Cost-effective Adsorbent Research Articles

Biochar as an Enzyme Immobilization Support and Its Application for Dye Degradation

Wastewaters generated by the textile industry often contain significant amounts of harmful (carcinogenic and mutagenic) cationic dyes, whose efficient removal is of crucial importance. This study investigates the laccase immobilization on biochar obtained from sour cherry stones (SCS-B), as a cost effective adsorbent, and evaluates its application for brilliant green (BG) degradation. The successful immobilization of laccase on biochar was achieved via adsorption and confirmed using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). An immobilization efficiency of 66% was achieved using 0.274 U/mL of laccase at pH 5 and a temperature of 40 °C. The adsorption kinetics of laccase followed a pseudo-second-order model, indicating that chemical adsorption plays a significant role in the immobilization process. The BG degradation by immobilized system was further optimized by evaluating effects of pH, temperature, dye concentration, and contact time. More than 92% of BG (50 mg/L) was removed within 4 h at pH 5 and temperature of 30 °C. These findings suggest that SCS-B can effectively be used as an enzyme carrier and be further utilized for the removal of emerging pollutants, positioning it as a sustainable solution for wastewater treatment.

Efficient treatment of Coking Wastewater by Coal-based Activated Carbon Prepared through Coal Blending Method

In this study, the adsorption performance of coal-based activated carbon produced from Shandong gas-fertilized coal, Taixi anthracite coal, and Datong weakly viscous coal, was investigated for coking wastewater treatment. All prepared activated carbons demonstrated excellent adsorption performance, boasting an iodine number surpassing 1000mg/g and achieving a chemical oxygen demand determined by the dichromate method (CODcr) removal rate of over 85% under static coking wastewater adsorption. A positive correlation exists between the total pore volume of activated carbon and its iodine number, methylene blue value, and caramel decolorization rate. Furthermore, dynamic adsorption experiments were conducted and there was an evident increase in the CODcr removal rate as the flow rate decreased. However, increasing the bed height beyond 400mm only marginally enhanced the CODcr removal rate. The burn-off rate of activated carbon and the ratio of raw materials significantly influenced the pore structure. Notably, with a high anthracite ratio (40%), elevating the burn-off rate (up to 70%) did not enhance the effective porosity of activated carbon. The mesopore volume, particularly within 1.2–2.8nm range, exerted a substantial influence on the coking wastewater adsorption efficiency. Overall, coal-based activated carbon demonstrated significant promise as a cost-effective adsorbent for coking wastewater treatment.

Ibuprofen Removal by Aluminum-Modified Activated Carbon (AC@Al) Derived from Coconut Shells

In this study, a new composite adsorbent consisting of aluminum-modified activated carbon (abbreviated hereafter AC@Al) was synthesized for the removal of the Ibuprofen compound (IBU), a non-steroidal anti-inflammatory drug (NSAID). Coconut shells were used as a source material for activated carbon, which was then modified with AlCl3 to improve its properties. Adsorbent dosage, pH and initial IBU concentration, as well as contact time and temperature, are some of the factors affecting adsorption that were investigated in this work. Specifically, at pH 2.0 ± 0.1 with the application of 0.5 g/L of AC@Al in 100 mg/L of IBU, more than 90% was removed, reaching 100% with the addition of 1.0 g/L of the adsorbent. The IBU kinetic data followed the pseudo-second-order kinetic model. Non-linear Langmuir, Freundlich, Sips and Redlich–Peterson isotherm models were used to interpret the adsorption. According to the correlation coefficient (R2), the Langmuir model was found to best match the experimental data. The maximum adsorption capacity (Qmax) according to the Langmuir model was found to be as high as 2053 mg/g. The positive values of ΔH0 (42.92 kJ/mol) confirmed the endothermic nature of the adsorption. Due to the increasing values of ΔG0 with temperature, the adsorption of IBU onto AC@Al proved to be spontaneous. Also, the adsorbent was regenerated and reused for five cycles. This study shows that AC@Al could be used as a cost-effective adsorbent.

