Colloidal materials and interfaces, with their profound impact on a myriad of applications, have witnessed an unprecedented surge in research activities. The amalgamation of diverse research endeavors has illuminated the multifaceted nature of colloidal materials and interfaces, showcasing their pivotal role across various disciplines [1][2][3]. Here the research topic "2022 Retrospective: Colloidal Materials and Interfaces" has unveiled the forefront of scientific inquiry and innovation within the dynamic realm of colloidal science. One of the key strengths of this collection lies in its ability to display the extensive diversity of research undertaken across the section.The research topic embarked on a journey through five distinct papers, demonstrating a wide range of applications, from enhanced drug delivery systems and innovative ophthalmic formulations to the profound implications of mineral surface charge in reservoir rock dynamics. Five subjects are included:(1) emerging the synthesis of NiO-ZnO and NiO-CuO nanocomposites as a promising avenue for photocatalytic degradation of pollutants, which opens avenues for sustainable solutions in environmental remediation, aligning with the ever-growing importance of eco-friendly technologies. [4]; (2) exploring the potential of oxybutynin-nanoemulgel for enhanced skin permeation, laying the foundation for future innovations in topical drug administration, fostering possibilities for enhanced patient compliance and therapeutic efficacy. [5]; (3) delving into the intricate world of reservoir rock dynamics, emphasizing the role of mineral surface charge in wettability alteration, contributing to the efficiency of hydrocarbon extraction, and underscoring the significance of interdisciplinary approaches in solving real-world challenges. [6]; (4) comprehensively reviewing the unfolded the unique properties of nanocellulose from a colloidal material perspective, navigating through the colloidal intricacies of nanocellulose, shedding light on its unique properties that render it a material of choice in diverse applications. [7]; (5) presenting a breakthrough in ophthalmic drug delivery with the formulation and evaluation of microemulsions for enhanced topical administration of brinzolamide. [8]. These contributions collectively underline the interdisciplinary nature of colloidal science, where researchers seamlessly integrate principles from chemistry, physics, biology, and engineering to unravel the complexities of colloidal materials and interfaces.As we close this special issue, we extend our heartfelt appreciation to the authors, whose meticulous research has enriched our understanding of colloidal science. Additionally, we express gratitude to the reviewers for their invaluable contributions in ensuring the quality and rigor of the presented work. This research topic stands not only as a reflection on the past but also as a beacon guiding future exploration. The insights gained from these contributions will undoubtedly serve as a foundation for future breakthroughs, inspiring researchers to dig deeper into the details of colloidal materials and interfaces.We look forward to the continued evolution of colloid materials and interfaces, anticipating the next wave of discoveries that will shape our understanding of materials at the molecular and nanoscale levels. As we bid farewell to this special issue, we do so with a sense of anticipation, knowing that the journey of exploration and discovery is far from over.
Editorial25 March 2024
Editorial: 2022 Retrospective: colloidal materials and interfaces
The reservoir rock is made up of different minerals, which contribute to the overall formation wettability. These minerals in their natural state differ in chemistry and structure, thus, behave differently in an environment of varying composition and salinity. These have direct implications for enhanced oil recovery due to water flooding, or wettability alteration due to long-term exposure to brine. With the reservoir rock being a complex system of multiple minerals, the control of wettability alterations becomes difficult to manage. One of the dominant mechanisms responsible for wettability alteration is the mineral surface charge, which is dependent on pH, and fluid composition (salt type and salinity). For the first time, the surface charge development of barite, dolomite, and feldspar minerals in native reservoir environments (accounting for the formation brine complexity) is presented. Also, the effect of oilfield operations (induced pH change) on minerals’ surface charge development is studied. This was achieved by using zeta potential measurements. Zeta potential results show that barite and dolomite minerals possess positively charge surfaces in formation water and seawater, with the feldspar having a near-zero surface charge. Furthermore, the surface charge development is controlled by the H+/OH- (pH), electrical double layer effect as well as ion adsorption on the mineral’s surfaces. These findings provide key insights into the role of fluid environment (pH, composition) and oilfield operations on mineral surface charge development. In addition, results show that careful tuning of pH with seawater injection could serve as an operational strategy to control the mineral surface charge. This is important as negatively charged surfaces negate wettability alteration due to polar crude oil components. Also, the design of an ion-engineered fluid to control the surface charge of minerals was implemented and the results show that reduction in the Ca2+ concentration holds the key to the surface charge modification. Surface charge modifications as evidenced in this study play a critical role in the control of wettability alteration to enhance production.
Photocatalytic process over semiconducting oxide surfaces has attracted worldwide attention as potentially efficient, environmentally friendly, and low-cost methods for wastewater treatment. This study presented a straightforward, inexpensive, and rapid route for synthesis of Nickel oxide (NiO) and its composites with Zinc oxide (NiO/ZnO) and copper oxide (NiO/CuO) nanoparticles through chemical precipitation method using capping agent- hexadecyltrimethylammonium bromide (CTAB) for photocatalytic degradation of methylene blue dye. The structure, morphology, and elemental constituents were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The energy band-gap of pure NiO, NiO-ZnO and NiO-CuO composites was evaluated with Tauc plot from absorption spectra and resulted as 3.00, 2.90 and 3.25 eV, respectively. The optimum parameters for all photocatalysts were: pH 8, Irradiation time 175 min, Catalyst amount 75 mg, and Dye concentration 7 mg/L. At these optimum parameters, the degradation efficiency of the prepared photocatalysts towards MB dye achieved was: 89.8% for NiO, 97% for NiO/ZnO, and 94.2% for NiO/CuO. The highest activity of the p-type/n-type (NiO/ZnO) nanocomposite for MB degradation is possibly due to electron – hole pair recombination inhibition by charge transfer processes. Therefore, semiconducting composite based nanocatalysts like NiO/ZnO with high photocatalytic activity are promising for future industrial applications to remove undesirable organic pollutants from the environment.