Reduction-Magnetic Separation of Pickling Sludge by Biomass Pyrolysis Reducing Gas.

The neutralization process of carbon steel pickling wastewater produces a large amount of steel hydrochloric acid pickling sludge (SHPS), and improper treatment of this sludge poses a serious threat to the environment. Considering that SHPS contains a large amount of iron oxide and given the huge demand for iron concentrate in China's ironmaking industry, refining iron oxide in SHPS into iron concentrate will have great environmental and economic benefits. This paper proposes a new method that uses biomass (corncob) to replace conventional coal-based reductants for the recovery of iron components in SHPS to simultaneously utilize two kinds of solid waste resources. Factors that affect the iron recovery rate and iron grade of SHPS, such as the reaction temperature, corncob dosage, residence time, and magnetic field strength, were studied using a fixed bed and a magnetic separator. These studies were combined with thermodynamic analysis, thermogravimetric analysis, X-ray diffraction, inductively coupled plasma-mass spectrometry, gas chromatography, etc. The results showed that when the reaction temperature was 680 °C, the corncob dosage was 5%, the residence time was 20 min, and the magnetic field strength was 200 mT, the recovery rate of iron reached 91.83%, and the iron grade of the recovered products was 67.72%, meeting the level I requirements in GB/T 32545-2016. Based on this result, a process involving SHPS reduction roasting with corncob pyrolysis reducing gas-magnetic separation was established to recover iron from SHPS. This process not only effectively utilizes the iron oxide in SHPS by converting it into iron concentrate powder for the ironmaking industry but also proves that the pyrolysis gas of corncob has good reduction ability.

Composition and Leaching Toxicity of Hydrochloric Acid Pickling Sludge Generated from the Hot-Dip Galvanized Steel Industry.

Steel hydrochloric acid pickling sludge (SHPS), containing the heavy metals Fe, Zn, and Ni and a high chloride salt content, is considered a type of hazardous solid waste because of its potential harm to human health and the environment. In addition, the SHPS yield is large, but the main treatment currently used is only safe for landfills. Although studying the composition and leaching toxicity of SHPS is of great importance, only a small amount of related literature is available. This paper can help compensate for this deficiency. SHPS is analyzed from the aspects of its formation mechanism, pH, moisture content, elemental concentration, phase composition, microstructure, and leaching toxicity. The results show that its pH ranges from 2.25 to 11.11, and the moisture content ranges from 45.47% to 83.34%. Additionally, the concentration of Fe is the highest, with values from 29.80% to 50.65%, while other alkali metal elements, namely, Ca, K, and Na, have values of 0.36% to 23.07%, 0.02% to 19.82%, and 0.38% to 3.31%, respectively. Heavy metal elements, namely, Zn, Ni, Mn, Cr, and Pb, have values of 0.02% to 14.88%, 0.001% to 0.05%, 0.03% to 0.38%, 0.01% to 0.09%, and 0.02% to 0.19%, respectively. Anions, namely, SO4 2-, Cl-, F-, and NO3 -, have contents of 0.09% to 0.34%, 0.54% to 5.73%, 0.001% to 0.04%, and 0.01% to 0.15%, respectively. X-ray diffraction (XRD) analysis shows that Fe and Zn are mainly present in oxides, Ca is present as CaO and CaCO3, and chlorine is present in NaCl. Moreover, scanning electron microscopy (SEM) analysis shows that the microscopic structure consists mainly of bright and fluffy irregular spheres; stripes; flakes; and dark, very small irregular particles. The leaching toxicity test based on HJ/T 299-2007 (China) was performed, where SHPS samples were treated with a mixed solution of sulfuric acid, nitric acid, and pure water (pH = 3.20 ± 0.05) at a liquid-to-solid ratio of 10:1 for a period of 18 h. The leachate was filtered and analyzed for Cr, Ni, Mn, Zn, etc. The leaching results indicate that Zn and Ni are the main elements that cause SHPS to be hazardous to the environment. These research results can provide a reference for later researchers studying the effective treatment of SHPS, such as more effective treatments for reducing toxicity and resource utilization.

Co-pyrolysis of sewage sludge/cotton stalks with K2CO3 for biochar production: Improved biochar porosity and reduced heavy metal leaching.

The co-pyrolysis of sewage sludge and biomass is considered a promising technique for reducing the volume of sewage sludge, adding value, and decreasing the risk associated with this waste. In this study, sewage sludge and cotton stalks were pyrolyzed together with different amounts of K2CO3 to evaluate the potential of chemical activation using K2CO3 for improving the porosity of the biochar formed and immobilizing the heavy metals present in it. It was found that K2CO3 activation effectively improved the pore structure and increased the aromaticity of the biochar. Moreover, K2CO3 activation transformed the heavy metals (Cu, Zn, Pb, Ni, Cr, and Cd) into more stable forms (oxidizable and residual fractions). The activation effect became more pronounced with increasing amount of added K2CO3, eventually resulting in a significant reduction in the mobility and bioavailability of the heavy metals in the biochar. Further analysis revealed that, during the co-pyrolysis process, K2CO3 activation resulted in a reductive atmosphere, increased the alkalinity of the biochar, and led to the formation CaO, CaCO3, and aluminosilicates, which aided the immobilization of the heavy metals. K2CO3 activation also effectively reduced the leachability, and thus, the environmental risks of the heavy metals. Thus, K2CO3 activation can improve the porosity of the biochar derived from sewage sludge/cotton stalks and aid the immobilization of the heavy metals in it.

