A Bibliometric Analysis of Research on Supported Ionic Liquid Membranes during the 1995-2015 Period: Study of the Main Applications and Trending Topics

Bibliometrics of Functional Polymeric Biomaterials with Bioactive Properties Prepared by Radiation-Induced Graft Copolymerisation: A Review

Functional polymeric biomaterials (FPBMs) with bioactive characteristics obtained by radiation-induced graft copolymerisation (RIGC) have been subjected to intensive research and developed into many commercial products. Various studies have reported the development of a variety of radiation-grafted FPBMs. However, no reports dealing with the quantitative evaluations of these studies from a global bibliographic perspective have been published. Such bibliographic analysis can provide information to overcome the limitations of the databases and identify the main research trends, together with challenges and future directions. This review aims to provide an unprecedented bibliometric analysis of the published literature on the use of RIGC for the preparation of FPBMs and their applications in medical, biomedical, biotechnological, and health care fields. A total of 235 publications obtained from the Web of Science (WoS) in the period of 1985-2021 were retrieved, screened, and evaluated. The records were used to manifest the contributions to each field and underline not only the top authors, journals, citations, years of publication, and countries but also to highlight the core research topics and the hubs for research excellence on these materials. The obtained data overviews are likely to provide guides to early-career scientists and their research institutions and promote the development of new, timely needed radiation-grafted FPBMs, in addition to extending their applications.

Multiple Ensembles of the Hydrogen-bonded Network in Ethylammonium Nitrate versus Water from Vibrational Spectral Dynamics of SCN- Probe

We performed classical molecular dynamics simulations to monitor the structural interactions and ultrafast dynamical and spectral response in the protic ionic liquid, ethylammonium nitrate (EAN) and water using the nitrile stretching mode of thiocyanate ion (SCN-) as the vibrational probe. The normalized stretch frequency distribution of nitrile stretch of SCN- attains an asymmetric shape in EAN, indicating the existence of more than one hydrogen-bonding environment in EAN. We computed the 2D IR spectrum from classical trajectories, applying the response function formalism. Spectral diffusion dynamics in EAN undergo an initial rattling of the SCN - inside the local ion-cage occurring at a timescale of 0.10 ps, followed by the breakup of the ion-cage activating molecular diffusion at 7.86 ps timescale. In contrast, the dynamics of structural reorganization occur at a timescale of 0.58 ps in H 2 O. Hence, the time dependence of the frequency-frequency correlation function decay hints at the local molecular structure and ultrafast ion dynamics of the SCN - probe. The loss of frequency correlation read from the peak shape changes in the 2D correlation spectrum as a function of waiting time is faster in H 2 O than in EAN due to the enhanced structural ordering and higher viscosity of the latter. We provide an atomic-level interpretation of the solvation environment around SCN - in EAN and water, which indicates the multiple ensembles of the hydrogen bond network in EAN.

Assessment of environmental pollutants at trace levels using ionic liquids-based liquid-phase microextraction

Sample preparation is the crucial and most challenging part of analytical chemistry for the speciation of environmental pollutants' traces. Along with the development of the sample preparation methods, the ionic liquid-based microextraction technique plays an important role. Due to the unequivocally unique "green" characteristic of ionic liquids (ILs), they owe their tunable properties, such as highly selective and high reaction efficiency, reusability, and good thermal stability, to present advancements in the sample preparation process. The ionic liquid-based microextraction techniques miniaturize the sample preparation process. Liquid phase microextraction intermediate solvents, desorption solvent extractants, and mediators have been used. They are quoting the benefits and limitations of each method. A few essential sample preparation methods covered the microextraction technique. In this context, miniaturized microextraction methods have been developed. They are generally used for their unlimited positive features, including easy, simple, and environmentally friendly; they also extract inorganic and organic species with low-cost instrumentation. This review advances the sample preparation process using ILs-based liquid phase microextraction as an intermediate solvent, extractant desorption, and mediator solvents.

