新型Mg-Al吸附剂去除压水堆核电厂废水中高浓度硼 高等学校化学学报    2022, 43 (2): 20210516-.   DOI:10.7503/cjcu20210516

Scheme 1 Schematic diagram of the treatment and discharge of the boron?containing waste water generated from pressurized water reactor nuclear power plant

正文中引用本图/表的段落

图1（A）为原料Mg-Al LDH、 焙烧后形成的中间氧化物以及硼吸附后吸附剂的X射线衍射（XRD）谱图. 可见， 在原料中含有少量CaCO₃（PDF#72-1937）和氧化铝（PDF#75-0278）， 高温焙烧后， 原料LDH的特征峰消失， 同时出现了氧化镁结构的特征峰（PDF#75-1525）， 这个变化符合先前的报道［48］. 将吸附剂置于含硼溶液中， 通过XRD可以看出其又恢复为原本的二维层状结构. 图1（B）是前驱体（a）， 焙烧后中间氧化物（b）及吸附后材料（c）的红外光谱. 在图1（B）谱线a上3471 cm-1附近有较强的层板间羟基的伸缩振动吸收峰， 1543 cm-1附近出现的是结晶水羟基的弯曲振动峰， 1370 cm-1处是碳酸根的振动吸收峰， 1000~400 cm-1处是M—O—M和M—OH的相关振动吸收峰［49］， 2919和2849 cm-1处为样品中少量含碳酸钙杂质的吸收峰［50］. 焙烧后材料的红外谱图中的主吸收峰变窄［图1（B）谱线b］， 结晶水的弯曲振动峰和碳酸根的对称伸缩峰分别出现在1634和1425 cm-1附近， 相较于谱线a均发生蓝移且峰形钝化， 表明层板间仍有少量结晶水［51］. XRD结果［图1（A）谱线b］显示焙烧后的产物中仍有少量碳酸钙， 因此仍能观察到碳酸根的峰. 吸附后材料红外谱图中的主吸收峰再次变强并且半峰宽明显增大［图1（B）谱线c］， 表明层状结构恢复. 1430和1371 cm-1处的峰可归属为BO₃的反对称伸缩振动振动， 971和877 cm-1处的峰可归属为BO₃的面外伸缩振动， 说明层间阴离子为B₃O₃（OH）₄-［49］.

本文的其它图/表

• Fig.1  Experimental XRD patterns(A) and FTIR spectra(B) of raw Mg?Al LDH(a), intermediate oxide from the calcination of LDH(b), and layered double hydroxide after B?anions adsorption(c)
• Scheme 2  Structural evolution of Mg?Al LDH upon calcination
• Fig.2  SEM images of the raw Mg?Al LDH(A), intermediate oxide from the calcination of LDH(B), and layered double hydroxide after B?anions adsorption(C)
• Fig.3  Influence of pH value on the removal of boron at an initial boron concentration of 2000 mg/LAdsorbent dose/solution volume ratio: 1/40 g/mL; temperature: 20 ℃; reaction time: 24 h.
• Table 1  Boron adsorption on intermediate oxide from aqueous solution with various initial B concentrations(Adsorbent dose/solution volume ratio: 1/40 g/mL, pH=7.43, contact time: 24 h)
• Fig.4  Linear fitting with the Langmuir model(A) and Freundlich model(B) for intermediate oxide
• Table 2  Langmuir and Freundlich isotherm parameters of B adsorption on intermediate oxide
• Fig.5  Influence of initial boron concentration(c₀) on the removal of boron at pH of 7.43Adsorbent dose/solution volume ratio: 1/40 g/mL;temperature: 20 °C; reaction time: 24 h.
• Fig.6  Influence of adsorbent dose/solution volume ratio on the removal of boron at an initial boron concentration of 2000 mg/L, pH=7.43, temperature of 20 ℃, and reaction time of 24 h
• Fig.7  Influence of agitation time on the removal of boron of calcined Mg?Al LDH(A) and un?calcined Mg?Al LDH(B)Initial boron concentration: 2000 mg/L, pH=7.43, adsorbent dose: 1/40 g/mL for calcined Mg?Al LDH, 1/100 g/mL for un?calcined Mg?Al LDH, temperature: 20 ℃.
• Fig.8  Influence of competition ion on the removal of boron at an initial boron concentration of 2000 mg/L, pH of 7.43, adsorbent dose/solution volume of 1/100 g/mL, and temperature of 20 ℃