Phosphate‐loaded industrial wastewaters have resulted in numerous environmental issues that have hard hit the Gulf of Gabes‐Tunisia, making the environmental protection one of the most compelling priorities. Consequently, this study aimed first to compare the amounts of phosphate adsorbed by two types of Tunisian activated clays. The second goal was to assess and optimize the phosphate removal efficiency of these clays, using Box–Behnken design (BBD) under response surface methodology. Results showed that the highest adsorption amounts of 130.16 mg g−1, 125.42 mg g−1 were yielded for Jebel Haidoudi clay and Douiret clay, respectively. These values demanded an initial phosphate concentration of 300 mg L−1, a contact time of 5 h, and a pH of 2). Thus, kinetic and isotherm studies of phosphate elimination from synthetic solutions demonstrated that for both activated clays, the pseudo‐second‐order and Langmuir equation fitted very well the experimental data, respectively. These results indicate that phosphate adsorption might be mainly a chimisorption phenomenon and a monolayer process. All these findings confirmed that both activated clays could be considered as a competent, cost‐effective, efficient and ecological alternative for the elimination of phosphate from industrial wastewaters.
Practitioner Points
Activated clay could be adopted as an efficient and cost‐effective adsorbent.
The optimum conditions were nominated as 300 mg L−1 of initial phosphate concentration, 5 h contact times and pH = 2.
The probable uptake mechanism of phosphate followed predominantly the acid‐base interaction and hydrogen bond.
Organoclay has a tremendous impact on both fundamental studies and practical applications in numerous fields. In this context, this chapter investigates the performance of Organoclay in wastewater treatment. In particular, the adsorption of various hazardous substances has been reviewed. This study aims to give an overview of the preparation methods of Organoclay. The second purpose was to discuss the removal efficiency and reliability of various pollutants by organoclay. The third goal discussed the isotherms and kinetics used for the data interpretation. This work revealed that the characteristics of Organoclay depend mainly on the type of clay used and the nature of the intercalated surfactant. Sorption efficiency was found to depend on the nature of Organoclay, type of pollutant, pH, contact time and the concentration of pollutant.
Estimating the amount of material without significant losses at the end of hybrid casting is a problem addressed in this study. To minimize manufacturing costs and improve the accuracy of results, a correction factor (CF) was used in the formula to estimate the volume percent of the material in order to reduce material losses during the sample manufacturing stage, allowing for greater confidence between the approved blending plan and the results obtained. In this context, three material mixing schemes of different sizes and shapes (gypsum plaster, sand (0/2), gravel (2/4), and Posidonia oceanica fibers (PO)) were created to verify the efficiency of CF and more precisely study the physico-mechanical effects on the samples. The results show that the use of a CF can reduce mixing loss to almost 0%. The optimal compressive strength of the sample (S1B) with the lowest mixing loss was 7.50 MPa. Under optimal conditions, the addition of PO improves mix volume percent correction (negligible), flexural strength (5.45%), density (18%), and porosity (3.70%) compared withS1B. On the other hand, the addition of PO thermo-chemical treatment by NaOH increases the compressive strength (3.97%) compared with PO due to the removal of impurities on the fiber surface, as shown by scanning electron microscopy. We then determined the optimal mixture ratio (PO divided by a mixture of plaster, sand, and gravel), which equals 0.0321 because Tunisian gypsum contains small amounts of bassanite and calcite, as shown by the X-ray diffraction results.
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