To solve the problems of long process and large amount of pollutants in metal extraction of waste zinc-based desulfurizer and copper-zinc-based catalyst,a technical method of efficient and clean synergistic separation and utilization of the copper and zinc in the two materials by vacuum carbothermal reduction method was proposed.On the basis of the characterizations of the chemical composition and main phase of the waste desulfurizer and copper-zinc-based catalyst,the experimental study of vacuum carbothermal synergistic extraction and separation of copper and zinc was carried out.The optimum zinc volatilization process conditions were obtained by adjusting the heating temperature,holding time and batch ratio,and the process mechanism was analyzed in depth.The results showed that the waste desulfurizer with ZnS as the main phase and the scrap copper-zinc-based catalyst with CuO and ZnO as the main phase could effectively reduce and volatilize the zinc in the two materials during vacuum carbothermal reduction.The mixture of copper-zinc-based catalyst,desulfurizer,and carbon with C∶(ZnO+CuO)as 1∶1(molar ratio)and CuO∶ZnS as 2∶1(molar ratio)was heated to 1100℃for 60min,the reduction and volatilization rate of zinc reached 99.56%,and the copper grade in the reduced slag was 59.46%with the copper existing mainly as Cu1.96S,which could be used as ice copper blowing raw materials.
The presence of various furan aldehydes in cellulose hydrolysate affects the fermentation of 1,2,4-butanetriol (BT) in a similar way. In this study, furfural was used as a representative for the modification of BT-producing E. coli for tolerance. The engineered Escherichia coli harboring the recombinant BT pathway had decreased the biomass by 58% and the BT titer by 52% in the presence of 0.4 g/L furfural. To improve the tolerance of the strain and the efficiency of BT synthesis in the hydrolysate, seven furfural tolerance genes, ucpA , fucO , groESL , lpcA , pncB , nadD , and nadE were introduced into the BT-producing E. coli . All these genes differentially improved the furfural tolerance performance of the cells. Overexpression of these tolerance genes reduces the accumulation of reactive oxygen species and promotes glycolysis. Oxidoreductase UcpA was the best candidate for improving cell growth. UcpA also increased the activities of Xdh and YqhD and the RNA levels of YjhG and KivD, leading to a 32% increase in BT yield per biomass and the best BT titer of 14.4 g/L in the presence of 0.4 g/L furfural. In the shaker and 5 L fermenter, the BT titer reached 5.2 g/L and 11.2 g/L, respectively, by using corn cob cellulose as substrate.
Bioplastics are polymers made from sustainable bio-based feedstocks. While the potential of producing bio-based monomers in microbes has been investigated for decades, their economic feasibility is still unsatisfactory compared with petroleum-derived methods. To improve the overall synthetic efficiency of microbial cell factories, three main strategies were summarized in this review: firstly, implementing approaches to improve the microbial utilization ability of cheap and abundant substrates; secondly, developing methods at enzymes, pathway, and cellular levels to enhance microbial production performance; thirdly, building technologies to enhance microbial pH, osmotic, and metabolites stress tolerance. Moreover, the challenges of, and some perspectives on, exploiting microorganisms as efficient cell factories for producing bio-based monomers are also discussed.
The gas sulfur reduction of phosphogypsum in the acid co-production of sulfoaluminate cement clinker is a new process for treating phosphogypsum. The reduction furnace of this system was studied and analyzed by combining computational fluid dynamics (CFD) and experimental validation. The effects of n(CaSO4)/n(S2), particle residence time, and kiln tail flue gas temperature on the performance of the reduction furnace were obtained. A second-order response model based on the response surface methodology was developed using a three-factor Box–Behnken design (BBD). The results show that the comparison error between the simulation and test data of the reduction furnace is acceptable. The above three conditions arranged in order of significance in terms of their effect on the performance of the reduction furnace is n(CaSO4)/n(S2) > particle residence time > kiln tail gas temperature. Finally, by optimizing the response surface model, the predicted optimal operation parameter combination is n(CaSO4)/n(S2) = 3.04, with the particle residence time and flue gas temperature at the kiln end given as 8.90 s and 1265.39 K, respectively.
Bromine chloride is an important halogenating reagent in industry.Its synthesis has many challenges such as high heat release,low production efficiency and serious potential safety hazards.The continuity and miniaturization of producing equipment is an important development direction of bromine chloride synthesis technology.To develop microreaction technology for preparing bromine chloride via absorbing chlorine by means of dichloromethane solution of bromine,the mass transfer performances of Corning G1 reactor,Jinde C1 reactor and self-made micromixer + micro packed reactor were investigated.Continuous and stable preparation of bromine chloride was realized and the space-time yield of the microreactors reached 2.25g/(min∙mL).Bromination of polystyrene was implemented using the bromine chloride prepared from microreactors,and brominated polystyrene products with mass percentage>66% bromine content and 5% thermogravimetric temperature>370℃ were obtained.
