Retraction notice to "A study on the role of surface functional groups of metakaolin in the removal of methylene blue: Characterization, kinetics, modeling and RSM optimization" [Environ. Res. 226 (2023) 115604]

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editors. Figure 1 is an XRD pattern showing two identical traces. On inspection of the two raw data files provided by the authors, the difference in intensity between sample 1 (MK) and sample 2 (R-MK) is constant (10) for all values of Angle 2θ. This is unrealistic and Editors have therefore lost confidence in the reliability of the findings presented in this article and are retracting it. Additionally, unauthorised authorship changes were made when the revised version of this paper was submitted, following suggestions for relatively minor revisions from the reviewers and Guest Editor, with authors Mohammad Ahmad Wadaan, Muhammad Farooq Khan and Woog Kim being added to the paper. 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, 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.