Synthesized and characterization of organobentonites for anionic dye removal: application to real textile effluent

Clays have been considered as potential alternative adsorbents due to their high adsorptive property, abundance and non-toxic compounds. Adsorption of cationic dyes by natural clays has been studied and appreciable results have been reported, but few researchers have been interested in anionic dyes. Anionic dyes are widely used by the textile industries, yet they are toxic, non-biodegradable and hardly adsorbable on natural clay; modified clay (e.g. organoclay) has emerged as an alternative adsorbent. In this study, organobentonites were prepared with hexadecyltrimethylammonium bromide at three cation exchange capacity levels and used as adsorbents for the removal of, reactive blue II - an anionic dye used in Tunisian textile industry to dye jeans. Obtained organobentonite-labelled H_i-bent (I = 1, 2 and 3) was characterized by several techniques in order to study the effect of a surfactant on texture and structure of the initial clay. H₃-bent and purified bentonite (Na-bent) were then tested as adsorbents. The amount of dye removal by H₃-bent (98%) was found to be around five times higher than that of Na-bent (19%). Adsorption process was well described by Freundlich, Dubinin-Radushkevic and Elovich isotherms model. Kinetic data were fitted by both pseudo-second-order and pseudo-first-order models. The use of Na-bent, as adsorbent, for real textile effluent treatment was tested, and significant results related to two other clay minerals were obtained.

Effect of sand dust accumulation on photovoltaic performance in the Saharan environment: southern Algeria (Adrar)

Many climatic conditions have a negative impact on production of photovoltaic (PV) systems, and sand dust could be one of the main reasons of degradation of PV panels. The objective of this study is to investigate the reduction in the electrical performance caused by sandstorm and the accumulation of sand dust on the photovoltaic module surface installed in the Saharan area of south Algeria (Adrar). For this purpose, four PV modules (ISO-100/24) were selected and their current-voltage characteristics were measured to evaluate the sand dust effect on their performances. Our results show that sandstorm and dust accumulation on the surface of the module reduce the performance in terms of energy and power, due to a decrease of the transmittance. Obtained outcomes show that in sandstorm periods, the particle deposition density is much higher. This study reveals that leaving PV module without any cleaning in the Saharan environmental conditions significantly reduces PV power output, in addition to the presence of the shading mismatch effects in case of partial cleaning.

[Target-controlled intravenous anesthesia during laparoscopic surgery for obesity]

BACKGROUND

The TCI is a mode of administration that provides greater security by allowing more accurate titration of the anesthetic agent. It leads to a better adaptation to the desired effects, and provide a great interest for the realization of anesthetic induction and the prediction of waking for a well- determined population.

OBJECTIVE

The aim of our prospective study was to evaluate the feasibility of TCI in patients with morbid obesity undergoing laparoscopic surgery for obesity.

METHODS

Thirty patients were included in this study. Age and BMI means were 32 years and 49.31 kg / m2. Our protocol was proposed to associate an hypnotic agent (propofol) to an opioid one (remifentanil) using the technique of the TCI, with respectively Schnider and Minto models.

RESULTS

The induction protocol has brought good conditions for laryngoscopy with no hypertensive peak or desaturation episode. The period of unconsciousness was 89 seconds with an average target concentration of propofol of 5.1 mg / ml. We also noted hemodynamic stability in 79% of patients at induction. During both preparation phase and final installation of the patients, a low ERC to 2 hg / ml was consistent with a suitable hemodynami profile. We obtained hemodynamic stability by adapting target concentration of remifentanil at different operating times (Surgical incision: 3.64 hg / ml, insufflation of the peritoneum: 5.37 hg / ml, jejuno-jejunal resection anastomosis: 9 hg / ml, gastric resection and gastrojejunal anastomosis: 14.2 hg / ml). During this period, no episodes of bradycardia or hypotension were noticed. During the recovery phase and while doing the distribution of CEP and CER according to the BMI of patients, we identified two groups: Group 1 (BMI <49 kg / m2): fast time extubation (11 min) and target concentrations of propofol and remifentanil respectively at 1.3 mg / ml and 1.25 hg / ml which is similar to most publications on this subject and Group 2 (BMI> 49 kg / m2): time-delayed extubation (23 min) with very low values of CEP and CER inconsistent with the literature data.