Accurate prediction of the colloid-driven transport of radionuclides in porous media is critical for the long-term safety assessment of radioactive waste disposal repository. However, the co-transport and corelease process of radionuclides with colloids have not been well documented, the intrinsic mechanisms for colloids-driven retention/transport of radionuclides are still pending for further discussion. Thus the controlling factors and governing mechanisms of co-transport and co-release behavior of Eu(III) with bentonite colloids (BC) were discussed and quantified by combining laboratory-scale column experiments, colloid filtration theory and advection dispersion equation model. The results showed that the role of colloids in facilitating or retarding the Eu(III) transport in porous media varied with cations concentration, pH, and humic acid (HA). The transport of Eu(III) was facilitated by the dispersed colloids under the low ionic strength and high pH conditions, while was impeded by the aggregated colloids cluster. The enhancement of Eu(III) transport was not monotonically risen with the increase of colloids concentration, the most optimized colloids concentration in facilitating Eu(III) transport was approximately 150 mg L⁻¹. HA showed significant promotion on both Eu(III) and colloid transport because of not only its strong Eu(III) complexion ability but also the increased dispersion of HA-coated colloid particles. The HA and BC displayed a synergistic effect on Eu(III) transport, the co-transport occurred by forming the ternary BC-HA-Eu(III) hybrid. The transport patterns could be simulated well with a two-site model that used the advection dispersion equation by reflecting the blocking effect. The retarded Eu(III) on the stationary phase was released and remobilized by the introduction of colloids, or by a transient reduction in cation concentration. The findings are essential for predicting the geological fate and the migration risk of radionuclides in the repository environment.

Aflatoxin M₁ (AFM₁) and ochratoxin A (OTA) are highly toxic mycotoxin metabolites that are found as food pollutants, posing health risks to humans and animals. The objective of the current study is to establish a sensitive, reliable method for determining AFM₁ and OTA using high-performance liquid chromatography (HPLC) and attempting to assess the efficacy of bentonite, date pit, and chitosan nanoparticles for AFM₁ and OTA detoxification from contaminated milk. As revealed, AFM₁ was found in 65.7% of analyzed samples ranging from 4.5 to 502 ng/L, while 25.7% of examined samples contained OTA ranging from 1.45 to 301 ng/L. Furthermore, for AFM₁ and OTA. The advanced procedure was thoroughly validated by evaluating linearity (R² > 0.999), LOD (0.9615 and 0.654 ng/L), and LOQ (2.8846 and 1.963 ng/L), recovery (93–95% and 87–91%), as well as precision (≤ 1%RSD). The experimental data revealed a higher removal efficiency of bentonite and date pit than chitosan nanoparticles in the case of AFM₁ (68%, 56%, and 12%) and OTA (64%, 52%, and 10%), respectively with slight change in nutritional milk components like fat, protein, and lactose. Eventually, it is concluded that bentonite and date pit can be considered efficient adsorbing agents to extract AFM₁ and OTA from contaminated milk.

The leakage of chemical compounds in landfill leachate led to serious environment pollution, especially, the compounds termed endocrine disruptors such as bisphenol A (BPA). It is very important to study the adsorption behavior of endocrine disruptors in modified soil for predicting and evaluating the potential harm of endocrine disruptors to the soil. Bentonite-amended Chinese loess mixtures, with various proportions of bentonite, were used for the removal of BPA from an aqueous solution. A batch test was used to investigate the adsorption properties of bisphenol A on bentonite and Chinese loess mixtures. The influences of bentonite proportion, temperature, reaction time, pH, and soil-water ratios on the adsorption process were considered. The Fourier transform infrared spectra (FTIR) was used to clarify the change of functional groups before and after the adsorption of BPA on soil. The adsorption mechanism of BPA on soil was discussed preliminary. The results show that the addition of bentonite to the loess can improve the adsorption rate of BPA. The adsorption of BPA was mainly a spontaneous, exothermic, entropy decreasing physical adsorption process. The interaction between bentonite content and reaction concentration had a beneficial effect on BPA adsorption. The linear relationship between bentonite content and adsorption capacity was obtained. The results indicate that bentonite amended loess can provide a good liner for BPA.

