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China's salt lakes contain an abundance of magnesium resources as high-magnesium brine, a by-product of potash fertiliser production is often discharged into salt lakes, causing environmental damage. Magnesium oxide from salt-lake brine can be used to produce magnesium oxychloride cement (MOC), but the calcium impurities present in salt lakes affect the properties of MOC. To investigate the effects of these impurities, magnesium oxide was produced by calcining a magnesium hydroxide precursor. By adding calcium hydroxide or calcium chloride, the incorporated calcium impurities were 0, 5 and 10% by mass of magnesium oxide. The compressive strength, heat of hydration, composition of the hydration product phases and the pore structure development of MOC samples were evaluated. It was found that Ca2+ ions increased the early strength and the rates of setting and hardening of the MOC. However, the presence of calcium impurities did not change the hydration phase composition. This is primarily because the Ca2+ ions promoted the participation of magnesium oxide in the hydration reaction and enhanced the early strength of the MOC. The findings of this study demonstrate the technical feasibility of utilising magnesium resources from salt lakes to prepare magnesium oxide and apply it in the production of MOC. [ABSTRACT FROM AUTHOR]

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Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The pyrolysis of cotton straw is a promising technology because a large variety of chemical species can be produced from the thermal degradation of biomass. A more promising chemical, levoglucosan, was the subject of this study. A techno‐economic analysis of a plant producing levoglucosan via fast pyrolysis of cotton straw and extraction of levoglucosan from the produced bio‐oil was conducted by modeling a 200 000 ton per year feedstock‐processing plant. Experimental and modeling data were gathered from recent publications and used for analysis. For the modeled feedstock handling capacity, the results indicated that levoglucosan production capacity could reach around 18 000 tons per year. The estimated levoglucosan net production cost, including byproduct credits, was $3.0/kg. Sensitivity analysis also showed that the yield of levoglucosan from bio‐oil, the cotton straw cost, the calcium hydroxide cost, the hydrochloric acid concentration, and the number of days of operation are the main factors in levoglucosan net production costs. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

Cost-effective and eco-friendly washing agents are in demand for Cd contaminated soils. Here, we used leonardite-derived humic substances to wash different types of Cd-contaminated soils, namely, a silty loam (Soil 1), a silty clay loam (Soil 2), and a sandy loam (Soil 3). Washing conditions were investigated for their effects on Cd removal efficiency. Cadmium removal was enhanced by a high humic substance concentration, long washing time, near neutral pH, and large solution/soil ratio. Based on the tradeoff between efficiency and cost, an optimum working condition was established as follows: humic substance concentration (3150 mg C/L), solution pH (6.0), washing time (2 h) and a washing solution/soil ratio (5). A single washing removed 0.55 mg Cd/kg from Soil 1 (1.33 mg Cd/kg), 2.32 mg Cd/kg from Soil 2 (6.57 mg Cd/kg), and 1.97 mg Cd/kg from Soil 3 (2.63 mg Cd/kg). Cd in effluents was effectively treated by adding a small dose of calcium hydroxide, reducing its concentration below the discharge limit of 0.1 mg/L in China. Being cost-effective and safe, humic substances have a great potential to replace common washing agents for the remediation of Cd-contaminated soils. Besides being environmentally benign, humic substances can improve soil physical, chemical, and biological properties. [ABSTRACT FROM AUTHOR]

The nonferrous metal smelting industry-an influential industry in China- produces a large quantity of arsenic-containing acidic wastewater (ACAW) that seriously hinders the development of the industry. In this study, low-cost and effective methods for treating acidic wastewater were systematically examined. Lime neutralization and compound salt precipitation were used to remove arsenic (As) from acidic wastewater. The residues produced during neutralization and compound salt precipitation were treated harmlessly by H 2 SO 4 leaching, and As 2 O 3 was recovered from the sulfuric acid leach solution (ALS). The results showed that the appropriate pH for the neutralization process was 3. The arsenic concentration in the solution after compound salt precipitation was <0.5 mg/L at pH 8.5 and suitable molar ratios (Cu/As: 0.45 to 2.3, Fe/As: 1.20 to 6.0, and Zn/As: 1.20 to 6.0). After acid leaching of residues obtained during neutralization and compound salt precipitation, the content of CaSO 4 in the leach residue reached the specified value (CaSO 4 ≥ 75 wt%) of industrial byproduct gypsum (GB/T 21371–2019 of China), and the concentration of arsenic in the toxicity leaching experiment was <5 mg/L. The ALS was reduced by SO 2 to recover arsenic trioxide, and the recovery of arsenic reached 96.5%. Compared to the NaOH neutralization reagent, the lime treatment process is cost-effective and produces non-hazardous solid waste. • Direct treatment of As(III)-containing wastewater without oxidation. • Arsenic in precipitated residue can be recovered. • Heavy metals in precipitated residue can be reused. • Hazardous solid waste can be harmless and used to produce cement. [ABSTRACT FROM AUTHOR]

