A new layered organic-inorganic nanohybrid material in which an agrochemical, 4-(2,4dichlorophenoxy)butyrate (DPBA) is intercalated into inorganic interlayers of zinclayeredhydroxide (ZLH) was synthesized by direct reaction of aqueous DPBA solution with zinc oxide. The resulting nanohybrid is composed of the organic moieties, DPBA sandwiched between ZLH inorganic interlayers. The nanohybrid afforded well ordered crystalline layered structure, a basal spacing of 29.6 Å, 23.5% carbon (w/w) and 47.9% (w/w) loading of DPBA. FTIR study shows that the absorption bands of the resulting nanohybrid composed the FTIR characteristics of both the DPBA and ZLH which further confirmed the intercalation episode. The intercalated organic moiety in the form of nanohybrid is thermally more stable than its sodium salt. Scanning electron micrograph shows the ZnO precursor has very fine granular structure and transformed into a flake-like when the nanohybrid is formed. This work shows that the nanohybrid of DPBA-ZLH can be synthesized using simple, direct reaction of ZnO and DPBA under aqueous environment for the formation of a new generation of agrochemical.

The feasibility of durian tree sawdust (DTS), coconut coir (CC) and oil palm empty fruit bunch (EFB) as low-cost biosorbents for the removal of Cu(II), Pb(II) and Zn(II) ions from aqueous solutions was investigated. The effects of solution pH and initial metal concentration on adsorption capacity were examined in batch experiments. The affinity and the adsorption capacity of DTS, CC and EFB were evaluated. The adsorption behaviour of Cu(II), Pb(II) and Zn(II) ions onto DTS, CC and EFB was described using Freundlich and Langmuir isotherm models. The separation factor (RL) analysis suggests that the removal of metal ions onto three agricultural wastes studied was favourable. The maximum adsorption capacities (Q) estimated from the Langmuir isotherm model for Cu(II), Pb(II) and Zn(II) were 18.42, 20.37 and 22.78 mg/g for DTS, 18.38, 37.04 and 24.39 mg/g for CC, and 26.95, 37.59 and 21.19 mg/g for EFB, respectively. The characterisation studies were carried out using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectrometer (EDX) and Fourier Transform Infrared Spectrometer (FTIR). The surface morphology of the biosorbents changed significantly following interaction with metal ions. The primary adsorption mechanism was complexation between metal ions and binding sites of biosorbents. Both hydroxyl and amine groups are the main binding sites in DTS, CC and EFB.

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The efficacy of coconut tree sawdust (CTS), eggshell (ES) and sugarcane bagasse (SB) as alternative low-cost biosorbents for the removal of Cu(II), Pb(II) and Zn(II) ions from aqueous solutions was investigated. Batch adsorption studies were carried out to evaluate the effects of solution pH and initial metal concentration on adsorption capacity. The optimum biosorption condition was found at pH 6.0, 0.1 g biomass dosage and at 90 min equilibrium time. The adsorption data were fitted to the Freundlich and Langmuir isotherm models. The adsorption capacity and affinity of CTS, ES and SB were evaluated. The Freundlich constant (n) and separation factor (RL) values suggest that the metal ions were favourably adsorbed onto biosorbents. The maximum adsorption capacities (Q) estimated from the Langmuir isotherm model for Cu(II), Pb(II) and Zn(II) were 3.89, 25.00 and 23.81 mg/g for CTS, 34.48, 90.90 and 35.71 mg/g for ES, and 3.65, 21.28 and 40.00 mg/g for SB, respectively. The characterisation studies were performed using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectrometer (EDX) and Fourier Transform Infrared Spectrometer (FTIR). Interaction with metal ions led to the formation of discrete aggregates on the biosorbents surface. The metal ions bound to the active sites of the biosorbents through either electrostatic attraction or complexation mechanism.

Two phenoxyherbicide nanocomposites, namely cloprop-layered double hydroxide and cloprop-zinclayered hydroxide nanocomposites, have been synthesized by using co-precipitation and direct reaction method. PXRD pattern showed an expansion of interlayer spacing with the value of 21.0 Å and 22.7 Å for cloprop-layered double hydroxide and cloprop-zinclayered hydroxide nanocomposite, respectively. It is evident from FTIR and elemental analyses that both nanocomposites were successfully intercalated between the interlayers of layered metal hydroxide. Controlled release of cloprop anion from interlayer of nanocomposites for both cloprop-layered double hydroxide and cloprop-zinc-layered hydroxide nanocomposite into phosphate solution was rapid initially and slow thereafter. The percentage of accumulated release of cloprop anion from cloprop-zinc-layered hydroxide nanocomposite was slightly higher than that from cloprop-layered double hydroxide nanocomposite. Kinetic behavior of cloprop release was governed by pseudo-second-order for cloprop-layered double hydroxide nanocomposite while parabolic diffusion for cloprop-zinc-layered hydroxide nanocomposite. Results from this study highlight the potential of both nanocomposites as capsulated material for controlled release of cloprop phenoxyherbicides anion.

The article addresses an interesting issue in the development of hybrid surfactants for waterin-CO2 (w/c) microemulsion stabilisation: the role of surfactant headgroup on the surfactant performance. The synthetic procedure, aqueous properties, and phase behaviour of a new hybrid sulfoglutarate surfactant are described. The compound resembles sulfosuccinate surfactants, commonly used to stabilize w/c phases, but with an extra methylene group incorporated into the hydrophilic headgroup. For comparison purposes, the related hydrocarbon (AOT14 and AOT14GLU) and fluorocarbon (di-CF2 and di-CF2GLU) surfactants are used to form w/c microemulsions. In general, the aqueous properties and w/c phase stability of both sulfoglutarates and sulfosuccinates are found to be similar, which shows the secondary role of the hydrophilic headgroup. Interestingly, the newly synthesised hybrid CF2/AOT14GLU (sodium (4H,4H,5H,5H,5H-pentafluoropentyl-2,2-dimethyl-1-propyl)-2-sulfoglutarate) proved to be more efficient than the normal sulfosuccinate, hybrid CF2/AOT14 (Ptrans = 383 bar, γcmc = 26.8 mN m -1 ) in terms of the aqueous behaviour and w/c phase stability.Switching to the sulfoglutarate compound, hybrid CF2/AOT14GLU (Ptrans = 232 bar, γcmc = 20.6 mN m -1 ) more effectively decreases the air-water surface tension by about ~ 5 mN m -1 as compared to the sulfosuccinate. High-pressure phase behaviour studies show significant improvements in stabilising w/c microemulsions at much lower cloud pressures. The results indicate distinct effects of the headgroup structure on the phase behaviour and physicochemical properties, particularly for this hybrid surfactant.

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