Surface modification of aluminum phosphate by sodium dodecylbenzenesulfonate (SDBS) A new nano-structured adsorbent for an improved removal of Ponceau S"

International audienceThe removal of increasing number of pollutants in water needs the search of new adsorbents, or the improvement of known adsorbents. In this paper, the adsorption capacity of aluminum phosphate AlPO4 was investigated after its chemical modification by adsorption of the surfactant sodium dodecylbenzenesulfonate (SDBS). The new adsorbent SDBS-modified AlPO4 was characterized by X-ray diffraction (XRD), Fourier Transform Infra-red (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and the Brunauer, Emmet and Teller (BET) method. SDBS-modified AlPO4 was applied to the removal of Ponceau S (PS) or Acid Red 112 which is suspected to be carcinogenic from aqueous solutions.The influential parameters like pH, PS concentration, contact time and temperature were studied. The results showed that the removal of PS was fast and that the equilibrium was reached in 30 min. The kinetics showed that adsorption followed a pseudo-second-order model and the adsorption at equilibrium was in agreement with the experimental values. The isothermal adsorption led to an adsorption capacity of 60.8 mg/g for SDBS-modified AlPO4. This result shows that the SDBS modification improves the adsorption efficiency of AlPO4. The adsorption models of Langmuir, Freundlich and Sips were applied. Sips model gave the best fitting. The temperature did not affect the adsorption. The regeneration of aluminum phosphate modified by SDBS was carried out by calcination leading to a material which was again modified by SDBS and then used as adsorbent of PS with an adsorption capacity of 28.13 mg/g. © 2020 Elsevier Ltd

Removal of ponceau S by adsorption onto alumino-phosphate: Efficiency and modeling

International audiencePonceau S (PS) is an azo dye widely used for versatile applications in foods and biochemistry; nevertheless, it is suspected to be toxic and carcinogenic. In this research article, the removal of PS from aqueous solution was investigated by adsorption onto alumino-phosphate (AlPO4). This adsorbent has been synthesized by precipitation from solution of aluminum salt. It was an amorphous solid with a specific area and pHzpc of 100 m2/g and 4.6, respectively. The efficiency of PS sorption as a function of pH, initial PS concentration, AlPO4 dose and temperature was studied. The present PS sorption dynamics followed the pseudo-first-order model and the calculated sorption capacity was in good agreement with the experimental values. The compliance of isotherm models such as Langmuir, Freundlich and Sips was also verified. Among the isotherm models, Sips was deemed to be the better fit than others. PS sorption as a function of temperature explicates an exothermic nature of sorption which decreased from 9.12 mg g-1 (300 K) to 6.08 mg g-1 (315 K). The adsorbed PS on AlPO4 was easily desorbed by washing at pH 7 and the adsorption equilibrium was established in the first 8 min. The PS laden adsorbent was also regenerated by heating at 600°C for 30 min and the regenerated AlPO4 was attempted for its continual utilization for the adsorption of PS successfully. © 2017 Desalination Publications. All rights reserved

Clorazepate removal from aqueous solution by adsorption onto maghnite: Experimental and theoretical analysis

The removal of a benzodiazepine (clorazepate, CLZ) from aqueous solution by adsorption onto maghnite clay is investigated supported by theoretical simulations. The Fourier-transform infrared (FTIR), Ultraviolet (UV), X-ray diffraction (XRD), and scanning electron microscope (SEM) analyses were used to characterize the adsorbent. To individuate the optimum conditions for adsorption, equilibrium, and kinetic tests are performed to assess the efficiency of this adsorbent to remove CLZ from polluted water in different operating conditions like pH, initial concentration, adsorbent dosage, and contact time. Adsorption is maximum at low pH, and it is mainly driven by electrostatic interactions between the benzenic ring of CLZ molecule and the montmorillonite layer of maghnite adsorbent. The kinetics obeys to the pseudo-first-order kinetic model, while the Freundlich isotherm model was found to better describe the adsorption equilibrium. The maximum observed adsorption amount of CLZ onto maghnite was about 50 mg g−1 at pH 4.66. A complementary theoretical study is performed to quantify the CLZ/maghnite interactions using Monte Carlo simulations. Interestingly, the results show that the CLZ assumes a horizontal position on the maghnite surface upon adsorption, characterized by high energy adsorption

Treatment of artificial pharmaceutical wastewater containing amoxicillin by a sequential electrocoagulation with calcium salt followed by nanofiltration

International audienceThe present study deals with the treatment of an artificial pharmaceutical waste which contained amoxicillin (AMX) by using successively an electrocoagulation (EC) with Ca(NO3)2 as an electrolyte and a nanofiltration (NF) with a Nanomax-50 membrane. The effect of the current intensity and of the operating pressure was investigated for separately EC and NF, respectively. The AMX removal as a function of pH and initial AMX concentration was also investigated for the separately conducted EC and NF processes. The best percentage removal of AMX by EC and NF was recorded to be 52.7 % and 99.0 %, respectively. In the case of the sequential processes EC followed by NF, the removal of AMX was 98.2 % and 97.5 % at pH 2.5 and 10, respectively. The contribution of both EC and NF towards the AMX removal efficiency in the case of the sequential process was very much significant. It is remarkable that the EC pre-treated feed into NF was explored with several benefits such as high removal efficiency, calcium involved in EC process, prolonged membrane life and reduced power consumption. The electrogenerated solids (the sediment and the cathode deposit) were characterized using Fourier Transform Infra-red spectroscopy (FTIR), Energy Dispersive Spectroscopy (EDS) coupled to Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) and Thermo Gravimetry Analysis (TGA). It appeared that calcium was involved in the electrogenerated solids. It gave a cathode deposit of Ca(OH)2 in which some AMX was embedded