Initial Solution Concentration Research Articles

Preparation of g-C3N5 composites for butyl xanthate photocatalytic degradation

The nitrogen-rich graphite-phase carbon nitride (g-C3N5) supported TiO2 photocatalyst (Ti-CN) was prepared using TiO2 and 3-amino 1, 2, 4-triazole as raw materials for butyl xanthate residual (SBX) removal from mineral processing wastewater. The crystal, morphology, specific surface area and optical properties of the Ti-CN were characterized by XRD, TEM, UV–vis DRS, BET and PL. These results showed that TiO2 particles were uniformly dispersed on g-C3N5 nanosheets, and the heterojunction was formed. The formation of heterojunction improved its response to visible light, and promoted the separation of photoelectron-hole, contributing to improving its photocatalytic activity. The influence of catalyst dosage, initial SBX concentration and pH value of the SBX solution on SBX photocatalytic degradation removal was investigated. The Box-Behnken design of the response surface was used to optimize the process conditions to obtain the optimal experiment conditions with the pH of 7.04, catalyst dosage of 50.2 mg and SBX concentration of 56.6 mg/L. The SBX photocatalytic degradation removal of Ti-CN is 98.15 %, which is close to the predicted value of 97.75 % at the optimal experiment conditions. Meanwhile, the SBX degradation removal of Ti-CN still had 90.21 % after five cycles, indicating that Ti-CN has good stability. These results indicate that Ti-CN can be used as the promising photocatalyst for SBX from mineral processing wastewater.

Evaluation of a pH- and time-dependent model for the sorption of heavy metal cations by poultry litter-derived biochar

Common isotherm and kinetic models cannot describe the pH-dependent sorption of heavy metal cations by biochar. In this paper, we evaluated a pH-dependent, equilibrium/kinetic model for describing the sorption of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) by poultry litter-derived biochar (PLB). We performed sorption experiments across a range of solution pH, initial metal concentration, and reaction time. The sorption of all five metals increased with increasing pH. For Cd, Cu, and Pb, kinetics experiments demonstrated that sorption rates were greater at pH 6.5 than at pH 4.5. For each metal, all sorption data were described using single set of four adjustable parameters. Sorption edge and isotherm data were well described with R2 > 0.93 in all cases. Time-dependent sorption was well described (R2 ≥ 0.90) for all metals except Pb (R2 = 0.77). We then used the best-fit model parameters to calculate linear distribution coefficients (KD) and equilibration times as a function of pH and initial solution concentration. These calculations provide a more robust way of characterizing biochar affinity for metal cations than Freundlich distribution coefficients or Langmuir sorption capacity. Because this model can characterize metal cation sorption by biochar across a wider range of reaction conditions than traditional isotherm or kinetic models, it is better suited for estimating metal cation/biochar interactions in engineered or natural systems.

Pengaruh Konsentrasi Awal Larutan Ion Logam Cd2+ terhadap Penyerapan Biomassa Kulit Langsat (Lansium domesticum) yang Dimodifikasi Metanol

Industrial activities have been growing rapidly lately. Increased industrial activity can improve the quality of human life, but behind it there are adverse effects on the environment and human health. There are many harmful heavy metals found in industrial waste. One of them is cadmium metal, which is one of the dangerous heavy metals that if accumulated in the body can threaten human health. Langsat fruit peel waste can be utilized as an adsorbent. Adsorbent is an absorbent substance/material to absorb heavy metal ions. Biomass was characterized using AAS instrument to determine the concentration of Cd2+ metal ion absorption in langsat peel biomass. This study was conducted to determine the effect of the initial concentration of solution on the absorption of Cd2+ metal ions in methanol-modified langsat peel biomass. The results showed that the optimal absorption of Cd2+ metal ions in methanol-modified langsat peel biomass was at a concentration of 400 mg/L with an absorption capacity of 9.387 mg/g.