Mitigation of Fluoride Contamination in Drinking Water Supply Sources by Adsorption Using Bone Char: Effects of Mineral and Organic Matrix

This study focused on fluoride (F−) contamination of water sources in Bahimi village, Cameroon. After the first investigation, results revealed that all water samples collected had elevated concentrations of fluoride ions (2.3 ± 0.1) mg/L to (4.5 ± 0.2) mg/L above the WHO guidelines (less than 1.5 mg/L). To mitigate the F− levels, the use of bone char (BC) as an adsorbent material was proposed and its performance was tested. BC was prepared from bovine bones at different calcination temperatures (350 °C, 450 °C, 550 °C and 650 °C) and residence times (1 h and 2 h). The prepared materials were characterized in detail by SEM/EDS, BET, FTIR, and XRD. The BET findings indicated that the surface area of BC samples decreased with increasing calcination temperature and residence time. At a lower heating temperature and holding time (350 °C, 1 h), the prepared BC exhibited a higher specific surface area (112.3 ± 0.3) m2/g and adsorption capacity for F− in the sampled water. Also, the batch adsorption experiments showed that the optimized adsorbent dose of 8 g/L facilitates the reduction in the F− level of the sampled water below the acceptable limit level (1.5 mg/L) within 5 min of treatment. The presence of Ca2+ and Mg2+ in natural water has a positive effect on the removal of F− in BC resulting in a high adsorption performance range of (72.5 ± 1.4)% to (80.3 ± 0.6)%. It was found that the adsorption of Ca2+ on the BC surface occurs via cation exchange with Na+. However, an increase in dissolved organic carbon (DOC) in the treated water limited the application of BC. Overall, the study presented a cost-effective adsorbent for the removal of this recalcitrant ion in the water source.

Adsorption isotherms and removal of lead (II) and cadmium (II) from aqueous media using nanobiochar and rice husk

Removal of Cd(II) and Pb(II) from aqueous solutions is a challenging task and the search for novel adsorbents is underway. This study examined the efficiency of nanobiochar (NB) and rice husk (RH) in the adsorption and removal of Cd(II) and Pb(II) from water. The effect of various physicochemical parameters such as initial pH, initial Cd and Pb concentration, adsorbent dosage, and contact time were tested. SEM/EDX images confirmed the adsorption of Pb and Cd with surface physical and chemical changes. The maximum Pb removal was noted at pH 6 using NB (96%) and at pH 8 for RH (90%), and the maximum Cd removal by NB was recorded at 8 pH (91%) and by RH at pH 6 (87%). The decline in adsorption intensity at lower pH suggested protonation of the adsorbent surface causing cation-cation repulsion. Most of the adsorption occurred within the initial 60 min. A continuous gradual increase in the adsorption with time suggested multilayer formation. Of the three isotherms, the Freundlich model fits the present data best, implying an infinite surface coverage and indicating the potential for multilayer adsorption of Pb and Cd on the surfaces of RH and NB adsorbents. In conclusion, this study highlights the promising potential of NB as a cost-effective adsorbent for the removal of Cd and Pb ions from aqueous solutions.

Synthesis of Montmorillonite-Silica Nanocomposite Using Millet Husk and Montmorillonite Clay and Optimization of Adsorption Parameters for Congo Red Dye Adsorption

Dyes are substances that, when applied to a substrate provides color by a process that alters, at least temporarily, any crystal structure of the colored substances The discharge of these effluents into the receiving environments results in hazardous health problems as most of these dyes have carcinogenic effects on the living organisms. Generally, dyes are classified into three categories: a) anionic: direct, acid, and reactive dyes; b) cationic: basic dyes; and c) non-ionic: disperse dyes. The chromophores in anionic and non-ionic dyes mostly consist of azo groups or anthraquinone types. However, Congo red, are difficult to biodegrade due to their complex aromatic structures, which provide them with physico-chemical, thermal, and optical stability. This study is aimed at synthesizing Montmorillonite-silica nanocomposite, a cost effective adsorbent from millet husk and Montmorillonite-clay with the determination of its optimum adsorption parameters for Congo Red Dye adsorption. Here, synthesis of Montmorillonite-silica nanocomposite and optimization parameters were carried out using standard procedures. The unbiased result demonstrated that the percentage yield was found to be 94.51 %. The optimum adsorption parameters studied were adsorbent dose, adsorbate concentration, pH and Kinetics studies. The optimum adsorption parameters were found to be 8.0 g/L, 2.0 mg/L, 8 and 30 minutes, respectively. Hence, the synthesized Montmorillonite-silica nanocomposite obtained from montmorillonite clay and millet husk ash can serve as a cost-effective adsorbent for the removal of Congo Red Dye from waste waters.

