Selective Removal of Sodium Ions from Aqueous Media Using Effective Adsorbents: Optimization by RSM and Genetic Algorithm

This study aimed to determine the best adsorbent among Moringa oleifera-derived activated carbon (AC), eggshell-derived CaO nanoparticles and CaO/Fe3O4 for sodium (Na+) removal from aqueous media. In the first step, the appropriate adsorbent for sodium adsorption was determined among the three adsorbents, which the results showed that the AC had the highest sorption efficiency. Then, response surface methodology (RSM) was used to evaluate the impact of different factors on the Na+ ion sorption efficiency using the AC. The highest removal efficiency was obtained to be 95.91% at optimum conditions such as pH of 11, contact time of 45 min, temperature of 25 °C, sodium ion concentration of 900 mg/L, and adsorbent dosage of 5 g/L. Also, the best conditions using the genetic algorithm was obtained at contact time of 94.97 min, adsorbent dosage of 3.52 g/L, Na+ ion concentration of 939.92 mg/L and pH value of 10.92. Moreover, the maximum sorption capacity using the Langmuir model was obtained to be 249.67 mg/g, which was a significant value. Besides, the equilibrium and kinetic studies indicated that the experimental data of sodium adsorption process were fitted well with the Langmuir isotherm model and the pseudo-second-order kinetic model, respectively. Furthermore, the thermodynamic study indicated that the sorption process was endothermic. Generally, among the three adsorbents used, activated carbon with a high removal efficiency and significant sorption capacity can be considered as a promising adsorbent for the removal of sodium from wastewater on an industrial scale.

Methylene blue removal using prepared activated carbon from grape wood wastes: adsorption process analysis and modeling

An adsorption study has been conducted for activated carbon obtained from grape wood wastes to assess their capability to remove methylene blue (MB) from the aqueous solutions. The properties of prepared activated carbon were characterized using FTIR, BET and SEM analyses. The effects of independent variables such as initial concentration of MB (100–500 mg L−1), initial pH of solution (3–11), adsorbent dosage (0.25–12.25 g L−1) and contact time (10–90 min) on the MB adsorption have been optimized using response surface methodology. The highest MB removal efficiency was 98% when pH, MB and adsorbent dosage were 11, 100 mg L−1 and 12.25 g L−1, respectively. The experimental data have been tested using Langmuir and Freundlich isotherm models, and the achieved data were fully fitted with the Langmuir model (R2 = 0.99), which indicates the monolayer adsorption. The adsorption kinetics well followed by the pseudo-second-order model with R2 of 0.99. This prepared activated carbon as a low-cost and eco-friendly adsorbent can be used widely for water and wastewater treatment.

Adsorption Study of Soluos Dumpsite Leachate Treatment Using Musa sapientum Peels as Biosorbent

Dumpsite leachate has the potential to pollute ground and surface water as well as vegetation within the vicinity of the dumpsite. Its treatment therefore needs adequate attention. The aim of this work is to study the adsorption of Soluos dumpsite leachate treatment using Musa sapientum peel as biosorbent with a view of establishing the adsorption isotherm model. Musa sapientum peels sourced from Ayetoro market in Epe area of Lagos State, Nigeria were used to prepare the adsorbent. Batch adsorption was carried out with various dosage of the prepared absorbent in leachate collected from Soluos dumpsite in Lagos. The adsorption data obtained were fitted into Linear, Freundlich, Langmuir, Temkin and Hasley isotherm models. The results showed that the concentration of total dissolved solids (TDS) in the dumpsite leachate decreased as the adsorbent dosage increased. At adsorbent dosage of 10 g/L, the concentration of TDS in the leachate was 485.7 mg/L which was less than the 500 mg/L stipulated by National Environmental Standard and Regulatory Agency (NAESRA) for the discharge of wastewater. The coefficient of determination (R2) values for Linear, Freundlich and Hasley, Langmuir and Temkin isotherm models were 0.9944, 0.9936, 0.8562 and 0.9723 respectively. Linear isotherm model was jettisoned because the plot did not pass through the origin and Freundlich isotherm model was ignored as a result of N value which was less than unity hence Hasley isotherm model was adopted in this work. A good correlation existed between the experimental and predicted values, having a R2 value of 0.9965 which further validated the Hasley isotherm model as the best adsorption model for the treatment of Soluos dumpsite leachate using Musa sapientum peel as biosorbent. It was concluded that Musa sapientum peel as biosorbent can be used for treatment of Soluos dumpsite leachate.

