An organogel, a viscoelastic system, can be regarded as a semi-solid preparation which has an immobilized external apolar phase. The apolar phase is immobilized within spaces of the three-dimensional network structure formed due to the physical interactions amongst the self-assembling structures of compounds regarded as gelators. In general, organogels are thermodynamically stable in nature and have been explored as matrices for the delivery of bioactive agents. In the current paper, attempts have been made to understand the properties of organogels, various types of organogelators and some applications of the organogels in controlled delivery.

Amine functionalized graphene oxide (NH 2 -GO) decorated with ZnO-ZnFe 2 O 4 nanomaterials (NH 2 -GO/ZnO-ZnFe 2 O 4 ) was successfully synthesized by organic transformation reaction followed by hydrothermal method. The formation, composition, bonding, size, morphology, and surface area of synthesized nanomaterial were analyzed by XRD, FTIR, Raman, XPS, FESEM, HRTEM, and BET analytical techniques. The formation of ZnO-ZnFe 2 O 4 binary phase onto the amine functionalized GO was confirmed by XRD and HRTEM. The surface composition and functionalization of prepared nanocomposite were confirmed by XPS and FTIR analysis. The FESEM images revealed the formation of fine spherical ZnO-ZnFe 2 O 4 nanoparticle onto the NH 2 -GO surface. From TEM image, the average particle size of the composite nanomaterials was observed to be 8 nm. From N 2 adsorption−desorption study, it was found that NH 2 -GO/ZnO-ZnFe 2 O 4 composite nanomaterials show higher surface area (122 mg/g) than GO/ZnO-ZnFe 2 O 4 and NH 2 -GO. The obtained nanocomposite was used as novel adsorbent for remediation of chromium (Cr(VI)) from water. Batch adsorption experimental studies revealed that the Cr(VI) adsorption onto NH 2 -GO/ZnO-ZnFe 2 O 4 surface was pH dependent and maximum adsorption takes place at pH = 4. Compared to other prepared nanomaterials, adsorption capacity of NH 2 -GO/ZnO-ZnFe 2 O 4 was found to be higher because of the presence of more surface active sites by functionalizing ZnO-ZnFe 2 O 4 nanomaterials and also introducing amine group on the GO surface. Adsorptive removal of Cr(VI) onto nanocomposite surface follows a pseudo second order kinetics. Langmuir model was best fitted to the adsorption data. The process of adsorption was spontaneous and endothermic in nature. The maximum uptake capacity of NH 2 -GO/ZnO-ZnFe 2 O 4 was observed to be 109.89 mg/g and was higher than that of NH 2 -GO and GO/ZnO-ZnFe 2 O 4 nanocomposites. The mechanism of Cr(VI) adsorption follows electrostatic attraction and formation of chelate with amine groups.

No abstract