新文科背景下校本特色外语课程思政研究——以商务英语阅读课为例

全面推进课程思政建设是高校落实好立德树人根本任务的战略举措。新文科背景下如何有机结合校本特色,有效实现外语教育和思政建设同向同行,是高校需要探索的重要问题。为此,本文以华南理工大学“商务英语阅读”课为例,该课程以“3个4”教学方案(四个思政主题、四个教学步骤、四个教学课堂)为总体设计并提出融合华南理工大学校训精神的SDPR(Story-Discussion-Project-Reflection)教学模式,探讨具有校本特色的外语课程思政建设路径,以期实现全方位育人目标。

Selective recovery of Cu(II) from strongly acidic wastewater by zinc dimethyldithiocarbamate: Affecting factors, efficiency and mechanism

The selective recovery of copper from strongly acidic wastewater containing mixed metal ions remains a significant challenge.In this study,a novel reagent zinc dimethyldithiocarbamate(Zn(DMDC)_(2))was developed for the selective removal of Cu(II).The removal efficiency of Cu(II)reached 99.6%after 120 min reaction at 30°C when the mole ratio Zn(DMDC)_(2)/Cu(II)was 1:1.The mechanism investigation indicates that the Cu(DMDC)_(2) products formed as a result of the displacement of Zn(II)from the added Zn(DMDC)_(2) by Cu(II)in wastewater,due to the formation of stronger coordination bonds between Cu(II)and the dithiocarbamate groups of Zn(DMDC)_(2).Subsequently,we put forward an innovative process of resource recovery for strongly acidicwastewater.Firstly,the selective removal of Cu(II)fromactualwastewater using Zn(DMDC)_(2),with a removal efficiency of 99.7%.Secondly,high-value CuO was recovered by calcining the Cu(DMDC)_(2) at 800°C,with a copper recovery efficiency of 98.3%.Moreover,the residual As(III)and Cd(II)were removed by introducing H_(2)S gas,and the purified acidic wastewater was used to dissolve ZnO for preparation of valuable ZnSO_(4)·H_(2)O.The total economic benefit of resource recovery is estimated to be 11.54$/m^(3).Accordingly,this study provides a new route for the resource recovery of the treatment of copper-containing acidic wastewater.

Removal of Ni(Ⅱ) from strongly acidic wastewater by chelating precipitation and recovery of NiO from the precipitates

Strongly acidic wastewater produced in nonferrous metal smelting industries often contains high concentrations of Ni(Ⅱ), which is a valuable metal. In this study, the precipitation of Ni(Ⅱ) from strongly acidic wastewater using sodium dimethyldithiocarbamate(DDTC) as the precipitant was evaluated. The effects of various factors on precipitation were investigated, and the precipitation mechanism was also identified. Finally, the nickel in the precipitates was recovered following a pyrometallurgical method. The results show that, under optimised conditions(DDTC:Ni(Ⅱ) molar ratio = 4:1;temperature = 25 ℃), the Ni(Ⅱ) removal efficiency reached 99.3% after 10 min. In strongly acidic wastewater, the dithiocarbamate group of DDTC can react with Ni(Ⅱ) to form DDTC –Ni precipitates. Further recovery experiments revealed that high-purity Ni O can be obtained by the calcination of DDTC –Ni precipitates, with the nickel recovery efficiency reaching 98.2%. The gas released during the calcination process was composed of NO_(2), CS_(2), H_(2)O, CO_(2), and SO_(2). These results provide a basis for an effective Ni(Ⅱ) recovery method from strongly acidic wastewater.

pH-dependent release characteristics of antimony and arsenic from typical antimony-bearing ores

The pH-dependent leaching of antimony（Sb） and arsenic（As） from three typical Sb-bearing ores（Banxi, Muli and Tongkeng Antimony Mine） in China was assessed using a pH-static leaching experiment. The pH changes of the leached solutions and pH-dependent leaching of Sb and As occurred in different ways. For the Banxi and Muli Sb ores, alkaline conditions were more favorable for the release of Sb compared to neutral and acidic conditions, but the reverse was true for the pH-dependent release of As. For the Tongkeng Sb ore, unlike the previous two Sb-bearing ores, acidic conditions were more favorable for Sb release than neutral and alkaline conditions.The ores with lower Sb and As contents released higher percentages of their Sb and As after 16 day leaching, suggesting that they are the largest potential sources of pollution. This work may provide key information on the geochemistry of Sb and As in the weathering zone.

Organic ligand-induced dissolution kinetics of antimony trioxide

The influence of low-molecular-weight dissolved organic matter （LMWDOM） on the dissolution rate of Sb203 was investigated. Some representative LMWDOMs with carboxyl, hydroxyl, hydrosulfuryl and amidogen groups occurring naturally in the solution were chosen, namely oxalic acid, citric acid, tartaric acid, EDTA, salicylic acid, phthalandione, glycine, thiolactic acid, xylitol, glucose and catechol. These LMWDOMs were dissolved in inert buffers at pH = 3.7, 6.6 and 8.6 and added to powdered Sb203 in a stirred, thermostatted reactor （25℃）. The addition of EDTA, tartaric acid, thiolactic acid, citric acid and oxalic acid solutions at pH 3.7 and catechol at pH 8.6 increased the rate of release of antimony. In the 10 mmol/L thiolactic acid solution, up to 97% by mass of the antimony was released after 120 rain reaction. There was no effect on the dissolution of Sb203 for the other ligands. A weak correlation between dissolution rate with the dissociation constant of ligands and the stability of the dissolved complex was also found. All the results showed that the extent of the promoting effect of ligands on the dissolution of Sb203 was not determined by the stability of the dissolved complex, but by the dissociation constant ofligands and detachment rate of surface chelates from the mineral surface. This study can not only help in further understanding the effect of individual low-molecular-weight organic ligands, but also provides a reference to deduce the effect of natural organic matters with oxygen-bearing functional groups on the dissolution of antimony oxide minerals.

