Supercritical CO2 extract from microalga Tetradesmus obliquus: the effect of high-pressure pre-treatment

ABSTRACT: High-pressure pre-treatment followed by supercritical carbon dioxide (ScCO2) extraction (300 bar, 40 degrees C) was applied for the attainment of the lipophilic fraction of microalga Tetradesmus obliquus. The chemical profile of supercritical extracts of T. obliquus was analyzed by ultra-highperformance liquid chromatography-high-resolution mass spectrometry with electrospray ionization (UHPLC-ESI-HRMS). Moreover, the impact of ScCO(2 )on the microbiological and metal profile of the biomass was monitored. The application of the pre-treatment increased the extraction yield approximately three-fold compared to the control. In the obtained extracts (control and pre-treated extracts), the identified components belonged to triacylglyceroles, fatty acid derivatives, diacylglycerophosphocholines and diacylglycerophosphoserines, pigments, terpenes, and steroids. Triacylglycerols (65%) were the most dominant group of compounds in the control extract. The pre-treatment decreased the percentage of triacylglycerols to 2%, while the abundance of fatty acid derivatives was significantly increased (82%). In addition, the pre-treatment led to an increase in the percentages of carotenoids, terpenoids, and steroids. Furthermore, it was determined that ScCO2 extraction reduced the number of microorganisms in the biomass. Considering its microbiological and metal profiles, the biomass after ScCO2 can potentially be used as a safe and important source of organic compounds.info:eu-repo/semantics/publishedVersio

The immobilization of copper from waste printing developer sludge

The electrocoagulation (EC) treatment of the waste printing developer in laboratory conditions was produced the sludge with a high amount of copper. The solidification/stabilization (S/S) treatment of electrocoagulation sludge (ECS) has been conducted with four immobilization agents: Portland cement, calx, bentonite, and local clay. The efficiency of the S/S treatment was monitored by applying standard German (DIN 38414-4) leaching test. The characterization of ECS in terms of its toxicity was evaluated by comparing the copper concentration levels in the leaching solution with maximum allowed concentrations according to current regulations

The influence of electrode combinations on the kinetics removal of organic substances from the printing effluent

In this research, the electrocoagulation/flotation (ECF) reaction kinetics of organic substances removal from the waste fountain solution was investigated. The ECF reaction kinetics of the organic substances removal from the printing effluent can be described by a pseudo-second rate equation. Obtained results have shown that the trend of decrease in pseudo-second order constant for organic substances removal follows the trend of decrease in the efficiency of electrode combinations (Fe(-)/Al(+) > Al(-)/Fe(+) > Al(-)/Al(+) > Fe(-)/Fe(+)) and current density (8 > 4 > 2 mA cm-2 ) of the ECF treatment

The combined electrocoagulation/flotation and adsorption processes for organic substances regeneration of waste printing developer

This paper investigates the possibility of reducing the content of organic substances in waste printing developer using a combination of electrocoagulation/flotation (ECF) and adsorption (AD) processes. The content of organic substances in waste printing developer was monitored by analysis of total organic carbon (TOC), chemical oxygen demand (COD) and biological oxygen demand (BOD5) before and after the ECF and AD processes, respectively. When combining the two processes, a removal of 99.4, 92.9 and 96.0% of the TOC, COD and BOD5 was achieved, respectively. Obtained results confirm the improvement in the printing industrial effluent quality and height removal of organic substances by the combined ECF and AD treatments

Enhanced coagulation with pre-oxidation for the removal of arsenic from groundwater

One of the most wide-spread problems with current drinking water resources globally is the natural presence of arsenic in groundwaters. The aim of this work was to investigate the removal of arsenic by a variety of combined oxidation/coagulation processes, in order to identify and optimise the most critical process parameters. The most significant gains made by both preoxidation steps were observed in the techniques which combined aluminum and ferric chloride based coagulation. The most efficient coagulation treatment investigated involved application of preozonation at a dose of 7.5 mg O3/l with subsequent combined coagulation with PACl–FeCl3 (30 mg Al/l and 10 mg FeCl3/l)

Energy Resolution Performance of the CMS Electromagnetic Calorimeter

The energy resolution performance of the CMS lead tungstate crystal electromagnetic calorimeter is presented. Measurements were made with an electron beam using a fully equipped supermodule of the calorimeter barrel. Results are given both for electrons incident on the centre of crystals and for electrons distributed uniformly over the calorimeter surface. The electron energy is reconstructed in matrices of 3 times 3 or 5 times 5 crystals centred on the crystal containing the maximum energy. Corrections for variations in the shower containment are applied in the case of uniform incidence. The resolution measured is consistent with the design goals

Feasibility of electrocoagulation/flotation treatment of waste offset printing developer based on the response surface analysis

In the printing plate developing process, the offset printing developer undergoes changes, as well as enrichment by the various chemicals, i.e. metals, organic binders and photosensitive compounds. The objective of this study was to investigate the electrocoagulation/flotation (ECF) treatment efficiency for the removal of copper, turbidity and organic substances from the waste offset printing developer (WOPD). The effect of operational parameters, such as electrode materials, current density, interelectrode distance and operating time, was studied. Also, the response surface analysis was applied to evaluate the effect of main operational variables and to get a balanced removal efficiency of investigated WOPD parameters by ECF treatment. The removal efficiency increases significantly with the increasing of operating time and mainly increases with the increasing of current density. The obtained results show that the interelectrode distance and combinations of electrodes determine the removal efficiency of copper, turbidity and organic substances. Based on the obtained results, the optimized parameters for the ECF treatment removal of investigated WOPD parameters were identified as: Al(−)/Fe(+) electrode combination with interelectrode distance of 1.0 cm, operating time of 5 min and current density of 8 mA cm−2. This study confirms the practical feasibility of ECF method for treating real printing industrial effluent under optimum conditions