A State-of-the-Art Review on Biowaste Derived Chitosan Biomaterials for Biosorption of Organic Dyes: Parameter Studies, Kinetics, Isotherms and Thermodynamics

Chitosan is a second-most abundant biopolymer on earth after cellulose. Its unique properties have recently received particular attention from researchers to be used as a potential biosorbent for the removal of organic dyes. However, pure chitosan has some limitations that exhibit lower biosorption capacity, surface area and thermal stability than chitosan composites. The reinforcement materials used for the synthesis of chitosan composites were carbon-based materials, metal oxides and other biopolymers. This paper reviews the effects of several factors such as pH, biosorbent dosage, initial dye concentration, contact time and temperature when utilizing chitosan-based materials as biosorbent for removing of organic dyes from contaminated water. The behaviour of the biosorption process for various chitosan composites was compared and analysed through the kinetic models, isotherm models and thermodynamic parameters. The findings revealed that pseudo-second-order (PSO) and Langmuir isotherm models were best suited for describing most of the biosorption processes or organic dyes. This indicated that monolayer chemisorption of organic dyes occurred on the surface of chitosan composites. Most of the biosorption processes were endothermic, feasible and spontaneous at the low temperature range between 288 K and 320 K. Therefore, chitosan composites were proven to be a promising biosorbent for the removal of organic dyes.

Pristine and Magnetic Kenaf Fiber Biochar for Cd2+ Adsorption from Aqueous Solution

Development of strategies for removing heavy metals from aquatic environments is in high demand. Cadmium is one of the most dangerous metals in the environment, even under extremely low quantities. In this study, kenaf and magnetic biochar composite were prepared for the adsorption of Cd2+. The synthesized biochar was characterized using (a vibrating-sample magnetometer VSM), Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption batch study was carried out to investigate the influence of pH, kinetics, isotherm, and thermodynamics on Cd2+ adsorption. The characterization results demonstrated that the biochar contained iron particles that help in improving the textural properties (i.e., surface area and pore volume), increasing the number of oxygen-containing groups, and forming inner-sphere complexes with oxygen-containing groups. The adsorption study results show that optimum adsorption was achieved under pH 5–6. An increase in initial ion concentration and solution temperature resulted in increased adsorption capacity. Surface modification of biochar using iron oxide for imposing magnetic property allowed for easy separation by external magnet and regeneration. The magnetic biochar composite also showed a higher affinity to Cd2+ than the pristine biochar. The adsorption data fit well with the pseudo-second-order and the Langmuir isotherm, with the maximum adsorption capacity of 47.90 mg/g.

Long-Term Effects of TBBPA-Contaminated Pyrogenic Organic Matters under The Abiotic Aging: Insights on Immobilization Capacity, Surface Functionality Correlation, and Phytotoxicity to Thinopyrum Ponticum

A large amount of annual global carbon input is reported from pyrogenic organic matters (POMs) production, motivating numerous research studies. Given to Tetrabromobisphenol A (TBBPA) can be frequently exposed to...

THE SIZE DEPENDENCIES OF PROPERTIES OF MO-W ALLOY OF EQUIATOMIC COMPOSITION

Основываясь на параметрах парного потенциала межатомного взаимодействия Ми-Леннард-Джонса для Mo и W были рассчитаны параметры потенциала для сплава замещения Mo - W эквиатомного состава. Получены размерные зависимости для уравнения состояния, модуля упругости, коэффициента теплового расширения, изобарной теплоемкости, поверхностной энергии и производной поверхностной энергии по температуре. Также получены температурные зависимости коэффициента теплового расширения изобарной теплоемкости для макро- и нанокристаллов сплава Mo - W. Было показано, что температурная зависимость коэффициента теплового объемного расширения для нанокристалла лежит выше, чем зависимость для макрокристалла, также обнаружено, что с уменьшением размера уменьшается модуль упругости, коэффициент теплового объемного расширения возрастает, а удельная поверхностная энергия нанокристалла сплава Mo - W уменьшается. Based on the parameters of the Mie-Lennard-Jones pair-wised potential of the interatomic interaction for Mo and W , the potential parameters for an equiatomic Mo - W substitution alloy were calculated. Size dependences for the equation of state, modulus of elasticity, coefficient of thermal expansion, isobaric heat capacity, surface energy and surface energy temperature derivative were obtained. Temperature dependencies of coefficient of thermal expansion and isobaric heat capacity for macro- and nano-crystals of Mo - W alloy were also obtained. It was shown that the temperature dependence of the thermal expansion coefficient for a nanocrystal is higher than that for a macrocrystal. It was also found that with a decrease in size, the elastic modulus decreases, the thermal volume expansion coefficient increases, and the specific surface energy of the alloy nanocrystal Mo - W decreases.

