Biochars - effective sorbents for pollutant removal.

The growing amount of contaminants in the water has been a serious problem. Sorption is one of the effective methods for removal of various contaminants, such as drugs, detergents, or microplastics. Various sorbents are applied, whether commercial or laboratory prepared, as zeolites, bentonites, activated carbon and, more recently, various types of biochar, which are prepared by pyrolysis from variety of biomass residues. Their surface varies according to the preparation conditions (max SBET around 300 m2 / g) and there are tested under various conditions on variety of contaminants. Comparative studies of different types of biochar are rather lacking, similarly as their comparisons with commercial sorbents such as activated carbon. For these reasons, this study aims to compare the sorption properties of three biochars prepared from different types of plant biomass (sunflower husks, seaweed Ecklonia Maxima and freshwater microalgae Chlorella Vulgaris), whose sorption properties were compared with commercial activated carbon, Supersorbon. The effectiveness of sorbents has been tested on diclofenac (a non-steroidal anti-inflammatory and anti-rheumatic drug) whose consumption is enormous worldwide and it is commonly found in water, owing to that most wastewater treatment plants do not capture it. All sorbents showed considerable efficiency, with the best results being obtained using a biochar prepared from freshwater microalgae (95%). Its high effectiveness has been verified in removing the contaminant triclosan (antibacterial and antifungal disinfectant). The concentration of contaminants (1 ppm) was chosen for testing, which corresponds to the concentrations commonly found in wastewater. Based on the result, it was found that all prepared sorbents are comparable effective with activated carbon, however, their preparation is more economically advantageous, because the price of activated carbon increases the need for subsequent activation.