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Nanoemulsions are colloidal systems with a wide spectrum of applications in several industrial fields. In this study, crude oil-in-water (O/W) nanoemulsions were formulated using different dosages of the anionic sodium dodecylbenzenesulfonate (SDBS) surfactant. The formulated nanoemulsions were characterized in terms of emulsion droplet size, zeta potential, and interfacial tension (IFT). Additionally, the rheological behavior, long-term stability, and on-demand breakdown of the nanoemulsions via a pH-responsive mechanism were evaluated. The obtained results revealed the formation of as low as 63.5 nm average droplet size with a narrow distribution (33–142 nm). Additionally, highly negative zeta potential (i.e., −62.2 mV) and reasonably low IFT (0.45 mN/m) were obtained at 4% SDBS. The flow-ability of the nanoemulsions was also investigated and the obtained results revealed an increase in the nanoemulsion viscosity with increasing the emulsifier content. Nonetheless, even at the highest SDBS dosage of 4%, the nanoemulsion viscosity at ambient conditions never exceeded 2.5 mPa·s. A significant reduction in viscosity was obtained with increasing the nanoemulsion temperature. The formulated nanoemulsions displayed extreme stability with no demulsification signs irrespective of the emulsifier dosage even after one-month shelf-life. Another interesting and, yet, surprising observation reported herein is the pH-induced demulsification despite SDBS not possessing a pH-responsive character. This behavior enabled the on-demand breakdown of the nanoemulsions by simply altering their pH via the addition of HCl or NaOH; a complete and quick oil separation can be achieved using this simple and cheap demulsification method. The obtained results reveal the potential utilization of the formulated nanoemulsions in oilfield-related applications such as enhanced oil recovery (EOR), well stimulation and remediation, well-bore cleaning, and formation fracturing.

Synthetic dyes are persistent pollutants resistant to conventional treatment, necessitating effective removal strategies. This study examines the adsorption of Crystal Violet (CV) onto a ZIF-8/graphene quantum dot (Z8GD) composite under varying conditions. Batch experiments revealed strong sensitivity to operational parameters, with capacities ranging from 76 to 971 mg/g. Adsorption capacity increased from 195 to 460 mg/g as the dose decreased (0.10 → 0.04 g/L), from 200 to 401 mg/g with higher CV concentration (25 → 75 ppm), and from 162 to 971 mg/g with longer shaking time (3 → 24 h). Response Surface Methodology identified these factors as highly significant ( p  < 0.0001) and yielded a robust predictive model (R² = 0.9869). Kinetic analysis showed that the Avrami model (R² = 0.9993) best described the process, suggesting multi-mechanistic uptake. The maximum adsorption capacity reached ~ 7162 mg/g, with the Redlich–Peterson isotherm providing the best fit (R² = 0.9969). Thermodynamic analysis indicated an endothermic process (ΔH = 20.9 kJ/mol), with Gibbs free energy becoming more negative at higher temperatures (ΔG = − 30.6 to − 33.9 kJ/mol). Post-adsorption XRD and FTIR confirmed Z8GD’s structural stability and revealed multiple interactions, including π–π/CH–π stacking, hydrogen bonding, and electrostatic attraction. Machine learning models further enhanced predictive capability, with the SVR + XGB hybrid achieving the highest accuracy (R² = 0.9986). Shapley Additive Explanations identified shaking time and initial dye concentration as the most influential variables. Overall, Z8GD demonstrated exceptional adsorption capacity and mechanistic versatility, while the integration of RSM and ML provided both optimization and interpretability for adsorption behavior.

Zeolitic imidazolate frameworks (ZIFs) are increasingly gaining attention in many application fields due to their outstanding porosity and thermal stability, among other exceptional characteristics. However, in the domain of water purification via adsorption, scientists have mainly focused on ZIF-8 and, to a lesser extent, ZIF-67. The performance of other ZIFs as water decontaminants is yet to be explored. Hence, this study applied ZIF-60 for the removal of lead from aqueous solutions; this is the first time ZIF-60 has been used in any water treatment adsorption study. The synthesized ZIF-60 was subjected to characterization using FTIR, XRD and TGA. A multivariate approach was used to investigate the effect of adsorption parameters on lead removal and the findings revealed that ZIF-60 dose and lead concentration are the most significant factors affecting the response (i.e., lead removal efficiency). Further, response surface methodology-based regression models were generated. To further explore the adsorption performance of ZIF-60 in removing lead from contaminated water samples, adsorption kinetics, isotherm and thermodynamic investigations were conducted. The findings revealed that the obtained data were well-fitted by the Avrami and pseudo-first-order kinetic models, suggesting that the process is complex. The maximum adsorption capacity (qmax) was predicted to be 1905 mg/g. Thermodynamic studies revealed an endothermic and spontaneous adsorption process. Finally, the experimental data were aggregated and used for machine learning predictions using several algorithms. The model generated by the random forest algorithm proved to be the most effective on the basis of its significant correlation coefficient and minimal root mean square error (RMSE).

