Thermogravimetric and kinetic analysis of bio-crude from hydrothermal liquefaction of Enteromorpha prolifera

Removal of Pb(ii) and Cr(vi) from aqueous solutions using the prepared porous adsorbent-supported Fe/Ni nanoparticles

In this study, Fe/Ni nanoparticles supported by a novel fly ash-based porous adsorbent (FBA-Fe/Ni) for Cr(vi) and Pb(ii) removal were investigated. In order to enhance the reactivity of zero-valent iron (ZVI), ZVI particles were deposited on the surface or in the inner pores of FBA as a support material and Ni nanoparticles were introduced. FBA was prepared with the solid waste such as Enteromorpha prolifera, bentonite and fly ash. FBA-Fe/Ni was characterized via Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and the Brunauer-Emmett-Teller model and energy-dispersive spectrometry. The effects of various parameters on Cr(vi) and Pb(ii) removal by FBA-Fe/Ni, such as FBA-Fe/Ni dosage, pH of the solution, reaction temperature, Cr(vi) and Pb(ii) concentrations, co-existing ions and ionic strength were discussed. The possible removal mechanisms were proposed and the results indicated that there was a three-step reaction including the adsorption of Cr(vi) and Pb(ii) on the surface of FBA-Fe/Ni, the subsequent reduction and precipitation. The removal capacity of Cr(vi) and Pb(ii) by FBA-Fe/Ni was 25.07 mg g-1 and 164.19 mg g-1 at 303 K with an initial concentration of 1000 mg L-1 and FBA-Fe/Ni dosage of 0.20 g. In conclusion, this work demonstrated that FBA-Fe/Ni was a promising alternative material for Cr(vi) and Pb(ii) removal.

Studies on thermokinetic of Chlorella pyrenoidosa devolatilization via different models

The thermokinetics of Chlorella pyrenoidosa (CP) devolatilization were investigated based on iso-conversional model and different distributed activation energy models (DAEM). Iso-conversional process result showed that CP devolatilization roughly followed a single-step with mechanism function of f(α)=(1-α)³, and kinetic parameters pair of E₀=180.5kJ/mol and A₀=1.5E+13s^-1. Logistic distribution was the most suitable activation energy distribution function for CP devolatilization. Although reaction order n=3.3 was in accordance with iso-conversional process, Logistic DAEM could not detail the weight loss features since it presented as single-step reaction. The un-uniform feature of activation energy distribution in Miura-Maki DAEM, and weight fraction distribution in discrete DAEM reflected weight loss features. Due to the un-uniform distribution of activation and weight fraction, Miura-Maki DAEM and discreted DAEM could describe weight loss features.

Combustion performance of biocrude oil from solvolysis liquefaction of Chlorella pyrenoidosa by thermogravimetry-Fourier transform infrared spectroscopy

The kinetic behavior and evolution characteristics of gaseous products during the combustion of biocrude oil from solvolysis liquefaction of Chlorella pyrenoidosa were investigated by thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR). The results indicated the biocrude oil obtained from different ethanol/water mixed ratio had obvious difference with each other. The ignition temperature of biocrude oil from ethanol-water co-solvent was lower than that from pure water solvent, which promoted the comprehensive combustion index. Especially, BO40 (biocrude oil obtained from 40% ethanol content) achieved the lowest ignition temperature (163.4°C) and high comprehensive combustion index (1.24×10^-06min^-2°C^-3). CH, CO, CC, CO₂, CO and HCN were the main gaseous products. Compared to other biocrude oil samples, BO40 had high first peak intensity of CH, CO and CC, and low peak intensity of CO, which performed better combustion characteristic.