Release kinetics of vanadium from vanadium titano-magnetite：The effects of pH, dissolved oxygen, temperature and foreign ions

As part of a broader study of the environmental geochemistry behavior of vanadium（V）, the release kinetics of V from the dissolution of natural vanadium titano-magnetite under environmentally relevant conditions was investigated. In both the acidic and basic domains, the V release rate was found to be proportional to fractional powers of hydrogen ion and dissolved oxygen activities. The dependence of the rate on dissolved oxygen can also be described in terms of the Langmuir adsorption model. The empirical rate equation is given by： r= k′α（H＋）α（Kα（O2））/（1＋Kα（O2）） where, α = 0.099–0.265, k′ = 3.2 × 10-6–1.7 × 10-5, K =2.7 × 104–3.9 × 104 mol/L in acid solution（pH 4.1）, and α =-0.494-（-0.527）, k′ = 2.0 × 104–2.5 × 10-11, and K = 4.1 × 103–6.5 × 103 mol/L in basic solution（pH 8.8） at 20°C. Based on the effect of temperature on the release rate of V, the activation energies of minerals at p H 8.8 were determined to be 148–235 k J/mol, suggesting that the dissolution of vanadium titano-magnetite is a surface-controlled process. The presence of Na＋, Ca2＋, Mg2＋, K＋, NO3-, Cl-, SO42-and CO32-was found to accelerate the V release rates. This study improves the understanding of both the V pollution risk in some mine areas and the fate of V in the environment.

Antimony leaching release from brake pads: Effect of pH,temperature and organic acids

Metals from automotive brake pads pollute water, soils and the ambient air. The environmental effect on water of antimony （Sb） contained in brake pads has been largely untested, The content of Sb in one abandoned brake pad reached up to 1.62 × 10^4 mg/kg. Effects of initial pH, temperature and four organic acids （acetic acid, oxalic acid, citric acid and humic acid） on Sb release from brake pads were studied using batch reactors. Approximately 30% （97 mg/L） of the total Sb contained in the brake pads was released in alkaline aqueous solution and at higher temperature after 30 days of leaching. The organic acids tested restrained Sb release, especially acetic acid and oxalic acid. The pH-dependent concentration change of Sb in aqueous solution was best fitted by a logarithmic function. In addition, Sb contained in topsoil from land where brake pads were discarded （average 9 × 10^3 mg/kg） was 3000 times that in uncontaminated soils （2.7 ± 1 mg/kg） in the same areas. Because potentially high amounts of Sb may be released from brake pads, it is important that producers and environmental authorities take precautions.

Clean and effective removal of Cl(-I)from strongly acidic wastewater by PbO_(2)

Recycling strongly acidic wastewater as diluted H_(2)SO_(4) after contaminants contained being removed was previously proposed,however,Cl(-I),a kind of contaminant contained in strongly acidic wastewater,is difficult to remove,which severely degrades the quality of recycled H_(2)SO_(4).In this study,the removal of Cl(-I)using PbO_(2) was investigated and the involved mechanisms were explored.The removal efficiency of Cl(-I)reached 93.38%at 50℃ when PbO_(2)/Cl(-I)mole ratio reached 2:1.The identification of reaction products shows that Cl(-I)was oxidized to Cl_(2),and PbO_(2) was reduced to PbSO_(4).Cl_(2) was absorbed by NaOH to form NaClO,which was used for the regeneration of PbO_(2) from the generated PbSO_(4).Cl(-I)was removed through two pathways,i.e.,surface oxidation and•OH radical oxidation.•OH generated by the reaction of PbO_(2) and OH−plays an important role in Cl(-I)removal.The regenerated PbO_(2) had excellent performance to remove Cl(-I)after six-time regeneration.This study provided an in-depth understanding on the effective removal of Cl(-I)by the oxidation method.

Release kinetics of vanadium from vanadium(Ⅲ,ⅣandⅤ)oxides:Effect of pH,temperature and oxide dose

Batch experiments were performed to derive the rate laws for the proton-promoted dissolution of the main vanadium（Ⅲ, Ⅳ and Ⅴ） oxides at pH 3.1–10.0. The release rates of vanadium are closely related to the aqueous pH, and several obvious differences were observed in the release behavior of vanadium from the dissolution of V2O5 and vanadium（Ⅲ, Ⅳ） oxides. In the first 2 hr, the release rates of vanadium from V2O3 were r = 1.14·（[H＋]）-0.269 at pH 3.0–6.0 and r = 0.016·（[H＋]）-（-0.048） at pH 6.0–10.0; the release rates from VO2 were r = 0.362·（[H＋]）-0.129 at pH 3.0–6.0 and r = 0.017·（[H＋]）-（-0.097） at pH 6.0–10.0; and the release rates from V2O5 were r = 0.131·（[H＋]）--（0.104） at pH 3.1–10.0. The release rates of vanadium from the three oxides increased with increasing temperature, and the effect of temperature was different at pH 3.8, pH 6.0 and pH 7.7. The activation energies of vanadium（Ⅲ, Ⅳ and Ⅴ） oxides（33.4–87.5 kJ/mol） were determined at pH 3.8, pH 6.0 and pH 7.7, showing that the release of vanadium from dissolution of vanadium oxides follows a surface-controlled reaction mechanism. The release rates of vanadium increased with increasing vanadium oxides dose,albeit not proportionally. This study, as part of a broader study of the release behavior of vanadium, can help to elucidate the pollution problem of vanadium and to clarify the fate of vanadium in the environment.