Lignin recovery from cocoa bean shell using microwave-assisted extraction and deep eutectic solvents

Lignin is the second most abundant natural polymer after cellulose, and valorisation of lignin-rich streams has attracted increasing attention recently. This paper presents a novel and sustainable method to recover lignin from Cocoa Bean Shells (CBS) using Deep Eutectic Solvents (DES) and microwaves. A DES containing p-toluenesulfonic acid, choline chloride and glycerol (2:1:1 M ratio) was selected based on its dielectric properties. Under 200 W microwave power, the optimum yield of 95.5 % lignin was achieved at 130 °C and 30 min. DES-extracted lignin exhibited unique structural characteristics including larger particle sizes (242.5 µm D50 size), structural diversity (410.4 µm D90-D10 size) and H/G sub-unit ratio (71.9 %) compared with commercial Kraft lignin (77.2 µm, 157.9 µm and 0.1 % respectively), indicating the potential of DES in the modification and upgrading of lignin for novel value-added products

Comparison of bio-oils derived from crop digestate treated through conventional and microwave pyrolysis as an alternative route for further waste valorization

A total of 120,000 tonnes per year of crop waste from contaminated land has been used as a feedstock for anaerobic digestion (AD). This produces only around 20% of biogas from the total crop and results in a large amount of digestate with heavy metal content. This crop digestate was analyzed across a calendar year to identify the variation in composition, and any potential high-value components that could be targeted for recovery. The chemical characterization revealed that approximately 65% of this residual waste is lignocellulosic material (20% hemicellulose, 24% cellulose, 24% lignin) and about 10% is ash, with no observable difference across the seasons. Three different pyrolysis technologies were studied with the same crop digestate as alternative route to maximize the value of this solid residue by transforming this lignocellulosic material into further bio-based products. Slow pyrolysis at operating temperatures between 355 and 530 °C resulted in bio-oil yields of 35–46% wt, fast pyrolysis at 460–560 °C produced 36–40% wt, and microwave pyrolysis using a power input of 500 and 700 W generated 8–27% wt from the digestate. Chemical compounds found in these bio-oils were categorized into seven chemical groups: acids, aldehydes and ketones, alcohols, furans, sugars, phenolics, and others. This analytical study opens other scenarios to explore the upgrading of these pyrolytic bio-oils for green product generation from the same waste

Correction to: Comparison of bio-oils derived from crop digestate treated through conventional and microwave pyrolysis as an alternative route for further waste valorization

In this article the Table 3 with SD± was not properly adjusted. The original article has been corrected

Correction to : Comparison of bio-oils derived from crop digestate treated through conventional and microwave pyrolysis as an alternative route for further waste valorization

In this article the Table 3 with SD± was not properly adjusted. The original article has been corrected

Comparison of bio-oils derived from crop digestate treated through conventional and microwave pyrolysis as an alternative route for further waste valorization

A total of 120,000 tonnes per year of crop waste from contaminated land has been used as a feedstock for anaerobic digestion (AD). This produces only around 20% of biogas from the total crop and results in a large amount of digestate with heavy metal content. This crop digestate was analyzed across a calendar year to identify the variation in composition, and any potential high-value components that could be targeted for recovery. The chemical characterization revealed that approximately 65% of this residual waste is lignocellulosic material (20% hemicellulose, 24% cellulose, 24% lignin) and about 10% is ash, with no observable difference across the seasons. Three different pyrolysis technologies were studied with the same crop digestate as alternative route to maximize the value of this solid residue by transforming this lignocellulosic material into further bio-based products. Slow pyrolysis at operating temperatures between 355 and 530 °C resulted in bio-oil yields of 35–46% wt, fast pyrolysis at 460–560 °C produced 36–40% wt, and microwave pyrolysis using a power input of 500 and 700 W generated 8–27% wt from the digestate. Chemical compounds found in these bio-oils were categorized into seven chemical groups: acids, aldehydes and ketones, alcohols, furans, sugars, phenolics, and others. This analytical study opens other scenarios to explore the upgrading of these pyrolytic bio-oils for green product generation from the same waste. Graphical Abstract: [Figure not available: see fulltext.

Unravelling the mechanisms of microwave pyrolysis of biomass

This study uses empirical observations and mass transfer simulations to establish a new mechanism for microwave pyrolysis of biomass. Experiments were conducted on cellulose and hemicellulose, using microwave equipment that could vary the observed heating rate. No microwave-absorbing additives were used. At high heating rates it is shown categorically that microwave pyrolysis can significantly reduce the pyrolysis temperatures for hemicellulose and cellulose, but when microwave heating is used to deliver a low heating rate the pyrolysis behaviour is identical to that obtained with conventional heating. Dielectric properties are shown to vary by over an order of magnitude depending on the heating rate. The implications of heating rate on mass transfer and phase behaviour are developed and discussed within the paper, with liquid-phase water identified as a key driver for the observed differences in the microwave pyrolysis process. This is the first study in microwave pyrolysis that is able to reconcile microwave heating phenomena against simple and well-understood mass transfer and phase equilibria effects. As a result, a number of processing strategies have emerged with the potential to use microwave heating to enable more selective pyrolysis and bio-oils with more targeted quality than has been possible with conventional approaches

Revista Temas Agrarios Volumen 26; Suplemento 1 de 2021

1st International and 2nd National Symposium of Agronomic Sciences: The rebirth of the scientific discussion space for the Colombian Agro.1 Simposio Intenacional y 2 Nacional de Ciencias Agronómicas: El renacer del espacio de discusión científica para el Agro colombiano