Improving abiotic reducing ability of hydrothermal biochar by low temperature oxidation under air

Efficient removal of methylene blue by activated hydrochar prepared by hydrothermal carbonization and NaOH activation of sugarcane bagasse and phosphoric acid

“…4c and f ), respectively. 50 The quantitative area analysis of O 1s spectra also suggested the relative percentage of C O and O C–O increased, while that of C–O decreased in AHC compared with HC. The above analyses convinced that NaOH activation treatment increased the carboxyl content on the surface of AHC, which contrariwise was beneficial for improving its MB adsorption capacity.…”

Effect of Heavy Metal (Zn) on Redox Property of Hydrochar Produced from Lignin, Cellulose, and d-Xylose

“…In contrast to biochar, it is usually generated under mild conditions (low heating temperature) with a low environmental impact. 18 Our experiment 19 demonstrated that the products of hydrothermal carbonization of herbaceous biomass, Spartina alternif lora, exhibit comparable or even higher reducing capacity in contrast to pyrolytic biochar. 13 Previous studies also indicated that the hydrothermal process is effective for the separation of heavy metals from biomass and yielded crude biooil from a hyperaccumulator, Sedum plumbizincicola.…”

“…Hydrochar TRC was quantified by a series of batched equilibrium tests according to our previous experiment . In brief, 100 mL of Fe­(III) solution (0.00357 mol/L, pH = 2) and 0.05 g of hydrochar were mixed in a 250 mL glass flask.…”

“…The mixture was thoroughly stirred and then transferred into a 100 mL Teflon liner. After a purge with a N 2 stream (100 mL/min) for 20 min to expel air from the dispersion, the autoclave was air-tightly sealed, heated up to 240 °C (at a rate of 8 °C/min), and kept at that temperature for 4 h. 19 Then, the autoclave was naturally cooled to room temperature, and the solid sample was filtered, alternatively washed with anhydrous alcohol and DI water for three times, and oven-dried at 80 °C overnight for further use. To prepare Zn(II) containing hydrochar, ZnSO 4 solution (10, 500, 5000, 10 000 mg/L, based on ZnSO 4 ) instead of DI water was used as hydrothermal liquid, and the other procedures were the same as those described above.…”

Removal of lead, copper, cadmium, zinc, and nickel from aqueous solutions by alkali-modified biochar: Batch and column tests

“…Song et al [14] and Wang et al [15] found that MnOx-loaded biochars have enhanced sorption ability to aqueous copper and arsenic. Oxidation chemical agents such as hydrogen peroxide were also used to modify biochars to enhance their sorption ability to heavy metals in aqueous solutions [8,16]. All these modifications dramatically alter the surface properties of the biochars and greatly enhance their sorptive ability to heavy metals in aqueous solutions.…”