Bamboo-Based Biochar: A Still Too Little-Studied Black Gold and Its Current Applications

Abstract

Biochar (BC), also referred to as “black gold”, is a carbon heterogeneous material rich in aromatic systems and minerals, preparable by the thermal decomposition of vegetable and animal biomasses in controlled conditions and with clean technology. Due to its adsorption ability and presence of persistent free radicals (PFRs), BC has demonstrated, among other uses, great potential in the removal of environmental organic and inorganic xenobiotics. Bamboo is an evergreen perennial flowering plant characterized by a short five-year growth period, fast harvesting, and large production in many tropical and subtropical countries worldwide, thus representing an attractive, low-cost, eco-friendly, and renewable bioresource for producing BC. Due to their large surface area and increased porosity, the pyrolyzed derivatives of bamboo, including bamboo biochar (BBC) or activated BBC (ABBC), are considered great bio-adsorbent materials for removing heavy metals, as well as organic and inorganic contaminants from wastewater and soil, thus improving plant growth and production yield. Nowadays, the increasing technological applications of BBC and ABBC also include their employment as energy sources, to catalyze chemical reactions, to develop thermoelectrical devices, as 3D solar vapor-generation devices for water desalination, and as efficient photothermal-conversion devices. Anyway, although it has great potential as an alternative biomass to wood to produce BC, thus paving the way for new bio- and circular economy solutions, the study of bamboo-derived biomasses is still in its infancy. In this context, the main scope of this review was to support an increasing production of BBC and ABBC and to stimulate further studies about their possible applications, thus enlarging the current knowledge about these materials and allowing their more rational, safer, and optimized application. To this end, after having provided background concerning BC, its production methods, and its main applications, we have reviewed and discussed the main studies on BBC and ABBC and their applications reported in recent years.

Reactive Oxygen Species (ROS)-Mediated Antibacterial Oxidative Therapies: Available Methods to Generate ROS and a Novel Option Proposal

“…The EPFRs decay in atmosphere depends on reaction of EPFRs with molecular oxygen. By reaction with atmospheric oxygen, they generate high levels of reactive oxygen species (ROS), via electron transfer, such as hydroxyl radicals and superoxide anion radicals, thereby inducing cellular oxidative stress [23,24]. For this reason and their possible redox recycling, EPFRs are emerging as environmental pollutants with a ROS-dependent significant toxicity to organisms, including humans, plants, animals, and microorganisms.…”

“…It has been used in photocatalytic and photothermal systems, for photothermal conversion, to construct electrical and thermal device, as well as 3D solar vapor-generation devices for water desalination [24]. All these potentials are due to its high surface area and rich pore structure, which determines great physical absorptivity [23]. Additionally, they also depend on the chemical characteristics of BC, which in turn depend on the type of biomass used to produce BC, on the original biomass chemical composition, and pyrolysis conditions [299,300].…”

“…To make possible an enlargement of the clinical use of ROS to counteract MDR pathogens and related biofilm, the development of other delivery strategies for increasing the selectivity of ROS for microbial pathogens over the host tissue is necessary. In this regard, based on our recent studies on biochar (BC) [23,24], we profit of this review to propose a possible innovative method to be studied to produce ROS by a natural low-cost source. Biochar (BC) is a carbonaceous material obtained by pyrolysis of different vegetable and animal biomass feedstocks and waste, at 200−1000 °C in the limited presence of absence of oxygen.…”

“…PFRs are reactive species due to unpaired electrons, that can persist up to several months, in contrast to traditional transient radicals [24]. Studies reported that PFRs are the main responsible for the BC capacity to degrade organic pollutants through the generation of active oxygen species (ROS) and sulfate radicals [23]. It was reported that the generated ROS, including radical (•OH, •O2 − , •O2H, SO4• -) and non-radical species ( 1 O2) successfully degrade several organic pollutants, hormones and eDNA, by advanced oxidation processes (AOPs).…”

Biochar-Derived Persistent Free Radicals: A Plethora of Environmental Applications in a Light and Shadows Scenario

“…Additionally, cow dung (CD), sheep manure (SM), lotus stem (LS), and eggshell (ES) biomasses, representative of farm wastes, have been reported to provide BC containing PFRs [ 41 ]. Bamboo is an emerging starting material that is perfect for synthesizing BC and activated carbon (AC) due to its inexpensive cost, high biomass yield, and accelerated growth rate [ 42 , 43 ]. However, only a few researchers and scientists have used bamboo as a unique source for developing BC so far, as established by the number of publications on bamboo-derived BC developed in the last ten years (current year excluded) (331) vs. those on BC derived from different sources (13,630) ( Figure 2 ).…”