Abstract: Disclosed is a method of preparing a carbon quantum dot from soybean dregs by hydrothermal synthesis, including: mixing the soybean dregs with water, and subjecting the reaction mixture under heating at 100-500° C. in an autoclave for reaction; cooling the reaction mixture when the reaction is completed, and removing insoluble substances from the reaction mixture; and dialyzing the reaction mixture, and lyophilizing the dialyzed product to produce the carbon quantum dot. The invention further provides the carbon quantum dot prepared by the above method and a use thereof in the detection of Fe3+ and Hg2+ in water, where the lowest detection limit can reach 30 nmol/L and the detection range is 0.1-50 ?mol/L.

Abstract: A high-concentration anaerobic fermentation apparatus includes a liquid accumulation tank, a fermentation vessel, a feeding assembly, and a biogas residue collecting bin. The feeding assembly includes a hopper and a return conveyor belt including a first portion extending downward from the hopper till below a liquid level, a second portion extending upward from a bottom end of the first portion till above the liquid level, a third portion extending downward from a top end of the second portion till the liquid level, and a fourth portion extending upward from a bottom end of the third portion till out of the liquid level and above the biogas residue collecting bin. A pressure-feed flange is disposed at an outer side of the fermentation vessel, a feed channel is formed between the pressure-feed flange and the first portion, and a discharge channel is formed between the pressure-feed flange and the fourth portion.

Abstract: Disclosed is a method of preparing a carbon quantum dot from soybean dregs by hydrothermal synthesis, including: mixing the soybean dregs with water, and subjecting the reaction mixture under heating at 100-500° C. in an autoclave for reaction; cooling the reaction mixture when the reaction is completed, and removing insoluble substances from the reaction mixture; and dialyzing the reaction mixture, and lyophilizing the dialyzed product to produce the carbon quantum dot. The invention further provides the carbon quantum dot prepared by the above method and a use thereof in the detection of Fe3+ and Hg2+ in water, where the lowest detection limit can reach 30 nmol/L and the detection range is 0.1-50 ?mol/L.