Résumé
Chromium is a harmful contaminant showing mutagenicity and carcinogenicity.Therefore,detection of chromium requires the development of low-cost and high-sensitivity sensors.Herein,blue-fluorescent carbon quantum dots were synthesized by one-step hydrothermal method from alkali-soluble Poria cocos polysaccharide,which is green source,cheap and easy to obtain,and has no pharmacological ac-tivity due to low water solubility.These carbon quantum dots exhibit good fluorescence stability,water solubility,anti-interference and low cytotoxicity,and can be specifically combined with the detection of Cr(Ⅵ)to form a non-fluorescent complex that causes fluorescence quenching,so they can be used as a label-free nanosensor.High-sensitivity detection of Cr(Ⅵ)was achieved through internal filtering and static quenching effects.The fluorescence quenching degree of carbon dots fluorescent probe showed a good linear relationship with Cr(Ⅵ)concentration in the range of 1-100 μM.The linear equation was F0/F=0.9942+0.01472[Cr(Ⅵ)](R2=0.9922),and the detection limit can be as low as 0.25 μM(S/N=3),which has been successfully applied to Cr(Ⅵ)detection in actual water samples herein.
Résumé
Sulfate-reducing bacteria (SRB) are widespread in the environment. SRB are obligate anaerobes and capable of dissimilatory reduction of sulfate. SRB have application prospects in the control of environmental pollution due to that many pollutants can be removed by SRB. The biological characteristics and metabolic mechanisms of SRB are introduced, and the application of SRB in the treatment of environmental pollution is described in this paper. The research progress of Cr(Ⅵ ) reduction and Cr(Ⅵ ) removal from wastewater by SRB is reviewed, and future direction of research on the control of Cr(Ⅵ ) pollution by SRB is also analysed.
Résumé
Objective:Toresearch the characteristics about resistance and reduction on Cr(Ⅵ)ofCQMUXH-1. Methods:Simulating the environment of C(rⅥ)in the lab. Cultivating bacteria under different condition(reaction time,pH,temperature,C(rⅥ)concentration, other pollutants)and determining the growth quantity of bacteria and(or)concentration of residual Cr(Ⅵ)to evaluate the ability for tolerating and reducing C(rⅥ)of CQMUXH-1. Results:5~20 h is the logarithmic growth phase of CQMUXH-1 when cultured in 30℃ and vibration conditions. The resistant ability to Cr(Ⅵ)of CQMUXH-1 is better than the E. coli DH5? control bacteria. The reduction rate of CQMUXH-1 to 100 mg/L Cr(Ⅵ)is 73% when cultured in 37℃,200 r/min after 84 h. The weak base environment has bad effects to the growth of CQMUXH-1 and 37℃ can speed up its growth. Hg2+,As3+ can obviously restrain the growth of CQMUXH-1 and Cu2+ can promote its growth. Conclusion:CQMUXH-1 has strong ability to resist and reduce Cr (Ⅵ),which can be effectively used in the bioremediation of waste water with Cr(Ⅵ)pollution.