Functional ligand anchored nanomaterial based facial adsorbent for cobalt(II) detection and removal from water samples

Ligand anchored functional nanomaterials are increasingly gaining interest as efficient materials for various types of toxic pollutants. In this study, the organic ligand of N,N′di(3-carboxysalicylidene)-3,4diamino-5-hydroxypyrazole was densely anchored onto the mesoporous silica by the building-block approach as facial adsorbent, characterized and then examined for the cobalt (Co(II)) ion detection and removal from aqueous solutions. The fixed-time approach was employed for analytical signal measurement in the detection operation. At optimum conditions, the calibration curve was linear in the range of 0.002–0.10 mg/L Co(II) and the limit of detection was also achieved at 0.24 μg/L. Moreover, the diverse ions did not show any significant absorbance intensity. Therefore, the established facial adsorbent provided a simple, rapid, cheap and sensitive method for Co(II) detection and could be used to detect Co(II) ions in the environment. This study also examined the possibility of using facial adsorbent to remove low concentrations of Co(II) ions from water solution. The sorption capacity was significantly affected by solution acidity, contact time and initial Co(II) ion concentration. The higher sorption capacity of the Co(II) ions was observed at higher pH regions. The sorption isotherms fit the Langmuir sorption model well and the maximum Co(II) ion sorption capacity was 157.73 mg/g. The effective eluent of 0.20 M HCl was used to elute the Co(II) from the facial adsorbent, and the adsorbent was simultaneously regenerated into the initial form after rinsing with water. The elution and regeneration showed that the adsorbent could be reused without significant losses of its initial properties even after 8 sorption–elution–reuse cycles. Therefore, the facial adsorbent could be used as a promising adsorbent for fast Co(II) ion detection and removal and might provide a simple and effective method for the treatment of water containing Co(II).