Experimental study on adsorption of PbCl2 and CdCl2 on kaolin modified by leachates from municipal solid waste incineration power plant.

Six kinds of waste liquids produced in the treatment process of leachate in a waste incineration plant were used to improve the adsorption effect of raw kaolin on heavy metal chloride. The capture performances of these modified kaolin on PbCl2 and CdCl2 vapor were investigated in a two-stage fixed bed combustor. The results indicated that the adsorption effects of raw kaolin on PbCl2 and CdCl2 were improved in some experimental groups, main effective component was Na+ in the leachate, but the influences did not change regularly with the increase in the concentration of Na + introduced into kaolin. The adsorbents formed by modifying 10 g kaolin with 21.25 ml leachate 2 were the best adsorbents for PbCl2 and CdCl2. The capture efficiencies of PbCl2 and CdCl2 can reach 95% and 63.88%, with the increase of 36% and 53%, respectively. Using leachate as modifying agent had the same effect as directly using Na+. Adsorptions of PbCl2 and CdCl2 were still mainly chemical adsorptions. After adsorption of PbCl2, the modified kaolin not only generated PbA12Si2O8, but also produced other chemical compounds. The adsorption of CdCl2 by modified kaolin did not generate CdAl2Si2O8, but other chemical reactions occurred to generate CdAl2O4 and Pb8Cd (Si2O7)3.

One-step fabricated Zr-supported, CaO-based pellets via graphite-moulding method for regenerable CO2 capture.

Calcium looping (CaL) belongs to a promising high-temperature CO2 capture technology because of adopting cheap and extensive source CaO-based sorbents. However, CaO-based sorbents are prone to occur the issues of sintering and elutriation in the fluidized-bed reactors. To further enhance the practicability, the Zr-supported, CaO-based sorbent pellets were produced using the graphite-moulding method. Different synthesis modes (i.e., sol-gel, hydration-mixing, and wet-mixing) were compared for preparing CaO-based composite slurry before pelletization. Sol-gel is the promising synthesis mode to prepare Zr-supported, CaO-based pellets with outstanding CO2 capture performance due to achieving a more uniform distribution of inert CaZrO3 spacer. Moreover, the Zr-based stabilizer content within sorbent pellets produced by the combined method of sol-gel and graphite-moulding was further studied. The higher content of Zr-based stabilizer promotes the enhancement of cyclic stability and mechanical strength of Zr-supported, CaO-based pellets. After 17 cycles, the sorbent pellets containing 20 wt% of Zr-based stabilizer display a high CaO carbonation conversion of 74.1 %. Moreover, CaO-based pellets with 20 wt% of Zr-based stabilizer possess a higher compression strength of 4.84 ± 1.08 MPa, which is as high as 1.8 times that of the pellets with 5 wt% of Zr-based stabilizer.

Prediction and Trend Analysis of Regional Industrial Carbon Emission in China: A Study of Nanjing City.

Based on the Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) model, the impact factors of industrial carbon emission in Nanjing were considered as total population, industrial output value, labor productivity, industrialization rate, energy intensity, research and development (R&D) intensity, and energy structure. Among them, the total population, industrial output value, labor productivity, and industrial energy structure played a role in promoting the increase of industrial carbon emissions in Nanjing, and the degree of influence weakened in turn. For every 1% change in these four factors, carbon emissions increased by 0.52%, 0.49%, 0.17% and 0.12%, respectively. The industrialization rate, R&D intensity, and energy intensity inhibited the increase of industrial carbon emissions, and the inhibiting effect weakened in turn. Every 1% change in these three factors inhibited the increase of industrial carbon emissions in Nanjing by 0.03%, 0.07%, and 0.02%, respectively. Then, taking the relevant data of industrial carbon emissions in Nanjing from 2006 to 2020 as a sample, the gray rolling prediction model with one variable and one first-order equation (GRPM (1,1)) forecast and scenario analysis is used to predict the industrial carbon emission in Nanjing under the influence of the pandemic from 2021 to 2030, and the three development scenarios were established as three levels of high-carbon, benchmark and low-carbon, It was concluded that Nanjing's industrial carbon emissions in 2030 would be 229.95 million tons under the high-carbon development scenario, 226.92 million tons under the benchmark development scenario, and 220.91 million tons under the low-carbon development scenario. It can not only provide data reference for controlling industrial carbon emissions in the future but also provide policy suggestions and development routes for urban planning decision-makers. Finally, it is hoped that this provides a reference for other cities with similar development as Nanjing.

