFm phases. The results of the present study show that the chloride binding isotherms of LDH/AFm phases depend strongly on the liquid/solid ratio during the experiments. This is attributed to kinetic restrictions, which are, however, currently poorly understood. Chloride binding by AAS pastes is only moderately influenced by the employed activator. A steep increase of the chloride binding by AAS occurs at free chloride concentrations above approx. 1.0 M, which is possibly related to chloride binding by the C–(N–)A–S–H gel in the AAS. [ABSTRACT FROM AUTHOR]

The sorption capacity of microplastic in respect of heavy metals (Co, Ni, Cu, Cd, Pb) in the natural water of Lake Onego was investigated. Microplastic particles of polyethylene terephthalate were obtained by grinding a plastic bottle aged in natural conditions. The type of polymer used to produce microplastics and the degree of its destruction were investigated using Scanning electron microscopy with energy dispersive X-ray spectroscopy, Raman spectroscopy and micro Fourier Transform infra-red Spectroscopy. The concentrations of metal additives in the model aqueous solutions for the construction of isotherms were close to those in Lake Onego and its tributaries. Obtained isotherms of metals sorption on the surface of microplastics in natural waters differed from those widely reported in the literature for model solutions based on distilled water. Conventional Langmuir and Freundlich models were able to describe sorption processes in Lake Onego water only within certain ranges of element concentrations, what is primarily due to the presence of natural organic matter and Fe and Mn hydroxides in the water of Lake Onego. [ABSTRACT FROM AUTHOR]

The stabilization of heavy metals in soils is considered a cost-effective and environmentally sustainable remediation approach. In the current study, the applicability of water treatment residual nanoparticles (nWTRs) with the particle size ranged from 45 to 96 nm was evaluated for its efficacy in reducing arsenic mobility in clayey and sandy contaminated alkaline soils. Sorption isotherms, kinetics, speciation and fractionation studies were performed. Sorption equilibrium and kinetics studies revealed that As sorption by nWTRs-amended soils followed Langmuir and second-order/power function models. The maximum As sorption capacity (qmax) of Langmuir increased up to 21- and 15-folds in clayey and sandy soils, respectively, as a result of nWTRs application at 0.3% rate. A drastic reduction in non-residual (NORS) As fraction from 80.2 and 51.49% to 11.25 and 14.42% for clayey and sandy soils, respectively, at 0.3% nWTRs application rate was observed, whereas residual (RS) As fraction in both studied soils strongly increased following nWTRs application. The decline in percentage of As mobile form (arsenious acid) in both soils after nWTRs application indicated the strong effect of nWTRs on As immobilization in contaminated soils. Furthermore, Fourier transmission infrared spectroscopy analysis suggested reaction mechanisms between As and the surfaces of amorphous Fe and Al oxides of nWTRs through OH groups. This study highlights the effective management approach of using nWTRs as soil amendment to stabilize As in contaminated alkaline soils. [ABSTRACT FROM AUTHOR]

This research aimed to experimentally determine moisture sorption characteristics and mechanical thermal properties of different parts of red water lily (Nymphaea x rubra). The data obtained from dynamic vapor sorption (DVS) were modeled with six sorption isotherm models. The shape of sorption isotherms of dried petiole and rhizome was classified as Type III and II, respectively. Peleg model was the best fit with the experimental data. GAB and BET models were used to estimate monolayer moisture content (M0) of the samples and M0 of petiole ranged between 7.17 to 8.291% d.b. and 10.455 to 10.588% d.b. for GAB and BET models, respectively and M0 of rhizome ranged between 6.208 to 7.741% d.b. and 3.566 to 3.669% d.b. for GAB and BET models, respectively. Blahovec-Yanniotis model was used to describe the amount of bounded water and solution water in material and the contribution of solution water played an important role in both adsorption and desorption processes of dried petiole and rhizome. Dried red water lilies were equilibrated at different relative humidity levels. Dynamic mechanical thermal analysis (DMTA) was used to estimate the glass transition of the samples at different water activities. Increasing the solicitation frequency shifted the temperature of the relaxation to a higher temperature and Arrhenius equation described well the frequency dependency of the transition temperature. The apparent activation energies (Ea) of dried petiole and rhizome were in the range from 217.98 to 248.49 kJ/mol and 187.34 to 230.30 kJ/mol, respectively. [ABSTRACT FROM AUTHOR]

The adsorption properties of bentonite from the Ilnytskyi deposit (Ukraine) regarding the copper ions under conditions when bentonite is activated with ultrasound are investigated. Based on the methods of X‑ray diffraction and complex thermal analysis, it was determined that Ca, Mg-montmorillonite mainly represent a bentonite fraction with a particle size 10×10−6 m. Ultrasound-activated bentonite was found to have an increased sorption capacity of copper ions. Saturation of natural bentonite and bentonite activated with Cu2+ ions occurs according to the ion exchange mechanism. The sorption characteristics of natural and activated bentonites were compared by modeling the experimental data of the sorption isotherms using the Langmuir equation. The prospects of the use of ultrasound-activated bentonite for wastewater treatment from heavy metal ions are shown. [ABSTRACT FROM AUTHOR]

The everyday use of various pharmaceuticals to treat humans or animals means that they are increasingly found in the environment. Contamination of the soil can cause the active ingredients to be strongly sorbed to the soil or sediment. In the worst case, they can also be expected to occur in the aquatic environment due to their different polarity. In this study, four drugs from different therapeutic classes (trimetoprim, memantine, cefdinir, praziquantel) were used in dissolved form in two sediment and three soil samples to obtain data that can describe their fate and behavior in the environment. The sorption affinities of the pharmaceuticals were described using linear, Freundlich and Dubinin-Radushkevich sorption isotherms. The highest Kd values were obtained for cefdinir, while memantine and praziquantel tended to be present in water due to their very low sorption coefficients. The studied influence of pH showed a negative trend for memantine and trimetoprim, while an increase in ionic strength resulted in higher Kd values for all drugs. The sorption mechanism for all tested samples was best described by the pseudo-secondary kinetic model (R2 > 0.9999). [ABSTRACT FROM AUTHOR]

