RESULTS AND DISCUSSION
4.2 Turbidity Results
4.2.2 Bentonite solution with varies DTAB concentration
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As shown in figure 4.3, 32µm of drilling mud produce a high turbidity value at average of 460NTU at first reading. Then, all samples except sample with pH3 were increased rapidly at reading 2 and start to decrease from reading 3 to 6. This shows that the particles expand at early 10 minutes and start to flocculates with each other when attractive Van Der Waals dominates in the solution thus decrease the turbidit y value as the solution become clearer due to the sedimentation of the particles. However, pH5 sample shows slower settling rate as compared with other samples when the turbidity value is still high at reading 3 and decreased slowly until reading 6.
Different with 50µm of drilling bentonite, all samples except sample with pH5 shows rapid in decreasing value of turbidity at early time which indicates unstable particles due to the attractive force is higher than the repulsive force between particles.
Moreover, from the results it shows that at this particular particle size, the adsorption process between bentonite and the solution is less effective as less surface area of every particle of bentonite is exposed to the free ions. This is results in coagulating of same bentonite particles which cause the bentonite to settle down rapidly.
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temperature was determined to be 15.7 x 10-3 mmol/kg (Chauhan et. al, 2014). Thus, 5 different concentration of DTAB is prepared which are 11.7 x 10-3 mmol/kg, 13.7 x 10-3 mmol/kg, 15.7 x 10-3 mmol/kg, 17.7 x 10-3 mmol/kg and 19.7 x 10-3 mmol/k g.
Below shows the results of the turbidity test of every sample.
Turbidity reading (NTU) for 20μm nanoclay with DTAB
Reading 11.7 x10^-3 mmol/kg 13.7 x10^-3 mmol/kg 15.7 x10^-3 mmol/kg 17.7 x10^-3mmol/kg 19.7 x10^-3 mmol/kg
1 878 939 649 736 837
2 594 609 172 246 215
3 417 478 79.3 124 95
4 303 387 47.6 84 77.9
5 213 294 19.5 58.7 30.9
6 183 241 15.6 35.3 21.1
0 200 400 600 800 1000
1 2 3 4 5 6
turbidity (NTU)
Reading
20μm nanoclay with DTAB
11.7 x10^-3 mmol/kg 13.7 x10^-3 mmol/kg 15.7 x10^-3 mmol/kg 17.7 x10^-3mmol/kg 19.7 x10^-3 mmol/kg
Turbidity reading (NTU) 32μm nanoclay with DTAB
Reading 11.7 x10^-3 mmol/kg 13.7 x10^-3 mmol/kg 15.7 x10^-3 mmol/kg 17.7 x10^-3 mmol/kg 19.7 x10^-3 mmol/kg
1 744 774 955 953 959
2 246 391 520 331 331
3 115 235 318 147 163
4 58.1 175 228 74.1 95.1
5 21.4 132 170 47.9 52.6
6 18.3 75 114 24.7 45.4
Table 4.5. Results for 20µm nanoclay with DTAB (NTU)
Figure 4.5. Results for 20μm nanoclay with DTAB (NTU)
Table 4.6. Results for 32µm nanoclay with DTAB (NTU)
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As refer to Figure 4.5, the highest turbidity value is obtained when 13.7x10-
3mmol/kg is added into the solution. It is also shows that it gives the most optimum solution stability because the turbidity value from reading 1 to 2 is decreasing lesser as compared to other solutions. In higher concentration, it shows rapid in decreasing turbidity value from reading 1 to 2 and having a low value for the rest testing. However, in lower concentration which is 11.7x10-3mmol/kg the stability of the solution is likely same with 13.7x10-3mmol/kg but has less value in turbidity.
In addition, as refer to Figure 4.6 the trend of the turbidity results of the solutions are most likely same which they decreased rapidly at early times. However, too much and too less of DTAB concentration gives unstable solution as 11.7x10-
3mmol/kg concentration has lowest turbidity value while 19.7x10-3mmol/kg concentration shows rapid decreased in turbidity value at early times. Thus, from the results it shows that additional of 15.7x10-3mmol/kg of DTAB concentration gives the highest turbidity results and the most stable solution as compared to other solutions.
The bentonite suspension is said to be unstable due to electrostatic attraction between negatively charged faces and positively charged edges (E-F) of the particles (Ebru et al., 2006) .This is may be due to the excessive present of sodium chloride and potassium chloride in the surfactant. Thus, the remaining floc diameter of solution will deposited below the solution. The optimum result of modified-bentonite sample is the solution which do not have or less amount of the deposit below the solution.
0 200 400 600 800 1000 1200
1 3 5
Turbidity (NTU)
Reading
32μm drilling bentonite with DTAB
11.7 x10^-3 mmol/kg 13.7 x10^-3 mmol/kg 15.7 x10^-3 mmol/kg 17.7 x10^-3 mmol/kg 19.7 x10^-3 mmol/kg
Figure 4.6. Results for 32μm nanoclay with DTAB (NTU)
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Moreover, as compared with 20µm nanoclay with 13.7x10-3mmol/kg of DTAB concentration and 32µm drilling mud with 15.7x10-3mmol/kg of DTAB concentratio n both show decreasing in turbidity value from reading 1 to 6 but 32µm drilling mud with 15.7x10-3mmol/kg of DTAB concentration shows more rapid decreasing turbidit y value at early times and has less value for the rest of the results. Even though at first reading of 20µm nanoclay with 13.7x10-3mmol/kg of DTAB concentration has lower value which is 939NTU as compared with 955NTU but it decreased slowly and more stable than 32µm drilling mud with 15.7x10-3mmol/kg of DTAB concentratio n.
According to Ebru (2006), at high surfactant concentrations it will increase the positively charged surfactant which cause decreasing of the zeta potential of the bentonite thus coagulation is occurred.
Different results in both comparison solution is may be due to the several factors which are due to the size of the particles and the type of the bentonite its elf.
The smaller the size of bentonite particles will results in efficient adsorption of bentonite with DTAB particles. This is because as smaller the particle size, more space area is exposed for the adsorption process thus optimum number of particles could attracted with each other and stabilized the solution. In addition, the existence of contaminant in drilling mud may affect the adsorption process as other particles may ionized in the solution and attracted to bentonite particles instead of DTAB partic les thus reduce the stability of the solution.
4.2.3 Sample of 20µm nanoclay with 13.7x10-3mmol/kg of DTAB