**5. The social venturing entrepreneurship: economics**

Social venturing economics provides explanations and understanding of SVCE business model enterprise. The social venturing economics term was coined by professor Gert [8]. It borrows ideas from different economic schools of thought to explain, defend, analyze and predict the behavior of economic agent in SVCE business model enterprise.

Social venturing entrepreneurship is a society minded entrepreneurship. It is rooted in the study of welfare and political economics and supported in the literature of the Austrian School/economics (provides coherent suggestive theoretical constructs in entrepreneurship) and the New Institutional Economics (role of institutions in shaping economic behavior focusing on social and legal norms and rules that underlie economic activity) and Behavioral Economics. The starting point is not the neo-classical approach of maximization of utilization for each individual goal. By definition the approach is that people are not acting in a rational way to achieve the highest possible (financial) benefit and utilization. It studies the economy on the basis of society issues existing, in which choices have to be made how to approach them in a business manner and entrepreneurial approach. Most of the times in an environment in which market mechanisms are lacking or functioning poorly and also the A Practical and Theoretical Approach to Social Venturing Entrepreneurship http://dx.doi.org/10.5772/intechopen.72011 97

**Figure 5.** SVCE business model conceptual framework. Source: Siame [18]: p. 173.

government, private business sector and philanthropy have difficulties to bring lasting and sustainable results to these issues with the available instruments [8, 18, 68].

#### **5.1. The conceptual framework for SVE**

A needs assessment at the inception of the SVCE enterprise is done in order to establish the training needs for the delivery rights holders to be able to take part in social venture management. And establish also the interventions that are required to increase production and productivity of economic ventures that the stakeholders are already engaged in so that they are able to supply the value adding social venture with delivery rights of the right quality, the

Before exit, what economic, social, environmental, etc., impact ought to be achieved so that the SVCE business model enterprise remains sustainable even after partner exit? How will the

The proponents of SVE argue that SVCE business model enterprise is superior to traditional social venture enterprise (TSVE) business model on account of exit strategy building block that is integrated with SVCE business model. For example, Community, Market for Conservation (COMACO) business model (a TSVE business model shown in **Figure 4**), has been very successful in delivering economic and impact teleology to communities, but the lack of exit strategy for COMACO lenders the smallholders perpetually dependent on it. In case of COMACO winding-up for some reason the converted smallholders would revert to pouching since they social enterprise where they sell farm produce is no longer in existence ([65]: pp. 307–308).

Social venturing economics provides explanations and understanding of SVCE business model enterprise. The social venturing economics term was coined by professor Gert [8]. It borrows ideas from different economic schools of thought to explain, defend, analyze and

Social venturing entrepreneurship is a society minded entrepreneurship. It is rooted in the study of welfare and political economics and supported in the literature of the Austrian School/economics (provides coherent suggestive theoretical constructs in entrepreneurship) and the New Institutional Economics (role of institutions in shaping economic behavior focusing on social and legal norms and rules that underlie economic activity) and Behavioral Economics. The starting point is not the neo-classical approach of maximization of utilization for each individual goal. By definition the approach is that people are not acting in a rational way to achieve the highest possible (financial) benefit and utilization. It studies the economy on the basis of society issues existing, in which choices have to be made how to approach them in a business manner and entrepreneurial approach. Most of the times in an environment in which market mechanisms are lacking or functioning poorly and also the

**4.5. The difference between SVCE business model and the TSVE business model**

right quantity, at the right time.

96 Entrepreneurship - Trends and Challenges

impact be measured and communicated to stakeholders?

**5. The social venturing entrepreneurship: economics**

predict the behavior of economic agent in SVCE business model enterprise.

**4.4. Impact**

**enterprises**

The success of the SVCE business model enterprise across the supply chains is possible when the social venturing entrepreneur applies social venturing entrepreneurship rooted in new institutional economics, behavioral economics and exit strategy theory as shown in **Figure 5**. The conceptual framework is premised on the notion that SVCE business model enterprise performance and growth is influenced by: Social venturing entrepreneurship + social venturing exit theory + Institutional, legal and policy environment + Internal governance + incentive structure ([69]: p. 235).


