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The aim of this article is the study of the efficiency of toxic dyes removal (methylene blue MB, methyl red MR, methyl orange MO, methyl green MG, phenolphthalein QQ and gentian violet GV) from aqueous solution onto Mchounche clay. The adsorption phenomenon in batch manner was used as water treating method, this treatment was tested by UV-vis analysis to study the kinetics of adsorption; These results show that the uptake of the dyes onto clay surface is a speed phenomenon in the first minutes and after that it becomes slow. Furthermore, the kinetic parameters for the adsorption of the dyes using the PSO model are more suitable due to the highest R², lowest RMSE and the close between Qe exp and Qe cal values. The thermodynamic curves of the removal of the dye show that all the adsorption is an exothermic phenomenon as a physical type of adsorption depends on VDW interactions between adsorbent and adsorbate. The results of initial pH influence indicate that the removal of QQ increases on both acid and basic mediums, the removal of GV and MO increase in acid medium and a decrease in the basic medium. Oppositely, the removal of all rest dyes decreases in both acid and basic mediums. The Modeling of adsorption isotherm of toxic dyes presented that Freundlich fit is the best one due to the R² high values and RMSE low values. Finally, It can be concluded that Mchounche clay has removed the highest removal quantity of BM, MO, and MG with the adsorbed quantities at equilibrium Qe exp values 19.99, 19.74 and 19.24 respectively., {"references":["Vo, Anh Tuan, Van Phuong Nguyen, Abdelkader Ouakouak, and Aileen Nieva. 2019. \"Water E Ffi Cient Removal of Cr ( VI ) from Water by Biochar and Activated Carbon Prepared through Hydrothermal Carbonization and Pyrolysis :\" MDPI 11: 1–14.","Wang, Wenbo, Guangyan Tian, Li Zong, Yanmin Zhou, Yuru Kang, Qin Wang, and Aiqin Wang. 2017. \"From Illite/Smectite Clay to Mesoporous Silicate Adsorbent for Efficient Removal of Chlortetracycline from Water.\" Journal of Environmental Sciences (China) 51: 31–43. https://doi.org/10.1016/j.jes.2016.09.008.","Wong, Y C, Y S Szeto, W H Cheung, and G Mckay. 2003. \"Pseudo-First-Order Kinetic Studies of the Sorption of Acid Dyes onto Chitosan.\" Journal of Applied Polymer Science 92: 1633–45.","Wang, Xiaoli, and Yu Li. 2011. \"Measurement of Cu and Zn Adsorption onto Surficial Sediment Components: New Evidence for Less Importance of Clay Minerals.\" Journal of Hazardous Materials 189 (3): 719–23. https://doi.org/10.1016/j.jhazmat.2011.03.045.","Xu, Zhe, Jian Guo Cai, and Bing Cai Pan. 2013. \"Mathematically Modeling Fixed-Bed Adsorption in Aqueous Systems.\" Journal of Zhejiang University: Science A 14 (3): 155–76. https://doi.org/10.1631/jzus.A1300029.","Yin, Juan, Chaobing Deng, Zhen Yu, Xiaofei Wang, and Guiping Xu. 2018. \"Effective Removal of Lead Ions from Aqueous Solution Using Nano Illite/Smectite Clay: Isotherm, Kinetic, and Thermodynamic Modeling of Adsorption.\" Water (Switzerland) 10 (2). https://doi.org/10.3390/w10020210.","Yu, Sanchuan, Zhiwen Chen, Qibo Cheng, Zhenhua Lü, Meihong Liu, and Congjie Gao. 2012. \"Application of Thin-Film Composite Hollow Fiber Membrane to Submerged Nanofiltration of Anionic Dye Aqueous Solutions.\" Separation and Purification Technology 88: 121–29. https://doi.org/10.1016/j.seppur.2011.12.024."]}

Spent coffee grounds (SCGs) generated in coffee processing for beverages and other products are a very significant organic residue that needs to be properly treated. Waste valorization via oil extraction has the potential to obtain compounds that can be used for producing biodiesel or other high-value products, such as polymers. This work focuses on the ultrasound-assisted extraction of SCG oil using n-hexane as a solvent. Three key process parameters are analyzed: temperature, extraction time, and liquid/solid (L/S) rate of solvent, using a central composite rotatable design (CCRD), an analysis that, to the author’s knowledge, is not yet available in the literature. The data were analyzed using the software StatSoft STATISTICA 13.1 (TIBCO Software Inc., Palo Alto, CA, USA). Results show that all parameters have a statistical influence on the process performance (p < 0.05), being the L/S ratio the most significant, followed by extraction time and temperature. An analysis of variance (ANOVA) showed that the empirical model is a good fit to the experimental data at a 95% confidence level. For the range of conditions considered in this work, the optimal operating conditions for obtaining an oil extraction yield in the range of 12 to 13%wt are a solvent L/S ratio of around 16 mL g−1, for a temperature in the range of 50 to 60 °C, and the longest contact time, limited by the process economics and health and safety issues and also, by the n-hexane boiling temperature.