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Two-step hydrothermal conversion of biomass waste to humic acid using hydrochar as intermediate

Frontiers of Environmental Science & Engineering 2023年第10期17卷 17-26页

作者： Yuchao Shao Jun Zhao Yuyang Long Wenjing Lu School of Environment Tsinghua UniversityBeijing 100084China Department of Biology Institute of Bioresource and AgricultureHong Kong Baptist UniversityHong Kong 999077China Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling Instrumental Analysis CenterSchool of Environmental Science and EngineeringZhejiang Gongshang UniversityHangzhou 310012China

Converting biomass materials to humic acid is a sustainable method for humic acid production and achieve biomass valorization. A two-step hydrothermal treatment method was adopted in this study to produce humic acid from corn stalks. In the first step of the process, hydrochar was prepared at different hydrothermal temperatures and pH values. Their chemical properties were then analyzed, and the hydrochar-derived humic acids were produced under alkaline hydrothermal conditions (denoted as HHAalk). The hydrochar, prepared under high temperature (200 °C) and strong acidic (pH 0) conditions, achieved high HHAalk yields (i.e., 67.9 wt% and 68.8 wt% calculated based on weight of hydrochar). The sources of HHAalk formation were as follows: 1) production in the hydrochar preparation stage, and 2) increment under the alkaline hydrothermal treatment of hydrochar. The degree of hydrochar unsaturation was suggested as an indicator for evaluating the hydrochar humification potential under alkaline hydrothermal conditions. This study provides an important reference for the preparation of suitable hydrochar with high hydrothermal humification potential.

关键词： Biowaste Hydrochar Humic acid Hydrothermal parameter unsaturation

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Propagation of plane P-waves at interface between elastic solid and unsaturated poroelastic medium

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Applied Mathematics and Mechanics(English Edition) 2012年第7期33卷 829-844页

作者：陈炜昀夏唐代陈伟翟朝娇 MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang University Institute of Geotechnical Engineering Zhejiang University Institute of Geotechnics TU Bergakademie Freiberg

A linear viscoporoelastic model is developed to describe the problem of reflection and transmission of an obliquely incident plane P-wave at the interface between an elastic solid and an unsaturated poroelastic medium, in which the solid matrix is filled with two weakly coupled fluids （liquid and gas）. The expressions for the amplitude reflection coefficients and the amplitude transmission coefficients are derived by using the potential method. The present derivation is subsequently applied to study the energy conversions among the incident, reflected, and transmitted wave modes. It is found that the reflection and transmission coefficients in the forms of amplitude ratios and energy ratios are functions of the incident angle, the liquid saturation, the frequency of the incident wave, and the elastic constants of the upper and lower media. Numerical results are presented graphically. The effects of the incident angle, the frequency, and the liquid saturation on the amplitude and the energy reflection and transmission coefficients are discussed. It is verified that in the transmission process, there is no energy dissipation at the interface.

关键词： wave reflection wave transmission unsaturation poroelasticity wavepropagation porous medium

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EXPERIMENTAL RESEARCH OF EQUILIBRIUM AND NONEQUILIBRIUM DYNAMIC ADSORPTION OF Cd^(++) IN SOIL--EFFECT OF DIFFERENT ACIDITIES AND SATURATION

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Journal of Hydrodynamics 1992年第2期4卷 1-9页

作者： Huang Jun-qi Xie Xi-na Bai Yiao-dong, Institute of Porous Flow and Fluid Mechanics, NPCC and Academia Sinica, P.O.BOX 44, Langfang Hebei 102801, P.R.China

This paper studies water and solute transport in soil. It mainly deals with the adsorption behavior of heavy metal Cd^(++) in soil at different P^H values and the dynamic charac- ters of adsorption process in unsaturated state. Through theoretical analysis and experimental re- search, the adsorption isotherm and the equations of dynamic adsorption in saturated and unsatu- rated states are proposed.

关键词： soil adsorption dynamics unsaturation experiment

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A Study of Degradation in Vegetable Oils by Exposure to Sunlight Using Fourier Transform Infrared Spectroscopy

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Materials Sciences and Applications 2020年第10期11卷 678-691页

作者： Thiago Reixach Pires de Souza Laudilene Olenka Wilson Sacchi Peternella Department of Chemistry Federal University of Rond&ocirc nia Campus José Ribeiro Filho Porto Velho State of Rond&ocirc nia Brazil Department of Physics Federal University of Rond&ocirc nia Campus José Ribeiro Filho Porto Velho State of Rond&ocirc nia Brazil

There are a diversity and variability of oil producing plants and different extraction methods. These vegetable and essential oils are substances stored and released by plants from their fruits, leaves, flowers, bark and stem, being complete of plant origin that provides some benefits. In the plant these oils are also known as antioxidant substances, which have the function of natural protection. It is known that the extraction method has a strong influence on its quality and composition due to its variability and environmental conditions, besides possible adulteration. Oils that are rich in polyunsaturated fatty acids are the most relevant to the cosmetic industry but are most sensitive to oxidation. The oxidation of these oils generates what is known as rancidity, with the presence of smaller and undesirable molecules, thus reducing the quality of the oil beyond its nutritional value, making them harmful to human health. Stocking conditions, such as exposure to sunlight and heat, are major phenomena that accelerate the degradation of these oils. Infrared spectrometry with Fourier transform (FTIR) is a tool with potential to evaluate the degradation effect of vegetable oils. Infrared spectra of Almond (Prunus dulcis), Andiroba (Carapa guianensis aubl.), Copaíba (Copaifera langsdorffi) and Rosehip (Rosa aff. Rubiginosa) oils before and after exposure to sun light for 90 days were analyzed, with objective of evaluating the effect of the degradation on the composition of the oil, which were acquired in local commerce of the city Porto Velho. The spectra trends show the occurrence of oxidation, with the reduction of unsaturation, in addition to the fractionation of carbon chains and appearance of functional groups such as aldehyde and alcohol.

关键词： Vegetable Oil Oxidation unsaturation FTIR

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