Biochars and Activated Biocarbons Prepared via Conventional Pyrolysis and Chemical or Physical Activation of Mugwort Herb as Potential Adsorbents and Renewable Fuels

Abstract

The main objective of this study was to prepare a series of biochars and activated biocarbons via conventional pyrolysis as well as chemical or physical activation of solid residue after solvent extraction of wild growing plant (popular weed)–mugwort. The influence of the variant of the thermochemical treatment of the precursor on such parameters as elemental composition, textural parameters, acidic-basic character of the surface as well as adsorption abilities of the prepared carbonaceous materials was checked. Moreover, the suitability of the biochars prepared as renewable fuels was also investigated. It has been shown that the products obtained from the mugwort stems differ in many respects from the analogous materials obtained from mugwort leaves. The products were micro/mesoporous materials with surface area reaching 974.4 m2/g and total pore volume–1.190 cm3/g. Surface characterization showed that chemical activation with H3PO4 results in the acidic character of the adsorbents surface, whereas products of pyrolysis and especially physical activation show strongly alkaline surface properties. All the adsorbents were used for methylene blue and iodine adsorption from the aquatic environment. To understand the nature of the sorption process, the Langmuir, Freundlich and Temkin isotherm models were employed. The Langmuir model best described the experimental results, and the maximum sorption capacity calculated for this model reached 164.14 mg of methylene blue per gram of adsorbent. In case of iodine removal, the maximum capacity reached 948.00 mg/g. The research carried out for the biochars prepared via conventional pyrolysis showed that the value of their heat of combustion varies in the range from 21.74 to 30.27 MJ/kg, so they can be applied as the renewable fuels.

Preparation of biochars by conventional pyrolysis of herbal waste and their potential application for adsorption and energy purposes

“…The obtained results do not differ from the others reports. Moreover, the HHV of all the biochars prepared is comparable to the typical lignite briquettes, wood or wood pellets (~18–25 MJ/kg) [32] …”

“…Moreover, the HHV of all the biochars prepared is comparable to the typical lignite briquettes, wood or wood pellets (~18-25 MJ/kg). [32] As follows from the data presented in Figure 8c the biochars obtained via conventional pyrolysis of herbs are characterized by the similar values of energy densification ratio (~1. 3-1.6).…”

“…[38] The greatest amounts of polymers from the binary solution are adsorbed on the surface of biochar obtained from the mint herb as a result of the greatest development of MT_B biochar surface area. Pinewood Fast pyrolysis at 450 °C for 30 min 27.80 -- [11] Poultry litter Pyrolysis at 300 °C for 15 min 15.00 1.25 - [15] Mugwort leaves/stems Pyrolysis at 400 °C for 30 min 25.29 and 30.27 1.45 and 1.75 55.0 and 72.0 [32] Sewage sludge Torrefaction at 240 °C for 60 min 13.40 0.99 88.4 [33] Manure pellet biomass Microwave pyrolysis at 500 °C for 20 min 4.65 0.90 56.5 [34] Canola straw Microwave pyrolysis at 500 °C for 20 min 24.55 1.30 39.7 [34] Bamboo Carbonization at 200 °C for 60 min 18.52 -- [35] Dried sewage sludge Slow solar pyrolysis at 800 °C for 190 min 13.00 0.81 - [36] Coconut fiber Pyrolysis at 200 °C for 20 min 19.93 1.04 87.5 [37] Coconut fiber Pyrolysis at 330 °C for 20 min 25.36 1.32 53.5…”

Adsorption of Organic Pollutants on Carbonaceous Adsorbents Prepared by Direct Activation of Sweet Cherry Stones

“…The solutions absorbance was measured applying UV-Vis spectrophotometer Carry 1000 (Varian, USA) at wavelength 270 nm for Triton X-100), [34] 279 nm for BSA [35] and 664 nm for MB. [36] 0.025 g of the carbonaceous materials were added to 10 mL of Triton X-100 or BSA solutions with initial concentration 300 ppm. The adsorption process was carried out as a function of solution pH at 25 °C (at pH values: 2, 4, 6, 8, 10 and 12) and temperature at pH 6 (at temperatures: 15 °C, 25 °C and 35 °C).…”

“…All adsorption tests were performed using static method and lasted 24 hours. The solutions absorbance was measured applying UV‐Vis spectrophotometer Carry 1000 (Varian, USA) at wavelength 270 nm for Triton X‐100), [34] 279 nm for BSA [35] and 664 nm for MB [36] . 0.025 g of the carbonaceous materials were added to 10 mL of Triton X‐100 or BSA solutions with initial concentration 300 ppm.…”