Materials Science Forum Vol. 814

Abstract: Life cycle assessment (LCA) was carried out to quantify and analyze the environmental impact and benefit caused by the utilization of coal gangue as alternative raw material and fuel in cement clinker production. The optimal dosage of coal gangue was determined by comparing among different mixing amount scenarios and Portland cement clinker (clinker without adding any waste) considering the phases of coal gangue disposal, transportation, and raw meal grinding and clinker calcination. The results showed that: 1) After adding coal gangue to the raw meal, almost all the considered environmental impacts of cement clinker including human toxicity potential, photochemical smog potential, especially abiotic depletion potential decreased significantly. However, global warming potential and acidification potential increased slightly in comparison with Portland cement clinker. 2) Compared with the Portland cement clinker, the single environmental indicator reduced after adding coal gangue and the indicator decreased gradually with the dosage increasing.

Abstract: The removal of Fe³⁺, Cu²⁺,Cd²⁺,Cr³⁺ and Zn²⁺ ions from aqueous solution was studied by sorption onto polystyrene microcapsules containing 8-hydroxy-quinoline as extraction reagent. The micro-capsules containing 8-hydroxy-quinoline were prepared by solvent evaporation method with O/W emulsion and characterized by using optical microscope, Fourier Transform Infrared Spectroscopy (FT-IR). The uptake to Fe³⁺, Cu²⁺,Cd²⁺,Cr³⁺ and Zn²⁺ ions into the microcapsules was studied at deferent conditions. It showed that with the increasing dosage of microcapsules, the removal of metal ions increased too. The longer is standing time, the more is the increasing of adsorption capacity. The sorption of metal ions decreases with the initial pH of the solution increasing, and the sorption of microcapsule for metal ions is lower at 50°C. The sorption of Cr³⁺, Cu²⁺ and Zn²⁺ ions is highest at 45°C, and that of Fe³⁺, Cd²⁺ is at 40°C. The results showed that the microcapsules could absorb Cr³⁺ ions better than other metal ions.

Abstract: Based on producing and manufacturing process of key components, a light-duty battery electric passenger vehicle was selected as a research object, and the energy consumption and environmental emissions from raw materials production, electric vehicle manufacture and operation process in depth were analyzed. The results showed that, the energy consumption for the whole life cycle of EV was 438GJ. The production and operation process of EV accounted for 18.5% and 81.5%, respectively. The GHGs (including CO₂, CH₄ and N₂O) emission was 39.3tCO₂-eq. The production and operation processed of EV account for 17% and 83%, respectively. Five kinds of other gases emissions from the production and operation process of EV were as follows: 305kg SO_x, 206kg NO_x, 133kg PM, 69.3kg CO, and 14.6kg NMVOCs. The production and manufacture of key parts and components account for the largest share of the total energy consumption and environmental emissions. Battery system is in the next place, while motor system is least.

Abstract: Fly ash/CeO₂ composite (FA/CeO₂) was prepared by acid modification and precipitation method using a low-cost waste fly ash (FA) as a raw material and characterized by X-ray diffraction (XRD) and the BET surface analysis. The adsorption of FA and FA/CeO₂ for Congo Red (CR) from simulated dye wastewater was studied. The different regeneration methods for the CR-saturated FA/CeO₂ were investigated. The results show that the adsorption capacity and removal rate of CR on FA/CeO₂ can respectively reach 175.35mg/g and 97.42%, 4.5 times higher than those on FA. The adsorption process of FA/CeO₂ for CR at different temperatures (25°C~55°C) can well be described by the pseudo-second-order adsorption model and is mainly controlled by intraparticle diffusion. The adsorption rate decreased slightly with increasing temperature, and the obtained adsorption apparent activation energy is 15.08kJ/mol. This indicates that CR is easily adsorbed on FA/CeO_2, and the adsorption of the process is mainly physical adsorption with exothermic nature. The room temperature is favorable to the adsorption and actual operation. NaOH solution of 0.01 mol/L can make CR-saturated FA/CeO₂ regenerated three times, and corresponding removal rate for CR can reach 97.82%, 80.21% and 66.04%, respectively. As a new kind of low-cost and high-efficient adsorbent, FA/CeO₂ composite has the potential value in the application of wastewater treatment.

Abstract: Increasing air pollution caused mainly by exhaust emission has become a serious concern for public health. In order to efficiently control the exhaust emission from the origin, hot gas filtration is required in many industries, such as thermal power regeneration, metal refining/recycling, and biomass/coal gasification. This study aimed to develop a hybrid filter composed with ultrafine fibrous polyimide (PI) filtration layers and carbon woven fabric supporting layers for hot gas filtration. Uniform PI ultrafine fibers around 200 nm with small pores about 2.2 μm were electrospun on carbon fabrics supporting layers to serve as the filtration layer. During filtration test, NaCl aerosols (0.3 mm), which mimicked PM 2.5 particles were accumulated on the top of filtration layer and formed dust cake, but limited aerosols were observed on the carbon fabric supporting layers. It was proved that PI fiber mats played the key role in filtration. The filtration efficiency could be maintained above 95% after 9 min and reached 99.4 %. This research proved that the multi-scale polyimide/carbon fibers hybrid filters possessed the potential to serve as filtration media in bag filters for hot gas filtration.