An Overview to Technical Solutions for Molybdenum Removal: Perspective from the Analysis of the Scientific Literature on Molybdenum and Drinking Water (1990–2019)

A bibliometric analysis using the Scopus database was performed to investigate the research documents published from 1990 to 2019 in scientific sources related to molybdenum in drinking water and determine the quantitative characteristics of the research in this period. The results from the analysis revealed that the number of publications was maintained at a regular production of around 5 papers per year until 2009, followed by a fast linear increase in the production in the period from 2010 to 2016 (29 papers in 2016), but the scientific production regarding this topic was reduced in 2017 and 2018 to recover the production obtained in 2016 once again in 2019. The total contribution of the three most productive countries (USA, China and India, respectively) accounted for around 50% of the total number of publications. Environmental Science was the most common subject (51.4% contribution), followed by Chemistry (26.7% contribution). The research efforts targeted toward the search for technical solutions for molybdenum removal from water are not as important as the ones focused on the identification of molybdenum-polluted water bodies and the analysis of the health effects of the intake of molybdenum. Nevertheless, examples of technological treatments to remove molybdenum from the aqueous solution include the use of adsorption and ion exchange; coagulation, flocculation and precipitation followed by filtration; membrane technologies and biological treatments.

A state of the art review on electrochemical technique for the remediation of pharmaceuticals containing wastewater

Pharmaceutical wastewater is a frequent kind of wastewater with high quantities of organic pollutants, although little research has been done in the area. Pharmaceutical wastewaters containing antibiotics and high salinity may impair traditional biological treatment, resulting in the propagation of antibiotic resistance genes. The potential for advanced oxidation processes (AOPs) to break down hazardous substances instead of present techniques that essentially transfer contaminants from wastewater to sludge, a membrane filter, or an adsorbent has attracted interest. Among a variety of AOPs, electrochemical systems are a feasible choice for treating pharmaceutical wastewater. Many electrochemical approaches exist now to remediate rivers polluted by refractory organic contaminants, like pharmaceutical micro-pollutants, which have become a severe environmental problem. The first part of this investigation provides the bibliometric analysis of the title search from 1970 to 2021 for keywords such as wastewater and electrochemical. We have provided information on relations between keywords, countries, and journals based on three fields plot, inter-country co-authorship network analysis, and co-occurrence network visualization. The second part introduces electrochemical water treatment approaches customized to these very distinct discarded flows, containing how processes, electrode materials, and operating conditions influence the results (with selective highlighting cathode reduction and anodic oxidation). This section looks at how electrochemistry may be utilized with typical treatment approaches to improve the integrated system's overall efficiency. We discuss how electrochemical cells might be beneficial and what compromises to consider when putting them into practice. We wrap up our analysis with a discussion of known technical obstacles and suggestions for further research.

A Bibliometric Analysis of Research on Selenium in Drinking Water during the 1990-2021 Period: Treatment Options for Selenium Removal

A bibliometric analysis based on the Scopus database was carried out to summarize the global research related to selenium in drinking water from 1990 to 2021 and identify the quantitative characteristics of the research in this period. The results from the analysis revealed that the number of accumulated publications followed a quadratic growth, which confirmed the relevance this research topic is gaining during the last years. High research efforts have been invested to define safe selenium content in drinking water, since the insufficient or excessive intake of selenium and the corresponding effects on human health are only separated by a narrow margin. Some important research features of the four main technologies most frequently used to remove selenium from drinking water (coagulation, flocculation and precipitation followed by filtration; adsorption and ion exchange; membrane-based processes and biological treatments) were compiled in this work. Although the search of technological options to remove selenium from drinking water is less intensive than the search of solutions to reduce and eliminate the presence of other pollutants, adsorption was the alternative that has received the most attention according to the research trends during the studied period, followed by membrane technologies, while biological methods require further research efforts to promote their implementation.

Research Trends on Pillared Interlayered Clays (PILCs) Used as Catalysts in Environmental and Chemical Processes: Bibliometric Analysis

