Synthesis, Characterization, and Utilization of a Lignin-Based Adsorbent for Effective Removal of Azo Dye from Aqueous Solution

Abstract

How to effectively remove toxic dyes from the industrial wastewater using a green low-cost lignocellulose-based adsorbent, such as lignin, has become a topic of great interest but remains quite challenging. In this study, cosolvent-enhanced lignocellulosic fractionation (CELF) pretreatment and Mannich reaction were combined to generate an aminated CELF lignin which is subsequently applied for removal of methylene blue and direct blue (DB) 1 dye from aqueous solution. 31 P NMR was used to track the degree of amination, and an orthogonal design was applied to determine the relationship between the extent of amination and reaction parameters. The physicochemical, morphological, and thermal properties of the aminated CELF lignin were characterized to confirm the successful grafting of diethylenetriamine onto the lignin. The aminated CELF lignin proved to be an effective azo dye-adsorbent, demonstrating considerably enhanced dye decolorization, especially toward DB 1 dye (>90%). It had a maximum adsorption capacity of DB 1 dye of 502.7 mg/g, and the kinetic study suggested the adsorption process conformed to a pseudo-second-order kinetic model. The isotherm results also showed that the modified lignin-based adsorbent exhibited monolayer adsorption. The adsorbent properties were mainly attributed to the incorporated amine functionalities as well as the increased specific surface area of the aminated CELF lignin.

Pyridine‐Rich Novolac‐Based Network as an Effective Adsorbent for Removing Azo Dyes

“…The isotherm showed progressive and linear increase in adsorption which indicates the porous character of the network. The S BET of 1 was 7.2702±0.3000 m 2 g −1 , which is comparable with those reported for typical porous polymer materials . Figure (B) displays the pore size distribution as estimated by the corresponding Barratt‐Joyner‐Halenda (BJH) method.…”

“…This is believed to intensify the physical forces ( hydrophobic, π‐π stacking, hydrogen bonding) only participated in the adsorption process. Further, the attractive physical forces including π‐π stacking interaction between the adsorbent and the anionic organic dyes at higher pH (basic condition) might be dominant disfavoring the adsorption of competing OH − ions. However, the adsorption of OG/OII by 1 is higher than MO attributing to the presence of more number of functional groups and extra π‐surface in OG/OII structures.…”

Preparation and Characterization of Highly Porous Cellulose Nanofibrils/Chitosan Aerogel for Acid Blue 93 Adsorption: Kinetics, Isotherms, and Thermodynamics Analysis

“…Azo dyes such as AB93 are widely used in a number of industrial and biological applications, and among other dyes, they attribute most detrimental environmental impacts. , In this study, AB93 was selected as representative of azo dye to investigate the CNFs, CS, and their aerogel ability to adsorb pollutants from the aqueous system.…”

Epoxy as Filler or Matrix for Polymer Composites

“…In addition to synthetic fibers, natural fibers received considerable attention in past decades in view of environmental concerns [56][57][58][59]. Natural fibers are mostly sourced from plants or animals and are biodegradable and renewable [60,61]. Their replacement of synthetic fibers in composite applications can reduce carbon footprint, improve recyclability, and enhance environmental sustainability.…”