South African Journal of Chemical Engineering最新文献

Techniques such as selective ion exchange can be used to remove traces of heavy metals. The recently created resins provided quicker sorption kinetics and a high resin capacity for metal ions such as Lead (Pb²⁺), Copper (Cu²⁺), Zinc (Zn²⁺), Cadmium (Cd²⁺), and Nickel (Ni²⁺) ions. The elimination of Pb²⁺ and Cu²⁺ ions from aqueous solutions was examined in the current work. Purolite® C100, a strong acid cation-exchange resin, was used in experimental studies. Using packed-column chromatography, the impacts of operating factors on metal ion exchange were examined. These parameters included resin dose, initial pH, residence time, and metal ion concentration with ranges of 40 - 80 gs, 3 - 12, 30 - 90 min, and 50 -150 parts per million respectively. As part of exchange research, different doses of resin are brought into contact with a fixed volume of solution containing different concentrations and pHs of Pb²⁺ and Cu²⁺ ions for different periods. An Atomic Absorption Spectrophotometer (AAS) approach was used to measure the concentrations of metal ions. Experimental data on ion exchange were evaluated using Langmuir, Freundlich, and Temkin models.

The results showed that there is a clear competition between lead and copper, as it was found that there is a convergence between the removal rates for both metals under the same conditions. The ion-exchange recovery of Cu approached 94.37 %, but Pb recovery was 92.9 % with Purolite® C100 resin dose range of 40 g to 80 g in the pH range of 3 to 12.

The current study presents a comprehensive analysis of the operational efficiency and performance evaluation of the Hazelmere Water Treatment Plant over the period from 1999 to 2018. By focusing on the removal efficiencies of few parameters including iron (Fe), turbidity, and E. coli, the study provides valuable insights into the plant's ability to treat water effectively and produce high-quality drinking water. Leveraging data analysis techniques and computational tools, the research also explores the forecasting of water quality parameters beyond the study period, enhancing predictive capabilities for monitoring and managing water quality in the future. The Hazelmere Water Treatment Plant (WTP) has a daily capacity of 75 Ml it supplies water to the surroundings. Its intricate treatment process, featuring chemical dosing, clarification, filtration, and disinfection, operates harmoniously. The plant consistently exceeded global standards. Effluent turbidity consistently met stringent World Health Organization/South African National (WHO/SANS) discharge standards at ≤ 1 NTU. The turbidity removal efficiencies ranged from 65.88 to 99.61 % on average over the period from 1999 to 2018. Iron removal also adhered to WHO/SANS criteria, registering ≤ 2 mg/L. The removal efficiencies have ranged from 82 to 99% on average for the same period. Most impressively, E. coli removal efficiency maintained a flawless 100 % for the same period, indicating a pathogen-free effluent throughout the period, with a steady annual average of 0 MPN/100 m, some challenges have occurred including the contamination of the freshwater from the dam, the limited data availability, and issues related to sustainability and compliance. These challenges were overcome by using advanced tools for data analyses such as R package, developing a performance evaluation framework and establishing recommendations for the adoption of innovative technologies, and improvements in operation and maintenance practices. Overall, this study makes significant contributions to the field of wastewater treatment and water quality management, advancing our understanding of sustainable water resource management and environmental protection.

Excessive iron content in well water can degrade water quality and cause health problems such as indigestion, poisoning, intestinal damage, bleeding gums, and arthritis. Immobilization of activated carbon from refill water and coconut shells on yarns is an alternative adsorption method for reducing dissolved iron levels within wells. Activated-carbon-immobilized yarns are packaged in the form of fiber filters to widen the application and make separation easier without further filtration. The purpose of this study is to determine the adsorption characteristics of ferrous metal adsorption in the relatively new adsorbent design with contact times of 10, 20, 30, 60, and 120 min. The research process began with the production of activated carbon, followed by the characterization, activated-carbon immobilized yarn, and adsorption study. Diluted HCl was the activating agent for samples (regenerated-water-refilled carbon and coconut shells carbon) and tapioca was the adhesive to stick carbon on the yarn. The best formula composition was just from the carbon-immobilized yarn stability, thickness, and surface homogeneity. The surface pores were observed by SEM and the metal absorbed was analyzed with the AAS method. The research finding shows that the optimum contact time of carbon-immobilized yarn with iron solutions was 30 min. Both the regenerated refilled carbon and coconut shell carbon follow the adsorption characteristics of the Freundlich isotherm model.