Graphene and its derivatives as multifunctional catalysts are in high demand, owing to their exceptional potential. Here, we synthesized Cu/Ni@rGO nanocomposite by using reduced graphene oxide (rGO) as a support which provided large surface area. A mixture of Cu and Ni nanoparticles (NPs) was embedded on its surface for sorption of heavy metal ions, i.e., Pb2+ and Cr6+, from binary mixture. Synthesis process of nanocomposite was monitored by UV-visible spectroscopy. FTIR analysis was performed to confirm the functional groups involved in synthesis and stabilization of the nanocomposite. The average size of nanocomposite was 26 nm calculated by XRD spectroscopy. SEM analysis revealed the thread-like structure of nanocomposite, while EDX gave information about elemental composition. Synthesized material was used to remove cations (Pb2+ and Cr6+) from binary mixture under tungsten lamp and without tungsten lamp. Under tungsten lamp, at 5 ppm concentration of binary mixture of cations, after 40 min of interaction with 10 mg adsorbent dosage at 45 °C temperature, 94% of cations was removed very efficiently. Thermodynamics studies showed that reaction of cations with nanocatalyst was spontaneous and exothermic in nature. Kinetics models were employed on experimental values and regression coefficient (R2) was near to unity (0.99) for pseudo 2nd order, which was considered the best fitted method for adsorption. Among sorption isotherms, the best fitted model was Freundlich isotherm as its R2 value (0.97) is near to unity. On these adsorption isotherms, error analysis was also applied to attain precision on results. Reusability of material was analyzed 5 times by desorption process which confirmed its stability and higher catalytic efficiency.Graphical Abstract: Graphene and its derivatives as multifunctional catalysts are in high demand, owing to their exceptional potential. Here, we synthesized Cu/Ni@rGO nanocomposite by using reduced graphene oxide (rGO) as a support which provided large surface area. A mixture of Cu and Ni nanoparticles (NPs) was embedded on its surface for sorption of heavy metal ions, i.e., Pb2+ and Cr6+, from binary mixture. Synthesis process of nanocomposite was monitored by UV-visible spectroscopy. FTIR analysis was performed to confirm the functional groups involved in synthesis and stabilization of the nanocomposite. The average size of nanocomposite was 26 nm calculated by XRD spectroscopy. SEM analysis revealed the thread-like structure of nanocomposite, while EDX gave information about elemental composition. Synthesized material was used to remove cations (Pb2+ and Cr6+) from binary mixture under tungsten lamp and without tungsten lamp. Under tungsten lamp, at 5 ppm concentration of binary mixture of cations, after 40 min of interaction with 10 mg adsorbent dosage at 45 °C temperature, 94% of cations was removed very efficiently. Thermodynamics studies showed that reaction of cations with nanocatalyst was spontaneous and exothermic in nature. Kinetics models were employed on experimental values and regression coefficient (R2) was near to unity (0.99) for pseudo 2nd order, which was considered the best fitted method for adsorption. Among sorption isotherms, the best fitted model was Freundlich isotherm as its R2 value (0.97) is near to unity. On these adsorption isotherms, error analysis was also applied to attain precision on results. Reusability of material was analyzed 5 times by desorption process which confirmed its stability and higher catalytic efficiency. [ABSTRACT FROM AUTHOR]

In this study, the effectiveness of softwood-derived biochar (BC) in the retention of potentially toxic elements (PTE, i.e., Cu(II), Pb(II), As(V), and Sb(V)) was evaluated at different pH values (4.5, 6.0, and 7.0), along with its capacity to alleviate PTE phytotoxicity. At all pH values, sorption and kinetic isotherms followed the trend: Pb(II) (e.g., ~ 0.56 mmol g−1 at pH 6.0) > Cu(II) (e.g., ~ 0.33 mmol g−1 at pH 6.0) > As(V) (e.g., ~ 0.29 mmol g−1 at pH 6.0) > Sb(V) (e.g. ~ 0.24 mmol g−1 at pH 6.0). Kinetic data strongly correlated with the pseudo-second-order kinetic equation; Langmuir and Freundlich isotherm models suggested monolayer sorption of Cu(II), Pb(II), and As(V) onto the BC surface and the interaction of Sb(V) with BC sites characterized by distinct sorption energy (i.e., multilayer sorption). Scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analysis of PTE-saturated BC showed that Pb(II) was mainly associated with O, Sb(V) with Ca and Fe, while Cu(II) and As(V) with Fe and O. This suggested that hydroxyl and carboxyl functional groups, amorphous Fe oxy-hydroxides, as well as PTE precipitation with BC components were likely responsible for BC sorption capacity. Treatment of PTE-saturated BC with Ca(NO3)2 and a range of environmentally relevant organic acids indicated that 6–11% of PTE were loosely bound and easily exchangeable, while up to 60% could be mobilized by the organic acids. Hydroponic plant-growth experiments using triticale plants showed that BC stimulated plant growth in the presence of PTE and reduced their phytotoxicity. [ABSTRACT FROM AUTHOR]

The equilibrium sorption isotherms of cholesterol on surface-imprinted Se-containing sorbents based on 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate were studied. The equilibrium sorption of cholesterol occurred on a homogeneous sorption surface of the molecularly imprinted polymer (template content 6 mol.%). The sorption surface had a higher affinity to template molecules compared to the monolayer. An increase in the amount of template introduced during modification of the polymer matrix led to an increase in the sorption surface area of solvated polymers available for cholesterol binding. [ABSTRACT FROM AUTHOR]

A study is performed of the effect the means of activation of bentonite-like clays (acidic, alkaline, combined) have on the adsorption characteristics of Fe3+ ions under static conditions. The mechanism of the acidic and alkaline activation of montmorillonite is identified and found to depend on the concentration of the activating agent. Solutions of sulfuric acid and lithium hydroxide are used as activating agents. It is shown that during combined treatment of enriched clay which includes activation with sulfuric acid and lithium hydroxide, its sorption capacity grows by 2.0–9.4 times, in relation to Fe3+ ions. [ABSTRACT FROM AUTHOR]

Isotherms of water-vapor sorption by aramid fibers and films of various nature were determined by static sorption methods. Structural and morphological characteristics of aramid fibers were investigated by the methods of transmission and scanning electron microscopy, X-ray structural analysis. It is shown that the studied industrial aramids are X-ray amorphous mesophases. The diffusion coefficients of water in aramids of various thermal prehistories have been determined. Greater interest is presented by the region of high humidity, where a rather sharp increase in the diffusion coefficients is observed for fibers and membrane films, which is associated with an increase in the segmental mobility of aramids and the onset of the process of devitrification of sorbents. The factor of complication of the transport paths during the transition from copolyamide membranes to fibers has been calculated. The sorption capacity of industrial aramid fibers in the entire range of water-vapor activity is significantly lower than the sorption capacity of films, membranes, and model sorbents. It is shown that paracrystalline mesophases act as "impermeable particles" in aramids. It is shown that absorbed water in polymers can exist in a nonassociated state or in the form of clusters. The number of water molecules included in the clusters has been determined. [ABSTRACT FROM AUTHOR]

