Higher contact angles or amplified wettability observed on surfaces of rough solid materials are typically expressed as a function of a physical dimension (roughness factor). Herein, we present a simple experimental approach that demonstrates that roughness may only magnify the inherent surface chemistry that seems to have direct influence on surface wettability. We investigate gradual change in surface chemistry (hydrophobisation) of rough and smooth glass surfaces, from a very low concentration (10−7 M) of dichlorodimethylsilane, DCDMS through various intermediate hydrophilic/hydrophobic states to when the surfaces are maximally hydrophobised with DCDMS at 0.1 M. The wettability of the modified glasses was studied by water contact angle measurements using drop shape analysis system (DSA). The data obtained indicate a deviation from Wenzel model, with the functionalized rough glass surfaces showing higher reactivity towards DCDMS when compared to the smooth glass surfaces, indicating that the two surfaces are not chemically identical. Our study reveals that just like transforming a solid material to powder, a well-divided glass (rough) surface may not only exhibit a greater surface area than the smooth counterpart as rightly predicted by the Wenzel model, but seems to be bloated with functional groups (–OH or –CH3) that can amplify surface interaction when such functional species dominate the solid surface.
This research investigates alteration in the composition of diesel and engine oil due to their treat ment with 35g of Potassium Alu miniu m Sulphate, (KAl(SO4) 2) for seven days at room temperature. Results reveal that after treatment, the Total Petroleu m Hydrocarbon (TPH) o f diesel increased fro m 7688.38mg/ l to 12505.10mg/l whereas that of engine oil increased fro m 4967.48mg/l to 7700.47mg/l. Th is suggests that within these seven days, the salt was able to alter the composition of the samples by breaking down h igher mo lecular weight hydrocarbon fractions within and above the C40 range to smaller mo lecular weight fractions with in the C6 to C40 range. The TPH of the treated diesel oil was similar to that of kerosene after treat ment and that of the treated engine oil was similar to that of the untreated diesel sample. Ratios calculated fro m fingerprints of the samples such as nC 20 /nC 24 , nC 18 /nC 24 , nC 18 /nC 20 , nC 7 /nC 9 , and ∑K/∑D for the treated diesel samp le (0.76, 0.57, 0.75, 0.16, and 0.84) respectively were slightly similar to that of kerosene (0.65, 0.79, 1.20, 0.5, and 1.08), but different fro m that of the untreated sample whereas ratios like nC 10 /nC 11 , nC 11 /nC 12 , nC 14 /nC 16 , nC 11 /nC 20 and nC 24 /nC 28 for the treated diesel sample (0.53, 0.35, 1.02, 0.67 and 4.44) were similar to that of the untreated diesel sample (0.52, 0.36, 0.92, 0.46 and 5.47). None of the ratios for the treated engine o il sample were similar to either those of the untreated engine oil samp le or those of diesel. Therefore, though the treatment of the samples with 35g of the salt caused alterations in the chemical co mposition of the samples, it d id not totally transform them to the fraction obtained before them during distillation process.
Possible effects of the treat ment of d iesel oil with various concentrations of an inorganic salt, PotassiumAluminiu m Sulphate (KA l(SO 4 ) 2 ) were studied at room temperature, with a view to assessing alterations in the total petroleum hydrocarbon of diesel oil. Results obtained revealed that various concentrations of the inorganic salt had different effects on the total petroleum hydrocarbon (TPH) of the samples. The sample treated with 55g of the salt had the lowest TPH concentration of 2255.75mg/l while the sample treated with 35g of the salt had the highest TPH concentration of 12505.10mg/l. Two samples had higher TPH concentration than the untreated sample wh ile five samp les had lower TPH concentrations. This may be ascribed to the fact that some concentrations of the salt were able to catalytically crack heavier hydrocarbon molecules in the diesel oil to fractions lower than C6 (wh ich may have been gases) thus leading to a decrease in the TPH concentration of those sample, while other concentrations of the salt were able to breakdown heavier hydrocarbon mo lecules to fractions with in the C6 to C40 range thus leading to an increase in the TPH concentrations of the samples. The treatment also led to decrease and increase in the density of the samples.
Non-wettable surfaces have recently attracted significant attention due to their enormous promising applications. These applications are primarily due to their ability to repel liquid drops and remain unwetted. In this review, the various names used in describing non-wettable surfaces are given. This is followed by the fundamental theories of wetting. Natural non-wettable surfaces are then considered, along with their importance. Thereafter, we discuss how artificial non-wettable (biomimetic) surfaces are prepared. Next, the basic properties of non-wettable surfaces, which make them promising candidates for a wide range of applications, are discussed. Furthermore, the various applications of non-wettable surfaces are discussed, with references made to review articles with specific coverage of named applications. We conclude with a summary, challenges limiting the application of non-wettable surfaces to some real-life situations and possible suggestions to mitigate them as well as opportunities for future work.
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