Removal of Boron and Manganese Ions from Wet-Flue Gas Desulfurization Wastewater by Hybrid Chitosan-Zirconium Sorbent

Exploring research on ecotechnology through artificial intelligence and bibliometric maps

Ecotechnology, quintessential for crafting sustainable socio-environmental strategies, remains tantalizingly uncharted. Our analysis, steered by the nuances of machine learning and augmented by bibliometric insights, delineates the expansive terrain of this domain, elucidates pivotal research themes and conundrums, and discerns the vanguard nations in this field. Furthermore, we deftly connect our discoveries to the United Nations' 2030 Sustainable Development Goals, thereby accentuating the profound societal ramifications of ecotechnology.

Chitosan: Structural and Chemical Modification, Properties, and Application

Chitosan is a polymer of natural origins that possesses many favourable properties [...].

Cerium(IV) chitosan-based hydrogel composite for efficient adsorptive removal of phosphates(V) from aqueous solutions

The excess presence of phosphate(V) ions in the biosphere is one of the most serious problems that negatively affect aqueous biocenosis. Thus, phosphates(V) separation is considered to be important for sustainable development. In the presented study, an original cerium(IV)-modified chitosan-based hydrogel (Ce-CTS) was developed using the chemical co-precipitation method and then used as an adsorbent for efficient removal of phosphate(V) ions from their aqueous solutions. From the scientific point of view, it represents a completely new physicochemical system. It was found that the adsorptive removal of phosphate(V) anions by the Ce-CTS adsorbent exceeded 98% efficiency which is ca. 4-times higher compared with the chitosan-based hydrogel without any modification (non-cross-linked CTS). The best result of the adsorption capacity of phosphates(V) on the Ce-CTS adsorbent, equal to 71.6 mg/g, was a result of adsorption from a solution with an initial phosphate(V) concentration 9.76 mg/dm3 and pH 7, an adsorbent dose of 1 g/dm3, temperature 20 °C. The equilibrium interphase distribution data for the Ce-CTS adsorbent and aqueous solution of phosphates(V) agreed with the theoretical Redlich-Peterson and Hill adsorption isotherm models. From the kinetic point of view, the pseudo-second-order model explained the phosphates(V) adsorption rate for Ce-CTS adsorbent the best. The specific effect of porous structure of adsorbent influencing the diffusional mass transfer resistances was identified using Weber-Morris kinetic model. The thermodynamic study showed that the process was exothermic and the adsorption ran spontaneously. Modification of CTS with cerium(IV) resulted in the significant enhancement of the chitosan properties towards both physical adsorption (an increase of the point of zero charge of adsorbent), and chemical adsorption (through the presence of Ce(IV) that demonstrates a chemical affinity for phosphate(V) anions). The elaborated and experimentally verified highly effective adsorbent can be successfully applied to uptake phosphates(V) from aqueous systems. The Ce-CTS adsorbent is stable in the conditions of the adsorption process, no changes in the adsorbent structure or leaching of the inorganic filling were observed.

Mapping the research on desulfurization wastewater: Insights from a bibliometric review (1991-2021)

Desulfurization wastewater in coal-fired power plants (CFPPs) is a great environmental challenge. This study aimed at the current status and future research trends of desulfurization wastewater by bibliometric analysis. The desulfurization wastewater featured with high sulfate (8000 mg/L), chlorite (8505 mg/L), magnesium (2882 mg/L) and calcium (969 mg/L) but low sodium (801.82 mg/L), and the concentrations of the main contaminants were critically summarized. There was an increasing trend in the annual publications of desulfurization wastewater in the period from 1991 to 2021, with an average growth rate of 15%. Water Science and Technology, Desalination and Water Treatment, Energy & Fuels, Chemosphere, and Journal of Hazardous Materials are the top 5 journals in this field. China was the most productive country (58.3% of global output) and the core country in the international cooperation network. Wordcloud analysis and keyword topic trend demonstrated that removal/treatment of pollutants dominated the global research in the field of desulfurization wastewater. The primary technologies for desulfurization wastewater treatment were systematically evaluated. The physicochemical treatment technologies occupied half of the total treatment methods, while membrane-based integrated processes showed potential applications for beneficial reuse. The challenges and outlook on desulfurization wastewater treatment for achieving zero liquid discharge are summarized.

