Weaving Hyper‐crosslinked Polymer from Alkaline Lignin for Adsorption of Organic Dyes from Wastewater

Abstract

Lignin is widely found in nature and attracts increasing concern as the renewable carbon material. In this work, hyper-crosslinked lignin was successfully prepared and applied for adsorbing dyes such as rhodamine B (RhB), methylene blue (MB) and Congo Red (CR) in wastewater. The characteristics of the alkaline lignin and hyper-crosslinked lignin were identified by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N 2 adsorption and desorption measurements. The results show that the hyper-crosslinked lignin is composed of uniform and porous nanoparticles with smaller size as compared to the sheet and-block structure of alkaline lignin. The specific surface area and pore structure of the hypercrosslinked lignin have been greatly optimized, while retaining the functional groups on the surface of the alkali lignin. The Brunner-Emmet-Teller (BET) surface area of the hyper-crosslinked lignin reaches up to 402.8 m 2 ⋅ g À 1 , and the adsorption capacity of RhB is up to 1332 mg ⋅ g À 1 . The isotherm model and thermodynamic results indicate that the adsorption process conforms to the Langmuir model, mainly showing a singlelayer spontaneous chemical endothermic process. In addition, HCPÀ L showed good selective adsorption performance for cationic dyes with the adsorption amounts of 228 mg ⋅ g À 1 for MB, while that of the anionic dye CR (89 mg ⋅ g À 1 ) was comparatively low. The adsorption mechanism was hydrogen bonding and π-π stacking in addition to the electrostatic effect caused by the negative charge on the surface of HCPÀ L.

Selective Adsorption of Methyl Orange and Methylene Blue by Porous Carbon Material Prepared From Potassium Citrate

“…The data indicated that the q e obtained by using the pseudo-second-order kinetic model was closer to the actual data, and the R 2 obtained from the pseudo-second-order kinetic model was higher than that obtained from the pseudo-first-order kinetic model. Therefore, the adsorption kinetics of MO and MB were more consistent with the pseudo-second-order model, which indicated that the adsorption processes of MO and MB were mainly determined by the chemisorption mechanism. , …”

“…Therefore, the adsorption kinetics of MO and MB were more consistent with the pseudo-second-order model, which indicated that the adsorption processes of MO and MB were mainly determined by the chemisorption mechanism. 49 , 50 …”

“…Therefore, the adsorption kinetics of MO and MB were more consistent with the pseudo-secondorder model, which indicated that the adsorption processes of MO and MB were mainly determined by the chemisorption mechanism. 49,50 Adsorption isotherms are mainly used to analyze the adsorption behaviors between the adsorbent and the adsorbate. Many adsorption isotherms have been proposed from different perspectives; the commonly used models include the Langmuir adsorption isotherm model, the Freundlich adsorption isotherm model, and the Temkin adsorption isotherm model.…”

A Systematic Integration Study of Traditional Hand-Weaving Techniques in Lingnan Region in the Context of Deep Learning

“…Four-step knitting is a whole lot more complicated than two-step knitting in that the yarns are only knitting yarns and no spool yarns [28]. A knitting cycle of the four-step method is divided into four steps, and each step of the yarn-carrier movement can only be stepped along the transverse or longitudinal direction respectively:…”