Glycine-acyl Surfactants Prepared from Black Soldier Fly Fat, Coconut Oil and Palm Kernel Oil

: Black soldier fly (Hermetia illucens) larvae are a new source of high-quality bio-based materials that can be implemented for technical applications. Black soldier fly larvae can be bred in high numbers in small areas and organic waste streams, making large scale industrial breeding possible. Fats from the black soldier fly are very rich in lauric acid, and the fatty acid profile resembles that of palm kernel and coconut oil. Therefore, black soldier fly fats could be envisaged to have similar applications to these plant-derived oils. : The aims of this work were (1) to use black soldier fly fat, palm kernel and coconut oil to synthesize a glycine-acyl surfactant by means of a Schotten-Baumann reaction; (2) to determine the yield and purity of the reaction products; and (3) to determine solubility, foaming capacity, surface tension and critical micelle concentration of the surfactants in comparison to a commercially-available glycinecoconut oil surfactant, Amilite GCS-11®. : The aims of this work were (1) to use black soldier fly fat, palm kernel and coconut oil to synthesize a glycine-acyl surfactant by means of a Schotten-Baumann reaction; (2) to determine the yield and purity of the reaction products; and (3) to determine solubility, foaming capacity, surface tension and critical micelle concentration of the surfactants in comparison to a commercially-available glycinecoconut oil surfactant, Amilite GCS-11®. : It is concluded that black soldier fly fats are a suitable alternative to coconut or palm kernel oil for the preparation of glycine-acyl surfactants.

Overcharge Cycling Effect on the Surface Layers and Crystalline Structure of LiFePO4 Cathodes of Li-Ion Batteries

Electrochemical cells using LiFePO4 cathode material are considered one of the safest and most resistant to overcharging among Li-ion batteries. However, if LiFePO4-based electrodes are exposed to high potentials, surface and structural changes may occur in the electrode material. In this study Li/LiFePO4 half-cells were overcharged under different modes with variable cut-off voltages and charge currents. The change in voltage profile, discharge capacity, surface layers composition, and crystalline structure were characterized after overcharge cycles. It was demonstrated that the cathode material is resistant to short-term overcharging up to 5 V, but undergoes irreversible changes with increasing overcharge time or potential. Thus, despite the well-known tolerance of LiFePO4-based batteries to overcharge, a long overcharge time or high cut-off voltage leads to destructive changes in the cathode and should be avoided.

Thermophysical properties of liquid Zr52.5Cu17.9Ni14.6Al10Ti5—prospects for bulk metallic glass manufacturing in space

Bulk metallic glasses are of critical interest for a wide range of applications, including their use in spacecraft gearboxes and mechanisms due to their excellent low-temperature, unlubricated wear resistance. Also of interest, is the potential for in-space manufacturing of metal alloys and the use of microgravity to determine fundamental thermophysical properties to inform ground-based modeling and experimentation. In this work, a Zr-based bulk metallic glass was processed in the electromagnetic levitator ISS-EML to determine undercooling, electrical resistivity, specific heat capacity, surface tension, and viscosity. A 6.5 mm sphere was vitrified during the processing, resulting in the first bulk metallic glass manufactured on board the international space station (ISS).

Изменение свойств алмаза из -=SUP=-13-=/SUP=-C при изотермическом сжатии

The parameters of atomic interaction pair potential for ^13C diamond have been determined from experimental data on the ratio of Raman frequencies for isotopically different diamonds. Based on these parameters, an equation of state and baric dependences of ^13C diamond lattice properties at 300 K have been calculated. Specifically, the Debye temperature; the first, second, and third Grüneisen parameters; elastic modulus; thermal expansion coefficient; heat capacity; surface energy; and pressure derivatives of these parameters along a 300 K isotherm have been determined. The results have been compared with available data for diamond having a natural isotopic composition, i.e., for ^12.01C.