Arsenic in drinking water: overview of removal strategies and role of chitosan biosorbent for its remediation

Accessibility to clean drinking water often remains a crucial task at times. Among other water pollutants, arsenic is considered a more lethal contaminant and has become a serious threat to human life globally. This review discussed the sources, chemistry, distribution, and toxicity of arsenic and various conventional technologies that are in option for its removal from the water system. Nowadays, biosorbents are considered the best option for arsenic-contaminated water treatment. We have mainly focused on the need and potential of biosorbents especially the role of chitosan-based composites for arsenic removal. The chitosan-based sorbents are economically more efficient in terms of their, low toxicity, cost-effectiveness, biodegradability, eco-friendly nature, and reusability. The role of various modification techniques, such as physical and chemical, has also been evaluated to improve the physicochemical properties of biosorbent. The importance of adsorption kinetic and isotherm models and the role of solution pH and pH_PZC for arsenic uptake from the polluted water have also been investigated. Some other potential applications of chitosan-based biosorbents have also been discussed along with its sustainability aspect. Finally, some suggestions have been highlighted for further improvements in this field.

Boron Removal by Sorption on Modified Chitosan Hydrogel Beads

An excess concentration of boron in irrigation and drinking water can negatively affect the yield of plants and the human nervous system, respectively. To meet the recommended levels, hybrid biosorbent hydrogel beads based on chitosan and manganese (II-IV) were employed for the removal of boron from aqueous media. The results showed that the biosorbent effectively removed boric acid from the aqueous medium at neutral pH over a sorption time of 2 h and the liquid/hydrogel ratio of 20 mL/g, achieving a maximum sorption capacity near 190 mg/g. The modeling of the sorption equilibrium data indicated that the Freundlich isotherm equation gave the best fit out of the isotherm models examined. A pseudo-second-order model was found to best describe the sorption kinetics. The favorable attachment of manganese to the chitosan structure enabled the sorption of boron and was confirmed by FTIR, RS, XRD, SEM and ICP-OES methods. Boron desorption from the spent biosorbent was successfully achieved in three cycles using a NaOH solution. In general, the results of this research indicate that this method is one of the possibilities for improving water quality and may contribute to reducing pollution of the aquatic environment.

Recent advances in adsorption and coagulation for boron removal from wastewater: A comprehensive review

The anthropogenic emission of boron to river has become a serious problem that deteriorates the water quality and endangers the ecosystem. Although boron is a micronutrient, it is toxic to plants, animals and humans upon exposure. In this review, we first present the sources of the boron-containing streams and their composition, and then summarize the recent progress of boron removal methods based on adsorption and coagulation systematically. The boron-spiked streams are produced from coal-fired and geothermal power plants, the manufacturing and the activities of oil/gas excavation and mining. The adsorbents for boron removal are classified into the ones functionalized by chelating groups, the ones on the basis of clays or metal oxide. Three subgroups reside in the coagulation approach: electrocoagulation, chemical precipitation and chemical oxo-precipitation. The hybrid technology that combines membrane process and adsorption/coagulation was covered as well. To provide a comprehensive view of each method, we addressed the reaction mechanism, specified the strength and weakness and summarized the progress in the past 5 years. Ultimately, the prospective for future research and the possible improvement on applicability and recyclability were proposed.

Polymeric Materials for Water and Wastewater Management

Water is a crucial point of interest nowadays due to its special management [...].

Luminescent Properties of Lanthanoid-Poly(Sodium Acrylate) Composites: Insights on the Interaction Mechanism

The interaction between polyelectrolytes and metal ions is governed by different types of interactions, leading to the formation of different phases, from liquid state to weak gels, through an appropriate choice of metal ion/polyelectrolyte molar ratio. We have found that lanthanide ions, europium(III) and terbium(III), are able to form polymer composites with poly(sodium acrylate). That interaction enhances the luminescent properties of europium(III) and terbium(III), showing that Eu³⁺/poly(sodium acrylate) (PSA) and Tb³⁺/PSA composites have a highly intense red and green emission, respectively. The effect of cations with different valences on the luminescent properties of the polymer composites is analyzed. The presence of metal ions tends to quench the composite emission intensity and the quenching process depends on the cation, with copper(II) being by far the most efficient quencher. The interaction mechanism between lanthanoid ions and PSA is also discussed. The composites and their interactions with a wide range of cations and anions are fully characterized through stationary and non-stationary fluorescence, high resolution scanning electronic microscopy and X-ray diffraction.