Adsorption of uranium (VI) from aqueous solutions using boron nitride/polyindole composite adsorbent

AbstractTurbostratic boron nitride (tBN) surface is modified with polyindole (PIn) by a facile polymerization technique and the uranyl adsorption efficiency of this mesoporous hybrid is investigated. The successful surface modification is confirmed by FT‐IR, Raman, XRD, TEM, SEM, EDX, EDS mapping XPS, BET, and zeta potential techniques. The batch experiments are performed in various temperatures (T), contact times (t), pH, and initial solution concentrations (C0) to evaluate its adsorption performance. The optimum adsorption performance is achieved at pH = 5.0–5.5, T = 307 K, t = 10 min, C0 = 18 mg L−1. These experimental results are evaluated using Freundlich, Redlich–Peterson, and Langmuir isotherm models, which presents equivalent regression coefficients. Maximum adsorption capacity (qm) of the nanoadsorbent (tBN/PIn), determined by the Langmuir isotherm, is 315.29 mg g−1. The adsorption kinetics of uranyl ions on tBN/PIn are in harmony with the pseudo‐second order model. tBN/PIn nanoadsorbent provides high adsorption efficiency even at exceptionally low UO22+ concentration range (4–40 mg L−1) and low adsorbent mass (0.005 g). XPS analysis results show that 0.05% of uranium is adsorbed on tBN/PIn via mainly U‐O coordination. The results of present study demonstrate that tBN/PIn can a potential adsorbent for removing uranium from aqueous solutions.

Adsorption of Cd2+ from aqueous solution onto composites based on powdered activated carbon and Maghnia clay adsorbents: experimental design, kinetic, equilibrium and thermodynamic study

ABSTRACT Cadmium and other heavy metals in landfills pose significant health and environmental risks due to their leaching potential into soil and groundwater when in contact with water or moisture. In this study, we synthesised two composites, composite I (C(I)) and composite II (C(II)), using Algerian clay and coconut shell-derived activated carbon. These composites are intended for controlled landfill waste management. The components are mixed at varying mass percentages, effectively adsorbing cadmium (Cd2+) from aqueous solutions. We conducted a parametric adsorption study using an experimental design. Cd2+ removal is more effective with composite C(II), reaching a Qmax of 163 mg.g−1 and an improved R of 59% at 25°C, while C(I) achieves a Qmax of 131 mg.g−1 and an R of 47%. The pH study indicated significant adsorption in the pH range [6–8]. The experiment utilised a screening design to optimise Cd2+ adsorption and establish the response surface. The coded variable Xi ranged from −1 (low) to + 1 (high) such as pH (X1: 2–6), temperature (X2: 25–45°C), composite mass (X3: 0.5–2.5 g.L−1), stirring speed (X4: 20–180 Oscillation/min), equilibrium time (X5: 60–120 min), and initial solution concentration (X6: 25–225 mg.L−1). The optimal values for X1, X4, and X6 were found to be 6, 180 Oscillation/min, and 185 mg.L−1, respectively.

Exploring the prebiotic potential of fermented glutinous rice filtrate: In vitro skin bacterial balance and biological activities

This study aimed to investigate the prebiotic potential of fermented glutinous rice filtrate (FRF) for the skin bacterial balance, evaluate its suitability for topical formulations, and gain insights into its prebiotic properties. The fermentation process was carried out using an inoculum of Saccharomycopsis fibuligera (S. fibuligera) under various conditions, including the amount of initial inoculum, inoculum strain, incubation time, and concentration of the rice solution. The fermented glutinous rice filtrate was screened for prebiotic activity, and the selected FRF candidate functional ingredient was evaluated for its composition and bacterial growth. An in vitro skin bacterial balance assessment was conducted using a cell culture model to examine the interaction between beneficial bacteria (Staphylococcus epidermidis) and pathogenic bacteria (Staphylococcus aureus). The viable counts of St. epidermidis were significantly higher in FRF treated than in Phosphate Buffer Saline incubation. Decreasing the amount of St. aureus were occurred in FRF incubated on the 2D and 3D skin models. Additionally, the antioxidant assay and anti-inflammation test were used to evaluate biological activities related to cosmetic applications. The results demonstrated that the prepared FRF had significant prebiotic activity on the skin bacteria model, with a nontoxic profile, making it a potentially useful tool for topical application. The finding of the study unveiled the potential of the optimized fermented glutinous rice within the green practices.

