Surface and Colloid Chemistry Experimental Report PDF

SURFACE and COLLOID CHEMISTRY EXPERIMENTAL REPORT UV-VİSİBLE ADSORPTİON EXPERİMENT GROUP NUMBER: 8 GROUP MEMBERS and STUDENT NO 1. YUNUS EMRE GÜVEN - 050210003 2. M. ATAKAN ALPARSLAN - 050190011 3. HAMZA DOĞAN - 050200016 4. MELTEM KARAM...

SURFACE and COLLOID CHEMISTRY EXPERIMENTAL REPORT UV-VİSİBLE ADSORPTİON EXPERİMENT GROUP NUMBER: 8 GROUP MEMBERS and STUDENT NO 1. YUNUS EMRE GÜVEN - 050210003 2. M. ATAKAN ALPARSLAN - 050190011 3. HAMZA DOĞAN - 050200016 4. MELTEM KARAMAN - 050210024 5. AYŞENUR KARAGÖZ - 050210042 6. CAN JOHN BÜKRECİ - 050220902 INSTRUCTOR : Prof. Dr. Orhan Ozdemir LABORATORY ASSISTANTS : CEYDA ŞAVRAN/ HALİDE NUR DURSUN DATE 25.12.2023 Name of Experiment: UV-VİSİBLE ADSORPTİON EXPERİMENT Group Number: 8 1. INFORMATION ABOUT EXPERIMENT The primary objective of this experiment was to investigate the adsorption characteristics of hexadecyl trimethyl ammonium bromide (HTAB), a cationic surfactant, on the surface of sepiolite. The study aimed to understand how the adsorption behavior varied with different concentrations of HTAB. 2. THEORETICAL INFORMATION UV/VIS spectrophotometry, also known as absorption spectrophotometry is a technique used to measure how much a chemical substance absorbs light. Relationship between substance and UV/VIS spectrum It is used in qualitative or quantitative analyses. UV/VIS spectrophotometers work by passing a beam of light through a sample and measuring the amount of light absorbed at each wavelength. The amount of light absorbed is directly proportional to the concentration of the absorbing compound. The more a material absorbs light of a particular wavelength, the higher the concentration of the known substance. VIS spectrophotometry uses the ultraviolet and visible regions of the electromagnetic spectrum. Lights between 190 and 400nm in wavelengths are detected in the UV field. On the other hand, lights between 400 and 700nm wavelengths in the visible area. 3. AIM OF EXPERIMENT The aim of the experiment was to help students get a better grasp of UV/Visible adsorption by transmitting a beam of light through a sample at different wavelengths and measuring the sample’s absorption. As the students observe this, it helps them better their understanding of surface and colloid chemistry. 4. EXPERIMENTAL PROCEDURE Experiment Materials 1-Methylene blue ISTANBUL TECHNICAL UNIVERSITY 1 Name of Experiment: UV-VİSİBLE ADSORPTİON EXPERİMENT Group Number: 8 2-Activated carbon 3-Pure water 4-Tetra T80+ UV/VIS Spectrophotometer 5-Centrifuge device 6-Filter paper 7-Glass utensils Experiment Procedure 1-The transparent part of the methylene blue is placed in the machine so that it can see the light. 2-The start button was pressed and adsorption measurement was made by the machine. 3-Activated carbon was added to the solution. 4-The solution was stirred for minutes. 5-Sedimentation of the grains was ensured using a centrifuge device. 6-The solution was filtered with filter paper. 7-The solution was placed in the machine and the adsorption amount was measured again. 8-Adsorption of pure water was measured. 9-The calibration curve has been calculated. 10-Certain inferences were made from the results. ISTANBUL TECHNICAL UNIVERSITY 2 Name of Experiment: UV-VİSİBLE ADSORPTİON EXPERİMENT Group Number: 8 5. RESULTS question 3) HTAB Standard Solution Concentration Amount of HTAB Stock Solution Water Total (M) (mL) (mL) (mL) 2,10-6 0.01 9.99 10 2,10-5 0.1 9.9 10 5,10-5 0.25 9.75 10 1,10-4 0.5 9.5 10 2,10-4 1 9 10 5,10-4 2.5 7.5 10 1,10-3 5 5 10 2,10-3 10 0 10 ISTANBUL TECHNICAL UNIVERSITY 3 Name of Experiment: UV-VİSİBLE ADSORPTİON EXPERİMENT Group Number: 8 a) HTAB Concentration (M) Zeta Potential (mV) 2,10-6 -33,4 2,10-5 -26,8 5,10-5 -21,6 1,10-4 -10,9 2,10-4 +9,7 5,10-4 +27,3 1,10-3 +38,2 2,10-3 +39,8 b) From the information provided, it appears there's a trend in the zeta potential concerning the concentration: At lower concentrations (between 2x10^-6 M and 1x10^-4 M), the zeta potential decreases (from -33.4 mV to -10.9 mV). There seems to be a turning point around 2x10^-4 M, where the zeta potential becomes positive and starts increasing (from +9.7 mV to +39.8 mV) as the concentration continues to rise. This change in zeta potential from negative to positive might indicate a shift in the behavior of the particles or solution. Negative zeta potentials typically suggest ISTANBUL TECHNICAL UNIVERSITY 4 Name of Experiment: UV-VİSİBLE ADSORPTİON EXPERİMENT Group Number: 8 more stability due to electrostatic repulsion between particles, whereas positive zeta potentials might suggest reduced stability or different interactions between the particles. This change could be related to various factors like changes in particle interactions, the onset of aggregation or precipitation, or alterations in the surface chemistry of the particles. question 4) HTAB Concentration (M) Absorbance Value 2,10-6 0,034 1,10-5 0,079 2,10-5 0,147 5,10-5 0,378 1,10-4 0,761 2,10-4 1,489 ISTANBUL TECHNICAL UNIVERSITY 5 Name of Experiment: UV-VİSİBLE ADSORPTİON EXPERİMENT Group Number: 8 question 5) a) Ci Cf Cf Adsorption Density Absorbance Value (M) (M) (mol/m2) 2,10-6 0,015 7,8*10-7 1,87*10^-8 2,10-5 0,138 1,7*10-5 4,61*10^-8 5,10-5 0,324 