Tomato peel in raw and modified form was used to remove uranium from aqueous solutions. The biosorbents were modified using acidic and alkaline solutions and tested in variable experimental conditions (metal concentration, pH, ionic strength, contact time and temperature). Adjustment of the experimental data of the isotherms obtained at pH 4.5 (Cinitial: 5–250 mg L−1) to the Langmuir and Freundlich models indicated significant sorption capacity (from 66.2 to 109.1 mg g−1 for the raw and modified sorbent respectively). Kinetic and thermodynamic data as well as characterization using FTIR and SEM, demonstrated a complex mechanism including ion exchange and interactions between uranium and surface functional groups. [ABSTRACT FROM AUTHOR]

Pomegranate peel was investigated as biosorbent to remove uranium as well as thorium from aqueous solutions under different experimental conditions (concentration, counter ions, temperature). The material was used in raw and modified form after treatment with acidic and alkaline solutions to increase its sorption capacity. Isotherms were obtained at pH 4 and Cinitial: 5–300 mg L−1 for uranium and at pH 3 and Cinitial: 5–100 mg L−1 for thorium, respectively. The equilibrium data of the sorption study, which were adapted to the Langmuir and Freundlich models, indicated enhanced sorption efficiency (115 and 80 mg g−1 for uranium and thorium). Furthermore, kinetic and thermodynamic data as well as investigation by FTIR, XRD, and SEM revealed the complex sorption mechanism that can be explained by a combination of physical sorption accompanied by surface precipitation. [ABSTRACT FROM AUTHOR]

An investigation is performed for isotherms of the equilibrium sorption of glucose by surface-imprinted organic-inorganic sorbents based on 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate. It is shown that modifying the copolymer by forming imprint sites reduces the affinity of the sorption surfaces and the monolayer sorption of glucose molecules. In analyzing the match between experimental data obtained under conditions of sorption corresponding to those for the formation of imprint sites and theoretical models of sorption, it is found that introducing 6 mol % glucose molecules as a template produces homogeneous sorption surfaces. The surfaces of organo–inorganic sorbents available for the target sorbent in a liquid–solid system are determined using the Giles classification of experimental sorption isotherms and theoretical models of sorption isotherms. [ABSTRACT FROM AUTHOR]

Four ionic liquids (ILs) 1-methyl-3-tetradecylimidazolium chloride ([C14MIM]Cl), 1-n-butyl-3-n-butylimidazolium chloride ([C4BIM]Cl), 1-n-butyl-3-n-tetradecylimidazolium chloride ([C14BIM]Cl), and 1-tetradecylpyridinium chloride ([C14Py]Cl) were synthesized. Sorbents in nature of supported ionic liquid phases (SILPs) were prepared by impregnating ILs on solid carriers such as silica gel, XAD-7 and XAD-4 Amberlite ion exchange resins. Pt(IV) was recovered using these sorbents with the yields over 90%, however, the amounts of used ILs are much less than those of ILs used in extraction method and the process can easily be transferred to heterogeneous phase. The Pt(IV) sorption is affected by the structure of ILs and solid carriers, the IL loading, and IL/Pt molar ratio. The highest sorption yields were observed when using [C14MIM]Cl-based SILPs. Moreover, the sorption isotherms of [C14MIM]Cl/SiO2 SILPs with different IL loadings and IL/Pt molar ratios were investigated and sorption mechanism was also proposed. [ABSTRACT FROM AUTHOR]

Water treatment residuals produced after addition of polyaluminium chloride and anionic polyacrylamide (PAC-APAM WTRs) were evaluated for the potential to remove Cd2+ and Zn2+ from aqueous solutions by batch adsorption studies. The maximum adsorption capacity obtained from Langmuir modeling was 85.5 mg Cd2+/g PAC-APAM WTRs or 25.6 mg Zn2+/g PAC-APAM WTRs. A Dubinin-Radushkevich (D-R) model study showed that the adsorption process was chemically controlled. The pseudo-second-order model described the adsorption kinetic data better than the pseudo-first-order model, while kinetic studies showed that the adsorption process included external surface adsorption and intraparticle diffusion, which was likely the rate-limiting step. PAC-APAM WTRs adsorbed Cd2+ and Zn2+ in the pH range of 3–9 and in the temperature of 20–40 °C, and the immobilization ability for both ions increased with the increase of pH or an increase in temperature. FT-IR spectroscopy analysis illustrated that the carboxyl groups from APAM in WTRs participated in the adsorption reactions in addition to Fe(Al)-O functional groups and O–H groups. This short-term study showed that PAC-APAM WTRs could be a cost-effective media for the remediation of Cd2+ and Zn2+ contaminated soils. Further studies are needed to examine the slow adsorption mechanisms and determine the optimum mass ratio of soil to PAC-APAM WTRs under various soil conditions. [ABSTRACT FROM AUTHOR]

The sorption of lead, nickel, zinc, chromium(III), and chromium(VI) ions by Spirulina platensis microalga was studied. The effects of pH, metal concentration, and sorption time were assessed. The metal concentrations were measured by atomic absorption spectrometry. The kinetics of biosorption were described in terms of the pseudo-first, pseudo-second, Elovich, and Weber–Morris models. The Langmiur, Freudlich, and Temkin isotherms were used to fit the experimental data. The results showed that the biomass of Spirulina platensis microalga can be efficiently used to treat industrial effluents. [ABSTRACT FROM AUTHOR]