Adsorptive Removal of Chromium (VI) Ions from Aqueous Solution by Banana Pseudo Stem Adsorbent

The presence of Cr ions in wastewater must be treated before being released into the environment due to its detrimental impact on both the environment and human health. In this study, the removal of Cr (VI) ions from an aqueous solution was investigated by adsorption using an adsorbent derived from agriculture wastes, banana pseudo stem. The adsorbent was prepared by oven-drying the banana stem waste at 105C for 24 h. The surface structure of the adsorbent was characterized using scanning electron microscopy (SEM). Batch adsorption experiments were carried out to determine the removal efficiency of Cr (VI) ions based on four adsorption operation parameters: pH of the solution, adsorbent dosage, contact time and initial concentration of ion solution. At room temperature, the highest Cr (VI) ions removal of 88.2% was achieved using 0.5 g banana pseudo stem adsorbent, with an initial concentration of chromium solution of 500 ppm at pH 2 and after 90 min of contact time. For the equilibrium study, the experimental data were better fitted by the Langmuir isotherm model with a maximum adsorption capacity of 33.33 mg/g. Meanwhile, the kinetic isotherm was best fitted by the pseudo-second-order model. Therefore, the banana pseudo stem showed great potential as an efficient, low-cost and natural green adsorbent for Cr (VI) ions removal from an aqueous solution via adsorption.

Phosphorus removal from ore waste in aqueous solution with different mass of ore waste adsorbent from the Johor mine site

Abstract Mine waste management is becoming a growing global environmental concern for mining industries all over the world. Due to the abundance of ore waste from mining industries, this study aimed to observe the possibility of using ore waste to remove phosphorus from a solution. Although phosphorus is one of the essential elements for plant life, excessive phosphorus in water becomes one of the environmental issues, e.g., eutrophication. This study analysed the prediction contour of removal efficiency with the mass of adsorbent needed under different initial concentrations of solution. The batch experiment used an aqueous solution of 5 mg/L using potassium dihydrogen phosphate (KH2PO4) at different masses of adsorbent (2, 4, 6, 8, 10 g). The highest removal efficiency for phosphorus using 10 g of adsorbent is 54.3%. The data verified that the pseudo-second-order model (0.9976) fitted well. The adsorption between ore waste adsorbent and phosphorus was chemical sorption, whereas the analysis of isotherm models fitted the Freundlich model, with the occurrence of multilayer adsorption on the adsorption surface. The ability of ore waste to remove phosphorus was successful. This approach is one of the alternatives to enhance tertiary wastewater treatment technologies.

Preparation of modified expanded graphite and research on emulsified oil adsorption performance

Modified expanded graphite was prepared from expanded graphite and characterized by FT-IR, XRD and SEM. The results showed that the modified linear alkyl was successfully grafted onto the surface of expanded graphite, and the crystal structure and overall morphology did not change significantly after modification. Expanded graphite and modified expanded graphite adsorption columns were prepared, the adsorption experiment of emulsified oil was carried out. When the initial concentration of emulsion oil solution is 100 mg·L−1, the filling density is 3.5 g·L−1, and the flow rate is 3 L·h−1, the emulsion oil concentration decreases to 93 mg·L−1 and 6.5 mg·L−1, respectively, after adsorption by expanded graphite and modified expanded graphite, indicating that the adsorption performance of modified expanded graphite on emulsified oil is obviously improved. The saturated adsorbed modified expanded graphite was recycled by vacuum filtration. The results show that the modified expanded graphite still has good adsorption performance for emulsified oil after 1-3 times of regeneration, and can be used as adsorption material or recycled into sealing material.

