Резюме. A student research project for sampling and analysis of drinking water from different Bulgarian regions has been parallel incorporated into analytical and organic courses at the second level of high engineering education in Bulgaria. The degree of quality of drinking water has been evaluated in five cities from different Bulgarian regions: Stara Zagora, Gorna Oryahovitsa, Parvomai, Dupnica and Sofia. The students analyzed water samples for pH, hardness, organic compounds, sodium, potassium and heavy metals ions like cadmium, copper, iron, lead and manganese using titrimetric methods, atomic absorption and atomic emission spectrometry, potentiometry and voltamperometry. The article also describe pre-lab activities related to the “water quality project” in order to increase student motivation, independence, and critical thinking skills. Students have been motivated to perform the seminar and practical work and get used to an approach often used in the chemical engineering’ practice. Students have been explored parameters concerning water quality from different sources and had an opportunity to evaluate the data critically and to answer the pre-lab questions. Based on student results the “water project” became overwhelmingly popular with students while challenging them to think critically and work independently on problem solving tasks. Thanks to the “water quality project” we found that the student’s willingness to carry out a scientific work is increased. The students become more motivated and committed to the learning process.

Ключови думи: problem solving, drinking water project, analytical chemistry, organic chemistry

Introduction

Laboratory classes often have a wide range of learning objectives including an understanding of theory and calculus, an improvement of manual skills and time management, as well as the capability to collect and interpret data (Hofstein & Lunetta, 2004; Staver, 2007) As a result, students are often overloaded. Furthermore, it is often found that students come to classes totally unprepared. Hence, they are often found to follow lab manual procedures without understanding the context of the experiment and thus without learning anything. Therefore the pre-lab exercises are important to encourage the students in the learning process (Bulte et al., 2006; Schallies & Eysel, 2004). Good laboratory and practical work combining with prelab strategy can also help students develop expertise in critical enquiry, problem solving, experimental design, data analysis and presentation, and a long list of important academic and professional abilities. Some forms of pre-laboratory class exercises (pre-labs) are bene ficial in circumstances (Richter-Egger et al., 2010). Students are forced to engage with the material before the lab, so they know what they are doing and why. Other pre-labs are in the form of short questions, sample calculation or quizzes (Peteva et al., 2014). Students are asked to draw a fl ow chart of the experimental procedure or to look for health and safety regulations about chemicals. Unfortunately pre-labs are not currently used in the chemistry teaching labs in engineering education of analytical and organic chemistry in University of Chemical Technology and Metallurgy in Bulgaria. The practical classes in a basic courses (organic, inorganic and analytical chemistry) are “traditional”, namely the students just follow the instructions and thus gain some experimental experiences. Educational research indicates that traditional laboratory activities often fail to engage students in the discussion and analysis of main ideas and do not effectively promote the development of valued science practices (Xu & Talanquer, 2013; Lunetta et al., 2007; Singer et al., 2006; Psillos & Niedderer, 2002; Lazarowitz & Tamir, 1994).

We think that the students could be motivated to learn in the laboratory context if they can feel a spirit of excitement when investigating a scientifi c phenomenon, or when creating something that actually works. There is an increasing demand from students to make what they study more “relevant”, so this may have a positive impact. The water quality study has been motivated students to identify and apply research concepts, work collaboratively and communicate effectively in the labs (Richter-Egger et al., 2010; Arnold, 2003; Juhl et al, 1997; Latch, 2014). The students have been explored different decisions and argued for the method, which they have preferred for their further experimental work. The integration of student research into a general chemistry show that students believed they are doing work similar to a research scientist, that they appreciated this opportunity to do research, that it increased how much they like science in general, and that they are more likely to consider specializing in chemistry (Richter-Egger et al., 2010) .