This study evaluated the adsorption of the herbicide 2,4-D in a fixed bed adsorption system using organophilic clay obtained from the chemical modification of sodium bentonite commercialized as Fluidgel®. For this purpose, the operating conditions of the adsorption column were evaluated, such as flow rate (1, 3, and 5 mL min⁻¹) and initial pesticide concentration (10, 20, and 30 mg L⁻¹), and the operational parameters of the bed were calculated for each experimental condition. A flow rate of 1 mL min⁻¹ and initial concentration of 10 mg L⁻¹ were the operational conditions that provided the best operational results for the column, obtaining a rupture time of 1700 min, hMZT of 3.8 cm, and useful and total removal percentages of 96 and 76.6%, respectively. The mathematical models of Thomas and Yoon & Nelson were the most predictive to the breakthrough curves raised, obtaining high correlation coefficient values (R

The present study evaluates the performance of an indigenously developed ceramic ultrafiltration (UF) membrane in a lab-scale membrane bioreactor (MBR) process to treat real tannery effluent with varying organic loading (1500–6000 mg/L). UF membrane was prepared by the coating of bentonite clay on tubular clay-alumina macroporous support. The membrane surface was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, BET adsorption–desorption, contact angle measurement, and atomic force microscopy. In the side-stream MBR process, sewage sludge from a local sewage treatment plant was used as an activated sludge source with a constant sludge retention time of 30 days. Membrane filtration was performed in cross-flow mode using a single-channel membrane module. Artificial neural network (ANN) modeling tool was used to analyze the influence of various independent input variables, namely, the hydraulic retention time (4–10 h), mixed liquor suspended solid (MLSS) concentration (2–8 g/L), and influent COD concentration (1500–6000 mg/L) on COD removal (%) with feed-forward backpropagation method. Membrane study was done at a transmembrane pressure of 4.3 bar and feed flow rate of 7.5 L/min to observe the flux declination and fouling of the UF membrane with time. Average COD and BOD concentrations obtained in the treated effluent were 147.56 and 31 mg/L, respectively, and chromium concentration was < 0.1 mg/L; thus, treated effluent quality was found to be suitable for industrial recycling purposes apart from the safe environmental discharge. An in-depth study was undertaken to understand the removal mechanism in the MBR process, nature and extent of membrane fouling, changes in the morphology of the UF membrane, surface wettability, and surface topology by detailed surface characterization of the membrane pre- and post-filtration.

The objectives of this study were investigating the photodegradation of the polycyclic aromatic hydrocarbons (PAHs) in modified petroleum impregnated bentonite mulch through solar radiation, determining PAHs’ translocation in the soils that underlay the mulch and finding a solution to prevent the uncontrolled release of petroleum into the environment. For this research, various formulated mulches were prepared: mulch no. 1 was a mixture of 5:1 sandy soil: natural bentonite + petroleum; mulch no. 2 composed a mixture of 5:1 sandy soil: modified bentonite + natural bentonite + petroleum; and mulch no. 3 composed a mixture of 5:1:0.5 ratio of sandy soil: natural bentonite: modified bentonite mixed with petroleum at a ratio of 1:1. PAHs in surface mulches and subsurface sandy soil were monitored over 5, 20, 40 and 80 days. The results demonstrated that PAHs undergo numerous changes over time because of sunlight. Photodegradation is the most dominant process for low molecular weight (LMW) PAHs (≤ 3 fused aromatic rings) and high molecular weight (HMW) PAHs (≥ 4 fused aromatic rings). HMW PAHs could be sequestrated strongly within the soil particles because of their higher aromaticity and lower polarity; they were more resilient in the soil matrices than LMW PAHs. Mulch no. 2 retained more PAHs compounds (p > 95%) than mulch nos. 1 and 3, which could be attributed to the retention of numerous PAHs in its interlayers, preventing its movement into the underlying soil, environment and atmosphere.

The current research describes the synthesis, characterization and application of CoFe₂O₄/g-C₃N₄/bentonite as a novel nanocomposite for the efficient degradation of aniline blue under solar irradiation. Powder XRD, TIR, SEM, TEM, VSM and UV-DRS were used to describe the formation and morphology of the composite. The composite has been used as a heterogeneous photocatalyst to degrade aniline blue in the presence of H₂O₂. In the presence of H₂O₂ in solar radiation, it was possible to degrade 88.5% of 10 ppm aniline blue solution just in 50 min using 50 mg of the composite. The improvement in photodegradation rate in the existence of H₂O₂ was attributed to the advanced oxidation process (AOP) mechanism of photo-Fenton involving the production of reactive hydroxyl and perhydroxyl radicals. The degradation was found to follow first-order kinetics with high regression coefficient with elevated rate constant.

