Removal of iron and manganese from groundwater sources using nano-biosorbents

Background The presence of iron (Fe) and manganese (Mn) ions in rocky beds leads to groundwater pollution. Moreover, their excessive concentration causes bad taste and color stains of water. Methods Tea leaves-derived char (TLC), rice straw-derived char (RSC), and nanosilica (NS) were used to adsorb Fe and Mn ions from water sources. The effects of parameters such as contact time, composition percentage, and particle size of biosorbents in a fixed-bed adsorption column were investigated. Results The study on the adsorption of Fe and Mn ions showed that the amount of adsorption increased significantly by decreasing the particle size. Furthermore, the combination of nano-biosorbents with nanosilica improved the adsorption. The Thomas and Adams–Bohart models adequately indicated the adsorption of Fe and Mn ions onto nano-biosorbents in the column mode. The TLC and RSC with NS are applicable for the removal of Fe and Mn ions from groundwater. Conclusions According to the BET analysis results, with more crushing of biosorbents by ball mill and placing them in the furnace, specific surface area of tea leaves and rice straw increased from 0.29 to 3.45 and from 3.70 to 10.99 m2/g, respectively. The absorption of iron and manganese from the aqueous solution increased with the percentage of nano-silica. According to breakthrough curves, under best conditions (the seventh mode), nano-biosorbents could remove 98.05% and 97.92% of iron and manganese ions, respectively. The maximum equilibrium capacity of the adsorption column (mg/g) was 256.56 for iron and 244.79 for manganese. Graphical abstract

Simulation of CO2 Gas Adsorption Process Flow at Cyclone Gas Outlet in Palm Oil Mills Using Computation Fluid Dynamic Simulation

Cyclone separator is equipment used to control emissions from gas flow in industrial processes. The principle of removing particulates from the gas flow in this tool is to use the centrifugal force. The centrifugal force generated from the rotating flow will make dust particles wasted into the cyclone wall where the dust will then fall into the hopper. Adsorption is a series of processes for the accumulation of a substance (adsorbate) on the surface of another substance (adsorbent). Adsorption can occur because of the energy on the surface and the attraction force on the surface. This study aims to obtain a good CO2 adsorption efficiency from modifying the cyclone separator using an adsorption column, analyzing the CO2 gas adsorption process produced from the biomass system at the utility unit boiler station at the Palm Oil Mill (PMO) using a modified cyclone. This simulation was carried out using the Autodesk Inventor Professional 2017 (Student Version) application for the descripction of the tool as a preprocessor and Ansys 2019 R3 (Student Version) applications as a processor and post processor. The variations that were applied included the adsorption column bed height of 3100 mm and 4650 mm, respectively, CO2 gas flow rates of 10, 12.5, 15, 17.5, 20, 22.5 dan 25 m/s and mass loading 0,001 kg/s. The results obtained in the most optimal modification of the cyclone separator are at a bed height of 3100 mm with the highest adsorption percentage 93.437%, the highest flow 91.974% with a pressure drop of 1000 Pa.

Sequential three-step process for the treatment of slaughter house wastewater and its optimization using response surface modeling studies

The rapid growth in the world population and fast developing industrialization have resulted in the acceleration of environmental pollution due to inadequate treatment methods accompanied by depletion of freshwater. The current research focused on the batch treatment of slaughter house wastewater (SWW) using the sequential three-step electro-coagulation (EC)–electro-oxidation (EO)–adsorption column (AC) processes and to compare the optimized values with the Omani National Standards for the application in irrigation purpose. The characterization of SWW before and after treatment was carried out by measuring chemical oxygen demand (COD), total organic carbon (TOC), total dissolved solids (TDS), turbidity, ammoniacal nitrogen (NH4–N) and conductivity. The optimization of the treatment processes was performed by response surface methodology (RSM) using central composite design. The maximum response obtained using EC unit was 99% with an operating cost of 2.78 USD/m3. The optimum treatment conditions in EC method were found to be 4.0 pH, electrolysis time of 30 min and electrolyte dosage of 5 g/L, with a current density of 18.11 mA/cm2. The maximum reduction in COD was 97% with an operating cost 0.32 USD/m3. The optimum COD reduction in EO method was 84.5% with an operating cost of 6.87 USD/m3. The optimum process parameters in the EO process were observed at 5.0 pH, 56.22 min electrolysis time with 5 g/L electrolyte dosage and a current density of 5 mA/cm2. The response shows 56.27% reduction in COD with an operating cost of 0.088 USD/m3. The study demonstrates that both EC and EO processes for the reduction of COD have a significant effect on the current density. Using adsorption column (AC) studies, the maximum reduction in COD was 76.8% with negligible operating cost. The optimum pH in the case of AC was 7.5, with an effluent flow rate of 8.63 mL/min, and the responses were found to be 76.067%, which indicates both pH and flow rate have significant effect on the % removal of COD.

Fixed-Bed Adsorption Column Studies for the Removal of Methyl Orange from Water Using Polyethyleneimine-Graphene Oxide Polymer Nanocomposite Beads

Continuous fixed-bed column studies were performed using nanocomposite beads made up of chitosan, polyethyleneimine, and graphene oxide as adsorbents for the removal of methyl orange (MO) in water. The effects of different operating parameters such as initial MO concentration (5, 10, and 15 ppm), bed height (10, 17.5, and 25 cm), and flow rate (27, 43, and 58 mL/min) were investigated using an upward-flow fixed-bed column set-up. The breakthrough curves generated were fitted with Adams-Bohart, Thomas, Yoon-Nelson, and Yan et al. models. The results showed that Yan et al. model agreed best with the breakthrough curves having an R2 as high as 0.9917. Lastly, design parameters for a large-scale adsorption column were determined via scale-up approach using the parameters obtained from column runs.