Purpose: Sorption of organic compounds to soil largely determines their mobility and bioavailability in ecosystems. It is well known that molecular properties of the organic sorbates affect the sorbed amounts and sorption kinetics. But also changes in the hydration status of soils alter the physicochemical and sorptive properties of soil organic matter (SOM), which is the main sorbent for organic compounds in soils. This study elucidates the effects of varying SOM prehydration status on sorption of PAHs and PAH derivatives in peat soil. Materials and methods: For sorption experiments, topsoil samples of a peat soil with 51% SOM were adjusted to water contents of 15, 30, and 50% (w/w based on dry soil mass) and conditioned for different water contact times of up to 2 years at one constant water content. Sorption kinetics and isotherms of naphthalene, three naphthalene derivatives, phenanthrene, and pyrene to these samples were investigated in batch experiments. Effects of the sorbates' properties and SOM hydration on sorption were analyzed. Results and discussion: Sorption to the peat soil was nonlinear and varied among sorbates and differently prehydrated soil samples. Sorbate polarizability, molecular volume, and weight increased the sorbed amount. Sorption kinetics were two-phased with a fast and a slow sorbing fraction. Hydroxyl groups in sorbates acting as H-donor or acceptor led to an increase of the slow sorbing fraction. Increasing total water contents, amounts of non-freezable water in SOM, increasing pore sizes, and decreasing hydrophobicity of SOM decreased the total sorbed amount and the fast sorbing fraction while increasing the slow sorbing fraction. The latter effects increased with increasing polarity and dipole moment of the sorbate. The SOM matrix rigidity varied with prehydration status; higher SOM matrix rigidity led to non-ideal sorption processes, namely, higher sorption nonlinearity and slower sorption. Conclusions: The study revealed the effects and interplay of SOM prehydration status and molecular properties of the sorbates on sorption of PAHs and PAH derivatives. As sorbed amounts may decrease and become non-ideal upon aging at the presence of water, estimations of the mobility of organic compounds in the environment need to consider SOM prehydration status in high organic soils. [ABSTRACT FROM AUTHOR]

The reuse of flax shives, an agricultural waste, in the elaboration of cement composites offers an interesting alternative to meet the challenge of their elimination and solve an environmental problem. The composites studied are developed by adding flax shives to Portland cement and water. Due to their honeycomb structure the flax shives are used as lightweight aggregates and provide insulating properties to the composites. However they are hygroscopic and can release water-soluble molecules responsible for setting retardation, large dimensional variations and low mechanical strengths. In previous works these drawbacks have been reduced by the development of coating processes using lime, linseed oil and paraffin as coating substances. When coated shives are used the composites exhibited compressive strength 8 to 27-fold higher, drying shrinkage two to threefold lower compared to the raw shives composite, and belong to the insulating class of the lightweight concrete. The thermal conductivity of the composites may be negatively affected by environment humidity, so their hygric behavior must be determined. The establishment of the sorption isotherms and the evaluation of the water vapor transport allow the assessment of the hygric behavior. The treatment of the flax shives involves a decrease in the moisture adsorption capacity of the composites up to 48% for a paraffin coating. The composites can be ranked in descending order of hygroscopicity: raw, lime-coated, linseed oil-coated and paraffin-coated shive composites. Only the water vapor permeability and resistance factor of the paraffin-coated shive composite are significantly lower (46%) and higher (73%) compared to those of the raw shive composite. The analytical models (GAB, Janssen and Roels) adjust the experimental results and the influence of flax shives treatment on the composites hygric behavior is demonstrated. [ABSTRACT FROM AUTHOR]

Three commercial resins bearing sulfonic, amino phosphonic, or phosphonic/sulfonic reactive groups have been tested for the removal of iron and cadmium from phosphoric acid solutions. The sorption properties are compared for different experimental conditions such as sorbent dosage (0.5–2.5 g L−1), phosphoric acid concentration (from bi-component solutions, 0.25–2 M), and metal concentrations (i.e., in the range 0.27–2.7 mmol Cd L−1 and 0.54 mmol Fe L−1) with a special attention paid to the impact of the type of reactive groups held on the resins. The sulfonic-based resin (MTC1600H) is more selective for Cd (against Fe), especially at high phosphoric acid concentration and low sorbent dosage, while MTS9500 (aminophosphonic resin) is more selective for Fe removal (regardless of acid concentration and sorbent dosage). Equilibrium is reached within 2–4 h. The resins can be ranked in terms of cumulative sorption capacities according the series: MTC1600H > MTS9570 > MTS 9500. Sulfuric acid (0.5–1 M) can be efficiently used for the desorption of both iron and cadmium for MTC1600H, while for MTS9570 (phosphonic/sulfonic resin) sulfuric acid correctly desorbs Cd (above 96% at 1 M concentration), contrary to Fe (less than 30%). The aminophosphonic resin shows much poorer efficiency in terms of desorption. The sulfonic resin (i.e., MTC1600H) shows much higher sorption capacity, better selectivity, comparable uptake kinetics (about 2 h equilibrium time), and better metal desorption ability (higher than 98% with 1 M acid concentration, regardless of the type of acid). This conclusion is confirmed by the comparison of removal properties in the treatment of different types of industrial phosphoric acid solutions (crude, and pre-treated H3PO4 solutions). The three resins are inefficient for the treatment of crude phosphoric acid, and activated charcoal pre-treatment (MTC1600H reduced cadmium content by 77%). However, MTC1600H allows removing over 93% of Fe and Cd for H3PO4 pre-treated by TBP solvent extraction, while the others show much lower efficiencies (< 53%). [ABSTRACT FROM AUTHOR]

This paper aims at investigating the hygroscopic behavior and the thermodynamic characterization of the dandelion (Taraxacum officinale) leaves and root during moisture sorption phenomena. This study has been conducted by using the saturated salt solutions at different temperatures 30 °C, 40 °C and 50 °C. The obtained isotherms curves of all samples were of sigmoidal Type II. The optimal water activity was determined. Moreover, thirteen models are fitted and compared in order to choose the most suitable model that perfectly represents the relationship between moisture sorption content and water activity. The comparison of these models has been based on the coefficient of correlation as well as the standard error of estimate. Furthermore, several equations are used to determine the net isosteric heat of sorption, the sorption differential entropy, the spreading pressure, the specific surface area of sorption, and the enthalpy-entropy compensation theory. All these thermodynamic properties allow us to analyze the thermodynamic behavior of the leaves and the dandelion root during the sorption processes. [ABSTRACT FROM AUTHOR]

The study of ion sorption of Cu2+ on fungi isolated from mycelium Aspergillus niger chitin- and chitosanglucan complexes showed that these biopolymers have a fairly high sorption ability. As a result of mathematical modeling found that the theoretical models of Langmuir, Freundlich and Temkin are adequate, with a high coefficient of determination (R2 = 0.97–0.99) describe equilibrium sorption of Cu2+ on the studied biocomplexes. An analysis of the sorption parameters obtained from the regression equation shows that the mechanism of sorption of Cu2+ on chitin- and chitosan-containing complexes has a more complex character that differs from the theoretical premises of classical theories and, presumably, is based on the processes of ion exchange and complexation. [ABSTRACT FROM AUTHOR]