Modern indigo dyeing is achieved using chemical dye vats with toxic reducing agents that have an impact on the environment and human health. Consequently, there has been interest in traditional indigo dyeing processes and their potential for more environmentally friendly industrial production. Traditional indigo dyeing was studied by conducting a literature review (China, India, Indonesia, the Philippines, and Vietnam) and field surveys (Timor Leste, Indonesia, Laos, and China) in Southeast Asia and China (SAC). Traditional SAC blue and black dyeing processes can be a combination of separate dyeing steps. Here, we documented plant species and ingredients in the blue to black dyeing processes used in addition to indigo yielding species. We recorded 80 plant species belonging to 39 families and 67 genera used in the "blue to black" dye processes in SAC. Owing to local use and phytochemicals or microbial substances of these species and their function in the dyeing processes, eight hypotheses for added species, including lime or ash water, microorganisms, food for microorganisms, electron donors, electron mediators, reducing sugars, metallic mordants, and tannins were suggested herein. The combination of hypotheses was supported by the findings and theories of previous studies and clarifies why these particular plant species are likely added to dye vats. The hypotheses and theories derived from this study pave the way for insights into indigo dyeing processes that reduce inorganic chemical additives using additional plant products, which consequently may provide a green route for cleaner production strategies. This research identifies gaps in knowledge and highlights where further work is needed to verify the hypotheses proposed for adding products to dye vats in the future. • Documented 80 plant species used in the traditional blue to black dyeing processes. • Proposed an explanatory model of indigo dyeing process to encourage further research. • Reduced inorganic chemical additives through use of additional plant products. • Sustainable dyeing strategies based on traditional indigo dyeing process. [ABSTRACT FROM AUTHOR]

[Display omitted] • An environment-friendly fine aggregate for the reuse of copper tailings was developed. • Use of specific grades to improve the reusability and specimen strength. • Effects of finer particles improved the strength of the copper tailings specimens. • Specific grades of fine-grained tailings provided hydration to fill the pore space. Although it is estimated that approximately 300 million tons of copper tailing is produced in China annually, only about 8.2% of this byproduct is reused. Therefore, to promote natural material sustainability, and value-added utilization of copper tailings in China, tailings from Hubei (HT) and Jiangxi (JT) were explored as replacement materials for the fine natural aggregate. The water/cement ratio was fixed at 0.50, and various proportions of fine aggregate were replaced (0%, 30%, 50%, 70%, and 100%). The size distribution of the tailings particles was as follows: HT (1.18 to 0.15 mm) and JT (0.60 to 0.15 mm). This study was made to match the size distribution of the tailings with that of the fine aggregate it replaced. The mechanical properties and pore structure were assessed using the methylene blue test, flexural tensile strength test, compressive strength test, absorption test, fluidity test, mercury intrusion porosimetry (MIP) test, and scanning electron microscopy (SEM). The control group (without tailings) presented the highest flexural strength but the lowest compressive strength. The experiment group achieved the highest flexural and compressive strength under 50% HT content or 70% JT content. Overall, MIP results show that inclusions in tailings tend to reduce "harmless pores" (pores < 20 nm). SEM observations at 7 days revealed that unreacted tailings particles filled the macropores between fine aggregate and paste. Observations at 28 days revealed fewer unreacted tailings particles. The finer tailings particles reacted with calcium hydroxide in cement to form hydrated calcium silicate gel and fill pores, thereby enhancing the strength of cement mortar. [ABSTRACT FROM AUTHOR]

