Fabrication of Tannin-Based Dithiocarbamate Biosorbent and Its Application for Ni(II) Ion Removal

Modified natural biosorbents have been the research hot spot in wastewater treatment field. Natural polyphenol compounds, tannins with many functional groups can be easily modified to produce biosorbents. This work presents an environmentally friendly tannin-based dithiocarbamate (TDTC) with enhanced function of adsorption. TDTC was successfully synthesized by a two-step method involving Mannich reaction and esterification. The structure and synthetic mechanisms of TDTC were discussed through instrumental analysis. The BET-specific surface area analysis results showed that TDTC exhibited a mesoporous structure with an increased surface area. Parameters affecting adsorption such as initial pH, adsorbent dosage, contact time, initial concentration, and temperature were systematically examined. Results showed that the maximum adsorption capacity toward Ni(II) of TDTC was 112.49 mg/g. In addition, TDTC exhibited a fast adsorption rate and 80% of the Ni(II) was removed within just 20 min. The adsorption kinetics and adsorption isotherm were well described by the pseudo-second-order model and Langmuir model, respectively. Moreover, TDTC could be easily regenerated without obvious loss of adsorption capability after five adsorption–desorption cycles. All these results indicate that TDTC is an ideal candidate for the efficient removal of Ni(II). Removal of Ni(II) from water using environmental-friendly tannin-based dithiocarbamate biosorbents.