Green Chemistry Applications Using Complexing Materials for Water Treatment

In this study, two complexing materials were obtained for Mn²⁺, Zn²⁺, Fe³⁺ and Cr³⁺ removal from aqueous media. Synthetic cellulose powder (CELL) and cellulosic green material obtained from shredded maize stalk (MS) were modified with direct red 23 (DR 23), a complexing agent, obtaining MS-DR 23 and CELL-DR 23 using batch mode technique. Experimental parameters like interaction time, pH of aqueous solution, and initial concentration of DR 23 were studied to optimize the complexing process. The time necessary to reach equilibrium was 75 min for both cellulose materials. Also, pH 2 was the optimum adsorption value for adsorption of DR 23. The adsorption capacity for MS (56.8 mg/g) was more significant than for CELL (42 mg/g). The applicability of complexing materials was based on checking for Mn²⁺, Zn²⁺, Fe³⁺ and Cr³⁺ (M^x+) removal. The concentration of M^x+ retained on cellulosic materials was detected by the atomic adsorption spectrometry method (AAS). The complex formation between DR 23 and M^x+ was evaluated at pH 2.0, 4.0, 6.0, 8.0 and 10.0. Batch adsorption experiments were conducted to assess the adsorption of M^x+ onto MS-DR 23 and CELL-DR 23. A high level of M^x+ adsorption was reported at 4 mg/L. Reusability experiments were conducted and complexing cellulose was used for multiple cycles of M^x+ removal from aqueous media. Also, the developed complexing materials tested M^x+ removal from tannery wastewater. Based on experimental study, two complexing materials for metal removal were produced. The good adsorption and regeneration of complexing materials provide an excellent adsorbent for water purification.