Synthesis Methods, Properties, and Modifications of Biochar-Based Materials for Wastewater Treatment: A Review

Abstract

The global impact of water and soil contamination has become a serious issue that affects the world and all living beings. In this sense, multiple treatment alternatives have been developed at different scales to improve quality. Among them, biochar has become a suitable alternative for environmental remediation due to its high efficiency and low cost, and the raw material used for its production comes from residual biomass. A biochar is a carbonaceous material with interesting physicochemical properties (e.g., high surface area, porosity, and functional surface groups), which can be prepared by different synthesis methods using agricultural wastes (branches of banana rachis, cocoa shells, cane bagasse, among others) as feedstock. This state-of-the-art review is based on a general description of biochar for environmental remediation. Biochar’s production, synthesis, and multiple uses have also been analyzed. In addition, this work shows some alternatives used to improve the biochar properties and thus its efficiency for several applications, like removing heavy metals, oil, dyes, and other toxic pollutants. Physical and chemical modifications, precursors, dopants, and promoting agents (e.g., Fe and N species) have been discussed. Finally, the primary uses of biochar and the corresponding mechanism to improve water and soil quality (via adsorption, heterogeneous photocatalysis, and advanced oxidation processes) have been described, both at laboratory and medium and large scales. Considering all the advantages, synthesis methods, and applications, biochar is a promising alternative with a high potential to mitigate environmental problems by improving water and soil quality, reducing greenhouse gas emissions, and promoting the circular economy through residual biomass, generating value-added products for several uses.

Biocomposite Based on Polyhydroxybutyrate and Cellulose Acetate for the Adsorption of Methylene Blue

“…The absorbance was recorded at a wavelength of 664 nm [50]. For this purpose, MB solutions with concentrations of 5,10,15,20,25,25,30,35,40,45 and 50 ppm were prepared (Figure 8).…”

“…The absorbance was recorded at a wavelength of 664 nm [50]. For this purpose, MB solutions with concentrations of 5,10,15,20,25,25,30,35,40,45 and 50 ppm were prepared (Figure 8). As can be seen in Figure 8, the mathematical model that best fits the data is quadratic with 0.9915.…”

“…These technologies include electrocoagulation, flocculation, reverse osmosis, coagulation and filtration [8,9]. However, these treatment methods have disadvantages, because they can produce secondary contaminants and require a high operating cost [10,11]. Unlike other technologies for treating contaminated water, adsorption stands out as an efficient process, as it is easy to operate, economical, abundant in raw materials, and easy to recover [8,12], with activated carbon and zeolite being the materials most used in the removal of contaminants by adsorption due to their superior adsorbent characteristics compared to other materials, but it is essential to keep in mind that they also have a higher economic value [13][14][15].…”

Influence of lignin and cellulose from termite-processed biomass on biochar production and evaluation of chromium VI adsorption

“…It is not a single substance but a group of substances with a broad range of properties 9 . Consequently, biochar can be used for various applications, such as an adsorbent, soil improver, additive in animal feed, activated carbon, construction material additive, and catalyst or catalyst support 10 , 11 .…”