Retraction notice to “Novel 1-butyl-3-methylimidazolium bromide impregnated chitosan hydrogel beads nanostructure as an efficient nanobio-adsorbent for cationic dye removal: Kinetic study” [Environ. Res. 195 (2021) 110809](S0013935121001031)(10.1016/j.envres.2021.110809)

This article has been retracted: please see Elsevier policy on article withdrawal (https://www.elsevier.com/about/policies-and-standards/article-withdrawal). This article has been retracted at the request of the Editor. Concerns were raised on PubPeer at https://pubpeer.com/publications/09646A60AB7C93F65D14DB89C6A5E3, and the authors provided extensive documentation in an attempt to explain these concerns. The editor investigated the supporting data behind the unusual features of the FTIR spectra, Fig. 1, for example the observation that one wavenumber appears to have two absorbance values, contrary to the principles of FTIR spectrometry and understanding of the IR absorbance mechanism. Inspection of the excel data file of the FTIR spectrum (b) revealed that: (1) the interval between each wavenumber is inconsistent, (2) there is a missing gap between 1788 and 2975, which is significant, (3) the decimal formatting is inconsistent with that of the other three spectra, (4) there is evidence of backtracking, as reported on PubPeer, and (5) the date of this file is 2025, four years after the publication of the article. The editor therefore concludes that the FTIR spectrum (b) is unreliable. The editor also assessed the supporting data for Fig. 2, the XRD pattern of CS-BmImBr. In this case, the features observed in the PubPeer comment could possibly be attributed to issues which arose when the image was converted to black and while. Additionally, an unauthorised authorship change was made when the revised version of this paper was submitted, following suggestions for relatively minor revisions from the reviewers and Guest Editor, with author Yasin Orooji, who was suggested as a potential reviewer when the original submission was made, being added to the paper as a fourth corresponding author. No satisfactory explanation was given for this change, nor was it approved by the editor. This authorship change breaches the policies of the journal and as a result of this and the unreliability of the FTIR data, the editors no longer have confidence in this paper and are retracting it. The journal apologises for not having identified the problematic authorship change during the review process and for any resulting inconvenience. Authors Yasin Orooji and Mika Sillanpää do not agree with the retraction and dispute the grounds for it.