Screening analysis of river seston downstream of an effluent discharge point using near-infrared reflectance spectrometry and wavelet-based spectral region selection

Automated salting-out assisted single-phase liquid–liquid extraction of Cr(vi) from river water samples prior to its atomic absorption spectrometric determination

“…Study results indicated that the optimum pH of the single-phase mixture was 2, which agrees with the literature. 15,25,26 Despite the NaDDTC being highly unstable in an acidic medium, extraction efficiency was not affected because of the rapid formation of the Cr( vi )-DDTC complex. Cr( vi ) loss was minimized by pumping adequate amounts of buffer solution into the MC.…”

“…Cr(VI) loss was minimized by pumping adequate amounts of buffer solution into the MC. 25,28 Composition of the single-phase mixture As the composition of the water-ethanol-amyl alcohol singlephase mixture affected extraction efficiency, a ternary diagram of this system (Fig. 3) was constructed by titrating different mixtures of water and amyl alcohol (totalizing a volume of 10 mL) with ethanol up to reach opalescence.…”

“…Mumbaba river was chosen because it crosses the industrial district of João Pessoa city and is the main tributary of the Gramame river, which crosses the metropolitan region of João Pessoa and has very high levels of pollution. 25 The collected samples were stored in polyethylene containers.…”

“…River water samples were collected at ve locations of Mumbaba river (João Pessoa city, Paraíba State, Brazil): 7°1 2 0 32.4 00 S, 34°54 0 27.5 00 W; 7°12 0 31.5 00 S, 34°54 0 31.4 00 W; 7°1 2 0 30.9 00 S, 34°54 0 35.1 00 W; 7°12 0 30.5 00 S, 34°54 0 38.0 00 W; and 7°1 2 0 29.4 00 S, 34°54 0 43.0 00 W. Mumbaba river was chosen because it crosses the industrial district of João Pessoa city and is the main tributary of the Gramame river, which crosses the metropolitan region of João Pessoa and has very high levels of pollution. 25 The collected samples were stored in polyethylene containers.…”

Rapid detection of chemical oxygen demand, pH value, total nitrogen, total phosphorus, and ammonia nitrogen in biogas slurry by near infrared spectroscopy

“…For the second batch of anaerobic fermentation, the R p 2 value of TP was 0.39 and RPD was 1.36, indicating that the model performance was unsatisfactory and needed further improvement. The possible reason may be that in the water sample of a complex system, the TP in the particulate matter aer drying can be accurately predicted, 39 while the water in this study may have a great inuence on the NIRS prediction model of TP.…”