Microwave assisted hydrothermal preparation of rice straw hydrochars for adsorption of organics and heavy metals

Experimental, Thermodynamic and Kinetic Studies for the Adsorption of Phenolic Compounds Derived from Oilfield Wastewater by the Corncob Hydrochar

“…The carbon contents of the corncob hydrochar are increased by 12.64% in comparison with those of the pristine corncob. Notably, the carbon contents of the corncob hydrochar (58.95%) are lower than those of some hydrochars from other raw materials such as wood and grass reported in literatures [26], but higher than those of some hydrochars from rice straw [27].…”

Microwave-assisted hydrothermal treatments for biomass valorisation: a critical review

“…They concluded that the first increase might result from side reactions occurring between some lignin-derived volatile compounds and hemicellulose carbonised species, which overall increased the amount of solid matter, thus increasing the hydrochar yield. As an exception to these trends, Li et al 76 showed that increasing the temperature between 160 and 200 o C did not significantly impact the hydrochar yield during the MA-HTC of rice straw. Also, it must be borne in mind that higher temperatures may result in different outcomes for the hydrochar yield than those described above.…”

Hydrochars production, characterization and application for wastewater treatment: A review

“…The removal of heavy metals from aqueous solutions using hydrochars was successfully reached (Table 5). A recent study performed by Li et al [41] indicated that the removal of zinc and copper ions by rice straw hydrochar reached 216.9 and 226.8 mg/g, respectively. These considerable removal efficiencies were recorded despite the low specific surface area of the carbonized material (25.5 m 2 /g), which suggests that adsorption of heavy metals was not physically driven.…”

“…6, the van Krevelen diagram for the hydrochar (data in Table 1) shows that these hydrochars have the ratios within the limit of 0.6, recommended by the European Biochar Certificate (EBC) except for the sewage sludge. As a comparison between two feedstock types, the hydrothermal carbonization of two wastes at 200 and 250 � C for 1h conducted by Han et al [40] (Sawdust) and Li et al [41] (Swine manure) showed a significant difference in terms of H/C and O/C ratio (H/C: 1.26 vs. 0.12; O/C: 0.22 vs. 0.98, for sawdust and swine manure, respectively). The cellulose and lignin fractions present in the sawdust undergoes a depolymerization accompanied with the outer carbohydrate separation.…”