Application of xanthan gum as coagulant-aid for decolorization of synthetic Congo red wastewater.

In recent years, utilization of polysaccharides as natural coagulant and coagulant-aid has become a topic of interest, due to the nature of biopolymers that are renewable, biodegradable, and non-toxic. In this study, Congo red, as a model dye substance, was treated using polyaluminium chloride (PAC) as the main coagulant and xanthan gum as the coagulant aid. For this purpose, the effect of pH (3-9), xanthan gum dose (0.5-4 mg/L), and the initial concentration of Congo red dye (50-100 mg/L) to the dye removal and sludge volume were investigated. The outcome of this investigation indicates that the best pH for Congo red coagulation occurred at pH 3, due to the charge neutralization mechanism. The addition of coagulant-aid dose increases the %-removal and sludge volume until reaching the best coagulant-aid dose of 2 mg/L that results in a %-removal value of 93.81% and a sludge volume of 23.5 mL/L. Further addition of xanthan gum reduced the %-removal and sludge volume due to the inter-polymer force causing more difficult floc formation. The best initial concentration of dye occurred at a Congo red concentration of 50 mg/L, with a %-removal value of 93.81% with PAC (15 mg/L) and xanthan gum (2 mg/L) coagulants. This value is considerably higher than PAC and xanthan gum only which amounts to 81.16 and 7.18%, respectively. Based on these results, it is apparent that xanthan gum can positively contribute to dye coagulation while reducing the use of harmful inorganic coagulant.

Potato Peel Based Carbon-Sulfur Composite as Cathode Materials for Lithium Sulfur Battery.

Lithium sulfur battery has become one of the promising rechargeable battery systems to replace the conventional lithium ion battery. Commonly, it uses carbon-sulfur composites as cathode materials. Biomass based carbons has an important role in enhancing its electrochemical characteristics due to the high conductivity and porous structures. Here, potato peel wastes have been utilized to prepare porous carbon lithium sulfur battery through hydrothermal carbonization followed by the chemical activation method using KOH. After sulfur loading, as prepared carbon-sulfur composite shows stable coulombic efficiencies of above 98% and a reversible specific capacity of 804 mAh g-1 after 100 cycles at current density of 100 mA g-1. These excellent electrochemical properties can be attributed to the unique structure of PPWC showing mesoporous structure with large specific surface areas. These results show the potential application of potato peel waste based porous carbon as electrode's materials for lithium sulfur battery.

Ganyong Starch Derived Hard Carbon Anodes for Sodium Ion Batteries.

Hard carbons are one of the most promising carbon anode materials for sodium ion batteries (SIBs) due to the high specific capacity and excellent cycle properties. Among the precursors used to synthesize hard carbon, natural starches are of great interest due to their unique morphologies. In this paper, ganyong starch based hard carbons (GSHC) were prepared by direct carbonization at various temperatures (700-1100) °C. The obtained hard carbons exhibit high reversible capacities of sodium-ion batteries of about 239 mAh g-1 at current density of 0.1 C. after 100 cycles. The excellent cycle profiles are attributed to the unique morphology and defect carbon structures.

Delignification, Carbonization Temperature and Carbonization Time Effects on the Hydrothermal Conversion of Salacca Peel.

Hydrochar from the hydrothermal treatment of biomass is considered as a potential precursor for activated carbons (AC) which has been widely utilized not only for adsorbents but also for energy storage application. The advantages of hydrochar from hydrothermal treatment include its high Oxygenated Functional Group (OFG) and high porosity. The authors have been working on the biomass conversion for energy storage application. In our study, salacca peel was used as a biomass source. In previous research for the preparation of AC, conventional carbonization and activation methods were used, resulting in a high surface area of AC. In the current research, the authors investigated the biomass conversion in hydrothermal conditions. Water at a subcritical condition (with temperatures of 200, 225 and 250 °C and at a pressure of 50 MPa) and carbonization time of 4, 5 or 6 hours, with or without delignification, were critical in the research to investigate the conversion of salacca peel into hydrochar. The produced hydrochar from 225 °C, 5 h was chemically activated and compared to commercially-AC. The hydrochar and AC were then used as electrodes for the supercapacitor, and capacitance was measured by cyclic voltammetry (CV). The results showed that the capacitance of hydrochar was higher than that of AC while ACs from salacca peel exhibited much higher levels of capacitance compared to commercially-AC.

Preparation and Characterizations of Carbon Nanospheres Derived from Activated Carbons and Palm Oil as Anode Materials of Lithium Secondary Batteries.

Carbon nanospheres (CNSs) with diameter of around 100 nm were synthesized by pyrolysis technique using activated carbon as Fe-catalyst support and palm oil as carbon precursors with various ratios. Firstly, the Fe catalyst were deposited onto the activated carbon by incipient wetness impregnation method using Fe(NO3)2 x 9H2O as precursors with various content of catalyst (5%, 7% and 10% with respect to the carbon support). The carbon products were characterized by X-ray diffraction, transmission electron microscope, scanning electron microscope, Raman spectroscopy, nitrogen adsorption and X-ray photoelectron spectroscopy. Preliminary electrochemical characteristics of as-synthesized CNSs as anode materials of lithium secondary batteries were conducted using Cyclic Voltammetry to observe the mechanism of Li-ion insertion/extraction during charge-discharge tests.