Cellulose (2021) 28:9857–9871
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Results and discussion
same time, grants the fulfilment of peer review and all other essential requirements of scientific practice. Search was limited to dates comprised between 1975 and 2020, using the keyword string TITLE-ABS- KEY ( cellulose AND ( coagulant OR fl occulant )), obtaining 460 matches. We excluded non-related areas, e.g. , medicine and odontology, which fall far from the scope of this work, even though they fulfilled the search requirements.
Evolution of scientific production
The number of matches from the search engine, 460, is deemed suitable for a bibliometric analysis, given that it belongs to the usual range of results in bibliometric studies on similar topics (Zhang et al 2020; Malik et al. 2020). The year 1975 is a proper starting point to assess the progression of the scientific production, as therefrom publications occur on a continuous basis. During the two following decades there are few variations in the publications (Fig. 1). However, from 1995 onwards a change of trend can be observed as references gradually increase, and from 2010 growth is faster, evidencing the rising interest in research on cellulose applica- tions as flocculant and coagulant. These publications are mainly research articles (82%) written in English (89%), as can be seen in Figs. S1 and S2 (supple- mentary material).
Data analysis
Scopus matches were processed to extract the data that was required to analyse the number of publica- tions by year, the distribution of publications by affiliation and country, the universities and funding institutions accounting for most publications, the journals containing most publications and related citations, and the most relevant authors. Furthermore, the present work particularly emphasised the impor- tance of the keywords used in the scientific literature. For the analysis of keywords, we acknowledged that some terms can be used with the same meaning, such as bacteria and bacterium . Moreover, terms that could not contribute to the study were discarded (e.g., article ). For the same reason, while the use of paper as material was accepted, the use of paper as document was obviously rejected. This analysis encompassed keywords that appeared at least 5 times, obtaining a map which comprised a total of 332 terms. These terms could be classified into 5 groups or clusters. In order to consider an association of institutions as a scientific community, we inquired whether or not such association implied a tighter collaboration than the ones between each of those institutions and the rest of the research network. Scientific communities, attending to specific keywords in each case, were determined by means of two software packages: VOSviewer (Leiden University and CWTS), which allows for editing graphs in such a way that links between institutions or countries are shown as nodes, meaning tight collaboration. Likewise, the software OpenRefine (open source) was generally used to process the raw data provided by the search engine.
Analysis by subject area
As can be seen from Fig. 2, the branch of scientific knowledge accounting for the highest number of publications is Materials Science (22% of total). Over 80% was published within five subject areas, which, besides Materials Science, include Chemistry (19%), Chemical Engineering (16%), Engineering (14%) and Environmental Sciences (11%). Figure 2 shows how the study of cellulose-based coagulants and flocculants benefits from a
Fig. 1 Number of publications on cellulose based flocculants and coagulants from 1975 to 2020
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