Recently, Hu et al. [1]. published a paper with the above title. In section “Effect of contact time”, the authors stated, “In order to study the sorption rate constant of Ni(II) to goethite, the pseudo-second-order rate equation was used to fit the kinetic sorption of Ni(II) to goethite:” and referred to two self-citations published in 2008 and 2010 respectively [2, 3]. In fact, this kinetic model has already been published first in 1996 [4], and a modified model was presented in the following years to correct a mistake in the 1996 paper [5–7]. However the mistake in the model was duplicated by other researchers [8, 9]. In order to stop the proliferation of the mistake a comment has been made [10]. This type of error could be avoided if authors have had paid more attentions to details about the model from the original paper [11].

Accuracy in citing references is very important for the transmission of scientific knowledge. Citation errors reflect poorly on authors who republish original ideas that were already published. Hopefully, the identification of this type of problems will lead to improved accuracy in referencing [12]. Authors should make serious efforts to check the accuracy of references cited in their manuscripts as well as to read the original article before quoting it rather than citing from abstracts or cross-references [13]. It is recommended that more attention should be paid in preparing bibliographies and in checking quoted references [14].