Although nonionic surfactant is widely used for petroleum-contaminated soil washing, there is no definite conclusion on the main soil factors which determine the removal of petroleum hydrocarbons from the soil. In this study, the influences of soil properties on Triton X-100-aided soil washing were investigated using 12 soils in China. The sorption characteristic of Triton X-100 on soils was described as well. The sorption isotherms of Triton X-100 on 12 typical soils were fitted to the Langmuir adsorption model, and the maximum sorption amount of Triton X-100 (Qmax) varied from 1.54 to 15.15 mg/g. The removal rates of diesel for 12 soils were well fitted to the modified Michaelis-Menten equation, and the maximum removal rate of diesel (φmax) ranged from 62.92 to 90.36%. The correlation analysis indicated that the φmax is significantly correlated with the Qmax. The soil factors affecting diesel removal from soils followed the order of sand content > cation exchange capacity (CEC) > organic matter (OM) content > silt and clay content > SSA >> pH. The prediction model based on CEC, silt content, and pH explained 83.1% of variance of diesel removal from soils. This study will have important implication for successfully remediating organic-contaminated soil using nonionic surfactant-based soil washing. [ABSTRACT FROM AUTHOR]

Nanodiamonds (NDs) were investigated as potential carriers of 99mTc, which is widely used for the diagnosis of diseases in nuclear medicine. The sorption of 99Tc(VII), 99mTc(VII), and 99mTc(IV) by commercial NDs and their reduced, aminated, and oxidized forms was studied. The physicochemical parameters of the Langmuir and Freundlich isotherms for the sorption of 99Tc(VII) by the used ND samples were determined. The Sn(II): Tc(VII) ratio for the quantitative reduction of Tc to the oxidation state IV was optimized. It was shown that the initial (commercial) and oxidized NDs are promising carriers of 99mTc(IV) for nuclear medicine. [ABSTRACT FROM AUTHOR]

Milled olive stones are evaluated as a biosorbent for the removal of heavy metals such as Cd (II), Cu (II), Pb(II) and Cr(VI) from aqueous effluents. To this end, thermodynamic and kinetic studies for single and multimetal systems are performed through batch equilibrium isotherms. The biosorbent was characterized by elemental and FTIR analysis and scanning electron microscopy. The effect of the different parameters, such as contact time, pH, amount of adsorbent and initial metal concentration, on the sorption process is also investigated. The maximum removal percentage for 1 mg L−1 of cadmium, copper, and lead was 77.4%, 80.5%, and 94.5%, respectively, at pH 6 with 5 g L−1 of sorbent. In the case of Cr(VI), a removal percentage of 46% was obtained in 2 h at pH 2 using a larger amount of sorbent (10 g L−1) and an initial concentration of 2 mg L−1. Equilibrium data were analyzed by applying different adsorption isotherm models, resulting in—a good agreement with—the Langmuir model with maximum capacities of 0.557, 0.3 and 0.581 mg g−1 for Cu(II), Cd(II) and Pb(II), respectively, whereas for Cr(VI), the Temkin model provided the best fit with a maximum capacity of 2.34 mg g−1. The kinetic data fitted well into the pseudo-second-order model which allowed the adsorption rate constants to be calculated. Cd(II) resulted to have the highest kinetic constant, followed by Cu(II), Cr(VI) and Pb(II). The results showed that milled olive stones can be used as a biosorbent for the removal of these metals from aqueous solutions. Article Highlights: Trace concentrations of Cu(II), Cd(II), Pb(II), and Cr(VI) were adsorbed by olive stones. Removals of 77.4%, 80.5 and 94.5% were obtained for Cu(II), Cd(II), or Pb(II) at pH 6. For Cr(VI), a removal percentage of 46% was obtained at pH 2 with 10 g L−1 of sorbent. Langmuir isotherm model was fitted to Cu(II), Cd(II), and Pb(II) adsorption isotherm data. Cd(II) has the highest pseudo-second-order kinetic constant, followed by Cu(II), Cr(VI) and Pb(II). Milled olive stone is an effective and cheaper biosorbent to remove toxic metals. [ABSTRACT FROM AUTHOR]

Pigeon pea (PP), cowpea (CU), dolichos bean (DB), and jack bean (JB) are legumes that constitute the daily diet in many countries. Legumes are a good source of proteins, carbohydrates, and minerals. Considering that legumes present potentials to be used as ingredients for food formulation, the study of functional and physicochemical properties of flours obtained from legume seeds treated by high hydrostatic pressure treatment (HHPT) (200, 400, 600 MPa) was conducted. Flours were evaluated for polypeptide composition (SDS-PAGE), fluorescence spectroscopy, color, protein solubility (PS), water-holding capacity (WHC), oil-holding capacity (OHC), emulsion activity (EA), emulsion stability (ES), foaming capacity (FC), foaming stability (FS), and least gelation concentration (LGC). PS of PP, CU, and DB diminished with the increase of pressure and only CU showed an increase of PS (7–40%) at the isoelectric point. WHC of PP, CU, and DB varied with the pressure applied; however, WHC of JB was not modified by HHPT as we observed in lambda max fluorescence-emission values and PS. Only PP showed an increment of OHC at 400 and 600 MPa. EA of PP was not affected by HPPT, while DB and JB showed a decrease. ES of CU, DB, and JB was not affected by HHPT. FC of PP, DB, and JB diminished with the increase of pressure. FS of DB and CU (400 MPa) was improved and continued for 120 min. LGC values and the equilibrium moisture content of flours were not influenced by HHPT, but the last decreased with the increase of temperature. Moisture sorption isotherms of flours fitted adequately to H-H equation covering the practical range of water activity (0.10–0.90) at the three temperatures tested. High pressure processed flours of PP, CU, DB, and JB showed functional properties that could be useful for food formulation. [ABSTRACT FROM AUTHOR]

The effect of the degree of dispersion of sorbent particles derived from natural minerals (vermiculite and perlite) on their sorption properties towards heavy metal ions Cd(II),Cu(II), and Pb(II) is studied. The particle sizes of the sorbents vary in the range from submicrons to nanometers (from 250 μm to 100 nm), using a range of dispersion methods (grinding using centrifuge and planetary ball mills),which result in a reduction of the particle size by 1.5–100 times. It is found that the sorption of the examined metal ions on the surface of all the substates can be described by the Langmuir absorption model, regardless of the degree of sorbent dispersion. The low values of the heat of the sorption for ions studied indicate the physical nature of sorption. An increase in the dispersion degree of the sorbents contributed to a significant increase in the sorption activity of dispersed particles of vermiculite and perlite towards to the ions studied (up to 2-fold increase in the sorption degree values). The optimization of the sorption conditions made it possible to achieve high sorption efficiency with the sorption degree ~99.9% towards Cd(II), Cu(II), and Pb(II) ions at a 10-4 mol/L ion concentration and close to neutral conditions at ambient temperature. [ABSTRACT FROM AUTHOR]