**5. Conclusions**

*Hypersonic Vehicles - Past, Present and Future Developments*

*Comparison on simulated Mach contour of original waverider and integration vehicle. (a) Original waverider.*

*Comparison on simulated Mach contour of original Busemann inlet and integration vehicle. (a) Original*

**46**

**Figure 30.**

**Figure 27.** *Integration vehicle.*

**Figure 28.**

**Figure 29.**

*Busemann inlet. (b) Integration vehicle.*

*Lift-to-drag ratio versus angle of attack of the integration vehicle.*

*(b) Integration vehicle.*

Airframe-propulsion integration design method is investigated in the present study. The design methods for the waverider and each components of the scramjet are introduced. The integration method between the waverider and the scramjet is described. The overall optimization for the whole scramjet flowpath is optimized with quick engineering estimation method to provide appropriate performance criteria, which are then used to design three-dimensional component configurations.

Additionally, optimization is performed for the waverider and scramjet components with surrogate modes and CFD simulations. Numerical studies are carried out to find out the performances of the waverider and each component of the scramjet to check whether they can work normally under the design conditions. In the future, the design method for the dual-mode combustor (ramjet and scramjet) will be considered. The numerical simulation for the whole scramjet or dual-mode combustor is necessary to perform to verify the design method.


**2.2 Synthesis of silver nitrate (AgNO3) solution**

The silver nitrate solution is prepared by using 1.698 g silver nitrate powder in 100 ml of distilled water to form 100 mM concentration. From his prepared 100 ml of silver nitrate solution; 1 ml is used for preparation of 1 mM silver nitrate solution for silver nanoparticles synthesis. The complete process is performed under absence of light.

#### **Figure 3.**

*Displays the synthesis of dichlorofluorescein silver nanoparticles (DCF-SNP) employing AgNO3 and dichlorofluorescein under heating conditions. The change in color of the reaction mixture was noticed from light green to dark brown, demonstrating the formation of silver nanoparticles.*

#### **2.3 Synthesis of dichlorofluorescein silver nanoparticles**

The dichlorofluorescein silver nanoparticles (DCF-SNPs) is prepared by mixing 97.5 ml of AgNO3 (1 mm) and 2.5 ml of dichlorofluorescein in conical flask at constant stirring. The complete reaction process is carried out under boiling condition for 1–2 min, the pH of the mixture is adjusted to 12 and the reaction completes after 24 hours. The chemical constituents or the functional group that are presents in the Dichlorofluoresceine (DCF) structure reduced the silver salt to form the silver nanoparticles called as dichlorofluorescein silver nanoparticles (DCF-SNPs). The complete process of synthesis of dichlorofluorescein silver nanoparticles (DCF-SNPs) using AgNO3 and dichlorofluorescein at 0 hr., 2 hr. and 24 hr. and observed changes in color from light green to dark brown, confirming the synthesis of silver nanoparticles synthesis is given in **Figure 3**.


2. Methods and materials

#### 2.1 The modified hyperbolic sine law for minimum creep strain rate and stress law

Xu's modified hyperbolic sine law is given as [12]:

$$
\dot{\varepsilon}\_{\min} = A \sinh(B\sigma^q) \tag{4}
$$

It was originally proposed by the first author for low Cr alloy [12], and its application was very successful [12].

Other existing and commonly used laws for high Cr P91 are listed Table 2; their suitability was examined first prior to the adoption of Xu's modified law.

The specific material used here is P91 (9Cr-1Mo-V-Nb). The experimental data of the minimum creep strain rate over a range of stress levels was taken from the published creep data [20] produced by the National Institute for Materials Science (NIMS), Japan.

Table 2.

The list of creep laws for the minimum creep strain rate and stress.

Modeling of Creep Deformation and Creep Fracture DOI: http://dx.doi.org/10.5772/intechopen.89009

## 2.2 Creep cavity fracture model


**7. Environmental Consideration and Potential Health Issues**

In addition to the studies that focused on the thermal enhancement that nanofluids can provide to energy systems, researchers have also explored the environmental impact and the potential hazardous towards human health from using these kind of suspensions [459]. In terms of environmental concerns, Meyer et al. [460] proposed an exergoenvironmental analysis method for designing an energy conversion system with an as low as possible

