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Per-and polyfluoroalkyl substances (PFAS) used in various industrial applications are pollutants of concern for the environment and human health. Drinking water consumption is one key exposure pathway to PFAS, as recently highlighted by multiple studies on their occurrence in tap and bottled water worldwide. However, PFAS quantification at low part-pertrillion (ng/L) or part-per-quadrillion (pg/L) concentrations remains challenging. PFAS presence in blanks and incomplete method recoveries can lead to false positives or negatives; PFAS concentration changes under different storage durations or conditions can also affect accuracy and precision. Here, we review the most recent data related to analytical methods that were used in research articles for the detection and quantification of PFAS from drinking water. Commonly encountered pitfalls are summarized, and analytical performance is appraised including detection limits, recovery, matrix effects, and other quality assurance/quality control endpoints. In addition, we collated available guidelines for health advisory levels of PFAS in tap water. Finally, we compiled concentration data on legacy and emerging PFAS in tap and bottled water.

This study aimed to develop non-metal elements for doping carbon quantum dots (CQDs) with nitrogen and sulfur (N, S-CQDs), which loaded inside hexagonal mesoporous silica (HMS) in order to effectively remove methylene blue dye (MB) from an aqueous solution. The histidine and cysteine amino acids were used as the source for synthesis N, S-CQDs through the hydrothermal method. Morphology and structure of the N, S-CQDs, and adsorbent (N, S-CQDs/HMS) were characterized by using different microscopic and spectroscopic techniques. The adsorption parameters such as adsorbent dosage (0.25–1 g/L), pH (2–10), contact time (15–75 min), and initial MB dye concentration (20–300 mg/L) were investigated. The maximum adsorption capacity and removal efficiency of MB were determined at 370.4 mg/g and 97%, respectively, under optimum conditions at 303 K. The adsorption isotherm studies were fitted with the Freundlich isotherm equation, and the dye removal kinetics of the adsorbent followed the pseudo-second-order model. Thermodynamic studies showed that the adsorption process had exothermic and spontaneous behavior. The removal of MB next to the Rhodamine B and Reactive Black 5 dyes indicated that the N, S-CQDs/HMS had excellent selective behavior for MB absorption. This prepared adsorbent could be well recycled with suitable activity after four repeated adsorption–desorption cycles. Results revealed that the porous characters, surface area, charge properties, reduction in the bandgap, and quantum yield of the N, S-CQDs/HMS were essential factors that affected dye adsorption.

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