In this article, dynamic simulation experiments have studied the effects of three capping materials, quartz sand (QS), aluminum-based phosphorus-locking agent (Al-PIA), and lanthanum-modified bentonite (LMB) in reducing phosphorus load in eutrophic water bodies. The changes of various forms of phosphorus in Al-PIA and sediment before and after the test were analyzed, and the mechanism of phosphorus migration and transformation in different capping systems was described. The dynamic simulation test lasted 95 days. The results showed that when the initial concentration of total phosphorus (TP) was 3.55 mg/L, the capping strength was 2 kg/m² and the hydraulic retention time of water circulation was 0.5 days, indicating that the average reduction rates of TP by LMB, Al-PIA and QS systems were 74.66%, 69.54%, and 3.64%, respectively, compared with the control system. The analysis of variance showed that there were significant differences (P < 0.05) in the TP concentration of the overlying water between the LMB, Al-PIA capping system, and the control system. Lanthanum ions in LMB can fix phosphorus. Al-PIA reduces the phosphorus concentration in water by means of ion exchange, adsorption, complexation, etc. LMB and Al-PIA promoted the migration of phosphorus in sediment. Among them, the phosphorus fixed by Al-PIA was mainly in the form of non-apatite inorganic phosphorus (NAIP) in inorganic phosphorus (IP), which can be seen; Al-PIA can effectively reduce the phosphorus load of eutrophic water.

Worldwide, freshwater environments are impacted by inputs of nutrients and dissolved organic matter from human activities. Yet, the recovery of aquatic systems is usually focused only on nutrient management. In our work, we presented the case of an urban and hypereutrophic environment (Pampulha reservoir, Belo Horizonte, Brazil) that receives discharges from several streams and was treated with lanthanum modified bentonite (Phoslock®) and microbial bioremediation (Enzilimp®). Our goals were to evaluate whether the treatment could improve the water quality and characterize the spatiotemporal variation of dissolved organic matter sources and indices according to absorbance and fluorescence measurements from the reservoir and streams post-application months (2018). In our results, the reservoir showed a relative decrease in its phosphorus concentration compared to data from before the treatment. On the other hand, carbon concentrations reached expressive values in the post-application months following a similar pattern found in the streams. Our data showed that the reservoir’s high resistance in its hypereutrophic condition was related to the elevated loading of external inputs coming from the streams. The parallel factor analysis (PARAFAC) identified four main carbon sources, two of them being potential tracers of organic pollution in the Pampulha reservoir and watershed, together with absorbance and fluorescence indices. Our findings suggest that carbon parameters can be essential tools to provide adequate monitoring and optimization of water recovery attempts in complex, polluted environments.

In this study, an innovative material (nitrogen, phosphorus, and oxygen controlling agent, NOC) was synthesized by calcium peroxide (CaO₂), magnesium chloride (MgCl₂), bentonite, zeolite, cement, stearic acid (SA), citric acid (CA), and silver sand. The treatment performance of NOC in mimic black-odor river water was investigated in lab-scale, and the results showed that over 73.7% phosphorus and 77% ammonia nitrogen were removed from river water with the addition of 470 g NOC at 30 mL h⁻¹ flow rate, demonstrating that the presence of NOC could remove phosphorus and ammonia nitrogen simultaneously. Moreover, the addition of NOC could release oxygen with tender influence on pH in water. Calcium phosphate (Ca-P), aluminum phosphate (Al-P), and ferric phosphate (Fe–P) in the river sediment increased from 1.6, 0.136, and 0.12 mg g⁻¹ to 2.16, 0.242, and 0.196 mg g⁻¹ for 28 days, respectively. The results manifested that the mobile phosphorus could be adsorbed by NOC and further transformed to inert phosphorus form, thereby restraining the release of endogenous phosphorus from sediment to the overlying water. Besides, the relative abundance of microorganisms could be enhanced with the existence of NOC, further promoting the removal of phosphorus. Hence, NOC could be applied to the efficient remediation of the black-odor river.