The kinetics of Co ions sorption on CoTreat® was investigated in the 5–40 mg/L concentration range at a bulk temperature of 30 °C in HNO3 (pH 2.6). A pseudo-second order kinetic model best describes the sorption kinetics at low Co ion concentrations, while a pseudo-first order kinetic model was the best fit at higher concentrations. The equilibrium data were examined using the three models, viz. the Freundlich, Langmuir and Dubinin–Radushkevich (D–R) isotherms. The Langmuir and the D–R isotherms were the best fits to data from which the monolayer sorption capacity (Q0) and mean sorption energy (E) can be determined. The estimated values of Q0 and E were calculated to be 3.20 mg/g and 8.45 kJ/mol respectively at 30 °C. The thermodynamic parameters ∆H° and ∆S° were determined to be + 32.52 kJ/mol and 0.19 kJ/(mol K) in the temperature range 30–60 °C respectively, yielding negative values of the Gibbs free energy (∆G°), indicating the spontaneous nature of the process. The competitive sorption study of Co, Ce, Ru, Sb and Sr ions revealed that the CoTreat® exchanger can effectively remove all the elements concurrently. [ABSTRACT FROM AUTHOR]

Grafting of quaternary ammonium group is the main goal of this research for uranium recovery. The sorbent was investigated by FTIR, SEM–EDX, elemental analysis, thermogravemetric and XPS analyses, it shows high and fast loading performance (176.49 mg U g−1), the total equilibrium reached within 25 min, fitted by first order rate equation and Sips model for sorption kinetics and isotherms respectively. Complete desorption achieved after 30 min by 1.0 M NaCl in 0.1 M H2SO4. Sorption/desorption was measured after 10 cycles without significant loss in the capacity. Finally, the sorbent applied for uranium recovery of leaching solution from sulfuric acid on gibbsite bearing shale ore materials. [ABSTRACT FROM AUTHOR]

An integrated approach is presented on wastewater treatment for power plants and the disposal of carbonate sludge—the waste forming at the make-up water pretreatment stage at power facilities. Usually, carbonate sludge accumulates on sludge waste sites located on the territory of power plants, which leads to an adverse impact on the environment. In addition to solid waste, the station also produces a large quantity of wastewater, which must be cleaned before being discharged into a waterbody. Concentrated wastewater is traditionally subjected to local treatment, which is associated with economic costs, while domestic and storm sewage is treated at general production wastewater treatment plants. The article proposes a wastewater biosorption technology at the Karmanovskaya GRES in which conditioned carbonate sludge is used as a sorption material. The sorption ability of carbonate sludge is confirmed by sorption isotherms of petroleum products and ammonium nitrogen. The kinetic curves obtained as a result of research confirm that biosorption wastewater treatment with carbonate sludge has a higher efficiency than conventional biological treatment. With the introduction of carbonate sludge into the aerotank for biosorption, the efficiency of wastewater treatment at the Karmanovskaya GRES increases significantly in terms of 5-day BOD, phosphate ion, chemical oxygen consumption (COD), ammonium nitrogen, and petroleum products. The use of carbonate sludge as a sorption material will improve the quality of treatment of all types of wastewater without their local treatment, which is equivalent to the wastewater's final biofiltration. When implementing the technology of biosorption cleaning with water treatment sludge, the prevented environmental damage to the Karmanovsky reservoir will amount to 1 463 000 rubles per year in the event of oil- and salt-containing wastewater discharge from the GRES into the inlet chamber. The economic calculation of the presented technology is performed: the payback period will be 3 years and 10 months and the economic effect will be 563 000 rubles per year. [ABSTRACT FROM AUTHOR]

Biodegradability and water resistance of cassava starch trays with different plasticizers [glycerol, sorbitol and polyvinyl alcohol (PVA)] were investigated. The degradability was tested by exposure at two amylolytic enzymes of microbial origin, one of them commercial (Termamyl®) and the other obtained in laboratory by the submerged cultivation of the fungus Penicilium echinulatum. The extent of degradation was analyzed by the percentage of weight loss and the concentration of released reducing sugars. The results showed that the packaging was sensitive to the action of the enzymes, because it was observed an increase in the concentration of reducing sugars in the first hours of reaction and percentages of weight loss near 90%. Water resistance was measured by solubility, contact angle and moisture sorption isotherms, with adjustment of the experimental data to mathematical models of Guggen-heim, Anderson de Boer (GAB), Brunauer-Emmet-Teller (BET), Oswin and Jaafar. Trays containing PVA addition showed less solubility, with greater contact angle and lower equilibrium moisture (in aw 0.98). The mathematical models of GAB and Oswin reproduced the best fit to the experimental data of the isotherms. The starch trays showed biodegradability independent of the material used as plasticizer. [ABSTRACT FROM AUTHOR]

Results are presented of a study of the sorption properties of iron-manganese bog ores, aimed to assess the possibility of using these ores to purify natural drinking water from underground sources to remove ions of manganese and iron. The kinetic dependences of the sorption process were examined, and the sorption characteristics of bog ores with respect to manganese and iron ions were determined. It was found that the natural material under study is an effective sorbent for extraction of manganese and iron ions from ground water without use of additional reagents. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the adsorption and desorption isotherms of Tunisian clay product at different temperatures with a water activity varying from 10.95 to 97% using the statistic gravimetric method, which is an important step to evaluate its hygroscopic character. It was found that when temperature increases, clay material becomes less hygroscopic due to physical and/or chemical changes in product. Ten mathematical models were used to fit experimental data of sorption isotherms. The fitting of the model to experimental data was evaluated with the correlation coefficient (R2) and the root mean square error (RMSE). The Oswin model was determined to be the best model for describing experimental data of adsorption and desorption in the investigated ranges of temperature and water activity. The net isosteric heat of sorption determined from sorption isotherms estimated from Oswin model and using Clausius-Clapeyron equation decreased continuously with increasing the equilibrium moisture content. [ABSTRACT FROM AUTHOR]