Automated kapok fiber-based pipette-tip solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry for rapid and sensitive analysis of tyrosine kinase inhibitors in plasma

This study delineates the development of a novel automated pipette-tip solid-phase extraction (SPE) methodology, employing kapok fiber as a naturally efficient and cost-effective adsorbent for the selective extraction of eleven tyrosine kinase inhibitors (TKIs) from plasma. The uniqueness of this method lies in its assembly, where kapok fibers are ingeniously wrapped around a stainless-steel spring within the pipette tip, ensuring an obstruction-free central space for effortless solution aspiration and dispensation. This design significantly minimizes backpressure, enhancing operational efficiency and ensuring compatibility with pipettors, including the implementation of an electric pipettor to streamline the sample preparation process and facilitate automation. The method's analytical performance, rigorously validated through liquid chromatography-tandem mass spectrometry, exhibits outstanding linearity in ranges of 0.1/0.5–200 ng mL-1 (R² > 0.993), commendable accuracy (86.3%–114.8%), and consistent precision (3.4–11.3%), alongside remarkably low detection limits that span from 0.024 to 0.130 ng mL-1. The assembly of kapok fiber within the pipette tip, in this unique configuration, results in a practical, cost-effective, eco-friendly, and automated pipette-tip SPE method. This innovation signifies a significant advancement in bioanalytical methodologies, offering an efficient and sustainable approach for extracting analytes from complex biological samples. This process notably enhances both the sensitivity and selectivity of subsequent instrumental analyses.

ZnO/nZVI nanoparticle-enhanced double-slope U-shaped solar distillation: A thermodynamic investigation of cephalexin adsorption

The increasing need for sustainable methods to remove pharmaceutical contaminants like cephalexin and improve water desalination is critical. This study explores ZnO/nZVI nanoparticles synthesized with Jackfruit peel extracts as eco-friendly, cost-effective adsorbents, enhancing water purification in solar desalination systems. This work used a matte black paint coating within a double slope U-shaped solar distiller (DSUD) in a discontinuous experimental setting to examine potential improvements in solar distillation performance. Activated carbon (AC) and bioactive powdered nanoparticles of ZnO/nZVI (nano zerovalent iron), produced from jackfruit peel extracts (JP) were combined in a synergistic way. The effectiveness of cephalexin removal was assessed taking into account the JPAC solution parameters, reaction duration, ZnO/nZVI concentrations in the nanocomposite dosage, and initial nanocomposite concentration. The best conditions for cephalexin adsorption were found to be pH 5 and reaction time of 50 min, which resulted in high absorption efficiencies of 94.74% (nZVI) and 97.53% (ZnO) at room temperature with a JPAC dose of 2.50 g L⁻1. The efficiency of the eco-friendly adsorbent in getting rid of cephalexin was calculated using “pseudo-second-order kinetics” for nanocomposites, which is consistent with the “Langmuir” isothermal absorption process. The nanocomposites as absorbent materials in solar thermal desalination processes, efficient heat transmission and energy storage have been established. JPAC and the addition of steel balls (S) with a silver hue to the DSUD improved the internal heat transfer mechanisms. Thermodynamic of Gibbs free energy and the Laplacian method (TGL), two thermodynamic concepts, were used to extensively study the temperature dynamics of the DSUD with SJPAC components. For ZnO/JPAC, an exceptional distillate production rate was noted from 8:00 to 18:00, with a noteworthy 4.932 L/m2 output in winter and 5.833 L/m2 per day in summer. Using silver balls, ZnO/JPAC generated significant yields over a 24-h period: 8.957 L/m2 in summer and 7.253 L/m2 in winter, with an ideal energy efficiency of 51.05%. The unique advancements in TGL procedures and their environmental consequences are presented in this paper. The field of thermal energy transduction will advance if silver balls are used in DSUD for the synthesis of JPAC, ZnO/JPAC, and nZVI/JPAC, as supported by the theoretical insights presented here.

