Modelling and Optimizing the Removal of Methylene Blue by a Mixture of Titaniferous Sand and Attapulgite Using Complete Factorial Design

This paper focuses on the removal of methylene blue by adsorption using a mixture of titaniferous sand and attapulgite. The different adsorbents were characterized by X-ray fluorescence spectroscopy and their different parameters such as pH, zero charge potential, and specific surface area were determined. The experiments performed were optimized and modeled by a full 2-level and 4-factor design. The four factors are the ratio of titaniferous sand and attapulgite, the concentration of methylene blue, pH, and time. These vary from 4 to 19, 20 to 100 mg/L, 2 to 9, and 30 to 150 min respectively. The study of the effects of the different factors showed that the effect of methylene blue concentration and pH significantly influence the adsorption capacity and removal efficiency of the dye. The optimum parameters (adsorbent ratio, adsorbate concentration, pH and time) obtained for the adsorption capacity through the desirability function are: 19, 100mg/L, 9 and 150min. Those obtained for the yield are: 4, 100mg/L, 9, 150min. The pseudo second order adsorption kinetics gave an equilibrium adsorption capacity qe (calculated) = 7.6863 mg/g which is almost equal to that obtained experimentally qe (exp) = 7.3562 mg/g. This shows that the pseudo second order kinetic model is the adequate mathematical model to describe the methylene blue adsorption phenomenon on the mixture of titaniferous sand and attapulgite. The thermodynamic study showed that the methylene blue adsorption reaction is exothermic, non-spontaneous, and the degree of disorder of the particles at the adsorbing surface decreases.

Methylene Blue and Iron (II) Adsorption onto Raphia Hookeri Seed: A Comparative Equilibrium Isotherm Study

In this study, activated carbon prepared from Raphia hookeri seed was employed as an adsorbent to take up methylene blue (an organic ion-in-solution) and iron (II), a metal ion-in-solution. The biosorbent was prepared using chemical activation using sodium hydroxide (NaOH) as an impregnating agent. Calibration was performed with a focus on the change in the adsorbate concentration. The equilibrium isotherms study was conducted by considering a range of sorbate concentrations, to determine the optimal conditions for the adsorption systems. The same sorbate volume (10 ml), and the same dosage (0.3g) of biosorbent were used for both adsorption processes. Linear analysis was used to compare the best-fitting isotherms. Langmuir, Freundlich, and Dubinin-Radushkevich models were tested. The highest coefficient of determination values (R2) for both iron (II) and Methylene blue was obtained from the Langmuir isotherm as 0.9266 and 0.9572, respectively, compared to values from the other isotherms tested – indicative of Langmuir isotherm’s superior fit. Estimated values of ‘separation factor’, KR, for Methylene blue (0.29457), however, was lower than that of iron (II) (0.42141) - an indication that the sorbent treats methylene blue better than iron (II), though both processes are feasible.

Freundlich Isotherm: An Adsorption Model Complete Framework

The absolute majority of modern studies dealing with the interpretation of experimental data on the basis of the Freundlich isotherm ignore the fact that the data obtained for regions of low and moderate adsorbate concentration/pressure can be analytically continued within the Freundlich adsorption model to the adsorptive saturation area with coverages tending to 100%. Needless to say, this would give valuable extended information about the corresponding adsorption process. This message proposes a framework to comprehensively analyse experimental data first recognised as complying with the Freundlich adsorption model. An algorithm-driven method is presented which enables one to translate the data obtained in the area of small and moderate the coverages of the area of adsorptive saturation regime. As examples, three sets of experimental data for adsorption of mercury (II) on N-rich porous organic polymers and of protein on carrier nano-Mg(OH)2 have been processed and presented according to the framework developed.

Adsorption of Pb2+ from waste water using modified and unmodified plantain pseudo stem waste as adsorbent

This study was carried out to evaluate the potentials of plantain pseudo stem waste as adsorbent in the removal of Pb2+ from aqueous solution. Filament obtained from Plantain pseudo stem were dried, cut into chips and ground using electric grinder. The powdered sample obtained was soaked in ethanol for 24 hours and wash with water several times to remove the extractive component. It was then dried in the oven. Modification reaction was carried out on the powdered sample using Fenton reagent (Fe2+/H2O2). Both the modified and unmodified adsorbents were used for the adsorption of Pb2+ from aqueous solution. Factors considered were effect of contact time and effect of adsorbate (Pb2+) concentrations. The results revealed that in all the adsorption studies, the adsorption capacity of modified adsorbent was higher than that of the unmodified adsorbent. However, adsorption capacities increase with increase in contact time and decreases with increase in the adsorbate concentration.

Wastewater Purification from Permanganate Ions by Sorption on the Ocimum basilicum Leaves Powder Modified by Zinc Chloride

The powder of Ocimum Basilicum leaves was treated by zinc chloride (ZnCl2) and applied as a new and low-cost sorbent for extraction of permanganate anions (MnO4−) from liquid phase. The functional groups of the ring stretching vibration, –NH2 deformation, stretching of C-O, stretching of CH, and stretching of –NH were found in the sorbent of zinc chloride Ocimum basilicum leaves powder (ZCOBLP) at 1516.21, 1629.33, 1047.00, 2929.88, and 3294.93 cm−1, respectively. This adsorbent has 8.3 pHZPC, 117.27 m2·g−1 surface area, 0.00711 cc·g−1 pore volume and average pore diameter of 264.144 Å. The outcomes of sorption experiments designate the positive impact for temperature, time of agitation, and started concentration of MnO4− and negative impact for pH. The optimal conditions were 1300 mg·L−1 as started adsorbate concentration, 55°C as solution temperature, agitation time of 420 min, and pH of 1.5. The outcomes of the equilibrium and dynamic approve that this sorption is spontaneous and heat-absorbing process, and the obtained data were described well by isotherm model of Langmuir and 2nd-order dynamic model. The capacities of this sorption were 588.235, 625.000, 666.667, and 714.286 mg·g−1 at 25, 35, 45, and 55 (°C), respectively. The superior sorption capacities of the uncostly ZCOBLP will make it successfully used for MnO4− ions extraction from liquid phases.

