Optimization of a cationic dye desorption from a loaded-lignocellulosic biomass: factorial design experiments and investigation of mechanisms

The sustainable management of loaded adsorbents with organic pollutants represents an important environmental challenge. The current research work investigates the regeneration process optimization of raw orange tree sawdust (ROS) loaded with methylene blue (MB) by using NaCl solutions as eluent. The MB desorption was assessed in static mode under different process variables, notably the desorbing NaCl solution’s pH and concentration and the MB-loaded biomass dose. A full factorial design composed of 24 experiments was employed to apprehend the statistical significance of each followed parameter. Experimental results showed that the maximum desorption yield was estimated to be about 82.4% for the following parameter’s values: aqueous pH $=$ 3, [NaCl] $=$ 0.2 M and MB-loaded-ROS dosage in the desorbing solution $=$ 1 g$\cdot$L$^{-1}$. The statistical study confirmed the good fit of the experimental data with the statistical model used as well as regression and adjusted regression coefficients of about 99.0% and 96.6%, respectively. Moreover, the ranking of the effect of each studied parameter in terms of standardized effect on the desorption efficiency of MB from ROS was assessed through ANOVA test. The desorption mechanisms involved were explored by using multiple analysis techniques. It appears that the MB molecules’ desorption from ROS’s particles is mainly driven by a counter chemisorption process based on cationic exchange with the sodium and hydronium ions present in the desorbing solutions

Slaughterhouse Wastewater Treatment: A Review on Recycling and Reuse Possibilities

Slaughterhouses produce a large amount of wastewater, therefore, with respect to the increasing water scarcity, slaughterhouse wastewater (SWW) recycling seems to be a desirable goal. The emerging challenges and opportunities for recycling and reuse have been examined here. The selection of a suitable process for SWW recycling is dependent on the characteristics of the wastewater, the available technology, and the legal requirements. SWW recycling is not operated at a large scale up to date, due to local legal sanitary requirements as well as challenges in technical implementation. Since SWW recycling with single-stage technologies is unlikely, combined processes are examined and evaluated within the scope of this publication. The process combination of dissolved air flotation (DAF) followed by membrane bioreactor (MBR) and, finally, reverse osmosis (RO) as a polishing step seems to be particularly promising. In this way, wastewater treatment for process water reuse could be achieved in theory, as well as in comparable laboratory experiments. Furthermore, it was calculated via the methane production potential that the entire energy demand of wastewater treatment could be covered if the organic fraction of the wastewater was used for biogas production.DFG, 414044773, Open Access Publizieren 2021 - 2022 / Technische Universität Berli

Optimization of a cationic dye desorption from a loaded-lignocellulosic biomass: factorial design experiments and investigation of mechanisms

The sustainable management of loaded adsorbents with organic pollutants represents an important environmental challenge. The current research work investigates the regeneration process optimization of raw orange tree sawdust (ROS) loaded with methylene blue (MB) by using NaCl solutions as eluent. The MB desorption was assessed in static mode under different process variables, notably the desorbing NaCl solution’s pH and concentration and the MB-loaded biomass dose. A full factorial design composed of 24 experiments was employed to apprehend the statistical significance of each followed parameter. Experimental results showed that the maximum desorption yield was estimated to be about 82.4% for the following parameter’s values: aqueous pH $=$ 3, [NaCl] $=$ 0.2 M and MB-loaded-ROS dosage in the desorbing solution $=$ 1 g$\cdot$L$^{-1}$. The statistical study confirmed the good fit of the experimental data with the statistical model used as well as regression and adjusted regression coefficients of about 99.0% and 96.6%, respectively. Moreover, the ranking of the effect of each studied parameter in terms of standardized effect on the desorption efficiency of MB from ROS was assessed through ANOVA test. The desorption mechanisms involved were explored by using multiple analysis techniques. It appears that the MB molecules’ desorption from ROS’s particles is mainly driven by a counter chemisorption process based on cationic exchange with the sodium and hydronium ions present in the desorbing solutions

Nutrient retention and release from raw exhausted grape marc biochars and an amended agricultural soil: Static and dynamic investigation

Biochar is the solid by-product of biomass thermochemical conversion via pyrolysis technique. Biochar addition to croplands as an organic amendment can improve soil properties and increase agricultural productivity. However, these positive effects depend largely on biomass feedstock and pyrolysis conditions. In this study, nutrient release from biochars derived from the slow pyrolysis of exhausted grape marc (EGM) at 300, 400 and 500 °C (EGM300, EGM400 and EGM500) was investigated through five successive leaching assays in batch mode for a total duration of 10 days. Then, nutrient leaching/retention kinetics of an agricultural soil amended with EGM500 (1% and 5% w/w) was assessed under dynamic conditions in columns. The batch experiments showed that with the exception of P, the nutrient release efficiency from the three biochars significantly increased with the increase of the number of leaching trials. The highest released amounts were observed at the fifth leaching cycle for K, Ca, P and Mg, which were about 45.5%, 41.5%, 229.5% and 48.9% higher than those registered during the first leaching assay. Regarding the column release experiments, a biochar content of 5% in the agricultural soil resulted in an increase of water leached NO3− and K+ by about 181.4% and 521.3%, respectively, and a significant reduction in Na+ and Ca2＋ transport as compared to unamended soil. In a second phase, outcomes of column feeding with a nutrient solution showed that PO43− and NO3− retention by biochar-amended soils is low. Thus, the use of EGM biochar as a slow release biofertilizer could be considered as a promising agricultural practice and a sustainable solution for biowaste management.This work was funded by FERTICHAR, Tunisia project. FERTICHAR is funded through the ARIMNet2 (2017) Joint Call by the following funding agencies: ANR (France), HAO-DEMETER (Greece), MHESRT (Tunisia). ARIMNet2 has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no. 618127. The authors gratefully acknowledge the funding agencies for their support