In the present work, removing of COD from wastewater generated via Al-Diwanya petroleum refinery plant located in Iraq by adsorption with activated carbon (AC) derived from avocado seeds was successfully performed via a two-step approach. In the first step, AC was prepared from avocado seeds via impregnating with H₃PO₄ at 400 °C where effects of H₃PO₄ concentration and calcination time on the specific surface area of AC were studied. Additionally, properties of the prepared AC were examined by XRD, SEM, and FTIR to knowledge the features of the internal structure of AC. Results showed that the prepared AC has mesopores structure with pore diameters in the range between 30.07 and 50.8 µm. Increasing the weight percent of H₃PO₄ led to an increase in the specific surface area of AC to reach a maximum value beyond which a decrease in the specific surface area was happened with further increasing in H₃PO₄ percent. Increasing the time resulted in an increase in the AC specific surface area to reach a maximum value beyond which a decrease in specific surface area was happened. The best value of AC specific surface area was 436.6 m²/g which obtained at 70 %H₃PO₄ and 4 h. At the second step, the performance of the prepared AC in removing of COD by adsorption process was evaluated via studying the effects of three operating parameters, namely adsorbent dosage (1–5 g/L), pH (3–9), and shaking speed (100–400 rpm) on the removal of COD(RE%) using a response surface methodology (RSM). Increasing AC dosage led to an increase in RE% while increasing each of pH and shaking speed resulted in lowering RE%. The optimum conditions for higher RE% were AC dosage of 5 g/L, pH of 3, and shaking speed of 100 rpm in which a removal efficiency of 94.54 % was obtained. The degradation of COD with time was found to obey a second order kinetic confirming the chemisorption is the rate limiting step in the adsorption process.

It is desired to improve the efficiency of liquid-liquid extraction processes in the fuel industry by reducing energy consumption and operational costs as well as reducing risk to health, safety and the environment. Co-solvent mixtures for extraction consisting of butane-1,4-diol, propane-1,2,3-triol (glycerol), and 2-methylpentane-2,4-diol (hexylene glycol) were assessed in terms of capital costs, operating costs and total annual costs relative to a baseline process that is employed for the liquid-liquid extraction of toluene from n-heptane. Commercial solvents such as sulfolane, morpholine-4-carbaldehyde (NFM), and dimethyl sulfoxide (DMSO) were used for the baseline processes that were simulated in ASPEN Plus V10. The capital costs ranged between 5.8–6.2 million US dollars, while the energy intensity ranged between 1000 - 1400 kJ/kg. The total annual costs for all solvents studied varied between 2.4 - 2.6 million dollars. The results highlighted that these co-solvent mixtures may offer some benefits in terms of total annual cost when the impact of solvent choice is holistically considered.

The measured thermobaric adsorption of anthracite coal “V_meas” contains 12 pairs of testing results at different temperatures (18∼72 °C) and corresponding pressures (1∼19 MPa), simulating the buried depth of 100∼1900 meter has been published by Zhang Qingling in 2008. A temperature-pressure-adsorption equation (TPAE) has been used to regress the measured data, then to calculate the 12 pairs of thermobaric adsorption data “V_cal”. The relative error and the standard deviation between the V_meas and the V_cal are calculated and used to verify TPAE's applicability for thermobaric adsorption data. The 3-dimensional TPAE surface is also used for verification. The other 3 sets of optimized thermobaric adsorptions (10 pairs, 8 pairs, and 6 pairs) have been created. To cover a range of temperature (18∼72 °C) and pressure (1∼19 MPa), there must be at least the minimum 6 pairs of thermobaric adsorptions including the lowest temperature 18 °C and pressure 1 MPa, and the highest temperature 72 °C and pressure 19 MPa.

