Preparation and property studies of ferric sulfoaluminate cement based on Bayer red mud and phosphogypsum.

The Bayer red mud (RM) and phosphogypsum (PG) accumulation have caused significant environmental contamination. However, practical and effective resource utilization technologies are still lacking currently. This work aims to develop ferric sulfoaluminate cement (FSAC) employing low-cost materials including Bayer red mud, phosphogypsum, and other materials. This method effectively improves the utilization rate of Bayer red mud and phosphogypsum. Under the premise of ensuring the performance of FSAC, the utilization rate of solid waste can reach up to 48.56%. The effects of different red mud dosages on cement mineral formation, workability, and mechanical properties are investigated. Then, untreated phosphogypsum is adopted as a retarder for FSAC, and the hydration process, working properties, mechanical properties, types of hydration products, and morphology of FSAC are explored. The results suggest that the crystal transformation of Ye'elemite C 4 A 3 S ¯  is promoted with the increase of Bayer red mud content. Cubic crystal system Ye'elemite C 4 A 3 S ¯ - c  with higher hydration activity is generated, which increases the early strength of cement but greatly reduces the setting time, hindering the later strength growth. Untreated phosphogypsum can effectively delay the early hydration process of FSAC, prolong the setting time of cement, and increase the strength of FSAC in the later stage. When the dosage of Bayer red mud and phosphogypsum is 17.64% and 9.21%, respectively, with phosphogypsum dosage of 20%, the prepared FSAC has satisfactory mechanical properties, and the 3-day and 90-day compressive strengths are 34.6 MPa and 57.1 MPa, respectively. In addition, the study of heavy metal leaching indicates that the FSAC prepared by Bayer red mud, phosphogypsum, and other raw materials will generate no environment pollution, and the solidification of heavy metal elements in the cement slurry is superior.

Study on harmless treatment of electrolytic manganese residue by low temperature thermochemical method.

The Electrolytic Manganese Residue (EMR) is a by-product of the electrolytic manganese metal (EMM) industry, containing high concentrations of potential pollutants such as NH4+-N and soluble Mn2+. These components pose a serious threat to the ecological environment. To explore accurate, efficient, and harmless treatment methods for EMR, this study proposes a low-temperature thermochemical approach. The orthogonal experiment design investigates the effects of reaction temperature, reaction time, quicklime (CaO), sodium carbonate (Na2CO3), sodium phosphate (Na3PO4) (Reviewer #3), and water consumption on manganese solidified and ammonia removal from EMR. The results indicate that optimal conditions are a reaction temperature of 60 ℃ (Reviewer #3) and a reaction time of 10 min. CaO precipitates Mn2+ as manganese hydroxide (Mn(OH)2) (Reviewer #3), achieving effective manganese solidified and ammonia removal. The addition of Na2CO3 causes Mn2+ to form manganesecarbonate (MnCO3) (Reviewer #3)precipitate, while Na3PO4 makes Mn2+ form Manganese phosphate trihydrate (Mn3(PO4)2·3H2O) (Reviewer #3). Increased water consumption enhances the interaction adequacy between ions. Under optimal conditions (CaO 10%, Na2CO3 1%, Na3PO4 0.5%, and 80% water consumption), the removal rate of ammonium ions reaches 98.5%, and the solidification rate of soluble Mn2+ is 99.9%. The order of influence on ammonium ion removal is CaO > water consumption > Na3PO4 > Na2CO3. Therefore, this study provides a new method for low-cost process disposal and efficient harmless treatment of EMR (Reviewer #3).

The Effects of Epistemic Trust and Social Trust on Public Acceptance of Genetically Modified Food: An Empirical Study from China.

Most studies exploring the public acceptance of genetically modified food (GMF) are based on social trust and the establishment of a causal model. The underlying premise is that social trust indirectly affects public acceptance of GMF through perceived risks and perceived benefits. The object of social trust is trust in people, organizations, and institutions. Different from the social trust, epistemic trust refers to people's trust in scientific knowledge behind the technology of concern. It has been shown that epistemic trust, like social trust, is also an important factor that affects the public perception of applicable risks and benefits. Therefore, it is necessary to incorporate epistemic trust into the causal model to derive a more complete explanation of public acceptance. However, such work has not been conducted to date. The causal model proposed in this paper integrated epistemic trust and social trust and divided social trust into trust in public organizations and trust in industrial organizations. A representative questionnaire survey (N = 1091) was conducted with Chinese adults. The model was analyzed by the partial least squares structural equation modeling (PLS-SEM) method. Three major findings were obtained: First, epistemic trust is an important antecedent of perceived risks and perceived benefits and exerts a significant indirect effect on the acceptance of GMF. Secondly, trust in industrial organizations negatively impacts perceived risks, while trust in public organizations positively impacts perceived benefits. Thirdly, contrary to the common opinion, trust in industrial organizations did not exert a significant direct effect on perceived benefits, and trust in public organizations did not demonstrate a significant direct effect on perceived risks. Therefore, trust in industrial organizations and trust in public organizations utilize different influence paths on GMF acceptance. This study enriches the understanding of the influence path of trust with regard to the acceptance of emerging technologies and is of great significance to relevant risk-management practices.