Release of antibiotics to the environment as a result of wastewater effluent discharge is a cause for concern worldwide, as they pose a potential threat to human health and the earth ecosystem. Penicillin and amoxicillin are widely used antibiotics. Despite their rapid hydrolysis in aqueous matrices, their presence in the environment is widely investigated. The current study reported and analysed the current state of four hospital wastewater treatment plants (WWTPs) in Gonbad Kavous, Iran, during 2019, from the perspective of amoxicillin and penicillin G removals. WWTPs were sampled at various stages of the treatment process to determine at which stage the antibiotics are being removed. Concentrations of amoxicillin and penicillin G in raw wastewater, analysed by HPLC, varied from 0.35 to 1.02 and 0.02-0.31 /AgL-1, respectively. These values reduced in the final effluent, corresponding to overall efficiency in removing the studied antibiotics of 20-60.5%. Anaerobic processes (i.e. septic tank) slightly outperformed aerobic biological processes for both antibiotics' removal, and penicillin G was removed more efficiently than amoxicillin. Effects of wastewater physicochemical properties, including chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS) on antibiotics removal, were also studied. Whereas statistically significant correlations were noticed between COD, amoxicillin and penicillin G removals, their decline showed no correlation with TSS removal. Our study shows that despite the deployment of treatment plants, a considerable amount of antibiotics is released into receiving water bodies, resulting in significant amounts of these pharmaceuticals entering the environment. There is abundant room for further progress in the detection and quantification of pharmaceuticals and other emerging contaminants in hospital wastewaters and their metabolites and biodegradation products.

A redução eletroquímica do agente anestésico inalatório isoflurano foi estudada em eletrodo de carbono vítreo na presença de cloreto de tetrafenil porfirinaferro(III) (Fe(TPP)Cl) em solução de dimetil sulfóxido (DMSO). A capacidade da Fe(TPP)Cl como potencial catalisador homogêneo para a redução de isoflurano foi testada por voltametria cíclica e cronomperometria. Revelou-se a excelente capacidade eletrocatalítica para a redução de isoflurano com sobrepotential de aproximadamente 1150 mV mais positivo do que o potencial observado para redução de isoflurano em solução de DMSO. Uma faixa linear entre 3,0 × 10-5 e 2,1 × 10-4 mol L-1 para a determinação de isoflurano em solução de DMSO contendo Fe(TPP)Cl foi obtida de medições de voltametria cíclica. Estimou-se o limite de detecção em 1,8 × 10-5 mol L-1. Um possível mecanismo catalítico é proposto.

The electrochemical reduction of the inhalational anesthetic agent isoflurane was studied at glassy carbon electrode in presence of iron(III) tetraphenylporphyrin chloride (Fe(TPP)Cl) in dimethyl sulfoxide (DMSO) solution. The ability of Fe(TPP)Cl as potential homogenous catalyst for the reduction of isoflurane was tested by cyclic voltammetry and chronomperometry. It showed excellent electrocatalytic ability for the reduction of isoflurane with overpotential of about 1150 mV more positive than the potential for observed reduction of isoflurane in DMSO solution. A linear range between 3.0 × 10-5 and 2.1 × 10-4 mol L-1 for the determination of isoflurane in DMSO solution containing 0.04 mmol L-1 Fe(TPP)Cl was obtained from cyclic voltammetry measurements. The limit of detection was estimated at 1.8 × 10-5 mol L-1. A possible catalytic mechanism is proposed.