Effects of biochar derived from sewage sludge and sewage sludge/cotton stalks on the immobilization and phytoavailability of Pb, Cu, and Zn in sandy loam soil.

Co-pyrolysis of sewage sludge and straws has been used to improve the pore structure and reduce the ecological risks of heavy metals in sewage sludge-derived biochars. However, to date, no study has focused on the effects of biochar derived from sewage sludge/straws on the immobilization and phytoavailability of heavy metals in soil. Here, we studied the effects of biochar derived from sewage sludge/cotton stalks (SCB) and that derived from sewage sludge alone (SSB) on the remediation of sandy loam soil contaminated by Pb, Cu, and Zn. SCB amendment decreased the bioavailable forms of Pb, Cu, and Zn in the soil by 19.0%, 34.9%, and 18.2%, respectively, and reduced their accumulation in ryegrass by 28.6%, 50.1%, and 30.0%, respectively, compared with those by SSB amendment. Furthermore, SCB amendment transformed more metals from the acid-soluble fraction to the oxidizable fraction than SSB amendment, indicating that complexation played a more critical role in SCB amendment than in SSB amendment. Both biochar amendments effectively improved soil water holding capacity, increased the supply of available P, N, and K, and promoted ryegrass growth. The findings of this study show the benefits of SCB over SSB for the remediation of heavy metal-contaminated soil.

Study on the Compressive Strength of Alkali Activated Fly Ash and Slag under the Different Silicate Structure.

Due to its high activation efficiency, waterglass has been widely used for alkali activations in geopolymer. In this study, the n(SiO2)/n(Na2O) (Ms) of waterglass was selected as the variable to investigate the role of the silicate structure on the mechanical properties of harden pastes. Ms was changed by the addition of NaOH to obtain the different silicate group, structure and experiments were performed by employing the liquid-sate 29Si nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and gel permeation chromatography (GPC) techniques. Furthermore, selected dissolution, scanning electron microscope (SEM-EDX), X-ray photoelectron spectroscopy (XPS) and FTIR experiments were used to measure the development of the amorphous gel and other materials with different curing condition. Results show that silicate structure of the waterglass was changed via the Si-ONa+ formation and the electric charge effect of Na+. Under the lower Ms waterglass, the Q0, Q1 and QC2 structure reverted to the main structure of the silicate group, which was kind of lower seize, molecule weight, linear or circular chain lower geopolymerization degree silicon structure. It would accelerate the geopolymerization speed of prepolymer formation. In addition, higher activity degree of Q0 and Q1 were useful to increase the formation amount of the gel structure with a low Si/Al ratio and size. Thus, silicate structure of waterglass controls the amorphous gel properties to adjust the compressive strength of alkali-activated materials.

MiR-21-5p reduces apoptosis and inflammation in rats with spinal cord injury through PI3K/AKT pathway.

BACKGROUND: To explore the effect of micro ribonucleic acid (miR)-21-5p on spinal cord injury (SCI) in rats and its mechanism of action. METHODS: The rat model of SCI was established, and the key miRNAs were screened using the microarray assay and miRNA-mRNA interaction network. After intrathecal injection of agomir-21 and antagomir-21, the effect of miR-21 expression on motor function recovery of rats was evaluated using the Basso-Beattie-Bresnahan (BBB) score. The expression level of miR-21 in spinal cord tissues was determined via quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and the effect of miR-21 expression on apoptosis in spinal cord tissues was determined via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay and Western blotting. Moreover, the effects of agomir-21 and antagomir-21 on SCI-induced expressions of inflammatory factors interleukin-8 (IL-8), IL-1ß, IL-6 and tumor necrosis factor-α (TNF-α) in spinal cord tissues were detected through qRT-PCR. Finally, Western blotting was performed to detect the effects of agomir-21 and antagomir-21 on the phosphatidylinositol 3-hydroxy kinase (PI3K)/protein kinase B (AKT) signaling pathway and its downstream molecules in each group. RESULTS: The screening results of the microarray assay revealed that the mRNA and miRNA expression profiles in spinal cord tissues had significant differences in model group from those in sham group. The BBB score was significantly higher in agomir-21 group than that in model group. Compared with that in model group, the apoptosis of spinal cord tissues was obviously weakened in agomir-21 group, while it was obviously enhanced in antagomir-21 group. Agomir-21 group had evidently lower Bax/Bcl-2, and Caspase-3 and Caspase-9 protein expressions, while antagomir-21 group had evidently higher Bax/Bcl-2 and Caspase-3 protein expression than model group. Besides, the expressions of inflammatory factors IL-8, IL-1ß, IL-6 and TNF-α were remarkably lower in agomir-21 group than those in model group, while they were remarkably higher in antagomir-21 group than those in model group. Finally, it was found that the protein expressions of phosphorylated PI3K (p-PI3K)/PI3K and p-AKT/AKT rose markedly, while the protein expressions of phosphatase and tensin homolog deleted on chromosome ten (PTEN) and endothelial nitric oxide synthase (eNOS) declined markedly in agomir-21 group compared with those in model group. However, the opposite results were observed in antagomir-21 group compared with those in model group. CONCLUSIONS: MiR-21-5p may reduce the apoptosis and inflammation in spinal cord tissues of rats through the PI3K/AKT pathway.

