(中南大學(xué) 化學(xué)化工學(xué)院，長(zhǎng)沙 410083)
摘 要: 研究不同苛性比(1.47~4.44)、不同氧化鈉濃度(50~382 g/L)的鋁酸鈉溶液紫外吸收光譜，對(duì)比發(fā)現(xiàn)高濃度鋁酸鈉溶液在320~340 nm處出現(xiàn)一個(gè)新的吸收峰，結(jié)合該處吸收峰隨時(shí)間的變化特征，反演出320~340 nm處吸收峰對(duì)應(yīng)的離子結(jié)構(gòu)；利用量子化學(xué)計(jì)算鋁酸鈉溶液中可能存在的含鋁離子或分子的紫外吸收峰以驗(yàn)證反演的離子結(jié)構(gòu)。結(jié)果表明：隨著氧化鈉濃度和苛性比的增大以及時(shí)間的延長(zhǎng)，鋁酸鈉溶液中聚合離子的數(shù)量以及聚合的復(fù)雜程度均呈上升趨勢(shì)；320~340 nm處出現(xiàn)的新吸收峰為在高濃度溶液中出現(xiàn)的以—Al—(OH)2—Al—橋連的聚合離子，其中鋁離子的配位數(shù)為4或者5。
關(guān)鍵字: 鋁酸鈉溶液；紫外吸收光譜；量子化學(xué)計(jì)算
（School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China）
Abstract:By comparing the UV absorption spectra of sodium aluminate solutions with caustic ratio ranging from 1.47 to 4.44 and the sodium oxide concentration ranging from 50 to 382 g/L, it is found that a new absorption peak appears at 320-340 nm in the sodium aluminate solution with high concentration. According to the characteristic of the absorption peak with time, the corresponding ionic structure for the 320-340 nm absorption peak was speculated. The quantum chemical calculation of the UV absorption spectra for the corresponding aluminum ions or molecules was used to verify the speculations. The results show that the concentration of sodium oxide, caustic ratio and time can affect the characteristics of polymerization ions in sodium aluminate solution. The new absorption peak of 320-340 nm corresponds to the polymerization ions connecting with —Al—(OH)2—Al— bridge with coordination number of 4 or 5.
Key words: sodium aluminate solution; UV spectrum; quantum chemical calculation
