Comparative study of a vitrinite-rich and an inertinite-rich Witbank coal (South Africa) using pyrolysis-gas chromatography

This study aims to compare iso-rank vitrinite-rich and inertinite-rich coal samples to understand the impact of coal-forming processes on pyrolysis chemistry.A medium rank C bituminous coal was density-fractionated to create a vitrinite-rich and an inertinite-rich sub-sample.The vitrinite-rich sample has 83 vol% total vitrinite (mineral-matter-free basis),whereas the inertinite-rich counterpart has 66 vol% total inertinite.The vitrinite-rich sample is dominated by collotelinite and collodetrinite.Fusinite,semifusinite,and inertodetrinite are the main macerals of the inertinite-rich sample.Molecular chemistry was assessed using a pyrolysis gas chromatograph (py-GC) equipped with a thermal desorption unit coupled to a time of flight mass spectrometer (MS) (py-GC/MS) and solid-state nuclear magnetic resonance (13C CP-MAS SS NMR).The pyrolysis products of the coal samples are generally similar,comprised of low and high molecular weight alkanes,alkylbenzenes,alkylphenols,and alkyl-subtituted polycyclic aromatic hydrocarbons,although the vitrinite-rich sample is chemically more diverse.The lack of diversity exhibited by the inertinite-rich sample upon pyrolysis may be interpreted to suggest that major components were heated in their geologic history.Based on the 13C CP-MAS SS NMR analysis,the inertinite-rich sample has a greater fraction of phenolics,reflected in the py-GC/MS results as substituted and unsubstituted derivatives.The greater abundance of phenolics for the inertinite-rich sample may suggest a fire-related origin for the dominant macerals of this sample.The C2-alkylbenzene isomers (p-xylene and o-xylene) were detected in the pyrolysis products for the vitrinite-rich and inertinite-rich samples,though more abundant in the former.The presence of these in both samples likely reflects common source vegetation for the dominant vitrinite and inertinite rnacerals.

Occurrence of pharmaceutical and personal care products(PPCPs)in wastewater and receiving waters in South Africa using LC-Orbitrap™MS

There is continued interest in the occurrence and monitoring of emerging contaminants(ECs)in wastewater treatment plants(WWTPs)to assess their potential impact when released into the environment.The objective of this study was to determine the occurrence of pharmaceutical and personal care products(PPCPs)in WWTP influents and effluents and receiving river waters in Pretoria,South Africa.Targeted screening and identification of PPCPs in the samples was done using liquid chromatography(LC)coupled with high resolution mass spectrometry(HRMS)Orbitrap™HRMS,after clean-up and preconcentration with Waters Oasis®hydrophilic-lipophilic-balanced(HLB)solid phase extraction(SPE)cartridges.Of the 156 target analytes screened in the study,120 could be satisfactorily determined under the study conditions,with 71 and 73 compounds being detected and quantified in the influent and effluent samples,respectively.Concentrations in the influents ranged from<ILOQ-14.2 mgL^-1and those in the effluent from<ILOQ-2.45 mgL^-1.It was found that 84%of the quantified compounds belonged to various classes of pharmaceuticals.Ibuprofen,caffeine,paracetamol and estradiol were the major individual contaminants in influent samples with average concentrations of 14.2,8.68,4.79 and 1.02 mgL^-1,respectively.In the effluent samples,the highest concentrations were recorded for estradiol(2.45 mgL^-1),ibuprofen(1.03 mgL^-1)and efavirenz(0.58 mgL^-1).The highest mean concentrations(above 0.5 mgL^-1)recorded in the river water samples were for ibuprofen,(4.14 mgL^-1downstream;3.19 mgL^-1upstream),caffeine(2.98 mgL^-1downstream;1.42 mgL^-1upstream),paraxanthine(1.22 mgL^-1downstream;0.798 mgL^-1upstream).Analysis of river water samples also revealed that PPCP contamination in the river system cannot be solely attributed to the WWTP effluents.Twenty-four compounds presented in this study are reported for the first time in South African surface waters.