Cellulose based polyurethane with amino acid functionality: Design, synthesis, computational study and application in wastewater purification

Synthesis of organic-solvent-soluble cellulose and preparation of fluorescent polyurethanes for the detection and removal of Hg+ ions

Modifying cellulose to obtain materials with favorable processing properties and functions is highly significant, especially, for the detection and removal of heavy metal ions. In this study, fluorescent cellulose-based polyurethane (PU) films containing naphthalimide fluorophore were synthesized and could use for the convenient detection and removal of Hg+ ions. Firstly, the microcrystalline cellulose was treated with SOCl2 to convert some -OH groups into -Cl. Simultaneously, a naphthalimide derivative (NAN) with -NH- groups was synthesized. Subsequently, a fluorescent cellulose-based probe (Cel-NAN) was prepared by utilizing the substitution reaction between -Cl on cellulose and -NH- on NAN. Finally, two cellulose-based fluorescent PU films (Cel-NAN-PU1 and Cel-NAN-PU2) were successfully synthesized by reacting the unreacted -OH groups on Cel-NAN with PEG-1000 and HDI/IPDI. These as-prepared PU films could serve as portable fluorescence test papers to Hg+ ions in aqueous solutions. Upon contact with Hg+ ions, the fluorescence was quenched, acting as a "turn-off" probe. Simultaneously, these films could serve as adsorbents for the removal of Hg+ ions from aqueous systems. Cel-NAN-PU1 film exhibited a removal efficiency over 80 % and an adsorption capacity of 8.4 mg·cm-2 for Hg+. These cellulose-based fluorescent PU films possess promising potential in the field of mercury pollution control.

Application of Taguchi method, response surface methodology, DFT calculation and molecular dynamics simulation into the removal of orange G and crystal violet by treated biomass

In this work, the efficiency of the treated plant Carpobrotus edulis (TPCE) as an effective biosorbent for removing the orange G (OG) and crystal violet (CV) dyes from aqueous solution was investigated. TPCE was characterized by FT-IR, Ss, pHz and SEM-EDX. The influence of parameters such as bioadsorbent dose, contact time, initial concentration, temperature and pH was tested using Taguchi experimental design (TED) with L8 orthogonal array (five parameters in two levels). The initial concentration, bioadsorbent dose and contact time are the main parameters for the removal of CV and OG dyes, while the effects of pH and temperature are minimal. The maximum removal efficiency of dyes under optimal operating conditions was 97.93 % and 92.68 %, respectively. which at the optimal conditions of 3 g/L, pH 10, 20 mg/L, 35 °C, 5 min and 15 g/L, pH 4, 20 mg/L, 35 °C, 60 min for CV and OG dyes, respectively. The results of response surface methodology (RSM) and analysis of variance (ANOVA) showed that the initial concentration Ci of CV dye was the most significant factor in the adsorption efficiency with a contribution of 51.56 %. On the other hand, the OG bioadsorbent dose is the most important factor in adsorption efficiency with a percentage contribution of 56.41 %. The Density Functional Tight Binding (DFTB) method shows that dyes strongly bind the adsorbent surface. Monte Carlo and molecular dynamics simulations show significant interactions between dye and adsorbent surface. The reusability of biomaterial indicated that the adsorption performance dropped very slightly up to five cycles.