Bio-adsorbent preparation based on Chinese Radix isatidis residue for Pb(II) removal

A series of bio-adsorbents with potential for Pb(II) removal from wastewater were prepared by treating Radix isatidis residue (RIR) with integrated chemical treatment and fermentation methods. Batch experiments were used to test the adsorption and desorption performance of different bio-adsorbents. The results showed that treated RIRs had significantly enhanced adsorption capacity of 23.5 and 27.6 mg g−1 for Pb(II) within 50 minutes, in contrast to the raw RIR's 12.2 mg g−1. RIR produced by modified chemical/fermentation treatment can remove up to 31.1 mg g−1. After five adsorption/desorption cycles, about 75% of the adsorption capacities were maintained. This study is a novel approach to reusing the enormous quantity of Chinese herbal medicine residues.

Adsorption of methyl orange from aqueous solution using chitosan/diatomite composite

A novel chitosan/diatomite composite was prepared by a simple mixture in the mass ratio to remove methyl orange (MO) from aqueous media in this study. The composite adsorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy analysis. The parameters to influence the adsorption of MO were studied under such conditions as kinetics, adsorption isotherm, pH effect, and thermodynamics. The results revealed that adsorption of MO was initially rapid and the equilibrium time was reached after 40 min. The optimal value of the pH was 5.0 for better adsorption. The equilibrium data were well fitted to the Langmuir isotherm compared to the Freundlich isotherm, and exhibited the highest capacity and a removal rate of 88.37% under an initial dye concentration of 50 mg/L. The kinetic data were well described by the pseudo-second order model. The thermodynamic calculations revealed that the sorption was viable, spontaneous, and exothermic under the conditions studied. In addition, the chitosan/diatomite composite had good adsorption and desorption performance with respect to reusability after six cycles. These results showed that the chitosan/diatomite could be considered as a potential adsorbent for the removal of MO in aqueous solution.

Characterization of Nanosilica of Tapioca Peel as Adsorbent for Biomethane Storage System

Biomethane is an alternative and renewable source that occurred naturally which produced from the anaerobic digestion of organic matter. It can be used as the electricity power generation, water heating and also vehicle fuel. In this study, the characteristics of the nanosilica of the tapioca peel as an adsorbent on the structural and physical properties to store the biomethane were investigated. To enhance the adsorption and desorption performance as well as the structural and physical properties, the nanosilica was modified with the metal oxides. The metal oxides that have been used to modify the nanosilica adsorbent are zinc (II) oxide (ZnO) and nickel (II) oxide (NiO). Both of the modified and unmodified nanosilica structural properties were characterized by using X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). While, the physical properties of both of the modified and unmodified nanosilica were characterized by using Brunauer, Emmet, Teller (BET) surface area measurement. The effects of both types of metal oxides with different concentration were investigated. Based on the results obtained, the structural and physical characteristics of the nanosilica were affected by the different metal oxides loading. It have been identified that 1% ZnO modified nanosilica has highest BET surface area (8.32 m2/g) with pore volume (19.23 cc/g) and pore size (82.8 nm). Thus, it concluded that 1% ZnO modified nanosilica improved the structural and physical structure. Hence, it enhances the capacity of methane adsorption and desorption prior to storage system.