Stalagmometrijsko određivanje napetosti površine uzoraka tenzida u ovisnosti o koncentraciji

master's thesis

• Author: Vlatka Blažeka
• Mentor: Iva Rezić (mentor)
• Committee member: Maja Somogyi Škoc (predsjednik povjerenstva)
• Committee member: Iva Rezić (član povjerenstva)
• Committee member: Karlo Lelas (član povjerenstva)
• Committee member: Mario Cetina (član povjerenstva)
• Granter: University of Zagreb; Faculty of Textile Technology; (Department of Applied Chemistry); Zagreb
• Defense date and country: 2020-09-10, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Textile Technology; Textile Chemistry

Abstract

Površinska napetost je prirodno nastojanje kapljevina da zauzmu minimalnu površinu kapljice, dakle kapljevine nastoje zauzeti sferičan oblik da bi minimalizirale površinu. Nastaje kao posljedica djelovanja kohezijskih sila između molekula i tekućina. Voda ima veliku površinsku napetost zbog jakih vodikovih veza. Dodatkom tenzida, površinska napetost se naglo smanjuje jer se monomeri počinju adsorbirati na površinu. Površinska napetost može se određivati raznim metodama (izravnim i neizravnim, npr. otkidanje prstena, podizanje razine u kapilari, povećanje površine opne), među kojima su najčešće metoda stalagmometra i metoda mjerenja težine kapi.
Metoda stalagmometra je jednostavna metoda koja se temelji na usporednim podacima mjerenja broja kapi tekućine poznate napetosti površine i broja kapi tekućine kojoj određujemo napetost površine.
Površinski aktivne tvari snižavaju površinsku napetost pa se koriste u formulaciji deterdženata, sapuna, emulzija, šampona i mnogih drugih proizvoda iz industrije i domaćinstva. Prema električnom naboju površinski aktivnog iona ili molekule u vodenoj otopini tenzidi su grupirani u četiri skupine: anionski, neionski, kationski i amfoterni tenzidi.
Do promjene u napetosti površine dolazi zato što se jedan dio molekule rasporedi tako da hidrofilni dijelovi molekule budu okrenuti prema vodi, a hidrofobni dijelovi strše prema zraku. Tenzidi predstavljaju najvažniju grupu sastojaka deterdženata i prisutni su u svim tipovima deterdženata Da bi deterdženti mogli zadovoljiti tako velike zahtjeve, sastavljeni su od više vrsta komponenata od kojih svaka zasebno ili u kombinaciji s drugima ima svoju zadaću u pranju.
Glavni sastojci nekog deterdženta su: tenzidi, bilderi, sredstva za kemijsko bijeljenje, stabilizatori bijeljenja, optička bjelila, nosioci prljavština, enzimi, inhibitori korozije, antimikrobna svojstva, regulatori pjene, omekšivači, mirisi, punila i bojila. Zbog velikih količina deterdženata koji se nakon upotrebe ispuštaju u kanalizaciju, njihovo se djelovanje na okoliš danas puno više proučava.

Abstract (english)

Surface tension is the natural effort of liquids to occupy a minimal surface area. It arises as a consequence of the action of cohesive forces between molecules and liquid.
Water has a high surface tension due to strong hydrogen bonds. With the addition of surfactants, the surface tension decreases sharply as the monomers begin to adsorb to the surface.
Surface tension can be determined by various methods (direct and indirect, for example tearing off the ring, raising the level in the capillaries, increasing the surface area of the membrane), among which the stalagmometer methods and the method of measuring the weight of the drops are the most common.
The stalagmometer method is a simple method based on comparative data measuring the number of drops of liquid of known surface tension and the number of drops of liquid by which we determine the surface tension.
Surfactants lower the surface tension and are therefore used in detergent formulations, soaps, emulsions, shampoos and many other products from inustry and household.
According to the electric charge of the surface-active ion or molecules in aqueous surfactant solution are grouped into four main groups: anionic, neionic, cationic and amphoteric surfactants.
The change in surface tension occurs because one part of the molecule is arranged so that the hydrophilic parts of the molecule face the water, and the hydrophobic parts protrude towards the air. Surfactants are the most important group of detergent ingredient and are present in all types of detergent.
In order for detergents to meet such high requirements, they are composed of several types of components, each of which individually or in combination with the others has its own task in washing.
The main ingredients of detergent are: surfactants, builders, chemical bleach agents, bleach stabilizers, dirt carriers, enzymes, corrosion inhibitiors, antimicrobial properties, foam regulators, softeners, fragrances, fillers and dyes.
Due to the large amounts of detergents that are discharges into the sewer after use, their impact on the enviroment is now a lot more being studied.

• Keywords: deterdžent; tenzidi; površinska napetost; stalagmometar; metoda stalagmometra
• Keywords (english): detergent; surfactants; surface tension; stalagmometer method
• Language: croatian
• URN:NBN: urn:nbn:hr:201:398657
• Study programme: Title: Textile Technology and Engineering; specializations in: Clothing Engineering, Textile Design and Management, Industrial Textile Design, Industrial Clothing Design, Textile Chemistry, Materials and Ecology, Textile Chemistry, Materials and Ecology; Course: Textile Chemistry, Materials and Ecology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka tekstilne tehnologije i inženjerstva (magistar/magistra inženjer/inženjerka tekstilne tehnologije i inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-10-02 11:10:44