Presence of phthalates in contact lens and cleaning solutions

A fast and simple method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been applied to identify and quantify four phthalic acid esters (PAEs) in different contact lens cleaning solutions. A migration study of these compounds from contact lenses has also been performed. The PAEs studied were dimethyl phthalate, diethyl phthalate, butyl benzyl phthalate and dibutyl phthalate. The migration of PAEs from contact lenses was performed by suspending each contact lens in an artificial tear solution at 37 °C and shaking it at 130 rpm for 24 h. The purpose of this study was to determine a possible migration of these compounds to the eyes as a result of the use of contact lenses and their cleaning solutions. The method was precise (with relative standard deviation (RSD) from 2.2 to 11.9%). It was also sensitive, with LODs of 0.03, 0.19, 0.31 and 2.62 μg L^− 1 for DMP, DEP, BBP and DBP respectively. The results obtained confirm the presence of these substances in some types of contact lens cleaning solutions. Furthermore, DBP and BBP were liberated from the contact lenses during the migration study.     

Evaluating the use of laser radiation in cleaning of copper embroidery threads on archaeological Egyptian textiles

Cleaning of copper embroidery threads on archaeological textiles is still a complicated conservation process, as most textile conservators believe that the advantages of using traditional cleaning techniques are less than their disadvantages. In this study, the uses of laser cleaning method and two modified recipes of wet cleaning methods were evaluated for cleaning of the corroded archaeological Egyptian copper embroidery threads on an archaeological Egyptian textile fabric. Some corroded copper thread samples were cleaned using modified recipes of wet cleaning method; other corroded copper thread samples were cleaned with Q-switched Nd:YAG laser radiation of wavelength 532 nm. All tested metal thread samples before and after cleaning were investigated using a light microscope and a scanning electron microscope with an energy dispersive X-ray analysis unit. Also the laser-induced breakdown spectroscopy (LIBS) technique was used for the elemental analysis of laser-cleaned samples to follow up the laser cleaning procedure. The results show that laser cleaning is the most effective method among all tested methods in the cleaning of corroded copper threads. It can be used safely in removing the corrosion products without any damage to both metal strips and fibrous core. The tested laser cleaning technique has solved the problems caused by other traditional cleaning techniques that are commonly used in the cleaning of metal threads on museum textiles.     

Direct contact ultrasound for fouling control and flux enhancement in air-gap membrane distillation

Air Gap Membrane distillation (AGMD) is a thermally driven separation process capable of treating challenging water types, but its low productivity is a major drawback. Membrane fouling is a common problem in many membrane treatment systems, which exacerbates AGMD’s low overall productivity. In this study, we investigated the direct application of low-power ultrasound (8–23 W), as an in-line cleaning and performance boosting technique for AGMD. Two different highly saline feedwaters, namely natural groundwater (3970 μS/cm) and RO reject stream water (12760 μS/cm) were treated using Polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) membranes. Theoretical calculations and experimental investigations are presented, showing that the applied ultrasonic power range only produced acoustic streaming effects that enhanced cleaning and mass transfer. Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy (ATR FT-IR) analysis showed that ultrasound was capable of effectively removing silica and calcium scaling. Ultrasound application on a fouled membrane resulted in a 100% increase in the permeate flux. Cleaning effects accounted for around 30–50% of this increase and the remainder was attributed to mass transfer improvements. Contaminant rejection percentages were consistently high for all treatments (>99%), indicating that ultrasound did not deteriorate the membrane structure. Scanning Electron Microscopy (SEM) analysis of the membrane surface was used to confirm this observation. The images of the membrane surface demonstrated that ultrasound successfully cleaned the previously fouled membrane, with no signs of structural damage. The results of this study highlight the efficient and effective application of direct low power ultrasound for improving AGMD performance.