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Herein, we have studied the mixed micellization of Cetyltrimethylammonium bromide (CTAB) and Sodium dodecyl sulfate (SDS), in aqueous/various salts medium at several temperatures (298.15–318.15 K) by conductivity measurement method. The extent of interaction between CTAB and SDS was assessed from the values of ideal critical micelle concentration (cmcid) as well as experimental cmc. In attendance of salts, cmc values are obviously decreased from the corresponding values in aqueous medium. The magnitudes of micellar mole fraction of CTAB (X1) and activity coefficients of CTAB & SDS (f1 & f2) were estimated based on different theoretical model and outcome disclose the effective involvement of CTAB in the mixed micellization. The executed values of both interaction parameters (β) and excess free energy of micellization were negative signifying the attractive interaction and stability of mixed micelles respectively. The executed negative values of Gibbs free energy change of micellization, ∆Gom illustrate the spontaneous micellization of individual/mixed surfactant system. The other thermodynamic parameters ΔHom (enthalpy change), and ∆Som (entropy change) were also calculated from the conventional standard equations. Molecular level interactions are disclosed by molecular dynamics (MD) simulation which showed that salts promote more interactions between the surfactants.

Conductometric and cloud point (CP) measurement techniques have been employed in order to investigate the interaction of antibiotic drug levofloxacin hemihydrate (LFH) with anionic surfactant, sodium dodecyl sulfate (SDS) as well as a non-ionic surfactant Tween-80 (Tw-80; polyethylene sorbitol ester) in the absence/occurrence of various salts over the temperature range 298.15–318.15 K keeping regular interval of 5 K. Two clear c* values were extracted for pure SDS along with (SDS + LFH) mixtures where the increase and decrease of c* values due to the addition of LFH and salts respectively demonstrated the happened interaction among the studied components where salts provided a convenient environment for aggregation of surfactants. Negative ∆G°m values of SDS in H2O/(SDS + LFH) mixtures revealed the spontaneous assembling of surfactant molecules and the stability of the aggregates. The values of ∆H°m and ∆S°m indicate the existence of hydrophobic & electrostatic interactions between drug (LFH) and surfactant (SDS). Enthalpy and entropy contributions on the standard free energy of micellization were also calculated. The CP magnitudes of Tween-80 were reduced with increasing its concentration. The occurrence of LFH/(LFH + salts) boosted to lessening the CP values. The positive ∆G°c values suggested the non-spontaneity of clouding while the obtained ∆H°c and ∆S°c values of this CP study demonstrated the two significant accelerating impacts (electrostatic/hydrophobic interactions) between LFH & Tw-80. The thermodynamic properties of transfer for both techniques were also evaluated and analyzed in detail in the current study.

The interaction of bovine serum albumin (BSA) with sodium dodecyl sulphate (SDS) in aqueous medium as well as aqua-organic mixed media has been performed using the conductivity measurement technique at several temperatures. The experiments were performed in the temperature ranges of 298.15–313.15 K with a gap of 5 K. The critical micelle concentration (CMC) and the degree of micelle ionization (α) have been computed from the specific conductivity versus the surfactant concentration plot. The CMC values achieved in the present study are dependent on the concentration of BSA, composition of the mixed solvent, and a variation of experimental temperature. For SDS + BSA mixture, an increase of BSA concentration causes a decrease in the values of CMC. Also, the values of CMC of SDS + BSA system in water-organic solvents were found to follow the order: CMCwater-DMF > CMCwater-AN > CMCwater-DMSO > CMCwater. In every case examined, the association of SDS + BSA mixture was spontaneous (negative ΔG0m). On the basis of observed ΔH0m and ΔS0m values for the SDS + BSA mixed system, it is expected that an electrostatic, hydrophobic, and ion–dipole interactions are in effect between SDS and BSA species, whereas the hydrophobic interaction is believed to be the main driving force for the aggregation process. In each of the case thoroughly detected, a linear relationship between ΔH0m and ΔS0m values was viewed, which is a strong indication in favor of the presence of enthalpy–entropy compensation phenomenon in the overall interaction process.

Investigation of the interaction of the beta-lactum antibiotic drug levofloxacin hemihydrate (LFH) with cetyltrimethylammonium bromide (CTAB) has been performed in aqueous solution and in the attendance of salts at various temperatures (298.15, 303.15, 308.15, 313.15 and 318.15 K). A single critical micelle concentration (CMC) was observed for pure CTAB and their mixture with the drug (LFH). The CMC values for mixed systems (LFH + CTAB) in the presence of salt showed lower in magnitude in comparison to their absence. This pointed out the early micellization of the mixture of LFH and CTAB. All the ∆ G0m values were found to be negative for all systems. The ∆ H0m and ∆ S0m values showed that hydrophobic and electrostatic interactions were boosted in the presence of salts compared to their absence at lower and higher temperatures respectively. The other thermodynamic parameters such as transfer energy (∆ G0m.tr.), transfer enthalpy (ΔH0m.tr.) as well as transfer entropy (∆ S0m.tr.) were also determined and discussed in detail. The intrinsic enthalpy gain (∆ H0,⁎m) and the compensation temperature (Tc) were also evaluated and discussed. Molecular dynamics simulation reveals that aqueous as well as salt environment have impact on the hydrophobic interaction between LFH and surfactant.