Performance Optimization of Sulfur Dioxide (SO2) Desulfurization by Oil Palm-based Activated Carbon Using Box-Behnken Design

Sulfur dioxide (SO2) emission into the atmosphere brought by the burning of fossil fuels in the industries posed significant negative effects on the environment and human beings. Adsorption using activated carbon from agricultural wastes is a viable method commonly used to counter this major problem. SO2 breakthrough experiment was conducted on a fixed bed reactor using oil palm empty fruit bunch activated carbon. The sorbent utilized in this study was characterized via N2 adsorption-desorption isotherm, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. Three parameters, i.e., reaction temperature, inlet SO2 concentration, and adsorbent dosage, were optimized using Box-Behnken Design. The highest SO2 removal was obtained at 70 °C, 2000 ppm of SO2, and 1 g of adsorbent with adsorption capacity of approximately 1101 mg SO2/g activated carbon. The developed model was validated using Analysis of Variance (ANOVA), and good agreement between predicted and actual values was obtained. Inlet SO2 concentration, adsorbent dosage, the interaction between these two parameters, and all quadratic terms were found to be significant factors, with adsorbent dosage being most significant based on its highest F-value.

Efficient Adsorption of Lead Ions from Synthetic Wastewater Using Agrowaste-Based Mixed Biomass (Potato Peels and Banana Peels)

The aquatic environment is continuously being polluted by heavy metals released from industrial, domestic, agricultural, and medical applications. It is difficult to remove heavy metals, as they are nonbiodegradable. Heavy metals cause genotoxicity and serious carcinogenic disorders. Various conventional methods have been used for the removal of heavy metals, but these are time-consuming and not economical, so green methods, being economical, are preferred over conventional methods. Adsorption, being effective, environmentally friendly, and cheap, is often preferred. The present investigation investigated the adsorption efficiency of agrowaste-based biosorbents for removal of Pb(II) ion from the synthetic wastewater. Mixed biomass of banana peel and potato peels was used to create biosorbents. The biosorbents were characterized in terms of structural and surface morphology by SEM, while functional groups were analyzed by FT-IR and XRD analysis. The adsorption of Pb(II) was studied by a batch method, and various experimental parameters were studied. Optimum conditions for the removal of lead were pH = 5, concentration = 10 ppm, adsorbent dosage = 1.0 g, and contact time = 2 h. Kinetic modelling studies showed that the adsorption of Pb(II) ions followed a pseudo-second-order mechanism, and the Langmuir isotherm model was found to fit well for this study. Highlights: Synthesis of biosorbents (mixed biomass of potato peel and banana peel, biochar, TiO2 nanocomposites). Characterization of prepared biosorbents (SEM, XRD, FT-IR). Optimized parameters (pH, initial concentration, adsorbent dosage, and contact time) for removal of pollutant.

Adsorption Of Methylene Blue By Imperata Cylindrica: Reaction Optimization By Response Surface Methodology (RSM)

Imperata Cylindrica (IC) is a solid waste that is readily available throughout the year known as one of the most important weed in the world and frequently causes major disposal issues. As a result, using IC as a low-cost adsorbent is beneficial from both, economic and environmental standpoint to remove colors from wastewater of textile industry. This work studies the reaction optimization of methylene blue (MB) removal using IC by response surface methodology (RSM). The RSM experiments were designed with 4 independent variables (initial adsorbent dosage, initial pH, initial dye concentration, and initial temperature) and 1 response variable (percent removal of MB). According to the pareto figure, the initial pH demonstrated the greatest impact on the percent removal of MB. The RSM data predicted the optimum condition of MB removal up to 86.61% using IC, by utilizing adsorbent dosage of 1.458 g/L, at 42 oC, initial pH of 6.8 and MB concentration of 235 ppm. The chacterization analysis revealed the physicochemical properties of IC in the adsoprtion process.

Comparative Analysis of Activated Carbons from African Teak (Iroko) Wood and Coconut Shell in Palm Oil Bleaching

This study compares the effectiveness of activated carbons from the African Teak/Iroko wood (Milicia excelsia) and coconut shell as adsorbents in Crude Palm Oil (CPO) bleaching. This was done in order to source for local agro-waste substitutes for the imported Fuller’s earth. The materials were activated using analytical grade CaCl2 in 25% solution at a temperature of 109OC in a laboratory hot air oven. The obtained activated carbon samples were subjected to proximate analysis to ascertain their percentage ash, moisture, volatile matter and fixed carbon contents. The CPO to be analysed was degummed, neutralized and further bleached using 2g, 4g, 6g, 8g, 10g, 12g and 14g of the adsorbent samples at a temperature of 130OC after which the obtained oils were analysed and results plotted. It was observed that the bleached oil samples generally had reduced specific gravity, opacity, colour, and free fatty acid (FFA) compared to the CPO. It was also observed that the opacity, colour, and FFA reduced as the adsorbent dosage increased. Conversely, the percentage colour reduction and the percentage FFA reduction increased with adsorbent dosage. Overall, the oil samples bleached by activated carbon from the African Teak/Iroko wood exhibited more desirable properties than the ones bleached by the coconut shell activated carbon.