Drilling issues such as shale hydration, high-temperature tolerance, torque and drag are often resolved by applying an appropriate drilling fluid formulation. Oil-based drilling fluid (OBDF) formulations are usually composed of emulsifiers, lime, brine, viscosifier, fluid loss controller and weighting agent. These additives sometimes outperform in extended exposure to high pressure high temperature (HPHT) conditions encountered in deep wells, resulting in weighting material segregation, high fluid loss, poor rheology and poor emulsion stability. In this study, two additives, oil wetter and rheology modifier were incorporated into the OBDF and their performance was investigated by conducting rheology, fluid loss, zeta potential and emulsion stability tests before and after hot rolling at 16 h and 32 h. Extending the hot rolling period beyond what is commonly used in this type of experiment is necessary to ensure the fluid’s stability. It was found that HPHT hot rolling affected the properties of drilling fluids by decreasing the rheology parameters and emulsion stability with the increase in the hot rolling time to 32 h. Also, the fluid loss additive’s performance degraded as rolling temperature and time increased. Adding oil wetter and rheology modifier additives resulted in a slight loss of rheological profile after 32 h and maintained flat rheology profile. The emulsion stability was slightly decreased and stayed close to the recommended value (400 V). The fluid loss was controlled by optimizing the concentration of fluid loss additive and oil wetter. The presence of oil wetter improved the carrying capacity of drilling fluids and prevented the barite sag problem. The zeta potential test confirmed that the oil wetter converted the surface of barite from water to oil and improved its dispersion in the oil.

Effective in situ scavenging of hydrogen sulfide (H2S) while drilling a sour formation is critical for limiting the prevalent related impacts and safety hazards. Thus, it is necessary to develop a specialized additive that can selectively react with H2S and remove it without generating harmful byproducts or impairing drilling fluid performance. Additionally, waste management and utilization will transfer the waste from being an environmental and economic burden to a valuable commodity. Accordingly, we report herein the management of steelmaking waste through its utilization as a novel H2S scavenger for water-based drilling fluids, as well as the evaluation of the effects of the steelmaking waste dosage (1, 2, and 3 g) on the mud H2S scavenging capability and key properties. The H2S scavenging capacity of the waste-containing mud was investigated and compared to that of the base mud and fluids containing the commercial scavengers (triazine- and iron gluconate-based materials). In addition, the mud rheology, alkalinity, and filtering performance were studied in the presence and absence of the waste, and the findings were compared to those of commercial scavengers. This study showed that adding 1, 2, and 3 g of the steelmaking waste to the base drilling fluid significantly improved the H2S scavenging capacity by 105, 399, and 503%, respectively, while the triazine- and iron gluconate-based materials increased the capacity by 179 and 131%. Similarly, when the proportion of the steelmaking waste increased, the rheological parameters, comprising apparent viscosity, plastic viscosity, and yield point, slightly increased. The inclusion of the steelmaking waste reduced mud pH to 10.4, 9.8, and 8.5 with a content of 1, 2, and 3 g, respectively, compared to 11.0 for the base mud, 11.1 for triazine-based material, and 7.9 for iron gluconate-based scavenger. When 1 and 2 g of the steelmaking waste were added, the obtained filtrated liquid volume was preferably lower than the base mud and even the commercial scavengers-contained muds. As a result, 2 g of steelmaking waste could be added for enhanced mud performance. Nevertheless, higher amounts of the steelmaking waste could be used instead to achieve maximal H2S scavenging capability, with an extra alkalinity controller added to ensure attaining the practical recommended properties.

The indiscriminate discharge of synthetic dyes into wastewater streams poses a severe threat to the environment as well as to human well-being. Among all these dyes, methyl orange (MO) attracts attention due to its widespread use and persistence in industrial effluents. This study investigated the use of zeolitic imidazolate framework and bentonite (ZIF-67@BNT) nanocomposite material for the removal of MO from the aqueous phase. Various characterization techniques were employed such as FTIR, XRD, and TGA to verify the successful synthesis of the ZIF-67@BNT adsorbent, which was subsequently utilized to investigate the adsorption of MO. Batch adsorption studies demonstrated a high MO adsorption capacity of 187 mg/g. A response surface methodology (RSM)-based modeling exercise was used to optimize the adsorption process. While assessing the impact of various operational factors, the initial MO concentration followed by ZIF-67@BNT dose were noted to be important. Adsorption kinetics and isotherm studies were also completed. The ZIF-67@BNT nanocomposite after adsorption analysis indicated multiple mechanisms facilitating MO uptake. Additionally, various machine learning (ML) models such ANN, SVR, RF, and GPR were also utilized to predict MO adsorption onto ZIF-67@BNT nanocomposite under a varying set of conditions.