Performance study of phenol sequestration from agricultural wastewater by chemical activated Montmorillonite

Agricultural by-products possess potential as cost-effective adsorbents for the remediation of phenolic contaminants in environmentally treated wastewater. This research focuses on the utilization of Algerian montmorillonite clay, specifically modified montmorillonite (Mo-5N), treated with 5N hydrochloric acid (HCl), compared to its untreated form (Mo-0N), for phenol sequestration from pesticide-laden waters. We employed various analytical techniques, such as chemical analysis, X-ray diffraction (XRD), and Fourier Transform Infrared (FTIR) spectroscopy, to characterize these adsorbents. The adsorption behavior was scrutinized under varying conditions, including pH, contact time, phenol concentration, and temperature. The maximum adsorption capacities achieved were 119.12 mg/g for Mo-5N and 100.89 mg/g for Mo-0N under optimal conditions of pH 5.72, a contact time of 120 minutes, and a temperature of 40°C. The kinetics of adsorption were best described by the pseudo-second-order and Elovich models, while the Freundlich isotherm model aptly described the equilibrium data. Thermodynamic analyses revealed that the phenol removal process using both forms of montmorillonite is spontaneous and endothermic. This study demonstrates the efficacy of Algerian montmorillonite clay in the removal of phenolic pesticides from agricultural wastewater.

Near-Complete Phosphorus Recovery from Challenging Water Matrices Using Multiuse Ceramsite Made from Water Treatment Residual (WTR)

Water treatment residual (WTR) is a burden for many water treatment plants due to the large volumes and associated management costs. In this study, we transform aluminum-salt WTR (Al-WTR) into ceramsite (ASC) to recover phosphate from challenging waters. ASC showed remarkably higher specific surface area (SSA, 70.53 m2/g) and phosphate adsorption capacity (calculated 47.2 mg P/g) compared to previously reported ceramsite materials (< 40 m2/g SSA and < 20 mg P/g). ASC recovered over 94.9% of phosphate across a wide pH range (3 – 11) and generally sustained > 90% of its phosphate recovery at high concentrations of competing anions (i.e., Cl-, F-, SO42-, or HCO3-) or humic acid (HA). We challenged the material with real municipal wastewater at 10°C and achieved simultaneous phosphate (>97.1%) and COD removal (71.2%). Once saturated with phosphate, ASC can be repurposed for landscaping or soil amendment. The economic analysis indicates that ASC can be a competitive alternative to natural clay-based ceramsite, biochar, or other useful materials. Therefore, ASC is an eco-friendly, cost-effective adsorbent for phosphate recovery from complex waters, shedding light upon a circular economy in the water sector.

Kinetics and thermodynamics investigations of efficient and eco-friendly removal of alizarin red S from water via acid-activated Dalbergia sissoo leaf powder and its magnetic iron oxide nanocomposite.

The present work aimed to highlight an efficient, readily accessible, and cost-effective adsorbent derived from Dalbergia sissoo (DS) leaf powder for removing the environmentally hazardous dye "alizarin red S" (ARS) from hydrous medium. A variant of the adsorbent is activated via sulfuric acid and composited with magnetic iron oxide nanoparticles (DSMNC). Both adsorbents are thoroughly characterized using techniques such as Fourier transform infrared spectroscopy, point of zero charge, energy-dispersive X-ray spectroscopy, and scanning electron microscopy, which show that they have a porous structure rich in active sites. Different adsorption conditions are optimized with the maximum removal efficiency of 76.63% for DS and 97.89% for DSMNC. The study was highlighted via the application of various adsorption isotherms, including Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich, to adsorption data. Pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were utilized to investigate the kinetics and mechanism of adsorption. The Freundlich model and pseudo-second-order kinetics exhibited the best fit, suggesting a combination of physical interactions, as confirmed by the D-R and Temkin models. The dominant adsorbate-adsorbent interactive interactions responsible for ARS removal were hydrogen bonding, dispersion forces, and noncovalent aromatic ring adsorbent pi-interactions. Thermodynamic parameters extracted from adsorption data indicated that the removal of the mutagenic dye "ARS" was exothermic and spontaneous on both DS and DSMNC, with DSMNC exhibiting higher removal efficiency.