Characteristics of biochars prepared by co-pyrolysis of sewage sludge and cotton stalk intended for use as soil amendments.

The safe disposal and utilisation of sewage sludge can be challenging because of the potential environmental risks posed by heavy metals in the sludge. Conversion of sewage sludge and agriculture biomass into biochars that can be used to improve or remediate contaminated soils is a promising solution to this problem. In this study, biochars were produced via co-pyrolysis of sewage sludge and cotton stalk (1:1, w/w) at temperatures ranging from 300°C to 600°C. Then, the potential environmental risks of heavy metals and properties of the biochars were investigated. The addition of cotton stalk promoted the migration and transformation of heavy metals from bioavailable to stable fractions, which significantly reduced the potential environmental risks of heavy metals in biochars. Moreover, compared with biochars obtained via pyrolysis of sewage sludge alone, the pH values, C contents, and adsorption capacities of biochars increased, while the yields, ash contents, specific surface areas and molar H/C ratios decreased. In summary, co-pyrolysis of sewage sludge and cotton stalk is a feasible method for alleviating the potential environmental risks of heavy metals in biochars used to treat soils.

Co-pyrolysis of sewage sludge and cotton stalks.

Proper disposal of ever-increasing amounts sewage sludge and cotton stalks is a challenge around the world, and conversion of these wastes into biochars via co-pyrolysis may be a promising solution. In this study, biochars were prepared via co-pyrolysis of sewage sludge and cotton stalks with different mixing ratios (cotton stalks/sewage sludge, w/w) at 650 °C for 2.0 h, and then, biochars were characterized to identify their potential agronomic and environmental benefits as soil amendments. Biochars prepared with higher mixing ratios had higher C contents and lower H/C and N/C ratios, which suggests that this approach has potential for improving C storage in biochar-treated soils to help offset greenhouse gas emissions. All biochars were mesoporous materials with an average pore size of 3-4 nm. The specific surface area increases indicated that these biochars would have relatively high water holding capacities and heavy metal adsorption capacities in heavy metal contaminated soils. The high ash contents and cation exchange capacity values in biochars prepared with lower mixing ratios indicate that these products would be useful for enhancing the nutrient supply and nutrient retention capacity in degraded soils. Moreover, the addition of more cotton stalks efficiently decreased the mobility and bioavailability of heavy metals in the biochars. At a certain level, co-pyrolysis of sewage sludge and cotton stalks to produce biochars would have both economic and environmental benefits.

[Hazard evaluation modeling of particulate matters emitted by coal-fired boilers and case analysis].

In order to evaluate the hazard of PM2.5 emitted by various boilers, in this paper, segmentation of particulate matters with sizes of below 2. 5 microm was performed based on their formation mechanisms and hazard level to human beings and environment. Meanwhile, taking into account the mass concentration, number concentration, enrichment factor of Hg, and content of Hg element in different coal ashes, a comprehensive model aimed at evaluating hazard of PM2.5 emitted by coal-fired boilers was established in this paper. Finally, through utilizing filed experimental data of previous literatures, a case analysis of the evaluation model was conducted, and the concept of hazard reduction coefficient was proposed, which can be used to evaluate the performance of dust removers.

[Analysis on the Shanghan new theory phenomenon in the Republic of China].

During the Republic of China, influenced by the introduction of western medicine and the special social, cultural and political background, research on Shanghanlun has presented different features from those before. This phenomenon was called 'Shanghan new theory phenomenon' for this kind of theory tried to expound Shanghanlun from the view point of western medicine or ancient formula school in Japan. Shanghan new theory phenomenon had the following characteristics: the academic viewpoint of this new theory and the edition of Shanghanlun were both influenced by the ancient formula school of Japan; emphasis was put on empirical study. With academic concern, doctors in the Republic of China put forward new theories regarding what are the six meridians, etiological theory, mechanism of herbal medicine for infection, mechanism of TCM formula and comparison between TCM and western medicine. As for its historical role, the new theory school was the main force in TCM academic development and played a role in the debate about whether TCM was scientific and whether it should be abolished. It was also valuable in the combination of TCM and western medicine and diversification of researches on Shanghanlun.