Optimizing the synthesis process for Lithium-Ion sieve adsorbents: Effect of calcination temperature and heating rate on reaction efficiency and performance

Processing-structure–property relationships play a crucial role in tuning the performance of materials for a given application in order to attain a suitable set of optimal conditions, and it is therefore imperative to evaluate the parameters of either the synthesis, delithiation, adsorption, and desorption process. Through an orthogonal test design of the solid-state synthesis process, it was determined that a heating rate of 1 ℃/min had consistently higher reaction efficiencies of 68.1 %, 68.6 %, and 72.3 % at the calcination temperatures of 650 ℃, 700 ℃, and 750 ℃ respectively compared to heating rates of 4 ℃/min and 7 ℃/min. Moreover, a decrease in delithiation efficiency with increase in calcination temperature (99 % at 650 ℃, 96.1 % at 700 ℃, and 94.2 % at 750 ℃) at the 1 ℃/min heating rate was observed which was attributed to an increase in the average crystallite size. Adsorption performance of the synthesis-optimized zinc-doped lithium metatitanate showed consistently high adsorption efficiency (>90 %) despite the low adsorption capacity (4.9 mg/g) which was attributed to the low initial lithium-ion concentration of the lithium chloride solution and high adsorbent dosage.

Electrocoagulation technique and statistical analysis for treatment of real effluent from the pulp and paper industry

The electrochemical treatment of Organic Pollutants is a promising technique for substances with biodegradability resistance. In this research, the black liquor effluent originating from the Rakta Paper and Paper Company's mill, which employs rice straw as a raw material for paper fiber production, was subjected to treatment using the electrocoagulation method utilizing monopolar aluminum electrodes. The experiments were carried out using a 2.5 L electrochemical cell equipped with monopolar aluminum electrodes connected in parallel. The study examined the impact of operating parameters such as initial pH, current density, number of plates and electrolyte concentration on percentage removal and power consumption. The results revealed a positive correlation between the percentage of color removal and the duration of electrolysis, current density, sodium chloride concentration, and the number of electrodes used. The maximum color removal was observed at initial solution pH 6.5, experimental time 120 min, current density 61.8 A m−2, initial NaCl solution concentration 2 g L−1 and six aluminum plates. The statistical and mathematical data based on experimental results were analyzed using the central composite design from response surface methodology (RSM). The quadratic model is deemed appropriate owing to its substantial coefficient of determination (R2 = 0.99) and statistically significant p-value (≤ 0.0002), suggesting the model's significance. The experimental results indicate that the utilization of electrocoagulation as a treatment method for paper mill effluents has demonstrated superior efficacy compared to the adsorption technique.

Reaction microkinetic model of xylose dehydration to furfural over beta zeolite catalyst

AbstractIn recent decades, there has been a growing interest in bio-refineries as a crucial element in transitioning to a low-carbon economy. One specific aspect of this interest is the conversion of carbohydrates into separate platform chemicals, such as furfural (FUR), which play a significant functional role in various daily life processes. This research paper focuses on investigating the use of a H-beta catalyst with SiO2/Al2O3 = 28 for producing furfural from xylose in water. Various conditions, such as temperature and initial solution concentration, are studied to determine their effect on FUR yield. The highest FUR yield (40 mol.%) is obtained when FUR is the only product species. We also report that about 90% yield from reaction with fresh catalyst can be achieved after catalyst regeneration. The activation energies for the reaction on the catalyst surface are found to be in the range of 38–75 kJ/mol. A mathematical kinetic model with three irreversible steps is derived to estimate the reaction sequence at 160, 180, and 200 °C. The model takes into account mechanisms such as adsorption, desorption, and transport (internal or external). Our results suggest that the H-beta catalyst shows high activity toward FUR yield and could be a promising alternative for mass-scale production of the latter.

