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In this study, a magnetite/chitosan/activated carbon (MCHAC) composite is proposed as an efficient adsorbent for the removal of atrazine from aqueous solutions. The prepared composite was characterized using Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) methods. Response surface methodology (RSM) coupled with composite central design (CCD) were used to optimize the effects of the four independent variables, pH, initial concentration of atrazine ( C 0 ), bed depth ( H ), and flow rate ( Q ), which influence the adsorption process. The experimental results modeled using response surface methodology (RSM) coupled with central composite design (CCD) (RSM-CCD) indicated a quadratic relationship with p < 0.0001 for adsorption capacity at saturation ( q s ) and fraction of bed utilization (FBU). The results of the experiments performed under the optimized conditions, pH = 5.07, C 0 = 137.86 mg L -1 , H = 2.99 cm and Q = 1.038 mL min -1 , showed a q s value of 62.32 mg g -1 and FBU of 72.26%, with a deviation value of less than 0.05 from the predicted q s and FBU values. The obtained breakthrough curves were fitted with four mathematical models, Thomas, Bohart-Adams, Yan and Yoon-Nelson, in order to determine the limiting step of the mass transfer of the atrazine adsorption onto the composite. A desorption study of the composite revealed the high reuse potential for MCHAC, thus, the prepared material could be used as a low-cost and efficient adsorbent for the decontamination of polluted wastewater., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, the wastewater from the Departmental Hospital Center of Atacora in Benin was characterized and then treated with activated carbon/potassium permanganate (AC/KMnO 4 ) composite in a fixed bed column system. The AC/KMnO 4 composites with impregnation ratios range 0.025-0.100 were prepared from peanut shell activated carbon and potassium permanganate. The wastewater characteristics revealed that 75% of Escherichia coli strains identified were extended-spectrum lactamases (ESBL) with CTX-M dominance, while 25% of Staphylococcus aureus strains produced Panton and Valentine leucocidin and 77.80% of Salmonella typhi strains were resistant to Trimethoprim/Sulfamethoxazole. The fixed bed column system results showed removal efficiency of 72.18 ± 4.98% turbidity, 63.12 ± 4.11% COD, 0.70 ± 0.04 log 10 against E. coli and 3.82 ± 0.01 log 10 against S. typhi strains using activated carbon as adsorbent with 0.7 cm bed depth after 3 h of treatment. The composite adsorbent AC/KMnO 4 significantly increased the effectiveness of treatment due to the strong oxidant power of KMnO 4 in the composite material. The results depicted a removal rate of 83.88 ± 5.00%, 89 ± 1.95%, 90 ± 0.65% turbidity, 66.47 ± 1.62%, 69.82 ± 2.00%, 78.20 ± 2.82% COD, 2.0 ± 0.08 log 10 , 5.0 ± 0.07 log 10 against E. coli and 3.82 ± 0.01 log 10 against S. typhi strains using AC/KMnO 4 with 0.025, 0.050 and 0.100 ratios respectively at 0.7 cm bed depth. Finally, AC/KMnO 4 revealed more adsorption potential and antibacterial property than AC, hence, the composite material could be used as a cost-effective adsorbent for efficient removing of multi-resistant bacteria from hospital wastewater., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Two caseins labelled as CaSMG (casein without fats) and CaMG (casein with fats) were extracted from coconut cream. Both caseins were used as coagulants for the aggregation of humic acid (HA) particles in synthetic water at pH = 6 during the jar-test essays. The optimum dosage of CaMG or CaSMG and the residual turbidities of treated water obtained depend on the type of used casein (CaMG or CaSMG) and the concentration of particles in solution. The optimal doses of CaMG and CaSMG are respectively 280 and 180 mg/L for solution S(1) (HA aqueous solution at 15 mg/L), and then 340 and 240 mg/L for solution S(2) (HA aqueous solution at 25 mg/L). The residual turbidities of treated water are respectively 6.88 and 3.85 NTU for solution S(1) and 4.52 and 2.53 NTU for solution S(2). The collected sediment volumes are respectively 1.2 and 1.5 mL for solutions S(1) and S(2). The electrophoretic mobility measurement and transmission electron microscopy images of flocs formed during the flocculation essays suggest that both caseins operate through both mechanisms (charge neutralisation and bridging process mechanism), this last one seems to be predominant. The aggregates formed are the large clusters and result from adsorption of HA particles by the casein molecules.