Nickel removal from wastewater using electrocoagulation process with zinc electrodes under various operating conditions: performance investigation, mechanism exploration, and cost analysis

Elimination of nickel ions in a packed column using clamshell waste as an adsorbent

The present investigation assessed the viability of utilizing a powdered clam shell in continuous adsorption to eliminate nickel ions from simulated wastewater. The breakthrough curves (BTC) were analyzed by altering the Q (inlet flow rate) in a glass column (ID 5 cm, H 35 cm) with a multi-port and filled with the powdered clamshell adsorbent (PCSA). The PCSA's nickel adsorption efficiency was maximum (87.68%) with Q = 8 mL/min at a bed length (H) of 25 cm with 1.05 mg/g adsorption capacity. Moreover, the mass transfer zone (MTZ) and idle bed length (Lu) were estimated from the corresponding BTC. The values of MTZ and Lu demonstrated fluctuations in response to changes in bed length, suggesting the presence of non-ideal circumstances. The validity of the Thomas model for predicting column dynamics was established, and the associated model parameters were assessed. Additionally, the parameters of the BDST model were assessed in order to aid in calculating the sufficient depth for a packed bed column (PBC) while scaling up. Therefore, a metal removal process from industrial effluent can be efficiently achieved by utilizing a PBC of powdered clamshell adsorbent.

Enhancing Zn (II) recovery efficiency: Bi-divalent nickel-cobalt ferrite spinel NiXCo1-xFe2O4 as a Game-changing Adsorbent-an experimental and computational study

This study presents a comprehensive investigation into NiXCo1-xFe2O4 (x = 0.5) spinel nanoparticles synthesized through a one-pot hydrothermal method using Co(NO3)2.6H2O and Ni(NO3)2.6H2O salts. XRD, FTIR, FESEM, and VSM analyses confirmed a cubic structure of NiXCo1-xFe2O4 (x = 0.5) nanoparticles without impurities. These nanoparticles exhibit efficient Zn (II) adsorption characteristics, following Langmuir isotherm and pseudo-second-order kinetics. The maximum adsorption capacity was measured to be 666.67 mg g-1 at pH = 7, with mechanisms involving both electrostatic attraction and cation exchange. Desorption studies indicate more than 75% Zn (II) recovery in an acidic environment (pH = 2) after three cycles. Computational analysis was used to validate the experimental results through Molecular Dynamics simulations, initially focusing on NiXCo1-xFe2O4 (x = 0.5). Further exploration involved variations in x at 0.25 and 0.75 to identify the optimal Ni and Co ratio in this bivalent cation spinel ferrite. Computational analyses reveal the superior performance of NiXCo1-xFe2O4 (x = 0.75) in Zn (II) removal, supported by radial distribution analysis, VdW energy, Coulombic energy, mean square displacement (MSD), root mean square displacement (RMSD), and interaction energy. This comprehensive study provides valuable insights into the adsorption behavior and structural stability of NiXCo1-xFe2O4 nanoparticles, showcasing potential applications in Zn (II) removal.

Optimization of iron electrocoagulation parameters for enhanced turbidity and chemical oxygen demand removal from laundry greywater

This study explores the optimization of iron electrocoagulation for treating laundry greywater, which accounts for up to 38% of domestic greywater. Characterized by high concentrations of surfactants, detergents, and suspended solids, laundry greywater presents complex challenges for treatment processes, posing significant environmental and health risks. Utilizing response surface methodology (RSM), this research developed a second-order polynomial regression model focused on key operational parameters such as the area-to-volume ratio (A/V), current density, electrolysis time, and settling time. Optimal treatment conditions were identified: an A/V ratio of 30 m2/m3, a current density of 10 mA/cm2, an electrolysis duration of 50 min, and a settlement period of 12 h. Under these conditions, exceptional treatment outcomes were achieved, with turbidity removal reaching 94.26% and COD removal at 99.64%. The model exhibited high effectiveness for turbidity removal, with an R2 value of 94.16%, and moderate effectiveness for COD removal, with an R2 value of 75.90%. The interaction between the A/V ratio and electrolysis time particularly underscored their critical role in electrocoagulation system design. Moreover, these results highlight the potential for optimizing electrocoagulation parameters to adapt to daily fluctuations in greywater production and meet specific household reuse needs, such as toilet flushing. This tailored approach aims to maximize contaminant separation and coagulant efficiency, balance energy use and operational costs, and contribute to sustainable water management.

A hybrid system for Nickel ions removal from synthesized wastewater using adsorption assisted with electrocoagulation

The presence of heavy metal ions in water environments has raised significant concerns, necessitating practical solutions for their complete removal. In this study, a combination of adsorption and electrocoagulation (ADS + EC) techniques was introduced as an efficient approach for removing high concentrations of nickel ions (Ni2+) from aqueous solutions, employing low-cost sunflower seed shell biochar (SSSB). The combined techniques demonstrated superior removal efficiency compared to individual methods. The synthesized SSSB was characterized using SEM, FT-IR, XRD, N2-adsorption-desorption isotherms, XPS, and TEM. Batch processes were optimized by investigating pH, adsorbent dosage, initial nickel concentration, electrode effects, and current density. An aluminum (Al) electrode electrocoagulated particles and removed residual Ni2+ after adsorption. Kinetic and isotherm models examined Ni2+ adsorption and electrocoagulation coupling with SSSB-based adsorbent. The results indicated that the kinetic data fit well with a pseudo-second-order model, while the experimental equilibrium adsorption data conformed to a Langmuir isotherm under optimized conditions. The maximum adsorption capacity of the activated sunflower seed shell was determined to be 44.247 mg.g-1. The highest nickel ion removal efficiency of 99.98% was observed at initial pH values of 6.0 for ADS and 4.0 for ADS/EC; initial Ni2+ concentrations of 30.0 mg/L and 1.5 g/L of SSSB; initial current densities of 0.59 mA/cm2 and 1.32 kWh/m3 were also found to be optimal. The mechanisms involved in the removal of Ni2+ from wastewater were also examined in this research. These findings suggest that the adsorption-assisted electrocoagulation technique has a remarkable capacity for the cost-effective removal of heavy metals from various wastewater sources.