There are abundant hydrocarbon resources in the deepwater region, so the exploration and development of deepwater oil and gas has become an important strategy for the Chinese petroleum industry. However, well cementing in deepwater, especially the cementing of the surface casing, is challenged due to the low temperature, which requires proper cementing accelerators to make the cement have certain strength at the early stage. Aiming to enhance the cementing quality of the surface casing, two kinds of lithium salt accelerators named LSA-1 and LSA-2 were developed in our early works based on the effects of different salts on oil well cement at low temperatures. In this paper, a comprehensive set of experiments was designed to test the effects of LSA-1 and LAS-2 on the Class-G oil well cement, including observations and measurements of the cement hydration products, the hydration heat and the developments of the static gel strength and the compressive strength. Based on these experiments, we discussed the mechanisms and performances of these two lithium salt accelerators at low temperatures. The experiment results indicate that both LSA-1 and LSA-2 can accelerate the hydration rate by advancing the hydration acceleration period and result in the earlier generation of Ca(OH) 2 and AFt. They can also induce the cement hydration products to form regular and compact gel structures, which contributes to the development of the static gel strength and the compressive strength of cement slurry at the early stage. Moreover, the two lithium salt accelerators have the characteristic of low hydration heat. This is helpful to reconcile the contradiction between the development of cement early compressive strength and the hydration heat, which can help to avoid channeling and hydrate decomposition in the strata containing gas hydrate. In general, LSA-2 has a stronger effect on accelerating hydration of oil well cement, while LSA-1 has less impact on cement hydration heat. Therefore, both LSA-1 and LSA-2 are qualified to serve as low-temperature accelerators for deepwater cementing, which are able to meet the diverse requirements of the deepwater low-temperature environment and the field cementing operation. [ABSTRACT FROM AUTHOR]

The rapid expansion of ceramic wastes in China has raised great many interests in their sustainable uses in building materials. This work reports a type of micro ceramic powder with the mean size down to ∼ 3.5 μm manufactured from ceramic wastes toward developing sustainable building materials. The micro ceramic powder was taken as a supplementary cementitious material to replace cement up to 40% for tuning the microstructure and mechanical properties of blend cement materials. Microscopic and macroscopic tests were conducted on the materials up to 180 curing days. Results indicate that the ultimate compressive strength of the blend mortars is over 80 MPa, and the bending strength is around 10 MPa. The filling and pozzolanic effects of micro ceramic grains increase the meso porosity (≤ 50 nm) and decrease the threshold pore size. The pozzolanic reactions between ceramic grains and calcium hydroxides form complex calcium-silicate-alumina-hydrates with the Ca/Si ratio around 1. The hybrid reactions of cement and ceramic grains increase the non-evaporable water but decrease the calcium hydroxide. Estimations suggest that 20% replacement of cement by the micro ceramic powder indicates an economical benefit of 9.6% in concrete manufacture and a decrease of 6.62% specific energy consumption in cement production. This work addresses the interactions between micro ceramic grains and cement hydrates for the sustainable uses of ceramic wastes in building materials. Image 1 • Micro ceramic powder was manufactured from ceramic wastes for partial cement replacement. • Waste ceramic powder refines the pore structure of cement materials. • Pozzolanic reaction enhanced the interactions between ceramic grains and cement matrix. • Waste ceramic powder enables a more sustainable concrete manufacture. [ABSTRACT FROM AUTHOR]

Data sources Cochrane Library, PubMed, Ovid, ScienceDirect, Wiley, China Biology Medicine (CBM), China National Knowledge Infrastructure (CNKI), Wan Fang and VIP Database for Chinese Technical Periodicals (VIP) databases were searched for articles dating from January 2000 to July 2018. Studies in languages other than English or Chinese were excluded. Study selection Randomised controlled trials comparing the clinical effectiveness of calcium hydroxide to formocresol or camphor phenol in acute pulpitis of deciduous teeth requiring root canal treatment were included. The primary outcome was clinical effectiveness while the secondary outcome was incidence of endodontic inter-appointment emergencies. Data extraction and synthesis Two authors independently screened titles and abstracts of all studies identified through the search and reviewed full articles against established inclusion/exclusion criteria. Any disagreements between the authors were resolved by consensus or by consulting relevant experts. Risk of bias assessment was carried out using the Cochrane collaboration tool. Clinical effectiveness and incidence of inter-appointment endodontic emergencies were expressed as odds ratio and 95% CI. Heterogeneity was assessed using Q-test and I2 measurement. Appropriate models were used for meta-analysis based on heterogeneity. Results A total of 16 randomised trials informed the meta-analysis. Clinical effectiveness of calcium hydroxide was compared to formocresol in 12 studies and pooled data indicate that calcium hydroxide was significantly better in terms of clinical effectiveness (OR = 3.37; 95% CI 2.54 to 4.48), and was associated with significantly decreased inter-appointment emergency visits (OR = 0.26; 95% CI 0.16 to 0.42). Calcium hydroxide was compared to camphor phenol in seven studies and was shown to be significantly superior in its clinical effectiveness (OR = 5.50; 95% CI 3.36 to 8.98). Conclusions Limited available evidence suggest calcium hydroixide was superior to formocresol and camphor phenol as intracanal medicaments in the management of acute pulpitis in deciduous teeth. [ABSTRACT FROM AUTHOR]