Intensifying of phenol removal from aqueous solutions using ACTF as a hybrid carbon nanostructure: Isotherms, kinetics and thermodynamics study

Activated carbon thin film (ACTF) was prepared via a single-step mixing method through thermal fabrication that was utilized for the removal of phenol in the batch aqueous media. The prepared adsorbent was characterized using TEM, XRD, FTIR, BET, EDX, Raman, and TGA analyses. Batch adsorption experiments were studied by using the effects of different parameters such as pH, temperature, dose, contact time, and initial concentration of phenol solution on adsorption. The maximum phenol removal by ACTF was approximately 89.5% at pH 4, adsorbent dose of 1 g/L, and 50 ppm for the initial concentration of phenol at room temperature through 150 min. Adsorption data were modeled using four adsorption isotherm models (Langmuir, Freundlich, Temkin, and D-R) and three kinetic models (pseudo first order, pseudo second order, and Intraparticle diffusion) using linear and non-linear regression methods. The chi-square (X 2) and the correlation coefficient (R 2) were both used as error analysis techniques to find the best-fitting equations. The results showed that phenol adsorption on ACTF adsorbent fitted more accurately with nonlinear regression models, which is consistent with Freundlich isotherm and pseudo-second order form. Also, thermodynamic results demonstrated that attachment of phenol onto ACTF adsorbent was spontaneous (negative value of ΔG) and exothermic (negative value of ΔH) with decreasing temperature from 55 °C to 25 °C. Synthesized ACTF showed good regeneration capacity with 0.1 M NaOH as the eluent, making it an appropriate adsorbent for the elimination of phenol. This study evidenced the efficacy of ACTF as a phenol adsorbent.

Preparation of agar functionalized graphene oxide-immobilized copper ferrite aerogel for dye degradation via dark-Fenton oxidative process

Dye and textile industries are one of the main causes of water pollution and put the environment and health of society at risk. Developing new materials to decontaminate industrial waste effluents containing dyes as pollutants is challenging due to numerous issues, including tailoring recyclable and biodegradable agents. This study focuses on applying an advanced oxidation process, electro-Fenton for the treatment of dye-containing wastewater using agar-functionalized graphene oxide-immobilized copper ferrite aerogel. The objective is therefore to determine the optimal conditions for the degradation of model pollutants methylene blue (MB). MB was oxidized and degraded through the dark-Fenton process using Agar@GO-CuFe2O4 as a new biobased catalyst. The effect of the operating parameters was then evaluated to determine the optimal conditions. The degradation process was screened for different initial concentrations of dye solution between 10 and 150 mg/l, a volume range of H2O2 between 0.5 and 2.5 ml, and different pH from 2 to 7. The results show that 99.89 % of the MB with the initial concentration of 150 ppm was degraded by 20 mg of the catalyst and 2 ml of H2O2 (30 % W/W) at 40 °C and pH = 6. Pseudo-second-order kinetics satisfactorily describes the experimental data. SynopsisThe prepared catalyst can be applied to oxidize industrial effluents before they are released into the environment.

Sorption of tartrazine dye from aqueous solution using activated carbon prepared from Cocos nucifera husk

Sorption of Tartrazine dye from aqueous solution using activated carbon prepared from Cocos nucifera (coconut) husk was investigated in this work. The coconut shell was first carbonized at 700°C in a muffle furnace and activated with NaOH for one hour. The activated carbon (AC) was applied to remove tartrazine from aqueous solutions over a concentration range of 50-250 mg/L respectively. Adsorbent features were determined using X-ray fluorescence (XRF), Fourier transformed infrared spectroscopy (FTIR), Scanning electron micrograph (SEM) techniques. Based on this investigation, adsorption of Tartrazine dye is strongly affected by initial solution pH, initial solution concentrations, dosage, and time of contact which favours the removal. Except for temperature which was found to decrease with increase temperature for AC, while adsorption capacity of Tartrazine was found to decrease with increase in adsorbent dosage for AC. The optimum pH for adsorption Tartrazine removal was found to be 3. The experimental data of Tartrazine was found to fit the linearized Langmuir isotherm better than the Freundlich isotherm and D-R model indicating a monolayer adsorption. On effect of initial solution concentration, adsorption capacity of Tartrazine was found to increase with increase in concentration for AC. Kinetic data fitted more into pseudo second order model than first order and intra particle diffusion model, suggesting that chemisorption dominate the rate limiting step. The calculated thermodynamic parameters – Gibbs free energy, enthalpy change and entropy change indicated that adsorption of Tartrazine was endothermic and not spontaneous meaning the chemisorption dominates physisorption.