Because of water is a substance that can contain different types of compounds it is subject to analysis of analytical, organic and physical chemistry. The quality of the drinking water is vitally important but it often easily degraded. The major categories of impurities in water are micro-organisms, pyrogens, dissolved inorganic salts, dissolved or ganic compounds, suspended particles and dissolved gases. Metals like aluminium, calcium, cadmium, chromium, copper , iron, lead, magnesium, manganese, zinc etc. may occur in drinking water due to geogenic reasons or may be due to anthropogenic activities such as uncontrolled discharge of waste waters of different types of industries. Some of the metals in the higher concentrations i.e. more than permissible limit are toxic for human beings. Higher concentrations of these metal ions result in to several types of human health problems (Farid et al., 2012; Sharma & Tyagi, 2013). 1) The “water quality projects” known in the literature have not reported the engaging student to collect drinking water probes from different regions and to motivate them to develop an experimental strategy based on equipment and time available to analyse these water probes in two parallel disciplines in the chemical engineering education.

And then? - How can we get our students to think and to be more motivated in the learning process? – A question asked by many faculties, regardless of their disciplines. Therefore our central goal was to make the pre-labs as fundamental part of laboratory classes parallel in two disciplines (analytical and organic chemistry) in second year of high education; a part of a process used to increase the responsibility of the students for their own work, and to prepare them for future situations in which they will take complete responsibility.

Research goals

The purpose of this study was to integrate the pre-labs into analytical and organic chemistry course at the second level of high engineering education in University of Chemical Technology and Metallurgy in Bulgaria. We also had the idea to combine and integrate the topic “water quality problem” in two chemical disciplines in order to give much more attention to the teaching, and hence the engineering students’ learning process. During the courses of analytical and organic chemistry the students were tested the drinking water pollution in several regions of Bulgaria (Fig. 1). A form of assessment was included to ensure that students do the pre lab exercises and that they see the pre-labs as an integral part of whole practical assignment.

Discussion

Analytical and Organic Chemistry are just a part of disciplines which are basically for the chemistry in University of Chemical Technology and Metallurgy-Sofi a. The analytical chemistry training is in two semesters of one academic year. First, the students learn the basics of the analytical chemistry, chemical equilibrium and the methods for quantitative components determination by titrimetry and gravimetry. The second semester is mainly devoted the instrumental methods for qualitative and quantitative components determination.

Organic chemistry enables students to become familiar with compounds and reactions taking part in different technology processes and organic compounds that have importance in pharmacy . The students also learn the basics of the organic chemistry - study of the structure, physical and chemical properties, and reactions of organic compounds, i.e., matter in its various forms that contain carbon atoms, parallel with the course by analytical chemistry in two semesters. Seminars and laboratory practices are complementary to lectures. Therefore the implementation of project in both disciplines is convenient and possible. Moreover, the two disciplines are the main part of second year engineering high education. Fig. 2 presents the correlation between the different chemical disciplines according to the “water project”.

The students in lab in second year chemical engineering education are divided in groups of seven to fifteen students. For “water quality problem” study the students from each group were divided into smaller groups of three to four students in the class that analyze water samples from different regions of Bulgaria for a particular chemical species using different methods. Each team was presented with a “water quality problem” (Table 1) that they working together to solve over the analytical and organic course of one education year.

We can describe the steps for the project implementation by Fug. 3, as follow:

Figure 3. Steps for “water quality project” implementation

Design the experiments samples

In order to evaluate the degree of quality of drinking water quality used for drinking purposes, sampling was done from tap drinking water passing through the urban areas of Stara Zagora (P1), Gorna Oryahovitsa (P2), Parvomai (P3), Dupnica (P4) and Sofia (P5) (Fig. 1).

Total twelve water samples were collected from the five different locations. The sampling work was undertaken according to specifi ed procedures. 2) Sampling was done in the properly cleaned plastic jars. These plastic sampling jars were rinsed three times before the water samples were collected.

