Showing papers by "Yong Sun published in 2016"

An enhanced approach for biochar preparation using fluidized bed and its application for H2S removal

Abstract: Fluidized bed efficiently intensifies the carbonization step for biochar preparation by significantly reducing carbonization duration down to 6 min at 450 °C. The BET specific surface area of the char carbonized at 6 min can reach 60 m2/g. The produced porous biochar possesses both micropores and mesopores. The produced biochars are found to be alkaline. The degree of heterogeneity on the surface of biochar is far more than that of commercial activated carbon. The maximum monolayer adsorption capacity from Langmuir model can reach 25 mg/g at room temperature and ambient pressure by using equilibrium isotherm approximation. The maximum sulfur removal can reach 70 mg/g using column dynamic adsorption. The moisture shows a beneficial effect on the adsorption of H2S on biochar. The maximum removal rate and saturation constants were obtained using Mechael’s—Menten type equation. The mass transfer diffusivities data indicate the surface diffusion being significant to the effective diffusivity at experimental conditions. The dynamic experimental results indicate a good performance of resultant biochar in H2S removal at room temperature.

Preparation of steam activated carbon from black liquor by flue gas precipitation and its performance in hydrogen sulfide removal: Experimental and simulation works

Abstract: Activated carbon was prepared from black liquor by steam activation. The BET specific surface area, pore volume and average pore diameter of resultant carbon activated at 900 degrees C can reach 1010 m(2)/g, 0.65 m(3)/g and 3 nm respectively. The relative humidity contributes to the adsorption of H2S on carbon, while the increased adsorption temperature and inlet concentration show an unfavorable condition for adsorption. Kinetic model yield a satisfactory result in parameters estimation and prediction for breakthrough time with different inlet H2S concentrations. The surface diffusion is significant to the effective diffusivity during mass transfer under experimental condition. The dynamic experimental results indicate a good performance in H2S removal. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

NH4Cl selective leaching of basic oxygen furnace slag: Optimization study using response surface methodology

Abstract: The basic oxygen furnace slag (SL) was selectively leached by NH4Cl. Response surface methodology and the central composite design (CCD) were employed in determining the optimal condition. The process parameters such as leaching duration, NH4Cl concentration, liquid solid ratio (LSR), and leaching temperature were chosen as independent variables in CCD. The quadratic model was developed for process optimization and statistical experimental designs. It is found that the leaching duration, NH4Cl concentration and liquid solid ratio are significant to the extraction of Ca2+ and Mg2+. The optimal conditions with setting maximum extraction of calcium and magnesium cations from SL are as following: 68min (X-1), 1.8mol/L NH4Cl (X-2), LSR 12mL/g (X-3), 53 degrees C (X-4), with the predicted Ca2+ and Mg2+ concentration reaching 13.3 and 3.2g/L, respectively. The proposed simplified leaching mechanism indicates a two-stage leaching. The prone leachable MgFe2O4 and Ca2Fe2O5 are extracted in the fast stage, while the extraction of CaO occurs throughout slow stage. (c) 2016 American Institute of Chemical Engineers Environ Prog, 35: 1387-1394, 2016

Clean production of porous MgO by thermal decomposition of Mg(OH)2 using fluidized bed: Optimization for CO2 adsorption

Abstract: Fluidized bed efficiently intensifies thermal decomposition of Mg(OH)2 for fast preparation of porous MgO. The shrinking core model is found to well describe the decomposition process. The initial stage of decomposition is controlled by chemical reaction with activation energy being 104 kJ/mol and the subsequent stage is then controlled by diffusion with activation energy being 15 kJ/mol. The response surface methodology (RSM) and the central composite design (CCD) are employed for determining optimal conditions to prepare adsorbent with maximum CO2 removal capacity. The operational parameters such as dehydration temperature (°C), duration (min) and FR-flow rate (Nm3/h) are chosen as independent variables in CCD. The statistical analysis indicates that the effects of dehydration temperature and combined effect of temperature and duration are all significant to the CO2 removal capacity. The optimal condition for achieving the maximum CO2 adsorption capacity is obtained as the following: temperature (480 °C), duration (42 min), FR (13.8 Nm3/h) with CO2 removal capacity reaching 33 mg/g. The employment of fluidized bed in process intensification significantly reduces the thermal treatment duration down to 0.7 h.

