A novel mesoporous Fe-silica aerogel composite with phenomenal adsorption capacity for malachite green

Used coffee grounds usually end up as landfill. However, the unique structural properties of its porous surface make coffee grounds can be transformed into biochar and performed as an alternative low cost adsorbent. Malachite green (MG) is a readily water soluble dye which is used extensively in textile and aquaculture industries. The mordant complex structures of MG generate destructive effects to animals and environment. In this study, adsorption of malachite green using spent coffee ground biochar as adsorbent was investigated. The experiments were designed in two methods: classical and optimisation by response surface methodology. Three parameters were studied, which are adsorbent dosage, contact time and pH while the responses in this study are malachite green removal (%) and adsorption capacity (mg/g). Optimisation studies were performed using response surface methodology. Quadratic model was chosen for both response and studied using central composite design. The correlation coefficient, R2 for the quadratic model of malachite green removal (%) and adsorption capacity (mg/g) were 0.95 and 0.99, respectively. The optimum malachite green removal (%) predicted was found at 99.27%, by using 0.12 g of adsorbent dosage, 43.05 minutes of contact time and pH of 9.45 at desirability of 1.0. The optimum adsorption capacity (mg/g) predicted was found at 118.01 mg/g, by using 0.02 g of adsorbent dosage, 60 minutes of contact time and pH of 10.24 at desirability of 0.98. So, it was concluded that the spent coffee ground biochar can be used as an effective adsorbent for malachite green removal from aqueous solution.

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Thermal Radiation in Silica Aerogel and its Composite Insulation Materials

Volume 10: Heat and Mass Transport Processes, Parts A and B ◽

10.1115/imece2011-62632 ◽

2011 ◽

Author(s):

Gaosheng Wei ◽

Yusong Liu ◽

Xinxin Zhang ◽

Xiaoze Du

Keyword(s):

Thermal Radiation ◽

Extinction Coefficient ◽

Silica Aerogel ◽

Extinction Coefficients ◽

Ceramic Fibre ◽

Insulation Materials ◽

Hot Strip ◽

Aerogel Composite ◽

Infrared Spectrometer ◽

Spectral Extinction Coefficient

This paper engages in experimental measurements on thermal radiative transfer in silica aerogel and its composite insulation materials (xonotlite-aerogel composite and ceramic fibre-aerogel composite). The samples of silica aerogel, xonotlite-type calcium silicate, and ceramic fibre insulation materials are all considered as a semi-transparent medium capable of absorbing, emitting and scattering thermal radiation. The spectral transmittances are then measured at different infrared wavelengths ranging from 2.5 to 25μm with a Fourier transform infrared spectrometer (FTIR), and subsequently used to determine the specific spectral extinction coefficient and the specific Rossland mean extinction coefficient of the sample. The radiative conductivities deduced from the overall thermal conductivities measured with the transient hot-strip (THS) method are compared with the predictions from the diffusion approximation by using the measured spectral extinction coefficient. The results show that the spectral extinction coefficients of the samples are strongly dependent on the wavelength, particularly in the short wavelength regime (<10μm). The total Rossland mean extinction coefficients of the samples are all decreasing with the temperature increasing. The radiative conductivities are found almost proportional to the cubic temperature, and decreases as the sample density increases.

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Lightweight, Flexible and Hydrophobic Cotton Fiber/Silica Aerogel Composite by Freeze-Drying for Organic Solvent/Water Separation and Thermal Insulation

Science of Advanced Materials ◽

10.1166/sam.2021.4060 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1820-1824

Author(s):

Jian-Chun Huo ◽

Hai-Xia Yang ◽

Yuan Ma ◽

Jie Bai

Keyword(s):

Thermal Insulation ◽

Cotton Fiber ◽

Silica Aerogel ◽

Low Cost ◽

Sol Gel ◽

Water Separation ◽

Organic Reagents ◽

Strong Adsorption ◽

Aerogel Composite ◽

Oil Water Separation

Natural cotton fiber used for reinforcement is low-cost, environmentally friendly, good flexibility and easy to obtain. In this study, a new cotton fiber/silica aerogel composite was developed by sol–gel method via freezedrying. The obtained composite has excellent flexibility and can be restored to its original state after bending for 180° without obvious cracks. After 20 cycles continuous compression, the total unrecoverable strain loss is only 20% under strain of 60%. The composite also shows very prominent hydrophobicity, and the contact angle with water reaches 145 degrees. It has strong adsorption capacity for organic reagents and oil, with adsorption ratios of 500% and 600%, respectively. In addition, the composite has a low thermal conductivity of 0.038 W/(m·K) at room temperature. The obtained composite exhibits considerable promise in oil-water separation and thermal insulation.

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