Sulfide recovery using fluidized bed homogeneous crystallization technology to produce nickel sulfide from wastewater that contains sulfides

Sulfide-containing wastewater, characterized by its foul odor, corrosiveness, and toxicity, can endanger human health. Fluidized-bed homogeneous crystallization (FBHC) avoids the excessive sludge production commonly associated with conventional chemical precipitation methods. In this study, FBHC is used to treat sulfur-containing synthetic wastewater. Furthermore, nickel-containing wastewater was utilized as a precipitant in the system, hence the advantage of simultaneous sulfur and nickel removal from the wastewater. The operating parameters, including pH, a precipitant dosage of [Ni2+]0/[S2-]0, and cross-sectional surface loading (LS, kg/m2h) are optimized. The optimum operating conditions of pH 9.8 ± 0.3, [Ni2+]0/[S2-]0 = 0.8, and LS = 1.5 kg/m2h results in total sulfur removal (TR) of 95.7% and crystallization ratio (CR) of 94.8%. The effect of organic compounds (acetic acid, oxalic acid, EDTA, and citric acid) and inorganic ions (NO3-, CO32-, PO43-, F-, and Cl-) on the nickel sulfide granulation process was discussed.

Iodine and Nickel Ions Adsorption by Conjugated Copolymers Bearing Repeating Units of Dicyclopentapyrenyl and Various Thiophene Derivatives

The synthesis of three conjugated copolymers TPP1-3 was carried out using a palladium-catalyzed [3+2] cycloaddition polymerization of 1,6-dibromopyrene with various dialkynyl thiophene derivatives 3a-c. The target copolymers were obtained in excellent yields and high purity, as confirmed by instrumental analyses. TPP1-3 were found to divulge a conspicuous iodine adsorption capacity up to 3900 mg g-1, whereas the adsorption mechanism studies revealed a pseudo-second-order kinetic model. Furthermore, recyclability tests of TPP3, the copolymer which revealed the maximum iodine uptake, disclosed its efficient regeneration even after numerous adsorption-desorption cycles. Interestingly, the target copolymers proved promising nickel ions capture efficiencies from water with a maximum equilibrium adsorption capacity (qe) of 48.5 mg g-1.

Performance evaluation and life cycle assessment of electrocoagulation process for manganese removal from wastewater using titanium electrodes

Excess manganese (Mn) concentrations can pose environmental and health risks. Currently, research on Mn removal by electrocoagulation (EC) using transition metal electrodes and the determination of its potential environmental impacts is limited. This study aims to assess the electrocoagulation process's performance with a titanium electrode as a sacrificial anode while also performing a life cycle assessment (LCA) of the process. The initial pH, current density (CD), electrode spacings, electrolyte types, concentrations, and electrode arrangement were all examined. For synthetic wastewater, most of the experiments used a concentration of Mn of 2 mg/L and sodium chloride as a supporting electrolyte at a concentration of 1 g/L. LCA software (OpenLCA 1.11) was used to assess the potential environmental impacts. Optimal operating conditions within the experimental range were as follows: initial pH = 7, CD = 10 mA/cm², gap distance = 2 cm, and 1 g/L NaCl. Under these conditions, the maximum Mn removal efficiency was 96.5% after 60 min. There was an improvement of 2% rise after 60 min when the temperature increased from 20 °C to 40 °C. For real wastewater, the highest removal efficiencies for Mn and chemical oxygen demand after 60 min were 91.3% and 92%, respectively. The pseudo second order model provides the highest coefficient of determination for expressing the experimental data. Global warming, human non-carcinogenic toxicity, and terrestrial ecotoxicity were the most important categories of impact examined in this work according to the LCA (0.00064 kg CO₂ eq, 0.00018 kg 1,4-DCB, and 0.00028 kg 1,4-DCB, respectively). To effectively remove Mn using EC with Ti electrodes, it appears that a period of electrolysis of 10 min would be sufficient under most of the conditions investigated in this study. The reduction in the electrolysis time will lead to a reduction in the operating costs of the system.

Removal of Ni(II) from Aqueous Solution by Novel Lycopersicon esculentum Peel and Brassica botrytis Leaves Adsorbents

The current work reports adsorption of Ni(II) using Brassica botrytis leaves (BBL), Brassica botrytis leaves-activated carbon (BBL-AC), Lycopersicon esculentum peel (LEP) and Lycopersicon esculentum peel-activated carbon (LEP-AC). The adsorption of Ni(II) was tested in batch experiments by varying different parameters such as pH, initial metal ion concentration, temperature, adsorbent dosage, and contact time. Thermodynamics and kinetics investigations were performed for Ni removal. The adsorption of Ni(II) was improved by incorporation of activated carbon to the parental Brassica botrytis leaves and Lycopersicon esculentum peel adsorbents. The studies revealed 40 min of equilibrium time for Ni(II) adsorption by different adsorbents. Adsorption of Ni was drastically declined by temperature with a minimum adsorption of 53% observed for BBL. Similarly, solution pH also played a vital role in Ni(II) adsorption by different adsorbents. A 95% adsorption of Ni was recorded in the case of LEP-AC at pH 7. The study concluded with the application of Lycopersicon esculentum peel and Brassica botrytis leaves as active adsorbents for Ni(II) adsorption from aqueous solution.