In this study, surface modification of a cation exchange membrane based on polyvinyl chloride was accomplished via electrochemical deposition of post-sulfonated waste-expanded polystyrene aiming to enhance its electrochemical properties and electrodialytic performance. The membrane was synthesized by the phase inversion method, modified with different concentrations of polyelectrolyte, characterized by FTIR and SEM analyses, and applied for electrodialytic desalination of NaCl solution. Deposition of sulfonated polystyrene with polyelectrolyte concentration of 2 g/l, current of 8 mA/cm^2, and period time of 30 min caused a reduction in electrical resistance up to 52 %. Furthermore, the sodium ionic flux through electrodialytic desalination was improved by 58 % as a result of the promotion of the electrochemical properties of the membrane.

The main challenge with membrane bioreactors is fouling, which leads to decreased flux performance and a shortened membrane lifespan. This study aims to provide a solution for the flux recovery and removal of irreversible fouling on Polyvinylidene Fluoride (PVDF) membranes without damaging their structure using sulfate radicals. Sulfate radicals are formed via peroxodisulfate precursors that are activated by Fe²⁺. The membrane flux recovery and irreversible fouling ratio were 88.45-99.04% and 11.60-0.96%, respectively, at operating temperatures of 298-308 K. The PVDF membrane has been tested for microfiltration and washed up to 6 times per cycle. The mechanical properties, XRD, SEM-EDX, and ATR-FTIR characterization of the PVDF membrane after washing with PDS/Fe²⁺ did not show a negative effect on the PVDF structure. Additionally, the results of the kinetic and thermodynamic studies showed that washing with PDS/Fe²⁺ inhibited the formation of fouling particles on the membrane surface. Based on this study, sulfate radical oxidants with PDS precursors activated by Fe²⁺ can be applied as cleaning chemicals for PVDF membranes without damaging their structures.

Hydrogen energy is a sustainable and clean source that can meet global energy demands without adverse environmental impacts. High-entropy oxides (HEOs), multielement (5 or more) oxides with an equiatomic or near-equatomic elemental composition, offer a novel approach to designing bifunctional electrocatalysts. This work explores (ZnNiCoFeY)_xO_y over MoS₂ as a bifunctional electrocatalyst (HEO–MoS₂) in an alkaline medium. The HEO was synthesized using a combustion process and loaded over MoS₂ using an ultrasonic method. The synthesized HEO over MoS2 exhibits excellent performance, including long-term stability for over 24 h, an overpotential of 214 mV vs the reversible hydrogen electrode (RHE) for the hydrogen evolution reaction (HER), and 308 mV for the oxygen evolution reaction (OER) at 10 mA cm⁻². This bifunctional electrocatalyst exhibits low overpotential for both the HER and the OER at high current densities. Additionally, HEO–MoS₂ demonstrates smaller solution and charge transfer resistance values. The electrolyzer was assembled using bifunctional HEO–MoS₂ electrodes for overall water splitting. These electrodes exhibited a low cell voltage of 1.65 V at 10 mA cm⁻². The novel electrocatalyst was fabricated using a facile and scalable method that appeals to industrial applications.

High performing hemodialyzers membranes such as high flux membranes, high cut-off membranes and medium cut-off membranes are always at research interest due to their better efficiency than conventional membranes. These membranes provide greater toxin clearance, however retention of essential solutes in a preferable way are still under study. This paper aims at the design of high performing membrane to study the role of its parameters in solute removal and its capability of holding back important molecules. One of the most effective design of experiments (DOE) tool, namely Taguchi Algorithm was used for the formation of fractional factorial design of parameters. The simulation results were benchmarked with that of experimental data from literature and with manufacturers data sheets. Once the benchmarking was done, the error quantification and significance of each design were analysed using statistical method, Analysis of Variance (ANOVA) testing. The most relevant parameters that helped in better clearance in these membranes were thus identified and substantial conclusions were drawn which can be used in the future for designing optimal dialyzer designs. Results shows that clinically used dialyzer membranes such as RevaclearMax and FxCorDiax series on modelling using COMSOL Multiphysics with a blood flow rate of 400 ml/min and dialysate flow of 500 ml/min showed better urea clearance rate of above 300 indicating that the membranes thus designed was superior to the conventional high flux membranes that have a clearance rate of 297 of less for the exact same functional, geometrical, and parametric conditions. The model replication and thus validation of the design helped in understanding the influence of various parameters in toxin clearance. These parameters can be further investigated, and optimal models can be delivered with more of clinical examinations and trials.