Special Issue on “Application of Biochar in Environmental Research”

In recent years, biochar has emerged as a key player in environmental science and technology [1]. Biochar is the solid by-product of the pyrolysis of organic waste, particularly excess forestry biomass [2]. While the primary objective of pyrolysis is carbon sequestration in a stable form, this material has proven to be highly effective in a variety of environmental applications. The first idea that probably comes to mind in scientific research when considering the uses of biochar is its fertilizing potential; however, many more applications have emerged in fields that are highly relevant to today's environmental research [3].

The papers published in this Special Issue on “Application of Biochar in Environmental Research” demonstrate the broad range of environmental applications of biochar, although improving soil conditions through the application of biochar remains a key topic [4]. Furthermore, the treatment of water and wastewater using biochar's excellent adsorptive properties has gained particular relevance. It is worth noting in this context that biochar is often used to remove specific and problematic pollutants, such as colorants or pesticides [5]. Another main topic arising from these papers and others published in this Special Issue is that the potential for using biochar in environmental applications increases exponentially when physical or chemical modifications enhance its properties.

Therefore, it seems that biochar research can be divided into two main areas:

(1)

Pristine biochar: Bulk biochar is used on a large scale as an alternative to activated carbon with similar properties, but which comes from organic waste and involves significant carbon sequestration. This is typically seen in its use in composting to reduce gaseous emissions or remove dissolved organic matter from drinking water.

(2)

Modified biochar: This is used for more specific applications, such as removing very recalcitrant pollutants from water, or even more interestingly, as a support material for catalysis. In this case, biochar can act as a catalyst when properly modified or doped with active chemicals, improving yield or selectivity under mild operating conditions [6].

As research into the uses of biochar beyond its role as a fertilizing agent is relatively new, it is difficult to predict which fields will be predominant in the following decades, given the large number of applications being published at present. On the one hand, large-scale applications require accurate techno-economic analyses (TEAs) and life cycle assessments (LCAs) to determine the actual benefits beyond the obvious carbon sequestration. On the other hand, the future of biochar is outstanding when it is used for very specific applications in areas where other solutions are very expensive or where its performance is much better than existing solutions.

In summary, this Special Issue provides researchers from various disciplines with useful information, including reviews and original research papers. These papers offer readers a reliable overview of the predominant fields of biochar research in the current literature, while also highlighting emerging fields that will become future research topics.