Separation and recovery of lignin and hydrocarbon derivatives from cardboard

Abstract

This study investigates the feasibility of acid precipitation for the separation and recovery of lignin and hydrocarbon derivatives from the waste stream of the alkali extraction of recycled cardboard. The recovery of chemicals from this effluent is complex due to their heterogeneity. Apart from the lignin and hydrocarbon derivatives, also, fillers, inks, and polysaccharides are present. A procedure of fractional acid precipitation was designed, reducing the pH from 10.7 to 8.8, 7.2, 5.1, 3.1, and 1.5. Each solid fraction was analyzed by infrared spectroscopy to determine its chemical composition and amount of precipitate. A mixture of lignin and hydrocarbon derivatives was detected in the solids obtained at pH 3.1. A dichloromethane extraction of the hydrocarbon derivatives was performed. Both recovered lignin and hydrocarbon were analyzed by infrared and gel permeation chromatography. The lignin showed similar characteristics (e.g., molecular weight ≈ 10.000 Dalton) as commercial lignin from virgin softwood. For the hydrocarbon derivatives, a molecular weight range between 10000 Dalton and 150 Dalton was observed. In conclusion, this paper shows that the recovery of lignin and hydrocarbon derivatives is scientifically and technologically possible from the waste stream of the cardboard recycling processes. Further research is necessary to improve the extraction efficiency that was around 7.9% for the lignin and around 5.5% of the total amount of extractives compared to their amount in cardboard. Despite the low extraction efficiency, the estimated 9.6 million tons of lignin present in cardboard and the lignin price around 300-500 USD/ton make this research of industrial interest.

Organosolv biorefinery: resource-based process optimisation, pilot technology scale-up and economics

“…These biopolymers and chemicals can be recovered and used to prepare a wide range of biomaterials and high-value chemicals. 10–15…”

Advanced Fractionation of Kraft Lignin by Aqueous Hydrotropic Solutions

“…Most processes for the fractionation of Kraft lignin are based on the solubility of the different lignin fractions in several organic solvents [ 9 , 10 , 11 , 12 ] or in membrane separation processes from black liquor [ 13 , 14 , 15 , 16 , 17 ]. While the use of organic solvents produces well-defined fractions of lignin, the safety and handling of this type of process at an industrial scale is a disadvantage.…”

Copyrolysis of Waste Cartons and Polyolefin Plastics under Microwave Heating and Characterization of the Products

“…The commonly used reactors for copyrolysis are currently fixed bed and fluidized bed. , However, they have the disadvantage that heat is transferred from outside to inside and partial energy is lost in the heat transfer process, so the heating rate is also low . Microwaves generate heat through dielectric heating, and energy is transferred directly to the material through the interaction of molecules and electromagnetic fields, without wasting time heating the surrounding area. , Compared with conventional heating, microwave heating has a higher heating rate, reducing the occurrence of secondary reactions. , The microwave reactor also reduces the requirements for the shape and size of the feedstock. − Therefore, the microwave reactor was used as the heat source in this study.…”

“… 21 , 22 The microwave reactor also reduces the requirements for the shape and size of the feedstock. 23 − 25 Therefore, the microwave reactor was used as the heat source in this study.…”