CO2 mineralization using basic oxygen furnace slag: process optimization by response surface methodology

Abstract: The basic oxygen furnace steelmaking slag (SL) is employed for CO2 mineralization. Response surface methodology and the central composite design were employed in determining the optimal condition. The optimization goal in this paper has been set for maximum CO2 capturing. It was found that the reaction temperature and CO2 pressure and their combination were significant. A quadratic model was developed for process optimization and statistical experimental designs. The CO2 capture capacity could reach 126 g CO2/kg SL at optimal condition. The increased reaction temperature will lead to an obvious decrease of CaCO3 and increase of MgCO3. If deployed, this optimized indirect CO2 mineral sequestration process could permanently capture 252,000 tons of CO2 per annum based upon current 2 million tons of SL productivity per annum.

Hydrochar preparation from black liquor by CO2 assisted hydrothermal treatment: Optimization of its performance for Pb2+ removal

Abstract: Hydrochar was produced from hydrothermal treatment of corn straw black liquor. Response surface methodology (RSM) and the central composite design (CCD) were employed for determination of optimal char with maximum Pb2+ removal capacity. The operational parameters such as hydrothermal temperature (°C), duration (min) and solid liquid ratio (LSR) were chosen as independent variables in CCD. The statistical analysis indicates that the effects of hydrothermal temperature, duration, LSR and combined effect of hydrothermal temperature and duration are all significant for the Pb2+ removal capacity. The optimal condition for achieving the maximum Pb2+ adsorption capacity is obtained as the following: hydrothermal temperature (205 °C), duration (28min), LSR (12) with Pb2+ removal capacity reaching 47mg/g. The BET specific surface area of char prepared at optimal conditions could reach 85m2/g.

Fast carbonization using fluidized bed for biochar production from reed black liquor: optimization for H2S removal.

Abstract: The biochar was produced from fast pyrolysis of reed black liquor using fluidized bed. Response surface methodology and the central composite design (CCD) were employed for determining optimal adsorbents with maximum H2S removal capacity. The operational parameters such as carbonization temperature (°C), duration (min) and space velocity (SV, L min−1 kg−1) were chosen as independent variables in CCD. The statistical analysis indicates that the effects of carbonization temperature, duration, SV and combined effect of carbonization temperature and duration are all significant to the H2S removal capacity. The optimal condition for achieving the maximum H2S adsorption capacity for biochar is obtained as the follows: carbonization temperature (500°C), duration (5.7 min), SV (7300 L min−1 kg−1) with H2S removal reaching 60 mg g−1. The dynamic experimental results indicate a good performance in H2S removal by the produced biochar.

Optimization of the preparation of activated carbon from steam activated cornstraw black liquor for phenol removal

Abstract: The activated carbon (AC) was produced from steam activation of cornstraw black liquor. Response surface methodology (RSM) and the central composite design (CCD) were employed for determining optimal adsorbents with maximum phenol removal capacity. The operational parameters such as activation temperature (degrees C), duration (min) and steam velocity (SV) (Lmin(-1)) were chosen as independent variables in CCD. The statistical analysis indicates that the effects of activation temperature, duration, steam flow rate and combined effect of activation temperature and duration are all significant to the phenol removal capacity. The optimal condition for achieving the maximum phenol adsorption capacity is obtained as the followings: carbonization temperature (850 degrees C), duration (2.1h) and SV (38Lh(-1)) with phenol removal capacity reaching 130mg/g. The BET specific surface area of AC prepared at optimal conditions could reach 800m(2)/g. (c) 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

Preparation of biomass derived porous carbon: Application for methane energy storage

Abstract: The porous carbon with high specific surface area of 3001 m 2 /g and pore volume of 1.59 cm 3 /g using corncob was prepared for methane storage. The low and high pressure adsorption equilibria were tested using the prepared carbon. The capacity of methane storage is evaluated using Tóth model with correction of fugacity using Benedict-Webb-Rubin equation of state in high pressure range. The theoretical maximum adsorption amount is achieved to be approximately 3.3 mmol/g. The adsorption process indicates physisorption dominates the adsorption with heterogeneous adsorption characteristic of sites on the surface of adsorbent at low pressure. The resultant carbon is ideal adsorbent for energy storage medium using methane.