Pre-lab tasks at the beginning of the fi rst semester

According to the lecture course and the “water quality problem” in the start of the project a small amount of pre-lab work was given to the students. The students were asked to answer a few simple questions for remembering, understanding and applying the information parallel in two disciplines and to search for some safety measures and given a bibliography to support the practical work by groups (Table 2-A and Table 2-B). Each group of students had to choose and answered of one of the questions to the end of the fi rst semester.

Tasks for applying the information in analytical chemistry

1. The label on the mineral water claims that it is pH =9. What do you think ‘pH =9’ means?

2. A glass of “ice tea” has [H3O+] = 4 x 10-4 M. What is the pH of the ice tea?

3. Atomic absorption method for calcium determination in water samples is used. 5.00 ml natural water were taken and diluted in a volumetric flask to 50.00 ml with distilled water. Then absorbance A = 0.475 is measured. The constant calibration is 1.102 [cm.mg/l] -1.What is the concentration ( μg / ml) of calcium in the water sample.

4. Determine the concentration of Cu ions in drinking water if the signal measured is E = -0.050 V. The coefficients of analytical function are calculated by regression analysis after calibration with external standard. There values are: slope: 30 V and intercept: -119.95 V. Which methods is used for the copper determination?

5. For determination of iron in water samples by atomic flame absorption method is obtained non-linear dependence: absorption-concentration. Explain the reasons for the observed effect and how to repair it?

6. The flame photometric detection is made for determination of K and N in drinking water. Volumes of 5.00; 1.00; 15.00; 20.00 and 25.00 ml standard solution containing 10.00 μg / ml K and Na, respectively were introduced in fi ve volumetric flasks (50.00 ml). The values of sodium radiation intensity measuring at the wavelength λ = 589.0 nm are: 0.290; 0.570; 0.850; 1.40 and 1.390, and the radiation intensity of K at λ = 766.0 nm: 0.245; 0.490; 0.750; 1.010 and 1,250. Volume of 1.00 ml from analyzed sample is diluted in a volumetric flask (50.00 ml) and the value of emission intensity for potassium and sodium are: I K = 0.620 and I Na = 0.800. Define the content of K and Na in mg / l in the sample.

7. Write out the reduction reaction for dichromate in determination of total oxygen in the water samples. What is the molar ratio of the reaction between oxygen and dichromate?

Pre-lab tasks at the beginning of the second semester

In the following step the amount of pre-lab work was increased, with the intention to help students to become more independent and to be fully conscious of the work they have to perform in the laboratory. Tasks in the second semester were mainly related to the methods used for analysis of the samples (Table 3). The aim of this pre lab tasks was the students to learn about principles of used analytical methods. The students prepared the most of the pre-lab tasks in oral presentation, which helped them for final project presentation.

Students’ data

The students were collected the water samples in the end of the second semester. Immediately after collection, the samples were analyzed for pH, hardness, organic compounds, sodium, potassium and heavy metals by the standard methods (Table 4). Because the problems were fairly open-ended, the first challenge the students face was defining the problem. Before jumping into the laboratory, the analytical teams prepared proposals, completed with a detailed analysis, and described their approach for attacking the problem in an oral presentation answering the pre-lab questions from the two semesters. After that the students used voltammetric, atomic absorption/emission, and ion-selective electrode methods for analysis after properly calibrating the equipment with standards for precised results. All work groups finished the laboratory work presenting the data as graphics or tables and gave their conclusions (Table 4-A and Table 4-B). The data indicate that the tap water used for drinking purpose from all Bulgarian regions is no polluted and suitable for human consumption.

In the end of the “water quality project” were given detailed feedback in oral presentation on each “water problem”. An overall list of tips was compiled for giving good student presentations: (i) well-structured with a clear introduction emphasizing the problem; (ii) extensive use of graphics, using time colors carefully; (iii) prepare and practice; (iv) speak slowly, clearly and loudly; (v) simple language and expression; (vi) good eye contact with audience.

In addition the results were also reported through a presentation to a public forum for “Tenth conference of students, young science and PhD students” at University of Chemical Technology and Metallurgy in May, 2014 (Fig. 4).