environmental impact. Furthermore, an Eco-indicator 99 life cycle impact assessment approach was employed by the scholars to evaluate the environmental impact in a quantitative manner. They obtained the ecoindicator point through undertaken a series of analyses such as the exposure and effect analysis, resource and fate analysis, and damage analysis. One of the main element in determining the fate analysis is the toxicity evaluation of the nanomaterial(s) that form(s) the nanofluid. However, the criteria for measuring the level of toxicity is still not clear, and as such uncertainty always exist [461]. In order to resolve the previous issue, Card and Magnuson [462] came with a two-step approach for evaluating the toxicity of nanomaterials in an objective manner. In the first step, the authors collected the available literature that are related to the toxicity of nanomaterials, after which they started to evaluate and rank these studies according to the suitability of the design, documentation of adopted approach, materials used, and research outcome to produce the reliability 'study score'. As for the next step, the fulfilment of the physicochemical characterization of the nanomaterials is assessed in every study, which is then used to generate a 'nanomaterial score'. In general, the optimum way to reduce the environmental impact is to lower the utilization of resources and the resulting gas emissions during operation condition. For systems the utilize nanofluids, this can be achieved through enhancing their thermal efficiency, reducing their overall system size, and/or reducing the number of nanomaterials used. The reader is guided to the following sources [463–471] for further details on the aforementioned.

On the other hand, users dealing with nanofluids are always under high health risk [472]. This is because in the preparation process of these suspensions there is an inevitable contact between the user and the nanomaterials used, which can therefore enter their blood streams and/or organisms through skin absorption, inhalation, and/or ingestion of these toxic materials. It is important to note that almost all carbon-based nanomaterials, including CNTs, NDs, and graphene, are toxic and that the level of their toxicity increases with the decrease in their size [473]. Moreover, it is important that the reader distinguish between the safety aspect of nanomaterials that are used as medication (or for inner body diagnostic) and those used for other non-medical applications [110,474–477]. The first are safe and non-toxic when transferred to the human body in the appropriate way, whereas the second have high health risks and should be dealt with safety precautions. Some of the studies that were mainly devoted towards evaluating the harm that nanomaterial can cause to human health can be found in the following literature [473,474,478–482], where the material type, shape, size, surface characteristics charge, curvature, free energy, and functionalized groups were taken into account. Although using personal protective equipment and following the safety handling procedures can lower the user health risks, it is believed that part of the problem associated with commercializing nanofluids is due to the increasing concerns from the potential stakeholders and a lack of sufficient research studies [472,481].


*3.5. Overall Process Performance and Quality of the Product*

The process flow sheet for the extraction of cobalt from the ZPR is shown in Figure 10. The flowsheet has similarities with the flowsheet presented in [1]. The similarity between the two flowsheets developed independently is an indication that this processing scheme is a viable route for the recovery of cobalt from a ZPR produced by cementation on zinc dust.

**Figure 10.** ZPR processing circuit to extract cobalt (See Table 10 for the composition of streams 1–6).

In order to assess the robustness of the proposed process, the whole processing sequence of Figure 10 was repeated with three ZPR feed samples. The previous sections gave the results of the repetitions obtained for the various stages of the process. Table 10 summarizes these results in terms of cobalt distribution. The repetitions show that the critical step in the proposed process is the oxidation/precipitation of the iron and manganese prior to the cobalt precipitation. The main cobalt losses occur at the Fe-Mn precipitation step. A problem or inaccuracy in the measurement of the Redox potential and the difficulties in the filtration of the Fe-Mn sludge cause some Co precipitation and an incomplete removal of impurities that will subsequently contaminate the cobalt product. Cobalt losses also occur at the final precipitation step, where recovery could be improved by using a pH above 3.0 and allowing more time for precipitation [1]. However, the use of a higher pH and of an increase precipitation time may cause more impurities to precipitate with the cobalt. This optimization problem of maximizing Co recovery under the constraint of an acceptable product purity can be adequately tackled down using a factorial Design Of Experiments (DOE) [19] if the process is to be continued with an optimization phase. The aspect of the process sensitivity to operating conditions, particularly the control of the Redox potential, addressed here is seldom discussed in the literature dealing with the recovery of cobalt from a ZPR, while it is as important as the process itself, especially if it is to go on to piloting.

**Table 10.** Distribution (%) of the cobalt in the process streams of the circuit of Figure 9.

In summary, the proposed processing flow sheet yields a Co product assaying 45 ± 4% Co at a recovery of 62%. Improvements to the reproducibility of the method can be achieved by improving the control of the Redox potential and the solids/liquid separation of the precipitated Fe-Mn sludge. These results cannot be compared to those of other processes used for processing a ZPR produced by cementation on zinc dust, as it was not possible to find such data in the literature.