Moisture sorption isotherms of chironji kernels were determined at 25, 35 and 45 °C over a water activity range of 0.11-0.93. Three sorption models i.e., Guggenheim-Anderson-de Boer (GAB), Brunauer-Emmett-Teller (BET) and Caurie were evaluated to find out their fitness to the sorption data. Thermodynamic properties of sorbed water were analyzed over the selected range of water activity and temperature. The result showed that the sorption isotherms reflected Type II BET sorption characteristics with a clear hysteresis at the temperatures. Of the three models, GAB and Caurie models were found superior predicting the sorption of chironji kernels over the entire range of water activity values. The monolayer moisture content values calculated by the best-fitted GAB and Caurie model for adsorption were 9.86 and 6.31%, 8.023 and 6.18%, 6.90 and 5.97% (db) and for desorption were 6.53 and 6.01%, 5.85 and 5.68%, 4.21 and 5.60% (db), respectively at 25, 35 and 45 °C. The value of isosteric heat decreased with increasing moisture content and approached the latent heat of pure water. Sorption entropy increased with increasing moisture content and decreased gradually with increase in moisture content. The spreading pressures, for both adsorption and desorption, increased with increasing water activity at the three selected temperatures. [ABSTRACT FROM AUTHOR]

Results of the development and evaluation of a sorption capacity of several polymer biosorbents combined with an inorganic matrix are provided. The potential use of whey to model sorption processes in an internal environment of the body is shown. Most effective combinations promoting selective elimination of an excess of accumulated metals from the body are proposed. [ABSTRACT FROM AUTHOR]

The thermal analyses and the water state diagrams of agavin and inulin were investigated. The thermogravimetric analysis and differential scanning calorimetry (DSC) were used to know the difference between fructans. Linear inulin (220.0 °C) showed a higher thermal stability than the branched agavins (206.7 °C). The samples displayed different physical states and lightness depending on the water activity of storage (aw). The agavin showed different physical states: powder (aw < 0.33), soft lump (aw ≈ 0.43), sticky (0.55 < aw < 0.77), and liquid (aw > 0.85), while inulin showed two physical states: an amorphous powder at aw < 0.55 and a semicrystalline solid at aw > 0.69. These physical states decreased the lightness of fructans. The GAB equation and the Gordon-Taylor equation showed a good fit to the experimental data (R2 > 0.95). The K constant of GAB equation predicted a lower water affinity of inulin powder, while the agavin powder presented a higher water affinity. The DSC showed a glass transition temperature of 118.1 and 135.3 °C for agavin and inulin anhydrous powders, respectively. An increase in water content in agavin showed a higher depression in the glass transition temperature than in inulin. Also, the inulin exhibited a melting point while agavin not. The water state diagrams showed the critical water activity at which the agavin (0.50) and inulin (0.59) powders were stable to physical changes. This knowledge is used to understand the physical and structural behaviors of agavin and inulin at the different water activities. [ABSTRACT FROM AUTHOR]

The aim of this paper was to study the moisture sorption characteristics of mixed biomass pellets. The pellets were developed using a mixture of woody (spruce or pine) and agricultural (reed canary grass or hay) biomass with a ratio of 1:1. The pellets were stored in a controlled environment until reaching the equilibrium moisture content. The temperature of the controlled environment was varied between 15 and 25 °C and relative humidity between 20 to 90%. The experimental results showed this temperature range had no effect on the moisture sorption isotherms. However, the equilibrium moisture content at higher relative humidity was found dependent on the type of the material and was higher for spruce-hay pellets compared to the other tested pellets. Oswin, Guggenheim-Anderson-de Boer, Henderson and Peleg models were tested for the prediction of the moisture isotherms. With a coefficient of determination varying between 0.998 and 0.995, a standard error between 0.054 and 0.071 and chi-square error ranging between 0.009 and 0.015, Oswin model was found more suitable to predict the moisture sorption isotherms of all biomass pellets. This result was further confirmed using the residuals plot, showing a more uniform distribution for Oswin model compared to the other models. [ABSTRACT FROM AUTHOR]

Purpose: Remediation of heavy metals by reducing their mobility and bioavailability without removing them from soils is considered to be a cost-effective and an efficient method to address their toxicity for living organisms and soil health. The main objectives of the current study, therefore, were to investigate the potential of sugarcane bagasse biochar in reducing the bioavailability of soil cadmium (Cd) and chromium (Cr) and assessing the impact of biochar application on soil microbial activities and plant growth in metal-contaminated soil.Materials and methods: Air-dried soil was artificially spiked with Cd and Cr metals by using Cd(NO3)2 and Cr(NO3)2 solutions. Biochar was homogenously mixed in metal-spiked soil. The experimental spiked soil was categorized as with and without biochar-amended soil. Mash bean crop was used as test plant. After crop harvesting, soil Cd and Cr were extracted by diethylenetriaminepentaacetic acid (DTPA) to estimate the mobility of heavy metals. Furthermore, the plant metal contents, microbial biomass carbon, urease activity, dehydrogenase (DHA) activity, total organic carbon, and plant biomass were determined. The Langmuir adsorption isotherms were studied for Cd and Cr in unamended soil, biochar-amended soil, and biochar only. The electronegative charges of biochar and biochar-amended soil were also measured using the zeta potential.Results and discussion: The results show that the application of biochar to Cr- and Cd-contaminated soil significantly reduced their availability by 85 and 63%, respectively. The application of biochar at 15 g kg−1 prominently reduced the extractable Cd contents by 29 and 32% in Cd-contaminated and Cr–Cd-contaminated soils, respectively. The Cr concentration in the plant decreased by 34 and 41% in Cr-contaminated and Cr–Cd-contaminated soil compared with spiked soil without biochar. The Langmuir model achieved the best fit; its isotherm predicted the biochar’s maximum adsorption capacity for Cd (0.42 mg g−1) and Cr (0.35 mg g−1). Biochar incorporation in Cd–Cr-contaminated soil significantly increased the microbial activity and mash bean biomass.Conclusions: Our findings indicate that the addition of sugarcane bagasse-derived biochar significantly reduces the Cd and Cr availability in single and co-contaminated soil. In addition, an increase in the microbial activity and plant growth and a significant reduction in the Cd and Cr uptake by mash bean are possible after biochar addition. [ABSTRACT FROM AUTHOR]

