RESUMEN
Steel hydrochloric acid pickling sludge (SHPS), containing the heavy metals Fe, Zn, and Ni and a high chloride salt content, is considered a hazardous solid waste. With the gradual reduction of high-grade metal mineral resources such as Fe, Zn and Ni, it is particularly urgent to recycle valuable metals such as Fe, Zn and Ni in solid waste SHPS in order to realize the resource utilization of SHPS and reduce the environmental harm caused by SHPS. In addition, SHPS usually contains different amounts of alkali chloride, which will have a serious adverse impact on the subsequent extraction and smelting process of Fe, Zn and other metals. Therefore, the removal of chloride plays an important role in the resource utilization of valuable metals in SHPS. Thus, in this study, the effects of water washing dechlorination process parameters such as liquid-solid (L/S) ratio, SHPS particle size, washing time and washing frequency on the chloride removal rate were investigated. The best experimental parameters of SHPS washing were obtained. At the same time, the microscopic morphology and crystal phase composition of SHPS before and after washing were explored. The results showed that the optimized conditions were as follows: room temperature, a L/S ratio of 3 : 1, an SHPS particle size of 100 mesh, and 10 min of water washing, repeated two or three times; under these conditions, the removal rate of Cl, Na, Ca, K, Mg, and S reached 96.64-99.68%, 97.38-99.89%, 36.40-60.37%, 49.11-54.82%, 39.18-40.22%, and 36.98-42.13% respectively. The contents of Cl, K, and Na in filter residue (FR) meets the requirements in GB/T 36144-2018 and GB/T 32545-2016. Conversely, the contents of Fe, Zn, Mn and Ni in the FR are enriched, which is more conducive to the subsequent resource utilization of SHPS. The scanning electron microscope (SEM) image shows the particle size of the FR particles is reduced after washing. The X-ray diffractometer (XRD) results proved that the chlorine salt content in the FR after washing was significantly reduced, the diffraction peaks of Al2O3 appeared in the FR, and the diffraction peak intensity of CaCO3, Fe2O3 and SiO2 increased.
RESUMEN
This study explores the production of flash graphene (AC-FG) from anthracite coal by using the flash Joule heating (FJH) method. This study demonstrates that AC-FG can be derived from anthracite coal by precisely controlling the system parameters, specifically the pulse voltage. The FJH process requires no catalyst. The produced material was characterized by using Raman, XRD, XPS, TG, SEM, TEM, and XPS techniques. The results reveal that the degree of graphitization of coal reaches its peak at 190 V. From an energy perspective, FJH provides a straightforward and cost-effective method for graphene preparation, offering a substantial avenue for the efficient utilization of coal resources and the cost-effective application of graphene.
RESUMEN
Old corrugated containers with low recyclability were used as raw materials to synthesize a series of aerogels with varying cellulose concentrations in NaOH/urea solution via a freeze-drying process. The resulting aerogels had a rich porous structure with specific surface areas in the range of 132.72-245.19 m2.g-1 and mesopore volumes in the range of 0.73-1.53 cm3.g-1, and were tested for CO2 sorption at ambient temperature and pressure, displaying excellent CO2 adsorption capacities in the range of 1.96-11.78 mmol.g-1. Furthermore, the CO2/N2 selectivity of aerogels decreased with decreasing specific surface area, which was mainly caused by the decrease in CO2 capture. In addition, the CO2 sorption capacity of the sample with 2% cellulose content, CA-2, exceeded the values reported so far for many other sorbents with higher specific surface areas, and showed reasonable cyclic stability for CO2 capture. Therefore, this adsorbent represents an attractive prospect for CO2 uptake at room temperature.