Ideally, to avoid paying refining charges from the selling of the cobalt hydroxide product to a custom Co refinery, one should aim at producing electrolysis-grade cobalt at the end of the ZPR-Co process. The concentration of cobalt in the solution released by the S/L separation of the Fe-Mn precipitate is low at 3 g/L, and should be increased to at least 45 g/L [20] to allow Co electro-winning. Solvent Extraction (SX) is an approach to increase the solution concentration and remove some of the accompanying impurities (See Table 9). The other option is to stock pile the produced Co hydroxide and to dissolve it under reducing conditions to convert Co(III) into Co(II) with a controlled amount of sulfuric acid to generate the solution to feed the electrolytic cells. Figure 11 shows the two options.

**Figure 11.** Processing options to produce electrolytic cobalt.

#### *3.6. Economics of the Process*

The analysis presented in this section focuses only on the operating costs of the process of Figure 10. It is a preliminary analysis and the calculated costs should be considered as Class 5 estimates (AACE International). Results are used to anticipate the economic viability of the process and decide on the continuation of the laboratory test work to optimize the proposed ZPR-Co process.

A cobalt price of 30.20 USD/kg (LME Price August 2020) is used to estimate the revenues that can be generated by processing the ZPR. The Net Smelter Return, if the cobalt hydroxide is to be sold to a refinery, is estimated by assuming that 90% of the cobalt in the hydroxide is payable and that the refining charges are 3.00 CAD/kg of Cobalt hydroxide. If the cobalt content of the produced Co hydroxide is 45% (see Table 9) then the revenues (assuming an exchange rate of 1.25 CAD/USD) generated per kg of cobalt hydroxide are:

$$\text{NSR} = 0.9 \times 0.45 \times 30.2 \times 1.25 - 3 = \frac{12.28 \text{ CAD\\$}}{\text{kg of Co hydroxide}^{\circ}} \tag{3}$$

Since the test work has shown that the processing of 75 g of ZPR yields 1.2 g of Co hydroxide, the potential revenues per kg of ZPR are 0.20 CAD/kg ZPR.

The operating costs considered here are due to the reagents and exclude the energy costs for heating the solution at the precipitation stage. Table 11 gives the calculated operating costs per kg of ZPR. The reagent costs are probably over-estimated as purchasing the sulfuric acid may not be required. Indeed some spent zinc electrolyte could be used for the Co process (see Figure 1). Additionally, it is very likely that recycling some of the solution streams of the ZPR-Co process could allow a reduction in the consumption of caustic and APS. This preliminary evaluation shows that the proposed process is not viable but the process certainly deserves to be optimized to increase the overall cobalt recovery and to reduce the consumption of APS that is the main contributor to the operating costs. The option of producing metallic cobalt rather than cobalt hydroxide should also be investigated.

**Table 11.** Preliminary estimation of the operating costs for the ZPR-Co process of Figure 9. (The reagent prices were obtained from quotations dating of 2019 and are used here only to give an order of magnitude).


**2. Efficient fabrication of single layer graphene oxide nanosheets**

### **2.1. Rheologically driven exfoliation of graphite oxide**

Conventional sonicators vigorously destroy the structure of GO, which results in producing small-sized GO nanosheets due to acoustical wave agitation in solution. An alternative way to minimize the destructive effect of exfoliation of graphite oxide is to use a homogenizer to apply a shear force in the solution (**Figure 2(A)**). The average lateral size of sonicated GO (SGO) nanosheets (a few square micrometers) was smaller than that of the homogenized GO (HGO) nanosheets (a few hundred square micrometers) in the optical images in **Figure 2(B)** and **(C)**. The SGO nanosheets exhibited some agglomerated GO on the silicon substrate due to the small size distribution of the sheets. To confirm the exfoliation effects of HGO and SGO sheets, we carried out homogeneous dispersion of GO sheets in aqueous solution without using small size graphite powder (70 μm). The rheologically derived or sonicated exfoliation and dispersion of GO sheets was accomplished (**Figure 1(d)**) in an aqueous NaOH solution at pH 10 for 1 h. After diluting it using dimethylformamide (DMF), the RGO solution was prepared by chemical reduction with hydrazine for preparing transparent conducting films. The enhanced sheet resistance of the reduced HGO (HRGO) thin film was found to be 2.2 kΩ/sq. at 80% transmittance. The effective exfoliation method has great potential for application for high performance GO-based flexible electrodes.