Interaction of the third-generation cephalosporin antibiotic drug ceftriaxone sodium trihydrate (CFT) with a cationic conventional surfactant cetyltrimethylammonium bromide (CTAB) has been carried out by conductometric technique in water and in the presence of various salts such as NaCl, Na2SO4 and Na3PO4 at varying temperatures with gaps of T = 5 K. Two critical micelle concentrations (c*1 and c*2) were obtained for (CFT + CTAB) mixtures in all the cases. The change of c⁎ values of CTAB due to the addition of CFT is indicative of the interaction between CFT and CTAB. For the (CFT + CTAB) mixed system, the values of c⁎ are higher in magnitude in contrast to that of pure CTAB in aqueous solution at a particular temperature. Both the c⁎ values for (CFT + CTAB) mixed system in the presence of different salts are lower in magnitude as compared to aqueous medium which means addition of salt favors the micellization of (CFT + CTAB) mixed system. The ∆ G0m values are obtained to be negative in all the cases. The heat capacity (ΔC0p.m.), transfer energy (∆ G0m.tr.), transfer enthalpy (ΔH0m.tr.) and transfer heat capacities (ΔC0p.m.tr.) were also determined and discussed as an extension of the usual thermodynamic quantities of micellization.

The formulation of drug considering the body fluid ingredients is important and therefore study of the interaction of drug-surfactant in fluid ingredients medium is very significant. Herein, we applied a conductivity technique to insight the interaction of cephradine monohydrate (CDM) drug with cationic surfactant- cetyltrimethylammonium bromide (CTAB) and anionic surfactant- sodium dodecyl sulfate (SDS)) while UV–visible spectroscopic was employed to observe the interaction of CDM with non-ionic surfactant, triton X-100 (TX-100). The experimental temperature ranges were 303.15–328.15 K and 293.15–323.15 K for CDM + CTAB and CDM + SDS systems respectively in the case of the conductivity study whereas for UV–visible spectroscopic study the temperature was kept in the range of 298.15–318.15 K. The values of critical micelle concentration (CMC) of CDM + CTAB and CDM + SDS systems were analyzed from their conductivity data in H2O and aqueous NaCl solution. The CMC values were found to be lower for CDM + CTAB and CDM + SDS systems as compared to corresponding pure surfactants. The CMC values were found to be influenced by the variation of experimental temperature. The micellization of CDM + CTAB and CDM + SDS systems was favored in the presence of NaCl and augmentation of NaCl concentration generates a more favorable condition for micellization of studied systems. The values of counter ion dissociation (α) were found to be temperature and additives dependent. The free energy of micellization (∆Gmo) indicates that micellization of CDM + CTAB and CDM + SDS systems was thermodynamically spontaneous which further augmented with the boost of NaCl concentration. The computed enthalpy and entropy values exhibit a linear relationship in all cases for CDM + CTAB and CDM + SDS systems. The binding constant (Kb) between CDM and TX-100 was found to be increased with the augmentation of CDM concentration and exhibit U-like variation as temperature increases. The binding between CDM and TX-100 was also thermodynamically spontaneous.

Cephalexin monohydrate (CLM) is a well-known antibiotic applied for prohibiting bacterial growth. Herein, the mode of interaction of CLM with both ionic (cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS)), and nonionic (triton X-100 (TX-100)) surfactants, was investigated using the conductivity measurement and UV–Visible spectroscopic techniques in H2O and NaCl + H2O media at numerous temperatures ranging from 293.15 to 328.15 K. In the current study, the critical micelle concentration (CMC) of CLM + CTAB and CLM + SDS mixed systems was estimated from a sudden and clear breakpoint of specific conductivity (κ) versus the concentration of surfactant plot. A single CMC was found for both CLM + CTAB and CLM + SDS systems in entirely experimental cases studied. The value of CMC of surfactants undergoes a drop in presence of CLM in an aqueous phase and hence, the drug causes an enhancement of the extent of micellization of surfactants. Also, the CMC values of CLM + CTAB and CLM + SDS mixed systems were found to reduce in NaCl + H2O medium and the CMC values were observed to experience a further reduction with increasing concentration of NaCl salt. A negative standard free energy change (∆Gmo) of micellization discloses that the CLM + ionic surfactant micellization is spontaneous. The different thermodynamic parameters of transfer and the enthalpy-entropy compensation parameters of micelle formation were also measured and demonstrated appropriately. The binding constant (Kb) of the CLM + TX-100 mixture has been evaluated from the Benesi-Hildebrand equation and the values were found to be dependent on CLM concentration and temperature. The ∆Hbo and∆Sbo values of CLM + TX-100 mixture reveal the survival of the electrostatic force of interaction along with the presence of hydrophobic interaction developed between the CLM drug and TX-100 surfactant.

