Review of Biochar Properties and Remediation of Metal Pollution of Water and Soil

Abstract

Background. Mining, waste disposal, and agrochemical residues have contributed to pollution of water and soil with toxic metals in most low- and middle-income countries, raising concerns of ecological safety and public health. This has prompted many studies into the production and utilization of biochars to adsorb toxic metal contaminants from soil and water. Objective. The present study presents a review of biochar properties, the mechanisms of toxic metal adsorption onto biochar, and sorption of toxic metal contaminants in water and soil in small scale applications and laboratory experiments. Methods. A total of 305 articles were collected, and after screening for relevance, a final of 164 articles from both high- and low- and middle-income countries were used in this review paper. Discussion. Biochar for sorption has proven effective and its raw materials are readily available, cost effective, environmentally stable and a good form of waste management. Conclusions. Different techniques of biochar production influence the properties of biochar and adsorption of toxic metals from water and soil. Competing Interests. The authors declare no competing financial interests.

Adsorption of Arsenic on Fe-Modified Biochar and Monitoring Using Spectral Induced Polarization

“…As a result, the 5% Fe-BC-500 is the most efficient under our testing conditions. Although a higher biochar concentration would imply a greater number of active sites and functional groups accessible to interact with As(V), particle aggregation in the column might cancel out any more adsorption sites, even lowering the overall number of available sites [33,51].…”

“…Previous research has investigated the range of electrostatic interactions between biochar/biochar-based catalysts and pollutants [26,[30][31][32]. Attraction between opposite charges, inherent chemical affinity with functional groups on the biochar surface, hydrogen bonding, and cation-cation interactions have all been conclusively demonstrated to play the most important roles [33,34].…”

Uranium Isotope (U-232) Removal from Waters by Biochar Fibers: An Adsorption Study in the Sub-Picomolar Concentration Range

“…The interaction of uranium with biochar-based adsorbents has been widely studied using different biomass types as starting materials [ 1 , 2 , 3 , 4 ], including plant fibers, which in addition to their abundance and low value present desirable adsorbent properties such as a tubular structure and large external surface, allowing for fast material exchange and increased sorption capacities [ 5 , 6 , 7 , 8 , 9 ]. These physical properties remain almost intact after carbonization and chemical oxidation by nitric acid.…”

Heavy Metal Contamination in the Aquatic Ecosystem: Toxicity and Its Remediation Using Eco-Friendly Approaches

“…Biosorption is affected by several factors including the morphology and types of biomass, the presence of more than one metal ion in the media, and the surrounding temperature and pH of the medium [ 66 ]. Commonly, a decrease in the pH is responsible for competition between cationic heavy metal ions.…”