#### **2.2. Extremely efficient liquid exfoliation of graphite oxide using unusual acoustic cavitation**

properties. As shown in **Figure 1**, GO nanosheets are typically produced by oxidizing graphite using strong acids and oxidants, followed by exfoliation in aqueous solutions [5–8]. It should be noted that, the characteristics of GO and RGO nanosheets critically depend on the oxidation states of graphite oxide and its exfoliation. Moreover, for real-life applications, the dispersion stability of RGO inks or pastes is a prerequisite. The dispersion of high-quality chemically exfoliated graphene (CEG) or RGO in polar solvents, which contain few oxygen functional groups and defects, has been impossible due to the hydrophobic nature of graphene without post treatment or addition of dispersant molecules. The stability of RGO dispersion is one of the crucial factors for preserving their unique properties such as electrical conductivity and mechanical strength. Therefore, this chapter describes some of the research on CEG nanosheets conducted over the past 8 years that addresses these and other challenges, with an emphasis on our own efforts. We began with the efficient fabrication method of single layer GO nanosheets from graphite, and then described the stable dispersion of RGO in solutions. Furthermore, we described the applications of GOs as p-type dopants, conductors and interfacial modifiers. We concluded with some discussion of future directions and the remaining challenges in chemically exfoli-

**Figure 1.** Production schematics of chemically exfoliated graphene from graphite. Here, GIC stands for graphite

**2. Efficient fabrication of single layer graphene oxide nanosheets**

Conventional sonicators vigorously destroy the structure of GO, which results in producing small-sized GO nanosheets due to acoustical wave agitation in solution. An alternative way

**2.1. Rheologically driven exfoliation of graphite oxide**

ated graphene technologies.

intercalation compound and LIB for lithium ion batteries.

128 Graphene Oxide - Applications and Opportunities

Acoustic cavitation, also called sonication, has been used to fabricate two-dimensional (2-D) nanosheets via exfoliation of bulk-layered crystal materials in solution to fabricate fascinating materials such as graphene, transition metal dichalcogenides, and transition metal oxides. The

**Figure 2.** Fabrication of GO and RGO nanosheets by using different exfoliation methods. (A) Exfoliation of graphite oxide by sonication (S) or homogenization (H).  (D) Fabrication of transparent conducting films (TCFs) with RGO nanosheets by the contact printing of filtrated RGO films. Here PDMS is polydimethylsiloxane, PET is polyethylene terephthalate, and RGO-TCFs are reduced graphene oxide transparent conductive films. The scale bars in (B) and (C) are 10 μm, and those in the respective insets are 2 μm [9].

amplitude at the 2.5 cm probe depth. Moreover, bubbling due to the liquid surface instability under acoustic oscillation is also helpful for the efficient exfoliation of graphite oxide. Bubbling by aeration at the liquid surface is also helpful for the dispersion of nanomaterials because bubbling can produce a greater shearing effect on the particles in suspension under an acoustic flow with lower energy. **Figure 3(b)** and **(c)** shows the scanning electron microscopy (SEM) images of exfoliated GO nanosheets under different cavitation conditions. The maximum size of GO was dramatically increased by adjusting the probe depth from 2.5 to 0.5 cm. At a probe depth of 2.5 cm, the lateral size of GO was less than 5 μm even at 10% amplitude after 10 min of sonication (**Figure 3(b)**) because of breakage in the stretched C–C or C–O–C bonds [10, 11] due to the high energetic physical phenomena of microjets and shock waves [12]. However, at a probe depth of 0.5 cm, GO nanosheets with a maximum 30 μm size were produced even at the high output power setting (amplitude 100%) by reducing the detrimental effect of the high

Chemically Exfoliated Graphene Nanosheets for Flexible Electrode Applications

http://dx.doi.org/10.5772/intechopen.77284

131

 **precursor-assisted dispersion of reduced graphene oxide in solution**

The problems associated with the aggregation of the RGO sheets in organic solvents were

charge screening candidate because it can interact electrostatically with oxygen moieties

isopropoxide (TIP)/acac stabilizer (1/5 molar ratio) solution, which was added to the GO

varied between 0 and 1.5. Just a 0.1 weight ratio was required to stabilize the RGO solution

mixture can be deposited onto the large area substrate by air-spraying without postreduction process. Usually, RGO films are fabricated by deposition of GO nanosheets on the substratem, followed by thermal or chemical reduction at elevated temperatures. Moreover, direct deposition of RGO solution onto the substrate induces formation of wrinkled structures,

graphene field-effect transistors (FETs) on heavily doped Si substrates, which are commonly employed as gate electrodes. It is worth noting that the conductivity of the RGO film at the neutral charge point was maximized for GO/TIP (1/0.7 ratio) by inserting a thin TiO2

