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

Abstract

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.

Innovative Membrane Technologies for the Treatment of Wastewater Polluted with Heavy Metals: Perspective of the Potential of Electrodialysis, Membrane Distillation, and Forward Osmosis from a Bibliometric Analysis

“…The clear supremacy of articles when compared to other types of publications was totally consistent with the results mentioned by other authors who investigated the research published regarding water pollutants and treatment technologies [39,55,56]. However, the relatively high contribution of reviews is not so frequently reported, since the importance of the contributions in congress is significant in several engineering fields, including chemical, civil, and environmental [37,[57][58][59], although some examples with a higher relative importance of reviews over congress contributions can be found [36,60,61]. Therefore, the higher importance of reviews when compared to conference papers can be linked to topics with elevated numbers of documents published, which can be revised and summarized by the corresponding reviews.…”

“…This approach enables access to relevant information and knowledge about the status of scientific research activities in specific disciplines, which helps researchers to identify novel schemes among the research [36]. Numerous bibliometric studies directly related to water pollution and wastewater treatment have been published [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52].…”

Adsorption Removal of Mo(VI) from an Aqueous Solution by Alumina with the Subsequent Regeneration of the Adsorbent

“…Molybdenum (Mo) is an essential microelement for humans, animals and plant life [1]. It is also widely used for different industrial applications such as high-speed tools, coating processes and metallurgy for improving alloys [2][3][4][5].…”

“…The average concentration of Mo in natural water reservoirs is normally 10 µg/L or less, but cases of significant excesses of this concentration (up to mg/L) are quite common [8]. The elevated Mo content in ecosystems is the result of anthropogenic activities such as mining and industrial activities associated with the production of alloys, catalysts, ceramics, lubricants and pigments [1,8]. In natural water reservoirs and industrial wastewater, Mo exists mainly in the form of Mo(VI) molybdate oxoanions.…”

Immobilisation of Molybdenum in a Sulphate-Reducing Bioreactor

“…Molybdenum, which is found as Mo(VI) in such wastewater and leachates, can be recovered via various methods [7,8], such as precipitation [9,10], adsorption [11,12] and solvent extraction [13,14]. Among the precipitation methods, sulphide precipitation is generally advantageous due to the lower solubility of metal sulphide precipitates, faster reaction rates, better settling properties and potential for selective metal removal and further valorisation of sulphide precipitates by smelting or hydrometallurgical treatment [15].…”