Assessing the effect of pyrolysis temperature on the molecular properties and copper sorption capacity of a halophyte biochar

Preparation of biochar by mango peel and its adsorption characteristics of Cd(ii) in solution

“…32,33 The pH values of the MP increased from 6.87 at 300 C to 9.06 at 700 C. Previous studies have also showed that biochar produced at higher temperatures exhibited a higher pH. 34,35 This is due to the degradation of acidic functional groups and the accumulation of inorganics during pyrolysis. 36 As the pyrolysis temperature increased, C content increased from 51.33% in MK to 78.61% in MP700, but contents of O, H and N and ratios of H/ C, O/C and (O + N)/C in MP decreased, suggesting that the volatile components, which form a large fraction of the surface functional group elements (H, N, and O), were gradually lost during pyrolysis.…”

“…42 From the DTG curve, the peaks at 232.5 and 332.9 C might be due to the decomposition of hemicelluloses and cellulose, the peaks at 432 C and 534 C might be related to the decomposition of lignin. 34,43 The decomposition patterns of MK and MP were obviously different, implying signicant transformation from feedstock with the increase of pyrolysis temperature. Compared to MK, the peaks on the DTG curve of all MP at 232.5 C and 332.9 C disappeared, indicating that the hemicellulose and cellulose were broken down during pyrolysis process from 200 C to 380 C (Fig.…”

Limited Cu(II) binding to biochar DOM: Evidence from C K-edge NEXAFS and EEM-PARAFAC combined with two-dimensional correlation analysis

“…The C K-edge NEXAFS measurement was conducted at the soft X-ray spectromicroscopy beamline (BL08U1A) of the Shanghai Synchrotron Radiation Facility, China. The preparation of specimens was described elsewhere (Wei et al, 2019b). Briefly, a freeze-dried DOM sample was dispersed uniformly with Milli-Q water and deposited onto a gold-sprayed silicon wafer to form thin films.…”

“…Each air-dried film was measured for C K-edge NEXAFS data at total electron yield mode from 280 to 310 eV with an increment of 0.1 eV. For the semi-quantitative assessment of C species abundance in biochar DOM, the NEXAFS spectra were deconvoluted by the PeakFit v4.12 software (SeaSolve) according to the method of Wei et al (2019b). Peak energy ranges and assignments for carbon functional group are summarized in SI Table S1.…”

“…Similarly, Wu et al (2019) found that the proportion of humic-like substances clearly increased with the increasing pyrolysis temperature, while the proportion of fulvic-like substances exhibited an opposite trend. Recently, advanced synchrotron-based spectroscopic techniques, such as carbon (C) K-edge near-edge X-ray absorption fine structure spectroscopy (NEXAFS), have been used to further probe the in-situ chemical state and functional groups of biochars (Singh et al, 2014;Wei et al, 2019b) and their released DOM (Wei et al, 2019a). This highly sensitive and non-destructive technique is particularly suitable for the analysis of DOM extracted from high-temperature biochar because of the scarcity of the DOM.…”