nanosheets, which was demonstrated by observing a significant blue shift of the G peaks in

to hydrazine reduction. The weight ratio between GO and TIP in the precursor TiO2

which can decrease their electrical properties. However, wrinkle-free RGO/TiO2

into the RGO multilayer film, despite the amorphous insulating characteristics of TiO2

in dimethylformamide (DMF) after hydrazine reduction. This stable RGO/TiO2

precursor sol, as shown in **Figure 4(a)**. Titanium dioxide is also a promising

carbons of the RGO sheets

precursor for RGO dis-

amount between the RGO

sol was

hybrid

layer

. This

precursor sol

precursor sol was prepared from a titanium

precursor sols were added into the GO solution prior

by automatic spray-coating. The electrical trans-

hybrid films were investigated by preparing

energy cavitation process (**Figure 3(c)**).

**3.1. TiO2**

and the TiO2

Raman spectra.

**3. Dispersion of reduced graphene oxide**

causing charge trapping [14, 15]. The TiO2

persion, the varying amount of TiO2

multilayer films can be built up on SiO2

port characteristics of the RGO and RGO/TiO2

addressed by introducing noncovalent interactions among the sp2

solution. In order to determine the minimum amount of used TiO2

was due to the hole-doping effect caused by increasing the TiO2

**Figure 3.** (a) Temperature change (*ΔT*) over time during sonication of pure water and of a GO suspension containing different initial amounts of graphite oxide. (b) and (c) FESEM images of GO nanosheets fabricated using probe sonication by dipping probe into the liquid surface by 2.5 and 0.5 cm, respectively, for 10 min. The large GO nanosheet was fabricated at 0.5 probe depth condition. (d) Shear viscosity of GO paste samples showing different rheological behavior due to their sizes. (e) Raman spectra of the chemically reduced GO nanosheets demonstrating the effect of acoustic cavitation at different probe depth on the crystalline structure of RGO (f) breakage of GO nanosheet initiated at the defect site or from the sp3 hybridized region during probe sonication. (g) Real THz conductivity of the GO, SRGO, and LRGO films prepared by sonication with probe depths of 0.5 and 2.5 cm [13].

high energetic transient acoustic cavitation; the formation, growth, and implosive collapse of bubbles at high ultrasonic intensities (10–30 W cm−2) in a liquid medium, allow to give physical effects on exfoliation of layered materials. However, the high energetic transient cavitation phenomenon can give a detrimental effect on 2D materials by generating defects on the surface, which decrease their electrical and other useful properties. Recently large (>10 μm) chemically modified graphene nanosheets have been developed from graphite oxide. These have fewer defects than those produced by other methods without requiring further separation processes and can be produced by combining ultrasonic acoustic cavitation with sufficient acoustic shearing and additional microbubbling by aeration in an extremely short time (10 min). It can be achieved by adjusting the ultrasound parameters (amplitude, time, and probe immersion depth) for the delivered power (related to temperature change (*ΔT*) **Figure 3(a)**), the acoustic flow rate, and the bubbling behavior in 200 mL water using conventional flat tip probes with a 12.7 mm diameter. In order to reduce the detrimental effect of transient cavitation, the probe tip was located at a 0.5 cm depth. Subsequently, the acoustic flow rate decreased from 0.62 to 0.47 m s−1 and then increased to 0.73 m s−1 at 100% amplitude, which was faster than the 10% amplitude at the 2.5 cm probe depth. Moreover, bubbling due to the liquid surface instability under acoustic oscillation is also helpful for the efficient exfoliation of graphite oxide. Bubbling by aeration at the liquid surface is also helpful for the dispersion of nanomaterials because bubbling can produce a greater shearing effect on the particles in suspension under an acoustic flow with lower energy. **Figure 3(b)** and **(c)** shows the scanning electron microscopy (SEM) images of exfoliated GO nanosheets under different cavitation conditions. The maximum size of GO was dramatically increased by adjusting the probe depth from 2.5 to 0.5 cm. At a probe depth of 2.5 cm, the lateral size of GO was less than 5 μm even at 10% amplitude after 10 min of sonication (**Figure 3(b)**) because of breakage in the stretched C–C or C–O–C bonds [10, 11] due to the high energetic physical phenomena of microjets and shock waves [12]. However, at a probe depth of 0.5 cm, GO nanosheets with a maximum 30 μm size were produced even at the high output power setting (amplitude 100%) by reducing the detrimental effect of the high energy cavitation process (**Figure 3(c)**).