Study on the ability to treat methylene blue in water and textile dyeing wastewater from sedge mats of the ZnAlCO<sub>3</sub> hydrotalcite modified by Cu<sup>2+</sup> ion under visible light

Hydrotalcite ZnAlCO3 and modified hydrotalcite CuZnAlCO3 were synthesized by a co-precipitation method from nitrate salts of Al, Zn and Cu as precursors. Using Na2CO3 salt to provide CO32- interlayer ion and NaOH 2N solution to adjust the pH of the reaction mixture to pH = 9.5. The obtained samples were characterized by physical analysis methods: XRD, EDX, SEM image, BET, UV-Vis DRS. The characterization results showed that the two synthesized samples H and 3CuH (molar ratio of Zn:Al and Cu:Zn:Al are 7:3 and 3:4:3 for H and 3CuH, respectively) had a lamellar structure similar to hydrotalcite with ions CO32- in the interlayer. The molar ratio of Zn:Al and Cu:Zn:Al in the samples is quite similar to the amount taken to synthesize the samples. The specific surface area increased from 16.1 to 33.9 m2/g, while the band gap energy Eg decreased from 3.02 to 1.25 eV, corresponding to H and 3CuH. The photocatalytic activity of the 3CuH sample in the decomposition reaction of methylene blue (MB) was much better than that of the sample H at the concentrations of MB investigated (10, 25, 50 ppm). The catalytic activity of the 3CuH material depended on the initial concentration of MB solution and the pH of the medium. Free radicals OH• and holes h+ play an important role in the photocatalytic activity of 3CuH material. In addition, the 3CuH sample is capable of effectively treating blue sedge textile dyeing wastewater with the decomposition efficiency of blue substances reaching over 94% after 4 hours of illumination, the mineralization efficiency of pigments reaching nearly 88% after 7 hours of lighting.

Porous metal-organic framework-acrylamide-chitosan composite aerogels: Preparation, characterization and adsorption mechanism of azo anionic dyes adsorbed from water

Micro- and nano-metal-organic frameworks with different adsorption properties were prepared by a time-modulation hydrothermal method. By comparing the adsorption properties, the most effective MIL-68(Fe)-12 was selected to be mixed with chitosan (CS), and porous metal-organic framework-acrylamide-chitosan composite aerogel (PMACA) was prepared by introducing acrylamide prior to glutaraldehyde crosslinking. The adsorption capacity of PMACA doped with acrylamide was as high as 2086.44 mg·g−1. The adsorption performance of PMACA was 1.48 times higher compared to the porous metal-organic framework-chitosan composite aerogel (PMCA) undoped with acrylamide. With the introduction of acrylamide, the stability of PMACA was improved, making it less prone to dispersion and decomposition. Structural characterization and adsorption properties were analyzed using methods such as XRD, FTIR, TGA, SEM, BET, and Zeta potential. The adsorption performance of PMACA was investigated further through batch tests with variables such as adsorbent dosage, pH, contact time, initial CR solution concentration, and temperature. The model fitting of PMACA was consistent with the pseudo-second-order model and the Sips model. The adsorption thermodynamics showed that high temperature promoted spontaneous adsorption behavior. PMACA showed a recovery rate of approximately 86 % after six cyclic adsorption tests. PMACA maintained a recovery rate of roughly 86 % after six cyclic adsorption tests. The combined effects of electrostatic attraction, hydrogen bonding, and π-π conjugation resulted in excellent adsorption performance, while pore filling also contributed to the efficient adsorption of Congo red (CR).

Fabrication of sodium alginate-doped carbon dot composite hydrogel and its application for La (III) adsorption and enhanced the removal of phosphorus.