Addressing the critical issue of water pollution, this review article emphasizes the need to remove hazardous dyes and phenolic compounds from wastewater. These pollutants pose severe risks due to their toxic, mutagenic, and carcinogenic properties. The study explores various techniques for the remediation of organic contaminants from wastewater, including an enzymatic approach. A significant challenge in enzymatic wastewater treatment is the loss of enzyme activity and difficulty in recovery post-treatment. To mitigate these issues, this review examines the strategy of immobilizing enzymes on newly developed nanostructured materials like graphene, carbon nanotubes (CNTs), and metal–organic frameworks (MOFs). These materials offer high surface areas, excellent porosity, and ample anchoring sites for effective enzyme immobilization. The review evaluates recent research on enzyme immobilization on these supports and their applications in biocatalytic nanoparticles. It also analyzes the impact of operational factors (e.g., time, pH, and temperature) on dye and phenolic compound removal from wastewater using these enzymes. Despite promising outcomes, this review acknowledges the challenges for large-scale implementation and offers recommendations for future research to tackle these obstacles. This review concludes by suggesting that enzyme immobilization on these emerging materials could present a sustainable, environmentally friendly solution to the escalating water pollution crisis.

The presence of toxic selenium species in aquatic streams is on the rise because of increased anthropogenic activities. The most dominant forms in which selenium is found in the environment are the inorganic selenite and selenate species. This study investigated the removal of selenite and selenate from binary system using novel MgCuAl-layered triple hydroxide (MgCuAl-LTH) along with response surface methodology (RSM)-based process optimization under a varying set of process conditions i.e., selenite concentration, selenate concentration, and adsorbent dosage. The characterization of synthesized MgCuAl-LTH indicated the formation of highly crystalline hydrotalcite mass that has a mesoporous structure. Quadratic models, yielding selenite and selenate removal responses, were also developed, and the factors that most significantly affected the responses were the adsorbent dose followed by the concentration of selenite and selenate. The process also indicated that an increase in selenite over selenate and vice versa also favors the selenium adsorption, hence emphasizing the effect of competitive adsorption. Multiple response optimizer feature in the RSM was also used to obtain the most suitable conditions for the optimal removal of both selenium species. Furthermore, an additional experiment with a higher MgCuAl-LTH dose showed greater than 99% and 95% selenite and selenate removal, respectively. The results obtained in this study demonstrated that the novel MgCuAl-LTH can be used for the treatment of selenite and selenate in combined waste streams.

The release of toxic hydrogen sulfide gas from subsurface oil wells during oil and gas drilling operations leads to serious health and safety problems for both the drilling structures and working personnel. The implementation of controls and mitigation techniques is vital to abating the high health and economic risks associated with H 2 S exposure. The effective removal of H 2 S gas in-situ during drilling operations is key to limiting these risks. On the other hand, utilizing waste cooking oils for formulating oil-based fluids will transfer these waste oils into valuable commodities, and will make the drilling operations greener and more sustainable. Thus, waste cooking oil was utilized in this study to formulate oil-based drilling mud (OBM). The mud contained zeolitic imidazolate framework-8 (ZIF-8) NPs as an emerging material with H 2 S scavenging capability. The synthesized ZIF-8 NPs were characterized by XRD, FT-IR, TGA, and the nitrogen (N 2 ) sorption isotherm. The influence of the ZIF-8 NPs on the H 2 S scavenging capacity and viscosity of this green and sustainable OBM were investigated and compared to the base mud without ZIF-8 NPs. The incorporation of ZIF-8 NPs significantly enhanced the H 2 S scavenging capacity of the drilling fluid. The breakthrough and saturation capacities of the drilling fluid were enhanced by 150 and 245% with the addition of ZIF-8 NPs. The plastic and apparent viscosities exhibited similar behavior and were not compromised by the incorporation of ZIF-8 NPs.

The elimination of toxic and long-lasting dyes like crystal violet (CV) from wastewater continues to be a major environmental challenge. Considering this, in this study, a novel amine-modified adsorbent was synthesized by functionalizing ZIF-67 with phosphorylethanolamine (PEA@ZIF-67) nanocomposite to enhance dye removal efficiency. Comprehensive characterization of PEA@ZIF-67 nanocomposite using FTIR, XRD, TGA, and BET techniques confirmed the successful incorporation of PEA into ZIF-67 without compromising the structural integrity of the ZIF-67. The BET specific surface area of PEA@ZIF-67 nanocomposite was noted to be 145.3 m2/g. Furthermore, the application of PEA@ZIF-67 nanocomposite for CV adsorption was investigated and optimized using the Response Surface Methodology (RSM) technique, with the adsorbent dosage, initial dye concentration, and temperature as the operational variables. Under optimized conditions, qmax was 4348 mg/g. Adsorption kinetic studies showed the Avrami model to best fit the respective CV adsorption results, suggesting a heterogeneous and time-dependent mechanism. On the other hand, the Redlich–Peterson adsorption isotherm, which signifies a hybrid adsorption behavior, was noted to be effective. The thermodynamic studies confirmed that the CV adsorption onto PEA@ZIF-67 is spontaneous, endothermic, and entropy-driven. The post-adsorption FTIR and XRD analyses indicated that the used PEA@ZIF-67 was stable, thus supporting its reuse capability.