Conclusions

Thanks to the “water quality project” at the beginning of the year we found that the student’s willingness to carry out a scientific work is increased. The students become more motivated and committed to the learning process. Over 80% of all project users passed the analytical and organic chemistry exams with better assessments at the end of the project. The results of the exams are given in Fig. 5. Moreover, many of the participants wanted to continue with scientific work as activity students in the both chemical disciplines.

NOTES

1. http://apps.who.int/iris/bitstream/10665/44584/1/9789241548151_eng.pdf

2. http://www.mwa.co.th/download/fi le_upload/SMWW_1000-3000.pdf

REFERENCES

Arnold, R.J. (2003). The water project: a multi-week laboratory project for undergraduate analytical chemistry. J. Chem. Educ. , 80, 58 – 60.

Bulte, A.M., Westbroek, H.B., de Jong, O. & Pilot, A. (2006) A research approach to designing chemistry education using authentic practices as contexts. Int. J. Sci. Educ. , 28, 1063 − 1086.

Farid S., Baloch K.M. & Ahmad, A.S. (2012). Water pollution: major issue in urban areas. Intern. J. Water Resources & Environmental Engineering, 4(3), 55-65.

Hofstein, A. & Lunetta, V.N. (2004). The laboratory in science education: foundations for the twenty-fi rst century. Sci. Educ., 88, 28−54.

Juhl, L., Yearsley, K. & Silva, A.J. (1997). Interdisciplinary project-based learning throughan environmental water quality study. J. Chem. Educ. , 74, 1431 – 1433.

Latch E.D. (2014). Instrumental analysis at Seattle University: incorporating environmental chemistry and service learning into an upper-division laboratory course (pp. 193 – 208). In: Roberts-Kircchoff, E.S., Mio, M.J. & Benvenuto, M.A. (Eds.). Service learning and envir onmental chemistry. New York: American Chemical Society.

Lazarowitz, R. & Tamir, P. (1994). Research on using laboratory instruction in science (pp. 94 – 130). In: Gabel, D.L. (Ed.). Handbook of research on science teaching and learning: relevant connections. New York: Macmillan.

Lunetta, V.N., Hofstein, A. & Clough, M. (2007). Learning and teaching in the school science laboratory: an analysis of research, theory , and practice (pp. 393 – 441). In: Lederman, L. & Abel, S. (Eds.). Handbook of research on science teaching. Mahwah: Lawrence Erlbaum.

Peteva Z., Makedonski L. & Stancheva M. (2014), Increasing students’ interest in chemistry with context-based approaches for control and assessment in the English language program at Medical University in Varna. Chemistry, 23, 73 – 87.

Psillos, D. & Niedderer, H. (2002). Teaching and learning in the science laboratory. Dordrecht: Kluwer.

Richter-Egger, D.L., Hagen, J.P., Laquer, F.C., Grandgenett, N.F. & Shuster, R.D. (2010). Improving student attitudes about science by integrating research into the introductory chemistry laboratory: interdisciplinary drinking water analysis. J. Chem. Educ. , 87, 862 – 868.

Schallies, M. & Eysel, C. (2004). Learning beyond school: establishing a laboratory for sustainable education. Chem. Educ. Res. Pract., 5, 111−126.

Sharma, B. & Tyagi, S. (2013). Simplification of metal ion analysis in fresh water samples by atomic absorption spectroscopy for laboratory students. J. Lab. Chem. Educ. ., 1(3), 54 – 58.

Singer, S.R., Hilton, M.L. & Schweingruber, H.A. (2006). National Research Council America’s lab r eport: investigations in high school science. Washington: National Academies Press.

Staver, J.R. (2007), Teaching science. Geneva: Educational Academy of Education.

Xu, H. & Talanquer V. (2013). Effect of the level of inquiry of lab experiments on general chemistry students’ written refl ections, J. Chem. Educ., 90, 21 – 28.