Batch adsorption studies for ketoprofen removal via Dillenia Indica peel activated carbon

Removal of ketoprofen using Dillenia Indica peel activated carbon was investigated using batch adsorption at a laboratory scale. Chemical activation method with the aid of phosphoric acid was utilised in preparing the activated carbon. The adsorption experiments were evaluated using various factors which, are initial concentration, adsorbent dosage, and pH of ketoprofen. The optimum condition was determined to be at pH 6 and adsorbent dosage of 0.4 g with a most KTP uptake of 8.354 mg/g. The experimental findings showed that adsorption is favorable at lower pH. Isotherm studies were conducted and the data indicated that Langmuir isotherm was well fitted to the adsorption process and the pseudo-second-order model was more preferable in simulating the kinetic process. In essence, Dillenia Indica peel activated carbon was proven as being a favourable adsorbent for the uptake of ketoprofen in batch mode.

Adsorption Features of Loess Calcareous Nodules to Heavy-Metal Ions in Aqueous Solution

This paper explores the use of calcareous tuberculosis as an adsorbent and heavy-metal ions (Cu2+, Zn2+, Cd2+, and Pb2+) as adsorbates, and the influence of varying levels of particle size, adsorption time, pH, adsorbent dosage, and initial concentration of heavy metals is studied through an experiment of single heavy-metal adsorption. In addition, the impact of the temperature and other factors on the adsorption of heavy-metal ions by calcareous nodules is analyzed to identify the optimal conditions for the adsorption of heavy-metal ions by calcareous nodules. As shown by the research findings, the adsorption rates of Cu2+, Zn2+, and Pb2+ gradually declined with the increase in particle size, with no evident effect on Cd2+. In the meantime, with further increases in factors such as the adsorption time, adsorbent dosage, and temperature, the adsorption rates of Cu2+, Zn2+, Cd2+, and Pb2+ experienced gradual increases. The adsorption rates of Cu2+, Zn2+, and Cd2+ gradually declined with the increase in initial concentration of heavy-metal ions, whereas the adsorption rate of Pb2+ experience increased first and then declined. As the pH increased, the adsorption rate of Cd2+ experience increased first and then declined at a slow pace. The adsorption rates of Cu2+, Zn2+, and Pb2+ increased first and then decreased. The adsorption capacity of calcareous nodules toward the four heavy-metal ions was in the order of Pb2+ > Zn2+ > Cu2+ > Cd2+. When the particle size was set to 0.25 mm, the adsorption time was set to 120 min, and the dosage was set to 0.6 g, the calcareous nodules included Pb2+, Zn2+, and Cu2+. Moreover, Cd2+ was able to achieve stronger adsorption capacity, with the adsorption rate able to reach 83.33%, 77.78%, 73.81%, and 81.93% of its maximum level. Therefore, as the particle size of the heavy-metal ions decreased, the adsorption capacity generally became stronger. As the adsorption time increased, the temperature and the amount of adsorbent also increased. The optimal pH value for the adsorption of calcareous nodules toward Pb2+, Zn2+, Cu2+, and Cd2+ was found to be 7, 6, 5, and 8, respectively, and the optimal temperature was 50 °C. In summary, calcareous nodules are a natural, low-cost, and effective adsorbent.

Use of Reactivated Spent FCC Catalyst as Adsorbent for Lead (II) Ions from Refinery-based Simulated Wastewater

Improper handling of wastewater from various industries causes environmental pollution. Hence, this study involved using a reactivated spent FCC catalyst, a cheap and reliable adsorbent for Pb2+ removal from refinery-based simulated wastewater. In contrast, response surface methodology (RSM) was used to determine the optimum operating condition. The adsorptive capacity of the reactivated spent FCC catalyst was observed using different parameters such as temperature, pH, adsorbent dosage, and contact time. At the end of the study, it was found that the optimum condition for removing Pb2+ was at pH of 7, adsorbent dose of 1.75 g, contact time of 75 mins, and temperature of 117 oC. At this condition, the maximum removal efficiency of Pb2+ was found to be 100 %. A quadratic model equation via central composite design under the RSM was developed to predict the Pb2+ removal from all the input parameters. Based on the F-statistic values, the temperature had the greatest influence on the removal of Pb2+ while adsorbent dosage and contact time were also significant.