Adsorption is an effective method for the removal of hazardous substances from wastewater. In this work, a low-cost and environmental-friendly composite hydrogel material of sodium alginate doped with nitrogen doped carbon dots (SA@NCDs) was fabricated by impregnation for lanthanide and enhanced phosphorus adsorption in wastewater. The effects of NCDs doping amount, dosage, pH, initial solution concentration, adsorption time and temperature on the process of La (III) adsorption by SA@NCDs were investigated. The adsorption isotherms fitted to Langmuir isotherm model (R2 = 0.9970-0.9989) and the adsorption kinetics followed pseudo-second-order kinetic model (R2 = 0.9992). The maximum adsorption capacity of the adsorbent for La (III) was 217.39mg/g according to the Langmuir model at 298.15K. After five cycles, the removal efficiency of La (III) adsorbed by SA@NCDs was still 85.1%. Moreover, the loaded La (III) enhanced the adsorption of phosphorus. The La (III)-SA@NCDs-5 hydrogel adsorbent greatly improved the adsorption capacity for phosphorus compared with the La (III)-free adsorbent, and the adsorption amount can reach 9.64mg-P/g. The SA@NCDs complex hydrogels for rare earth adsorption were prepared by introducing NCDs rich in amino group into SA hydrogels. The introduction of NCDs increases the adsorption sites of hydrogels, and also overcomes the problem that NCDs itself is difficult to recover in wastewater treatment applications. The lanthanide adsorbed material has a stable structure and can be used to remove phosphorus to deal with waste using the waste. It indicates the SA@NCDs hydrogel composite adsorbent have good potential for wastewater treatment.

A comparative study on the malachite green dye adsorption of chemically synthesized and green MgFe2O4 nanoparticles using gerbera floral waste extract.

The situation of discharging a large amount of dyes from the textile industries has caused many adverse effects on human health and the ecosystems. Emerging bio-nanomaterials represent a new trend in efficient dye removal in aqueous media. Herein, we mention that MgFe2O4 bioprepared using gerbera extract has been successfully used to adsorb malachite green (MG) in water. A comparison was made to determine the dye removal efficiency between biogenic MgFe2O4 (MFOB) and chemical MgFe2O4 (MFOC). The spherical MFOB material exhibited a large surface area of 85.0 m2 g-1 and high crystallinity. The obtained outcomes showed that the highest adsorption capacity of MG dye was 584.49 mg g-1 at a MFOB dose of 0.05 g L-1 and MG concentration of 10 mg L-1. Higher correlation coefficients in the Langmuir isotherm suggested monolayer adsorption of MG. The Box-Behnken design and response surface method were established to optimize MG removal percentage under the conditions, i.e., initial MG concentration (10-30 mg L-1), adsorbent dose (0.02-0.08 g L-1), and pH of dye solution (6-8). MFOB had good reusability with high removal efficiencies after three continuous cycles. Post reuse, this adsorbent still showed excellent stability through the verification of their structural properties in comparison with fresh MFOB, showing potential for practical applications.

Gold recovery from electronic wastes using a solvent extraction/selective back-extraction strategy

ABSTRACT The present lab-scale investigation describes a simple and efficient approach to the selective solvent extraction and recovery of gold, and copper as a by-product, from Waste Printed Circuit Boards (WPCBs) of different brands of used computers. The process comprised of three steps; leaching of scraps in aqua regia, solvent extraction process under optimized conditions, and ultimately selective back-extraction. The analysis of leach solution by inductively coupled plasma revealed, in addition to gold (0.14 wt%), copper (40.0 wt%), tin (11.9 wt%), and Ni (2.3 wt%) were the other main metals in the WPCBs. A solvent extraction procedure using trioctylamine, as extractant, dissolved in kerosene was employed for the extraction of gold as its anionic chloride-complexes from the leach liquor. The parameters affecting this process including hydrochloric acid concentration, equilibrium time, extractant concentration, initial gold concentration in the sample solution, and the aqueous/organic volume ratio were optimized by means of the statistical technique response surface methodology (RSM). Under the optimized extraction conditions, 99.6% of gold and 23.4% of copper were transferred into the organic phase, while the extracted percentage of other metal ions were negligible. Selective back-extraction by the solution 0.1 M NaOH resulted in the selective precipitation of copper, while the raffinate contained just gold ions.