No abstract

No abstract

The removal of heavy metals ions from wastewater by an economic, high-effective, and environmentally friendly method is particularly important. In this study, an effective lignin-based bio-adsorbent (SAPL-1.5), which contained specific functional groups and spatial cross-linking structures, was synthesized through chemical modification. SAPL-1.5 was comprehensively characterized by 31 P, 1 H, 13 C NMR, and elemental analysis as compared to the raw lignin. The results showed that the chemical reactivity of lignin was significantly improved after phenolation process, and the adsorption groups were successfully grafted onto lignin macromolecule. In addition, the influences of pH, SAPL-1.5 dosage, contact time, and initial Pb (II) concentration on the adsorption performance was systematically investigated. The highest adsorption capacity reached to 130.2 mg/g (Pb (II), 140 mg/L), and a removal efficiency of 100% was achieved (Pb (II), 20 mg/L). Moreover, the adsorption isotherm and adsorption kinetics indicated that the results were fitting well with the Langmuir and pseudo-second-order model, respectively. Furthermore, the removal efficiency of SAPL-1.5 for Pb (II) (20 mg/mL) still maintained over 85% after 5 cycles. Therefore, the lignin-based material obtained could be considered as a promising potential adsorbent with a low cost, high performance and reutilization for its application in the wastewater treatment process. It is believed that the lignin-based bio-sorbent can enlarge the lignin valorization in the current biorefinery process.

Anionic, cationic, and non-ionic surfactants with varying concentrations (0.2-1.2 %)were introduced to neutralize beads on lignin nanofibers by decreasing the surface tension of spinning dopes. The surfactants used in this work were sodium dodecyl sulfate (SDS), N,N,Ntrimethyl-1-dodecanaminium bromide (DTAB), and Triton™ X-100 (TX-100). The effects of viscosity, rheological properties, surface tension, and conductivity of the solutions on the morphology and physicochemical performances of fibers were investigated. As expected, the presence of certain amounts of surfactants eliminated the beads and resulted in the formation of smooth and bead-free fibers with small diameters. Furthermore, the gravimetric capacitance of carbon mat with 1 % SDS was slightly improved from 66.3 to 80.7 F g-1. The results suggested that the surfactants benefit the electrospinning of lignin and allow for the control over nanofiber morphology without compromising their performance as supercapacitor electrodes.

No abstract