CAJ | 학술논문

在一定pH值范围内,甲基红(M R)水溶液紫外-可见吸收光谱特征是酸式甲基红(HMR)最大吸收峰(530±15) nm)与碱式甲基红(MR-)最大吸收峰(435±20) nm)叠合在一起.本文用高斯多峰拟合技术实现了HMR和MR-叠合峰的分峰拟合计算.拟合计算输出两个吸收峰的积分面积即峰强度A1和A2,A1和A2之比与MR-和HMR浓度之比.进而计算甲基红水溶液酸离解平衡常数p(K)a.用本方法测量298.15 K时的p(K)a值为476.拟合优度高,拟合度R2、拟合优度(X2)分别达到0.998和10-5以下.深入探讨了表面活性剂十二烷基硫酸钠(SDS)、十六烷基三甲基溴化铵(CTAB)聚集行为对甲基红pKa的影响.与传统分光光度测量方法相比,紫外-可见吸收光谱结合高斯多峰拟合技术结果更可靠,测量步骤和数据处理过程更简单,更具有普适性.
재일정pH치범위내,갑기홍(M R)수용액자외-가견흡수광보특정시산식갑기홍(HMR)최대흡수봉(530±15) nm)여감식갑기홍(MR-)최대흡수봉(435±20) nm)첩합재일기.본문용고사다봉의합기술실현료HMR화MR-첩합봉적분봉의합계산.의합계산수출량개흡수봉적적분면적즉봉강도A1화A2,A1화A2지비여MR-화HMR농도지비.진이계산갑기홍수용액산리해평형상수p(K)a.용본방법측량298.15 K시적p(K)a치위476.의합우도고,의합도R2、의합우도(X2)분별체도0.998화10-5이하.심입탐토료표면활성제십이완기류산납(SDS)、십륙완기삼갑기추화안(CTAB)취집행위대갑기홍pKa적영향.여전통분광광도측량방법상비,자외-가견흡수광보결합고사다봉의합기술결과경가고,측량보취화수거처리과정경간단,경구유보괄성.
UV-visible electronic absorption spectra of methyl red (MR) aqueous solutions are characterized by the overlap of a principal peak at Amax ((520±15) nm) with a shoulder peak at λmax ((435±20) nm),which are assigned to acidic species (HMR) and basic species of methyl red,respectively.In this study,the spectra and the integrated absorbance of the MR and HMR peaks (denoted A1 and A2,respectively) were interpreted using a new multi-peaks Gaussian fitting method.From the absorbance ratio A1/A2 and the concentration ratio CMR-/CHMR,the average acid dissociation constant (pKa) was determined as 4.76 at 298.15 K.The goodness is high and the values of R2 (degree of fitting) and (X)2 (chi-square test for goodness of fit) were 0.998 and below 10-5,respectively.The effects of aggregation behavior of sodium dodecyl sulfate (SDS) and cetylammonium bromide (CTAB) on pKa were also investigated via this method.The multi-peaks Gaussian fitting method was shown to determine pKa more reliably and simply than traditional spectrophotometdc techniques.