Over the last four decades, a large number of studies have been published on pillared interlayered clays (PILCs) used as adsorbent materials and catalysts or supports for transition metals in heterogeneous catalysis. Particularly, PILCs have been used for water treatment through advanced oxidation processes (AOPs) to remove organic pollutants. They have also been studied in various chemical and environmental processes. Because of the growing interest in PILCs, this article is focused on analyzing scientific publications such as research/review articles and book chapters from the last four decades (from 1980 to 2019) through a bibliometric analysis (BA) to visualize and describe research trends on PILCs. By narrowing the bibliographic search to titles, keywords, and abstracts of publications related to PILCs, using Scopus and Web of Science (WoS) (the two scientific databases), a total of 3425 documents have been retrieved. The bibliometric dataset was analyzed by VantagePoint^®. The main research trends identified in the last four decades were the use of PILCs in environmental processes (34.4% of total publications) along with chemical processes (petrochemical reactions 17.5%, SCR NOx 10.8%, and decomposition 8.2%). In environmental processes, PILCs have been used in photo-oxidation (32%), CWPO (21.1%), and heterogeneous catalysis (19.4%). Phenols, dyes, and VOCs have been the main pollutants studied using PILCs as catalysts. Fe, Ti, Zr, Cu, and Co are the most supported active phases in PILCs. Other research trends grouped by characterization techniques, countries, research areas, institutes, scientific journals that have published the most on this topic, number of publications per 5-year period, and most frequently used keywords through the last four decades have been identified. It was determined that the number of publications on PILCs has increased since 1980 and the countries with the highest number of publications are China, Spain, and The United States of America.

Impact of Ionic Liquid Structure and Loading on Gas Sorption and Permeation for ZIF-8-Based Composites and Mixed Matrix Membranes

Carbon dioxide (CO2) capture has become of great importance for industrial processes due to the adverse environmental effects of gas emissions. Mixed matrix membranes (MMMs) have been studied as an alternative to traditional technologies, especially due to their potential to overcome the practical limitations of conventional polymeric and inorganic membranes. In this work, the effect of using different ionic liquids (ILs) with the stable metal-organic framework (MOF) ZIF-8 was evaluated. Several IL@ZIF-8 composites and IL@ZIF-8 MMMs were prepared to improve the selective CO2 sorption and permeation over other gases such as methane (CH4) and nitrogen (N2). Different ILs and two distinct loadings were prepared to study not only the effect of IL concentration, but also the impact of the IL structure and affinity towards a specific gas mixture separation. Single gas sorption studies showed an improvement in CO2/CH4 and CO2/N2 selectivities, compared with the ones for the pristine ZIF-8, increasing with IL loading. In addition, the prepared IL@ZIF-8 MMMs showed improved CO2 selective behavior and mechanical strength with respect to ZIF-8 MMMs, with a strong dependence on the intrinsic IL CO2 selectivity. Therefore, the selection of high affinity ILs can lead to the improvement of CO2 selective separation for IL@ZIF-8 MMMs.

Self-Healing Asphalt: A Systematic Bibliometric Analysis for Identification of Hot Research Topics during the 2003-2018 Period

The use of self-healing asphalt is a good option to extend the lifetime of roads and to improve the sustainability of pavement management systems. A bibliometric analysis based on the Scopus database was carried out to review the global research related to self-healing asphalt from 2003 to 2018 and to identify relevant quantitative characteristics from the research in this period. The results from this analysis revealed that the number of accumulated publications followed an exponential growth, which confirmed the relevance that this research topic has gained during the last years. The study revealed that China was the most productive country, followed by the Netherlands, where the most prolific institution is located: Delft University of Technology. Some important research features of the two main approaches most frequently used to develop asphalt mixtures with enhanced self-healing abilities (external heating and encapsulated rejuvenating agents) are compiled in this work.

An Analysis of Research on Membrane-Coated Electrodes in the 2001–2019 Period: Potential Application to CO2 Capture and Utilization

The chemistry and electrochemistry basic fields have been active for the last two decades of the past century studying how the modification of the electrodes’ surface by coating with conductive thin films enhances their electrocatalytic activity and sensitivity. In light of the development of alternative sustainable ways of energy storage and carbon dioxide conversion by electrochemical reduction, these research studies are starting to jump into the 21st century to more applied fields such as chemical engineering, energy and environmental science, and engineering. The huge amount of literature on experimental works dealing with the development of CO2 electroreduction processes addresses electrocatalyst development and reactor configurations. Membranes can help with understanding and controlling the mass transport limitations of current electrodes as well as leading to novel reactor designs. The present work makes use of a bibliometric analysis directed to the papers published in the 21st century on membrane-coated electrodes and electrocatalysts to enhance the electrochemical reactor performance and their potential in the urgent issue of carbon dioxide capture and utilization.