The ability of two municipal solid waste composts (MSW-Cs) to sorb antimony(V) in acidic conditions (pH 4.5) was investigated. Sorption isotherms and kinetics showed that both MSW-Cs could sorb antimony(V), even if in different amounts (~ 0.18 and 0.24 mmol g−1 of Sb(V) by MSW-C1 and MSW-C2, respectively). These differences were ascribed to the chemical composition of composts, as well as to the total acidity of their humic substances. The Sb(V) sorption by both MSW-Cs followed a pseudo-second-order kinetic model, while the sorption isotherms data fitted the Freundlich model better than the Langmuir one. The humic acids extracted from composts contributed to 4.26 and 8.24% of Sb(V) sorption by MSW-C1 and MSW-C2 respectively. SEM-EDX spectra of the MSW-C+Sb(V) systems showed a certain association of Ca(II) with Sb(V), while sequential extraction procedures indicated that more than 80% of the Sb(V) sorbed was strongly retained by MSW-Cs. On the other hand, treatment with oxalic acid at pH 4.5 favored the release of more than 98 and 65% of the Sb(V) sorbed by MSW-C1 and MSW-C2 respectively, supporting a possible role of calcium in Sb(V) retention. The results from this study suggest that MSW-Cs could be used as amendments for the in-situ immobilization of Sb(V) in acidic-polluted soils. [ABSTRACT FROM AUTHOR]

Various uranyl sulfate complexes are formed during the digestion of monazite mineral by sulfuric acid. Uranyl sulfate sorption by AMBERJET 4200 Cl has been studied to find out the proper mechanism, equilibrium and kinetics basis. At pH of 3.0 and 0.5 M SO the dominant solution species of U(VI) is [UO(SO)] anionic complex. High sorbent affinity and monolayer sorption mechanism are approved by different isotherms. The rate is found to be controlled by surface adsorption and intra-particle diffusion. The equilibrium equation and kinetic parameters are estimated. The thermodynamic studies reveal that the reaction is endothermic and spontaneous. [ABSTRACT FROM AUTHOR]

In the study, MDSC method was used to evaluate thermal properties of β-lactoglobulin-retinyl palmitate products enriched in disaccharides. Additionally, sorption behavior of powders was determined to define their stability. The obtained powders were also examined and visualized with scanning electron microscopy to find the relationship between food processing conditions and morphological changes in products. For the samples tested, a single glass transition was observed. The results have shown the impact of the composition of studied samples on the glass transition temperatures. The carbohydrate- β-lactoglobulin systems were characterized by higher T values than disaccharides alone. At low water activity, all powdered complexes showed typical sorption behavior of food systems with the sigmoidal shape of the curve. The present study has shown that spray-dried and freeze-dried powdered products with lactose or trehalose have different time-dependent crystallization behavior. Trehalose as a carbohydrate component of samples, in comparison with lactose, delayed the occurrence of crystallization. The obtained images presented the dependence of the shape of the particles on the drying method used. Spray-dried powders were characterized by a spherical or close to spherical structure with the surface of larger particles often deformed. In the case of freeze-dried particles, irregular structures were observed. [ABSTRACT FROM AUTHOR]

The distribution of Cu and Ni ions in an aqueous solution - flax fiber heterophase system was investigated. The specific surface area of the sorbent and the average pore radius were determined. The sorption isotherms were processed in terms of the Langmuir and Freundlich models and the theory of volume filling of micropores. It was shown that the sorbent behaves as a weakly acidic cation exchanger with the α-hydroxycarboxyl groups as sorption sites. The modification of flax fiber with polyvinylpyrrolidone allows one to noticeably increase its sorption properties. [ABSTRACT FROM AUTHOR]

Adsorption isotherms, at 4, 25 and 60 °C for microencapsulated extra virgin olive oil powder (MEVOP) prepared by rotor-stator homogenization (RSH) and ultrasonic homogenization (UH) methods before spray drying, were obtained using standard static gravimetric method. The sorption isotherms exhibited type III (J shape) behaviour. The sorption isotherms of MEVOP depended on temperature, chemical composition of particle surface and particle size of samples. The equilibrium moisture contents (EMC) decreased with increasing temperature. The sorption isotherm of MEVOP obtained with UH shifted up compared to that obtained with RSH because of the smaller particle size of MEVOP obtained with UH. The Guggenheim-Anderson-de Boer (GAB) model was the best fitting the experimental sorption data. Monolayer moisture contents of MEVOP were in the range of 0.036-0.079 kg HO per kg d.s. All K values of MEVOP were higher than 0.89. C values of MEVOP obtained with RSH and UH method varied in range of 7.17-13.86 and 8.42-27.76, respectively. Net isosteric heat of sorption was evaluated using the Clausius-Clapeyron equation and differential entropy decreased with increasing moisture content. Gibbs-free energy decreased with increasing equilibrium moisture content. The spreading pressure increased with the rise in water activity for all temperatures. [ABSTRACT FROM AUTHOR]

Sorption experiments of the Cd, Zn, and Pb(II) ions from aqueous solutions on waste dolomite powder were investigated. Waste dolomite powder is inconvenient during storage due to fine particle size; therefore, its practical application is needed. The sorption experiments were conducted with variables: initial metal concentration (500, 1000, and 2000 mg/dm) in single- and multi-element solutions, adsorbent dose (0.5, 1, and 2 g), and contact time (45, 90, and 180 min). Results showed that dolomite powder removed all ions from experimental solutions. For multi-element solution, Pb(II) was adsorbed almost in 100% at the initial concentration equal to 2000 mg/dm. For Cd and Zn, sorption properties decreased with the increase in the initial metal concentration and the maximum values at the initial metal concentration of 500 mg/dm were 42 and 47%, respectively. The results suggest that waste dolomite powder can be considered for application as sorbent in wastewater purification. [ABSTRACT FROM AUTHOR]

The grafting of arginine and glutamic acid on cellulose (through an intermediary step of chlorination) allows improving uranyl sorption of the biopolymer. The sorbents (Arg-Cell and Glu-Cell) were characterized by elemental analysis, FTIR spectrometry, XRD, SEM-EDX analysis and TGA. The sorption efficiency increases with pH; this can be attributed to the deprotonation of carboxylic acid and amine groups and to the formation of polynuclear hydrolyzed uranyl species. Sorption isotherms (fitted by the Langmuir equation) show sorption capacities at saturation of the monolayer of 147 and 168 mg U g for Arg-Cell and Glu-Cell, respectively (compared to 78 mg U g for raw cellulose); maximum sorption capacities at equilibrium (experimental values) reach 138, 160 and 73.4 for Arg-Cell, Glu-Cell and cellulose, respectively. Uranyl sorption is endothermic and is spontaneous for amino acid derivatives of cellulose (contrary to exothermic for cellulose). Uptake kinetics for the different sorbents are fitted by the pseudo-second-order rate equation. Uranium can be desorbed using sulfuric acid solutions, and the sorbents can be recycled for a minimum of five cycles of sorption/desorption: the decrease in sorption capacities at the fifth cycle does not exceed 13%. [ABSTRACT FROM AUTHOR]