Abstract: To explore NOx mitigation strategies in Chinese cement industry systematically, a material flow analysis was developed. The realistic output of cement production in China were identified and quantified. The inventory data of Chinese cement production were selected without denitration technology applications at that time. Then the life cycle impact assessment (LCIA) results were calculated with the principal of ISO 14040 and ISO 14044 of Life Cycle Assessment. The impact categories of global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), photochemical oxidant formation potential (POCP), and human toxicity potential (HTP) were used to calculate environmental impact. The results showed that the NOx emission was the major environmental damages and the following was CO₂ emission. This argument disagreed with the view that CO₂ emission was the major contributor of environmental load. The reason is that the NOx emission is far over the international level due to few denitration technology applications. In the assumption of selective non-catalytic reduction (SNCR) technology applications, there is still large emission mitigation potential according to the target scenario analysis. The application of selective catalytic reduction (SCR) technology with higher deNOx efficiency and the roadmap of deNOx of Chinese cement industry were also discussed. The SNCR technology with the auxiliary of SCR development over the coming decades will be decisive for the roadmaps of Chinese cement industry to reach deeper NOx emission cuts.

Abstract: Using the industrial limestone, fly ash and pure chemical reagents as raw materials, the blast furnace slag was prepared by the fast air-cooled method. Using orthogonal experiment method, the influence of process conditions such as heating rate, heat preservation time of the blast furnace slag in hearth, discharge temperature of slag and cooling speed on the glass content and hydraulic activity of blast furnace slag were studied, the main influence factors and the optimal process conditions of blast furnace slag were determined. The results showed that the discharge temperature of slag was the key factor influencing on the glass content of granulated blast furnace slag. The impact degree of all process conditions on the glass content of granulated blast furnace slag accord with the following sequence: discharge temperature of slag > heat preservation time > heating rate > cooling rate. And heat preservation time and cooling rate were the key factors influencing 28 days activity index of blast furnace slag, the impact sequence of all process conditions on the 28 days activity index of granulated blast furnace slag was as follows: heat preservation time > cooling rate > discharge temperature of slag > heating rate. This study also optimized the process conditions of granulated blast furnace slag for different indicators.

Abstract: Heat fusion method and hot-press method were applied to immobilize hydroxyapatite (HAp) particles onto the surface of PET filter fabric separately. The effects of treating temperature, treating time and HAp amount on immobilization rate of HAp and pore size of filter fabric were discussed. The high immobilization rate of HAp could be obtained and pore size could be maintained. FTIR, SEM and XRD were used to characterize the structure of filter fabric embedded with HAp particles. Good adsorption property of Cd²⁺ onto HAp immobilized filter fabric was achieved.

Abstract: In this study, different appearances, structures and morphologies of macro-clay G105-Polymer grade montmorillonite (PMMT) and nanoclay Lithium magnesium silicate (LMSH) were compared and analyzed, which were used in different conditions of non-adsorption and adsorption of crystal violent (CV). Adsorption kinetics and properties of the macro/nanoclay in CV solution were studied, and adsorption time, dye concentration and environmental pH were the main factors on the inspection in this work. The adsorption mechanisms of the macro-/nanoclay on CV were investigated. The results showed that adsorption actions of PMMT and LMSH on CV were some similar, such as time-dependent, linear growth of adsorbed CV amount with increasing CV concentration, adsorption capacity of macro-/nanoclay declined firstly and then increased in 10mg/L CV solution along with increasing pH value. But the adsorption differences in two systems of PMMT-CV and LMSH-CV were obvious. Adsorption behavior of LMSH-CV system showed two adsorption phenomena. Under neutral conditions, adsorbed CV amount in 0.5g LMSH was 1.69 times that of PMMT. Adsorption amount of LMSH was more significant to be affected by dye concentration and pH conditions. The research achievements further showed that adsorption mechanism was the root cause of the following difference. The adsorption of PMMT-CV relied mainly on iron-exchange effect of layers replaceable cations and surface adsorbed ions with CV cations, while the significant adsorption of LMSH-CV was mainly due to the electrostatic interaction from layers negative charge distribution and CV cationic properties in the solution, partly surface ions exchanges also existed in the adsorption process of LMSH-CV.

Abstract: The development of eco-materials has become an important direction of materials science. Using appropriate methods to evaluate the environmental impacts caused by materials production is important for eco-materials research. For the purpose of obtaining more objective results to environment impacts, several exergy-based methods to indicate resource depletion have been established. However, no proper exergy-based evaluation methods for emissions in China have been reported. The objective of this study is to establish comprehensive exergy-based characterization model for life cycle assessment, and to apply this model to steel production.