Typical Gaseous Semi-Volatile Metals Adsorption by Meta-Kaolinite: A DFT Study.

Kaolinite can be used as in-furnace adsorbent to capture gaseous semi-volatile metals during combustion, incineration, or gasification processes for the purposes of toxic metals emission control, ash deposition/slagging/corrosion inhibition, ultrafine particulate matter emission control, and so on. In this work, the adsorptions of typical heavy metals (Pb and Cd) and typical alkali metals (Na and K) by meta-kaolinite were investigated by the DFT calculation. The adsorption energies followed the sequence of NaOH-Si surface > KOH-Si surface > PbO-Al surface ≈ CdO-Al surface ≈ NaOH-Al surface > KOH-Al surface > NaCl-Al surface ≈ Na-Si surface > Na-Al surface > KCl-Al surface > Pb-Al surface > PbCl2-Al surface > CdCl2-Al surface ≈ K-Si surface ≈ PbCl-Al surface > K-Al surface > CdCl-Al surface > NaCl-Si surface > KCl-Si surface > Cd-Al surface. Si surface was found available to the adsorptions of Na, K, and their compounds, although it was invalid to the adsorptions of Pb, Cd, and their compounds. The interactions between adsorbates and surfaces were revealed. Furthermore, the discussion of combining with the experimental data was applied to the subject validity of calculation results and the effect of chlorine on adsorption and the effect of reducing atmosphere on adsorption.

High-temperature chlorination of PbO and CdO induced by interaction with NaCl and Si/Al matrix.

Municipal solid-waste incineration leads to emission of lead (Pb) and cadmium (Cd), which vaporize in furnace and condense in flue. NaCl in waste has been proven to enhance volatilization of Pb and Cd at high temperatures via chlorination of oxides to chlorides; however, this process was not well-understood so far due to its complexity. This study decoupled the indirect chlorination process and direct chlorination process so that these two processes were investigated separately. A horizontal tube furnace was used to heat the mixtures of NaCl and Si/Al matrix for indirect chlorination and the mixtures of NaCl, PbO/CdO and Si/Al matrix for direct chlorination. A set of dynamic sampling devices was designed and used to obtain dynamic data during temperature rising. The indirect chlorination process was initiated above 800 °C in O2 + H2O atmosphere and O2 atmosphere and above 1000 °C in N2 atmosphere. Al2O3 exhibited higher activity than SiO2 to react with NaCl, releasing HCl or Cl2. In the Cl release reaction, NaCl was in the gas phase. The direct chlorination process was initiated at 650-700 °C when the Si/Al matrix contained SiO2 only and at around 800 °C when the Si/Al matrix contained Al2O3 only or both SiO2 and Al2O3. SiO2 exhibited higher activity than Al2O3 in direct chlorination. The pre-reaction between PbO/CdO and Si/Al matrices was considered as the necessary condition for direct chlorination. During chlorination in O2 + H2O atmosphere, indirect chlorination and direct chlorination occurred simultaneously, and the latter dominated the volatilization of Pb and Cd.

Biomass fast pyrolysis in a fluidized bed reactor under N2, CO2, CO, CH4 and H2 atmospheres.

Biomass fast pyrolysis is one of the most promising technologies for biomass utilization. In order to increase its economic potential, pyrolysis gas is usually recycled to serve as carrier gas. In this study, biomass fast pyrolysis was carried out in a fluidized bed reactor using various main pyrolysis gas components, namely N(2), CO(2), CO, CH(4) and H(2), as carrier gases. The atmosphere effects on product yields and oil fraction compositions were investigated. Results show that CO atmosphere gave the lowest liquid yield (49.6%) compared to highest 58.7% obtained with CH(4). CO and H(2) atmospheres converted more oxygen into CO(2) and H(2)O, respectively. GC/MS analysis of the liquid products shows that CO and CO(2) atmospheres produced less methoxy-containing compounds and more monofunctional phenols. The higher heating value of the obtained bio-oil under N(2) atmosphere is only 17.8 MJ/kg, while that under CO and H(2) atmospheres increased to 23.7 and 24.4 MJ/kg, respectively.