4,24*10-5 1,16*10^-7 1,10-4 0,458 6,05*10-5 6,07*10^-7 2,10-4 0,565 7,49*10-5 1,92*10^-6 5,10-4 1,274 0,00017 5,07*10^-6 1,10-3 4,643 0,00062 5,84*10^-6 2,10-3 11,984 0,0016 6,15*10^-6 b) Based on the provided data, an adsorption isotherm can be constructed, illustrating the binding process of an adsorbate to an adsorbent surface. Isotherms typically reach saturation at a certain point, where the curve flattens out after a specific concentration. Prior to this point, as the concentration of the adsorbate increases, the rate of adsorption also increases. However, once saturation is reached, there's a diminishing increase in Adsorption Density even with higher ISTANBUL TECHNICAL UNIVERSITY 6 Name of Experiment: UV-VİSİBLE ADSORPTİON EXPERİMENT Group Number: 8 concentrations. From the given data, it's evident that as Cf values increase, the corresponding Adsorption Density rises but starts to plateau as it approaches saturation. This indicates that the adsorbent surface reaches a point where further adsorption becomes limited. Graphically, the isotherm curve generated from this data will typically exhibit a pattern where it flattens out after a certain point, indicative of reaching saturation. This signifies that beyond a certain concentration, the surface becomes unable to accommodate additional adsorbate. question 6) The experimental findings show a significant concentration-related trend in zeta potential. The zeta potential continuously drops from -33.4 mV to -10.9 mV at lower doses (2x10^-6 M to 1x10^-4 M). But when the concentration rises, there is a critical change that happens at about 2x10^-4 M, shown by the zeta potential going positive and gradually rising from +9.7 mV to +39.8 mV. This change in zeta potential from negative to positive indicates a major modification in the behavior of the particles or the properties of the solution. Positive zeta potentials may imply less stability or altered particle interactions, whereas negative zeta potentials usually suggest increased stability as a result of electrostatic repulsion between particles. Furthermore, patterns that are meaningful are shown by producing an adsorption isotherm using the data that is provided. The associated Adsorption Density rises with increasing concentration (Cf values), plateauing at a certain concentration. This plateau denotes saturation, implying that above a particular concentration, the adsorbent surface's ability to accept more adsorbate becomes ISTANBUL TECHNICAL UNIVERSITY 7 Name of Experiment: UV-VİSİBLE ADSORPTİON EXPERİMENT Group Number: 8 constrained. When depicted visually, the isotherm curve shows a distinctive flattening upon attaining saturation, signifying the adsorption process's saturation point. Moreover, theoretical details regarding UV/VIS spectrophotometry emphasize its usefulness in quantifying a substance's absorption of light. This method works in the visible and ultraviolet portions of the electromagnetic spectrum and is useful for both qualitative and quantitative research. The connection between substance and UV/VIS spectrum is based on the idea that the concentration of the absorbing compound directly affects how much light is absorbed, which helps to explain the concentration-dependent behavior shown in the experimental data. 6. DISCUSSION This experiment aimed to explore the adsorption behavior of hexadecyl trimethyl ammonium bromide (HTAB), a cationic surfactant, on the surface of sepiolite. Adsorption experiments were conducted at various HTAB concentrations using an orbital shaker. The quantities required for preparing HTAB solutions were determined, and zeta potential measurements were conducted in relation to solution concentrations. A calibration curve was established by obtaining the absorption spectrum of HTAB using a UV/VIS spectrophotometer. In the adsorption isotherm, a distinct trend was observed, indicating saturation concerning HTAB's adsorption onto sepiolite. Zeta potential results revealed a transition from negative to positive values at lower concentrations, signifying a significant alteration in particle behavior. Adsorption density calculations demonstrated saturation, indicating a limited capacity of the sepiolite surface to adsorb HTAB. The coating degree of HTAB on sepiolite provided quantitative insights into the effectiveness of the adsorption process. These findings contribute to the understanding of how HTAB's adsorption behavior on sepiolite evolves with changing concentrations. Future studies may involve techniques such as surface analysis and molecular dynamics simulations to unravel molecular interactions at different concentrations. ISTANBUL TECHNICAL UNIVERSITY 8 Name of Experiment: UV-VİSİBLE ADSORPTİON EXPERİMENT Group Number: 8 7. REFERANCE Butt, H., Liu, J., Koynov, K., Straub, B. B., Hinduja, C., Roismann, I., Berger, R., Li, X., Vollmer, D., Steffen, W., & Kappl, M. (2022). Contact angle hysteresis. Current Opinion in Colloid and Interface Science, 59, 101574. https://doi.org/10.1016/j.cocis.2022.101574 Eral, H. B., Mannetje, D. J. C. M. ’., & Oh, J. M. (2012). Contact angle hysteresis: a review of fundamentals and applications. Colloid and Polymer Science, 291(2), 247–260. https://doi.org/10.1007/s00396-012-2796-6 ISTANBUL TECHNICAL UNIVERSITY 9