Effect of non-toxic corrosion inhibitors on steel in chloride solution

International audienceThe effect of certain non-toxic inhibitors on the corrosion resistance of ordinary steel in chloride solution (2 × 10−2 M NaCl) at pH 8 was studied by polarisation curves, Raman spectroscopy and the electrochemical quartz crystal microbalance (EQCM).The inhibitors tested were ascorbic acid salts (SA) and 1-hydroxyethylidene, 1-diphosphonic acid salts (SHEDP), the results from addition inhibtors are carried in order to expect a combined effect.The polarisation curves indicated an improvement in polarisation resistance with the addition of SA or SHEDP alone. In the presence of (SA + SHEDP), the inhibiting effect were further improved. Raman spectroscopy analyses confirmed the presence of a film formed by the two inhibitors at the iron electrode surface.The individual behaviour of each inhibiteur was studied with EQCM for different chloride concentrations. The maximum of mass variation was obtained for a lower concentration in the case of SHEDP. The adsorption coverage was calculated. The Langmuir-Freundlich isotherm model is used to fit adsorption of the inhibitors. Interactions between adsorbed species were detected for SHEDP case.For inhibitor mixture, detected mass attained plateau for low(er) inhibitors concentration mixture. At higher concentration, the mass quantity was smaller than that calculated from the sum of detected mass for each alone coumpound. However it provided better protection

Evaluation of corrosion non toxic inhibitor adsorption for steel in near neutral solution: L(+) ascorbic acid

International audienceThe force of adsorption of a non-toxic inhibitor on iron surface was studied by electrochemical quartz crystal microbalance (EQCM). The value of standard free energy of adsorption, as calculated from Freundlich-Langmuir (LF) adsorption, indicates that L(+)ascorbic acid physisorbes on the iron surface at corrosion potential. At cathodic potential, the quantity of energy is more important. So, there is a slightly stronger interaction between inhibitor and iron surface. This behaviour can be explained by that this inhibitor occupies better the cathodic sites. The inhibition efficiency of ascorbic acid was carried out by the fact electrochemical impedance spectroscopy data (EIS). The film adsorbed on the surface is less protective for a long time of immersion

Elaboration of Highly Modified Stainless Steel/Lead Dioxide Anodes for Enhanced Electrochemical Degradation of Ampicillin in Water

Lead dioxide-based electrodes have shown a great performance in the electrochemical treatment of organic wastewater. In the present study, modified PbO2 anodes supported on stainless steel (SS) with a titanium oxide interlayer such as SS/TiO2/PbO2 and SS/TiO2/PbO2-10% Boron (B) were prepared by the sol–gel spin-coating technique. The morphological and structural properties of the prepared electrodes were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that the SS/TiO2/PbO2-10% B anode led to a rougher active surface, larger specific surface area, and therefore stronger ability to generate powerful oxidizing agents. The electrochemical impedance spectroscopy (EIS) measurements showed that the modified PbO2 anodes displayed a lower charge transfer resistance Rct. The influence of the introduction of a TiO2 intermediate layer and the boron doping of a PbO2 active surface layer on the electrochemical degradation of ampicillin (AMP) antibiotic have been investigated by chemical oxygen demand measurements and HPLC analysis. Although HPLC analysis showed that the degradation process of AMP with SS/PbO2 was slightly faster than the modified PbO2 anodes, the results revealed that SS/TiO2/PbO2-10%B was the most efficient and economical anode toward the pollutant degradation due to its physico-chemical properties. At the end of the electrolysis, the chemical oxygen demand (COD), the average current efficiency (ACE) and the energy consumption (EC) reached, respectively, 69.23%, 60.30% and 0.056 kWh (g COD)−1, making SS/TiO2/PbO2-10%B a promising anode for the degradation of ampicillin antibiotic in aqueous solutions

Adsorption mechanism of non-toxic organic inhibitors on steel in solutions at pH 8 determined by electrochemical quartz crystal microbalance measurements

International audienceThe adsorption on steel of two compounds, ascorbic acid salts (SA) and 1-hydroxyethylidene,1-diphosphonic acid salts (SHEDP), used alone or simultaneously, was studied using an electrochemical quartz crystal microbalance (EQCM). These products are considered to be non-toxic organic corrosion inhibitors. SA adsorption was greater at cathodic potentials than at the corrosion potential, while SHEDP adsorbed better at the corrosion potential. The effectiveness of these two inhibitors is discussed in relation to the polarization curves. Several hypotheses are discussed to explain the adsorption mechanism in the presence of the two compounds used either alone or together