Comment on "Removal of copper from aqueous solution by aminated and protonated mesoporous aluminas: Kinetics and equilibrium," by S. Rengaraj, Y. Kim, C.K. Joo, and J. Yi

This study presents a literature review concerning the precision of over 80 publications which originally cited Ho's pseudo-second-order kinetic expression for solute sorption on various sorbents. This model applies to a range of solid-liquid systems such as metal ions, dyestuffs, herbicides, oil, and organic substances in aqueous systems onto various sorbents. A reference section in a paper plays a key role to researchers who are interested in the paper's statement and following study or finding useful information from the paper. This section is as important as the core of a paper; however, it is easily ignored by the author. This comment offers information citing the original presentation of a pseudo-second-order kinetic expression. It is also suggested that an author not only must be creative but also must be careful while writing in order to publish more valuable and papers more worthy of reading.