RESUMEN
Spent coffee grounds (SCGs) have great potential as a useful, value-added biological material. In this context, activated carbon (AC) was prepared from SCGs by an activation process using H3PO4 at 600 °C in the air and used as an adsorbent for the azo dye AO7, a model molecule for dye colorants found in textile industry effluents. X-ray diffraction, SEM and BET revealed that the AC was predominantly amorphous, consisting of a powder of 20-100 µm particles with mesopores averaging 5.5 nm in pore size. Adsorption kinetics followed a pseudo-second-order law, while the Langmuir model best fitted the experimental isotherm data (maximum capacity of 119.5 mg AO7 per AC g). The thermodynamic parameters revealed that adsorption was endothermic and spontaneous. All the characterizations indicated that adsorption occurred by physisorption via mainly π-π interactions. The best experimental removal efficiency optimized by means of a Box-Behnken design and response surface methodology was 98% for an initial AO7 concentration of 20 mg·L-1 at pH 7.5 with a dose of 0.285 g·L-1 of AC and a contact time of 40 min. These results clearly show that activated carbon prepared from SCGs can be a useful material for efficiently removing organic matter from aqueous solutions.
RESUMEN
Composite flat membranes were prepared using a dry uniaxial pressing process. The effect of the sintering temperature (850-950 °C) and smectite proportion (10-50 wt.%) on membrane properties, such as microstructure, mechanical strength, water permeability, and treatment performances, was explored. It was observed that increasing the sintering temperature and adding higher amounts of smectite increased the mechanical strength and shrinkage. Therefore, 850 °C was chosen as the optimum sintering temperature because the composite membranes had a very low shrinkage that did not exceed 5% with high mechanical strength, above 23 MPa. The study of smectite addition (10-50 wt.%) showed that the pore size and water permeability were significantly reduced from 0.98 to 0.75 µm and from 623 to 371 L·h-1·m-2·bar-1, respectively. Furthermore, the application of the used membranes in the treatment of indigo blue (IB) solutions exhibited an almost total turbidity removal. While the removal of color and COD decreased from 95% to 76%, respectively, they decreased from 95% to 52% when the amount of smectite increased. To verify the treated water's low toxicity, a germination test was performed. It has been shown that the total germination of linseed grains irrigated by MS10-Z90 membrane permeate was identical to that irrigated with distilled water. Finally, based on its promising properties, its excellent separation efficiency, and its low energy consumption, the MS10-Z90 (10 wt.% smectite and 90 wt.% zeolite) sintered at 850 °C could be recommended for the treatment of colored industrial wastewater.
RESUMEN
In the present work, optimized ultrafiltration conditions, using a ceramic multi tubular titania membrane (150 KDa), were investigated for the treatment of tuna cooking juice, for water reuse in the industrial process. The interactive effects of the volume concentrating factor (VCF) (1.03-4.25), feed temperature (T) (20-60 °C), and applied transmembrane pressure (ΔP) (2-5 bar) on protein removal (R protein) and permeate flux (J) were determined. A Box-Behnken experimental design (BBD) with the response surface methodology (RSM) was used for statistical analysis, modeling, and optimization of the operating conditions. The analysis of variance (ANOVA) results proved that the protein removal and permeate flux were significant and represented good correlation coefficients of 0.9859 and 0.9294, respectively. Mathematical modeling showed that the best conditions were VCF = 1.5 and a feed temperature of 60 °C, under a transmembrane pressure of 5 bar. The fouling mechanism was checked by applying a polarization concentration model. Determination of the gel concentration confirmed the results found in the mass balance calculation and proved that the VCF must not exceed 1.5. The membrane regeneration efficiency was proven by determining the water permeability after the chemical cleaning process.
RESUMEN
This work aims to determine the optimized ultrafiltration conditions for industrial wastewater treatment loaded with oil and heavy metals generated from an electroplating industry for water reuse in the industrial process. A ceramic multitubular membrane was used for the almost total retention of oil and turbidity, and the high removal of heavy metals such as Pb, Zn, and Cu (>95%) was also applied. The interactive effects of the initial oil concentration (19−117 g/L), feed temperature (20−60 °C), and applied transmembrane pressure (2−5 bar) on the chemical oxygen demand removal (RCOD) and permeate flux (Jw) were investigated. A Box−Behnken experimental design (BBD) for response surface methodology (RSM) was used for the statistical analysis, modelling, and optimization of operating conditions. The analysis of variance (ANOVA) results showed that the COD removal and permeate flux were significant since they showed good correlation coefficients of 0.985 and 0.901, respectively. Mathematical modelling revealed that the best conditions were an initial oil concentration of 117 g/L and a feed temperature of 60 °C, under a transmembrane pressure of 3.5 bar. In addition, the effect of the concentration under the optimized conditions was studied. It was found that the maximum volume concentrating factor (VCF) value was equal to five and that the pollutant retention was independent of the VCF. The fouling mechanism was estimated by applying Hermia's model. The results indicated that the membrane fouling given by the decline in the permeate flux over time could be described by the cake filtration model. Finally, the efficiency of the membrane regeneration was proved by determining the water permeability after the chemical cleaning process.