This paper presents an experimental investigation of the sulfuration mechanism of concrete. The microstructure, mineral phase composition, substance content, and pH of the concrete were determined using scanning electron microscopy, X-ray diffraction, comprehensive thermal analysis, and pore-solution pH test. It was observed that light-grey spots appeared on the surface of the specimen, and a large amount of powdery precipitated substances appeared. At the initial stage of sulfuration reaction, the formation of ettringite blocked the concrete pores and densified its cracks and voids. Subsequently, ettringite reacted with H⁺ to form gypsum, and the continuous increase in gypsum in the pores increased the number of cracks and broadened their width. Gypsum was the final product of the sulfuration reaction, and the mass percentage of gypsum in the powdery precipitated substances at different water–cement ratios was more than 50%. When the water–cement ratios was 0.37, 0.47, and 0.57, the highest Ca(OH)₂ content was found for the lowest water–cement ratio. As the water–cement ratios increased, the amount of powdery precipitated substances decreased and the CaCO₃ content and pH increased.

Iron and steel industry emits a large amount of CO₂ and SO₂ in the process of steelmaking, and these acid gases lead to the serious corrosion damage of concrete structures. In this paper, the environmental characteristics and corrosion degree of concrete in a 41-year-old steelworks were investigated, and the neutralization life prediction of the concrete structure was carried out. The results showed that the temperature, relative humidity, CO₂ concentration, and SO₂ concentration in the steelworks were 1.32, 0.62, 1.28, and 13.93 times higher than those of the general atmospheric environment, respectively. These environmental characteristics in various sections were significantly different. The appearance change of concrete in the ingot casting bay was more serious than that of concrete in the billet bay. Both the compressive strength of concrete in the ingot casting bay and billet bay decreased, and the strength in the billet bay was relatively low. The neutralization depth of concrete in the ingot casting bay was 2.35 times larger than that of concrete in the billet bay. The prediction model of concrete neutralization depth was established, and the remaining neutralization service life in the ingot casting bay and billet bay were 194.68 a and 202.07 a, respectively.

The buckwheat hulls in the region of Jiaodong were used as the potential adsorbents for the removal of heavy metal ions from wastewater. The experimental results showed that the buckwheat hulls with 120 meshes had good adsorption capability for Hg(II) ions. Moreover, the adsorption process optimization of the buckwheat hulls for Hg(II) ions was performed through Central Composite Rotary Design using response surface methodology (RSM) by Design Expert Version 8.0.6.1 (Stat-Ease, Inc., Minneapolis, MN, USA). For the maximum biosorption of mercury ions from aqueous solutions by the buckwheat hulls, a total of 20 experimental runs were set and the experimental data fitted to the empirical second-order polynomial model of a suitable degree. The quantitative relationship between the mercury removal and different levels of the factors (initial pH, adsorbent dosage, and initial Hg(II) concentration) was used to work out optimized levels of these parameters by a full factorial design (2³). The analysis of variance (ANOVA) of the quadratic model demonstrated that the model was highly significant, and initial pH of 4.0, initial Hg(II) concentration of 802.36 mg/L, and adsorbent dosage of 2.0 g/L were found to be the optimum conditions for the maximum uptake of mercury ions of 110.07 mg/g in batched mode.