Characterization and Sodium Cations Sorption Capacity of Chemically Modified Biochars Produced from Agricultural and Forestry Wastes

Abstract

Excessive amounts of sodium cations (Na+) in water is an important limiting factor to reuse poor quality water in agriculture or industry, and recently, much attention has been paid to developing cost-effective and easily available water desalination technology that is not limited to natural resources. Biochar seems to be a promising solution for reducing high loads of inorganic contaminant from water and soil solution, and due to the high availability of biomass in agriculture and forestry, its production for these purposes may become beneficial. In the present research, wheat straw, sunflower husk, and pine-chip biochars produced at 250, 450 and 550 °C under simple torrefaction/pyrolysis conditions were chemically modified with ethanol or HCl to determine the effect of these activations on Na sorption capacity from aqueous solution. Biochar sorption property measurements, such as specific surface area, cation exchange capacity, content of base cations in exchangeable forms, and structural changes of biochar surface, were performed by FTIR and EPR spectrometry to study the effect of material chemical activation. The sorption capacity of biochars and activated carbons was investigated by performing batch sorption experiments, and adsorption isotherms were tested with Langmuir’s and Freundlich’s models. The results showed that biochar activation had significant effects on the sorption characteristics of Na+, increasing its capacity (even 10-folds) and inducing the mechanism of ion exchange between biochar and saline solution, especially when ethanol activation was applied. The findings of this study show that biochar produced through torrefaction with ethanol activation requires lower energy demand and carbon footprint and, therefore, is a promising method for studying material applications for environmental and industrial purposes.

Biochar modification methods and mechanisms for salt‐affected soil and saline‐alkali soil improvement: A review

“…Thus, acid helps increase CEC while reducing BC ash, without choosing between the two (Peiris et al, 2019). Medyńska-Juraszek et al (2021) noted that the oxygen-containing functional groups in wheat straw BC and sunflower BC decreased after being treated with hydrochloric acid, while the oxygen-containing functional groups in pine BC increased. Therefore, the influencing factors and mechanism of acid on the functional groups of BC derived from various raw materials require further investigation.…”

“…To avoid more Na + being introduced into the soil and to reduce soil exchangeable sodium (ESP) thereby reducing Na + toxicity to plants. Medyńska-Juraszek et al (2021) modified BC using ethanol and discovered that ethanol modification eliminates ash from BC while preserving K + , Ca 2+ and Mg 2+ and removing Na + . Organic matter often contains a large number of functional groups, which when loaded onto BC improves its adsorption of salts.…”

Recycled Materials in Civil and Environmental Engineering

“…In the paper by Medynska-Juraszek and coworkers [ 23 ], wheat straw, sunflower husk, and pine-chip biochars produced by torrefaction/pyrolysis conditions were chemically modified with ethanol and HCl for applications as Na + sorbents from aqueous solution. Wheat straw biochar, obtained by pyrolysis (550 °C), showed the best Na + sorption capacity.…”

Investigating the Effectiveness of Recycled Agricultural and Cement Manufacturing Waste Materials Used in Oil Sorption

“…When sorption is used to treat wastewater, oil products are removed using an adsorbent, for example: polypropylene, activated carbon, polyacrylamide, the base of which is made of chitosan [ 5 ]. Of all the methods used to remove pollution produced by wastewater treatment technologies, sorption proved to be the best due to its low price, simplicity, and effectiveness [ 7 ].…”