New Separation Material Obtained from Waste Rapeseed Cake for Copper(II) and Zinc(II) Removal from the Industrial Wastewater

Rapeseed cake biochar was produced by pyrolysis at 973.15 K for 2 h, in anoxic conditions. Porous structure, specific surface area and die composition of waste rapeseed cake were studied. The specific surface area of rapeseed cake biochar was 166.99 m2·g−1, which exceeded most other biochars reported, which made it an attractive material during wastewater treatment. The SEM study of the material demonstrated a large number of pores formed on the cell wall, with a pore volume Vp = 0.08 cm3·g−1. The results indicate lower aromaticity and increased polarity of the tested material. The observed H/C ratio of 0.29 is similar for activated carbons. Furthermore, sorption properties of the obtained carbon material in relation to copper(II), zinc(II) and arsenic(III) ions were also studied. Moreover, the impact of parameters such as: sorption time, temperature, adsorbate concentration, sorbent mass and solution pH on the efficiency of the adsorption process of the studied cations was also examined. Sorption studies revealed that the sorbent can be successfully used for the separation of Cu(II) and Zn(II) from technological wastewaters. Rapeseed cake biochar exhibits superior Cu(II) adsorption capacity (52.2 mg·g−1) with a short equilibrium time (6 h). The experimental data collected show a high selectivity of the obtained carbon material relative to copper(II) and zinc(II) ions in the presence of arsenic(III) ions.

First investigations on removal of nitrazepam from water using biochar derived from macroalgae low-cost adsorbent: kinetics, isotherms and thermodynamics studies

Emerging contaminants such as pharmaceutical compounds have potential hazards to the aquatic environment and human health. In this paper, the adsorptive removal of the drug Nitrazepam from water was investigated for the first time using biochar prepared from Sargassum macroalgae. The removal efficiency of Nitrazepam using 1 g/L of Sargassum macroalgae-derived biochar was 98% with a maximum adsorption capacity of 143.12 mg/g. Effects of solution pH, adsorbent mass, adsorbate concentration, contact time and temperature on the removal of Nitrazepam were investigated. Different adsorption isotherms and kinetics were also tested. It was found that the solution pH slightly influenced the removal efficiency. The adsorption data fit the Freundlich isotherm model and the adsorption process of Nitrazepam onto Sargassum macroalgae-derived biochar is spontaneous, endothermic and followed the pseudo-second-order kinetics. Based on this work, it was determined that the low-cost Sargassum macroalgae-derived biochar adsorbent could be a promising adsorbent to remove Nitrazepam from water effectively.

Kinetics and Isotherm Studies on Adsorption of Hexavalent Chromium Using Activated Carbon from Water Hyacinth

The present study is focused on the use of activated carbon derived from water hyacinth (WH-AC) as adsorbent for the removal of Cr(VI) from aqueous solution. The optimized WH-AC was found to be mesoporous and considered as granular. The surface area of 11.564 m2/g was found to have a good adsorption capacity. The adsorption data of the optimized WH-AC followed a pseudo-second order kinetics and the Freundlich isotherm model. Based on the correlation coefficient obtained from pseudo-second-order kinetic model, the R2 values were all above 0.99, which is closer to unity of one (1) indicating that it followed a chemisorption process. The adsorption capacity of WH-AC increased from 1.98 to 4.68 mg/g when adsorbate concentration increased from 20 to 50 mg/l. The overall study proved that the adsorption by activated carbon derived from water hyacinth can be an alternative and efficient technique in hexavalent chromium removal.

Adsorption and Characterization of Activated Sugarcane Bagasse Using Natrium Hydroxide

Sugarcane Bagasse can be used as an adsorbent both under natural conditions and modified by chemical activation using sodium hydroxide (NaOH). Activation of sugarcane bagasse with NaOH was carried out at variations of 5:1, 10:1, and 20:1 (w/w). The absorption ability of bagasse adsorbent to methylene blue solution was carried out with the parameters of variation of contact time (60, 90, 120, 150, and 180 minutes), adsorbate concentration (20, 30, 40, 50, and 60 ppm) and temperature (30, 40, 50, and 60 oC). The adsorbent's characterization included determining the functional groups using FTIR, morphology, and mass of elements using SEM-EDX, and determining the surface area and volume of adsorbent pores using the BET methods. The highest adsorption percentage results were found in the NASB10:1 adsorbent at 99.50%. The optimum conditions for the NASB10:1 adsorbent are with a contact time of 120 minutes, an adsorbate concentration of 50 ppm, and a temperature of 30 oC or 303 K. The NASB10:1 adsorbent has the highest surface area compared to other adsorbents, namely 2.803 m2/g so that it can perform the maximum absorption of methylene blue.