生态环境学报
生態環境學報
생태배경학보
ECOLOGY AND ENVIRONMENT
2013年
1期
129-134
,共6页
魏岚%刘传平%刘承帅*%李芳柏
魏嵐%劉傳平%劉承帥*%李芳柏
위람%류전평%류승수*%리방백
氧化铝矿物%硫化钠%异丙甲草胺%亲核试剂
氧化鋁礦物%硫化鈉%異丙甲草胺%親覈試劑
양화려광물%류화납%이병갑초알%친핵시제
soil minerals%sodium sulfide%metolachlor%nucleophile
采用批处理实验的方法研究γ-Al2O3界面上亲核试剂硫化钠作用下异丙甲草胺的转化动力学及其影响因素.结果表明,硫化钠作为一种亲核试剂,能促使异丙甲草胺发生亲核置换转化,且可以进一步提高异丙甲草胺在氧化铝多相反应体系中的转化速率.结果还表明,随着硫化钠浓度的升高,异丙甲草胺降解动力学常数k值也相应增加(当硫化钠浓度为5 mmol·L?1时,k值为0.043 h?1;而当硫化钠的浓度为100 mmol·L?1时,k值上升到0.974 h?1),以速率常数k值与硫化钠初始浓度作图,发现速率常数k与硫化钠浓度成正相关线性关系,其相关系数达到0.985;多相体系中反应溶液的pH会影响异丙甲草胺的转化速率,在含有10 mmol·L?1硫化钠的γ-Al2O3体系中(温度为25℃),溶液pH值由6.0上升到10.0,异丙甲草胺降解动力学常数k由0.046上升到0.195 h?1;异丙甲草胺的转化速率与多相体系中的反应温度呈显著正相关关系,转化速率取决于体系的反应温度,温度越高,转化速率越大;热力学Arrhenius经验式求得异丙甲草胺的活化能Ea=49.9 kJ·mol?1.转化速率与温度的关系为:lnk=?6.0054×103/T+17.868.
採用批處理實驗的方法研究γ-Al2O3界麵上親覈試劑硫化鈉作用下異丙甲草胺的轉化動力學及其影響因素.結果錶明,硫化鈉作為一種親覈試劑,能促使異丙甲草胺髮生親覈置換轉化,且可以進一步提高異丙甲草胺在氧化鋁多相反應體繫中的轉化速率.結果還錶明,隨著硫化鈉濃度的升高,異丙甲草胺降解動力學常數k值也相應增加(噹硫化鈉濃度為5 mmol·L?1時,k值為0.043 h?1;而噹硫化鈉的濃度為100 mmol·L?1時,k值上升到0.974 h?1),以速率常數k值與硫化鈉初始濃度作圖,髮現速率常數k與硫化鈉濃度成正相關線性關繫,其相關繫數達到0.985;多相體繫中反應溶液的pH會影響異丙甲草胺的轉化速率,在含有10 mmol·L?1硫化鈉的γ-Al2O3體繫中(溫度為25℃),溶液pH值由6.0上升到10.0,異丙甲草胺降解動力學常數k由0.046上升到0.195 h?1;異丙甲草胺的轉化速率與多相體繫中的反應溫度呈顯著正相關關繫,轉化速率取決于體繫的反應溫度,溫度越高,轉化速率越大;熱力學Arrhenius經驗式求得異丙甲草胺的活化能Ea=49.9 kJ·mol?1.轉化速率與溫度的關繫為:lnk=?6.0054×103/T+17.868.
채용비처리실험적방법연구γ-Al2O3계면상친핵시제류화납작용하이병갑초알적전화동역학급기영향인소.결과표명,류화납작위일충친핵시제,능촉사이병갑초알발생친핵치환전화,차가이진일보제고이병갑초알재양화려다상반응체계중적전화속솔.결과환표명,수착류화납농도적승고,이병갑초알강해동역학상수k치야상응증가(당류화납농도위5 mmol·L?1시,k치위0.043 h?1;이당류화납적농도위100 mmol·L?1시,k치상승도0.974 h?1),이속솔상수k치여류화납초시농도작도,발현속솔상수k여류화납농도성정상관선성관계,기상관계수체도0.985;다상체계중반응용액적pH회영향이병갑초알적전화속솔,재함유10 mmol·L?1류화납적γ-Al2O3체계중(온도위25℃),용액pH치유6.0상승도10.0,이병갑초알강해동역학상수k유0.046상승도0.195 h?1;이병갑초알적전화속솔여다상체계중적반응온도정현저정상관관계,전화속솔취결우체계적반응온도,온도월고,전화속솔월대;열역학Arrhenius경험식구득이병갑초알적활화능Ea=49.9 kJ·mol?1.전화속솔여온도적관계위:lnk=?6.0054×103/T+17.868.
The batch experiments were used to investigate the transformation kinetics and influencing factors of metolachlor on the surface of alumina. The results showed that sodium sulfide can act as a nucleophile, for resulting in the nucleophilic transformation of metolachlor. When with γ-Al2O3 presence, the nucleophilic transformation rate of metolachlor were further increased. With the sodium sulfide concentration increased, the transformation kinetics constants k values of metolachlor increased accordingly. When the sodium sulfide concentration was 5 mmol·L?1, the k value was 0.043 h?1 and when the sulfide increased to 5 mmol·L?1, the k value increased to 0.974 h?1. A plot of rate constant k values versus the initial concentrations of sodium sulfide showed a linear relationship with a slope (n) nearly equal to 1.0. The metolachlor transformation in this heterogeneous system followed the SN2 nucleophilic transformation mechanism. The solution pH and temperature were the main factors affecting the transformation rates. With the increase of pH from 6.0 to 10.0, the transformation rate of metolachlor accordingly increased from 0.046 to 0.195 h?1. When the reaction temperature increased from 10 ℃ to 50 ℃, the transformation rate of metolachlor significantly increased. Arrhenius equation was used calculate the apparent activation energy (Ea), obtaining the Ea value of 49.9 kJ·mol?1, which indicated that the nucleophilic transformation of metolachlor by sulfide on alumina minerals were exothermic reactions.