Herein, the interaction between Tween-80 (Tw-80) and antibiotic drug lomefloxacin hydrochloride (LMFH) has been studied through the cloud point (CP) measurement of Tw-80 + LMFH mixtures in the absence/attendance of electrolytes. Tw-80 is used for different formulations of drugs and foods. LMFH is widely prescribed for the treatment of numerous bacterial infections. The cloud point (CP) values of Tw-80 + LMFH mixture were determined and found to reduce with the augmentation of concentration of LMFH. The occurrence of salts reduces the CP of the Tw-80 + LMFH mixture which further enhances with an increase of salt concentration. The effectiveness of electrolytes in decreasing CP of Tw-80 + LMFH mixture was obtained to be followed the order: CPNaCl

This work investigated the pretreatment effect of four ionic liquids (ILs) on sugarcane bagasse (SCB) through reactivity, kinetic, and thermodynamic analysis. The ILs used in this study were 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]), 1-butyl-3-methylimidazolium methylsulfate ([Bmim][MeSO4]), Tris (2-hydroxyethyl) methylammonium methylsulfate ([MTEOA][MeSO4]), and trihexyltetradecylphosphonium chloride ([P66614] [Cl]). Pretreatment was carried out at 150 °C and 30 min, followed by thermal analysis of samples in a thermogravimetric analyzer (TGA). The activity parameters were obtained using TGA data. [P66614] [Cl] was completely absorbed in SCB, which strongly influenced the thermochemical behavior of [P66614] [Cl] treated sample. Results revealed that IL pretreatment greatly reduced ash content and increased the higher heating value (HHV) of SCB. Chemical composition analysis showed delignification of SCB by [Bmim][Cl], [Bmim][MeSO4] and [MTEOA][MeSO4]. However, [P66614] [Cl] increased lignin content indicating thermal stability. The obtained values of activation energy (Ea) for [Bmim][Cl], [Bmim][MeSO4], and [MTEOA][MeSO4] were much lower than that for untreated SCB, suggesting destruction of the lignocellulosic structure. Higher entropy change (ΔS) values after IL treatment implied higher disorder due to the breakage of SCB structure. The study demonstrated that the nature of cations and anions strongly influences the pretreatment potential of ILs for biomass undergoing thermochemical conversion processes.

Herein, antibiotic moxifloxacin hydrochloride (MFH) drug interaction with surfactants has been studied by means of the conductometric as well as cloud point (TCP) measurement techniques in the absence and presence of different electrolytes. In this study sodium dodecylsulfate (SDS) and Tween-80 (Tw-80) were used as anionic and non-ionic surfactants respectively. For pure surfactant (SDS) and (SDS+MFH) mixture two clear critical micelles concentration (c⁎) values denoted by c*1 (first) and c*2 (second) were observed. Variation of the c⁎ values in various systems signifies the interaction among the studied systems. The spontaneous surfactant assembly and stability of that aggregates were illustrated from the negative ∆G0m values of SDS/(SDS + MFH) in the H2O/ H2O + electrolytes medium. From ∆H0m and ∆S0m values it is clear that hydrophobic and electrostatic interactions are present between SDS as well as MFH. Various thermodynamic parameters of micellization were also determined. In the clouding phenomenon of Tw-80, the cloud pint (TCP) values were decreased with the enhancing content of Tw-80. In the presence of drug + salts, the TCP values decreased dramatically with additive concentration. The obtaining ∆G0c values were positive which indicates the non-spontaneity of clouding. On the other hand, the values of ∆H0c and ∆S0c show the presence of electrostatic/ hydrophobic relations among MFH & Tw-80. Various thermodynamic properties of transfer were also determined as well as explained thoroughly for both studied systems.

The interaction between ceftriaxone sodium trihydrate (CFT) drug and surfactants such as tetradecyltrimethylammonium bromide (TTAB), Triton X-100 (TX-100), and Tween-80 (TW-80) was studied under various conditions by using three different physico-chemical methods. CFT is used for the treatment of lung infections, urinary bladder, bone, joint, gonorrhea, meningitis, etc., depending on the bacterial disease. Different parameters such as critical micelle concentration (cmc), various thermodynamic parameters for drug-TTAB aqueous mixtures in an ethanol solvent, etc., have been measured. The varying cmc value of TTAB with the addition of CFT in the TTAB solution signifies the existence of interaction between TTAB and CFT. This interaction and the cmc values of mixtures of drug and TTAB, depend upon the employed concentration of alcohols and the system temperature. Negative values of the standard free energy of micellization (ΔGom), were obtained for all cases; this indicates the spontaneous nature of the currently employed system of drug and surfactant mixtures. Parameters such as heat capacity (ΔC°p.m.) and various transfer energies were also evaluated and are discussed. In the case of the cloud point (CP) method the phase separation of TX-100 in an aqueous system was intensified in the presence of CFT. The standard free energy of clouding (ΔGoc), for the (CFT-TX-100) system was evaluated and found to be positive; this indicates the non-spontaneous characteristic of this clouding action. For the system of CFT-TW-80 mixtures, the value of the binding constant (Kb) is dependent on temperature, and the types of solvent of different composition in both aqueous and alcoholic mediums. Therefore, hydrogen bonding and electrostatic interactions are important due to the binding interaction between CFT and TW-80.