Nano-biochar: recent progress, challenges, and opportunities for sustainable environmental remediation

Abstract

Biochar is a carbonaceous by-product of lignocellulosic biomass developed by various thermochemical processes. Biochar can be transformed into “nano-biochar” by size reduction to nano-meters level. Nano-biochar presents remarkable physico-chemical behavior in comparison to macro-biochar including; higher stability, unique nanostructure, higher catalytic ability, larger specific surface area, higher porosity, improved surface functionality, and surface active sites. Nano-biochar efficiently regulates the transport and absorption of vital micro-and macro-nutrients, in addition to toxic contaminants (heavy metals, pesticides, antibiotics). However an extensive understanding of the recent nano-biochar studies is essential for large scale implementations, including development, physico-chemical properties and targeted use. Nano-biochar toxicity on different organisms and its in-direct effect on humans is an important issue of concern and needs to be extensively evaluated for large scale applications. This review provides a detailed insight on nanobiochar research for (1) development methodologies, (2) compositions and properties, (3) characterization methods, (4) potentiality as emerging sorbent, photocatalyst, enzyme carrier for environmental application, and (5) environmental concerns.

Sustainable Technological Applications of Green Carbon Materials

“…Although biochar research in agriculture is a well-established area, its nanosized fraction, nanobiochar, is in the early stage of scientific research. Nanobiochar is being proposed for environmental remediation, although the mechanism of action is poorly understood [53][54][55][56]. Nanobiochar has superior physicochemical properties to biochar, such as high catalytic activity, a large SSA, and high environmental mobility [53].…”

“…Nanobiochar has superior physicochemical properties to biochar, such as high catalytic activity, a large SSA, and high environmental mobility [53]. The main applications of nanobiochar in environmental treatment technologies are in pollutant removal, like heavy metals, toxic organic substances, and emerging pollutants, via adsorption mechanisms like ion exchange, complexation, precipitation, electrostatic interaction, and physical adsorption [53][54][55]. As discussed above, the biochar's structure and properties depend on the raw materials and technological characteristics of the pyrolysis process, and the same is naturally observed for nanobiochar [54,55].…”

“…The main applications of nanobiochar in environmental treatment technologies are in pollutant removal, like heavy metals, toxic organic substances, and emerging pollutants, via adsorption mechanisms like ion exchange, complexation, precipitation, electrostatic interaction, and physical adsorption [53][54][55]. As discussed above, the biochar's structure and properties depend on the raw materials and technological characteristics of the pyrolysis process, and the same is naturally observed for nanobiochar [54,55]. Temperature is a critical factor for nanobiochar's functionality; for example, the SSA, ash content, and carbon content increase with the pyrolysis temperature, although this effect depends on the raw material [56].…”

Nano Biochar for Sustainable Agriculture and Environmental Remediation: A Comprehensive Review

“…The physiochemical parameters of nanobiochar are often influenced by its source material. According to Föhr et al [13], "materials with high lignin often form nanobiochar with great aggregation ability", "while biomass with high hemicellulose typically produces nanobiochar with low carbon content and high oxygen content" [16]. "Because of its nano-enabled properties, which include its extremely small size, varied mobilization, bioavailability, and consequent effect on soil and plant systems, nano-BC may be expected to have more attractive environmental management for intended purposes compared to bulk biochar materials" [15].…”

Hydrothermal Synthesis of Mg modified Nanobiochar from Spent Coffee Grounds for Effective Phosphate Removal: Kinetic and Isotherm Studies

“…For instance, plant-driven biochar has shown large aromatic clusters and higher oxygen surface functionalities which are essential for binding different inorganic pollutants. [5] Hence, the valorization of household or industrial byproducts or wastes represents an eco-friendly and circular economy approach. [6][7][8] Although biochar has important features as an adsorbent, its pristine form has often limited adsorption efficiency and recyclability.…”