An Evolutionary Approach to Technology Innovation of Cadastre for Smart Land Management Policy

In this study, we attempted to quantitatively determine the characteristics of keyword networks in the cadastre field using major contents of research drawn from international academic papers. Furthermore, we investigated the macroscopic evolution of cadastral research and examined its keyword network in detail (at a global scale) using semantic analysis. The analysis was carried out based on cadastral-research-related publications extracted from “Scopus” for 1987 to 2019. It was found that cadastre research has closely followed the recent trend of a growing interest in research on geospatial information and standardization. The results showed the advancement of technology innovation within the field of cadastres, as highlighted in the combination of relevant keywords (mostly from those related to spatial information technology and participation of civilians). These new issues are expected to drive the evolution of the academic scope in the future through synthesis with other fields for smart land management policy.

Development and Application of Supported Ionic Liquid Membranes in Microbial Fuel Cell Technology: A Concise Overview

Membrane separators are key elements of microbial fuel cells (MFCs), especially of those constructed in a dual-chamber configuration. Until now, membranes made of Nafion have been applied the most widely to set-up MFCs. However, there is a broader agreement in the literature that Nafion is expensive and in many cases, does not meet the actual (mainly mass transfer-specific) requirements demanded by the process and users. Driven by these issues, there has been notable progress in the development of alternative materials for membrane fabrication, among which those relying on the deployment of ionic liquids are emerging. In this review, the background of and recent advances in ionic liquid-containing separators, particularly supported ionic liquid membranes (SILMs), designed for MFC applications are addressed and evaluated. After an assessment of the basic criteria to be fulfilled by membranes in MFCs, experiences with SILMs will be outlined, along with important aspects of transport processes. Finally, a comparison with the literature is presented to elaborate on how MFCs installed with SILM perform relative to similar systems assembled with other, e.g., Nafion, membranes.

Supported Ionic Liquid Membranes for Separation of Lignin Aqueous Solutions

Lignin valorization is a key aspect to design sustainable management systems for lignocellulosic biomass. The successful implementation of bio-refineries requires high value added applications for the chemicals derived from lignin. Without effective separation processes, the achievement of this purpose is difficult. Supported ionic liquid membranes can play a relevant role in the separation and purification of lignocellulosic components. This work investigated different supported ionic liquid membranes for selective transport of two different types of technical lignins (Kraft lignin and lignosulphonate) and monosaccharides (xylose and glucose) in aqueous solution. Although five different membrane supports and nine ionic liquids were tested, only the system composed by [BMIM][DBP] as an ionic liquid and polytetrafluoroethylene (PTFE) as a membrane support allowed the selective transport of the tested solutes. The results obtained with this selective membrane demonstrated that lignins were more slowly transferred from the feed compartment to the stripping compartment through the membrane than the monosaccharides. A model was proposed to calculate the effective mass transfer constants of the solutes through the membrane (values in the range 0.5–2.0 × 10−3 m/h). Nevertheless, the stability of this identified selective membrane and its potential to be implemented in effective separation processes must be further analyzed.

Alternatives for Chemical and Biochemical Lignin Valorization: Hot Topics from a Bibliometric Analysis of the Research Published During the 2000–2016 Period

A complete bibliometric analysis of the Scopus database was performed to identify the research trends related to lignin valorization from 2000 to 2016. The results from this analysis revealed an exponentially increasing number of publications and a high relevance of interdisciplinary collaboration. The simultaneous valorization of the three main components of lignocellulosic biomass (cellulose, hemicellulose, and lignin) has been revealed as a key aspect and optimal pretreatment is required for the subsequent lignin valorization. Research covers the determination of the lignin structure, isolation, and characterization; depolymerization by thermal and thermochemical methods; chemical, biochemical and biological conversion of depolymerized lignin; and lignin applications. Most methods for lignin depolymerization are focused on the selective cleavage of the β-O-4 linkage. Although many depolymerization methods have been developed, depolymerization with sodium hydroxide is the dominant process at industrial scale. Oxidative conversion of lignin is the most used method for the chemical lignin upgrading. Lignin uses can be classified according to its structure into lignin-derived aromatic compounds, lignin-derived carbon materials and lignin-derived polymeric materials. There are many advances in all approaches, but lignin-derived polymeric materials appear as a promising option.