Surface charge alteration of charcoal derived from bamboo leaves and understanding the interaction with anionic and cationic dye

Cost-effective adsorbents derived from regenerative sources provide a sustainable solution to the pressing environmental pollution challenges. Conventional studies often rely on biochar-based adsorbents obtained at high carbonization temperatures in an induced environment. The present study explored the efficacy of carbon derived from the stems (CBS) and leaves (CBL) of bamboo plants as efficient dye adsorbents at low carbonization temperatures. CBL carbonized at 350 °C exhibited a remarkable dye adsorption efficiency of 90%, significantly outperforming CBS, which achieved only 39% efficiency. To enable the adsorption of both dyes, heterophase metal oxides, specifically Fe-doped ZnO and ZnFe2O4 were incorporated. Zeta potential measurements revealed a transition from negative to positive values with metal oxide incorporation, suggesting alterations in the surface acidity and functional group composition. The adsorption performance of the composite (WC20) sample was evaluated using Congo Red (CR) and Crystal Violet (CV) dyes. Comprehensive studies on the adsorption kinetics, isotherm modeling, and thermodynamics have been conducted to identify WC20 as the most effective composite. The equilibrium adsorption data aligned well with the Langmuir isotherm model, demonstrating maximum adsorption capacities of 65.31 mg g−1 for CR and 38.05 mg g−1 for CV at room temperature of 298 K with constant pH. Thermodynamic analysis indicated a hybrid adsorption mechanism, wherein CR adsorption was predominantly driven by chemisorption, whereas CV adsorption was governed by physisorption. Mechanistic insights have revealed that electrostatic interactions and π–π stacking play crucial roles in dye removal. These findings underscore the potential applicability of WC20 as a cost-effective and efficient adsorbent for the remediation of both cationic (CV) and anionic (CR) dyes in wastewater, highlighting its viability for future environmental management and pollution mitigation strategies.

Multiple-amine functionalized γ–Al2O3 for post-combustion CO2 capture: Performance, mechanism, and kinetics

High-efficiency and cost-effective adsorbents are crucial to dry capture of carbon dioxide (CO2). The polyethyleneimine (PEI) was co-impregnated with tetraethylenepentamine (TEPA) on γ-alumina (Al2O3) to synthesize the adsorbent and enhance the capture process. The influence of amine loading and operating parameters on CO2 adsorption was investigated, and the process parameters were modeled. The results depict that the optimal loading is 50 % when functionalized either PEI or TEPA individually, which is 3.7 and 4.6 times higher than γ–Al2O3. The CO2 capacity of γ–Al2O3 functionalized with multiple amines (30 %PEI+20 %TEPA) is 2.65 mmol/g, due to the synergies of the two amines to increase the chance of CO2 binding to the sites. Regeneration performance illustrates that the adsorbent remains at 90.2 % of the initial capacity after seven tests. The maximal capacity of 2.70 mmol/g occurs at 70 °C. Modeling results indicate the kinetics can be evaluated by the Avrami model (R2 > 0.990) with the activation energy of 5.65 kJ/mol. The process is controlled by physical–chemical adsorption, influenced by intraparticle diffusion, as described by the deactivation model. Finally, a comparison and assessment were conducted for their techno-economic performances, and the pathway to applications was also proposed in engineering practice.

Fluoride Removal in Water Using Kaolin and Eggshell Powder Blend Adsorbents

Fluoride contamination in water has emerged as a significant global concern due to its adverse health effects when consumed in excess. This study is focused on developing an eco-friendly, cost-effective adsorbent for fluoride removal using eggshells and kaolin. Adsorbent blends were prepared by mixing kaolin and eggshell powder in six different ratios, namely; 100:0, 80:20, 65:35, 50:50, 35:65, and 20:80. Cylindrical-shaped pellets were produced from each of the blends and subjected to the thermal treatment at 950 ◦C. Fluoride adsorption capacities of the pellets were investigated at different pH conditions (from pH 2 to pH 10) for a 5 mg/L fluoride solution with 1 g of adsorbent dosage and 60 min of contact time. Pellets with a 50:50 ratio (CKE3) were found to be the most effective adsorbent considering the adsorption capacity and stability at all the studied pH conditions. At pH 6, CKE3 showed an adsorption capacity of 0.06 mg/g compared to 0.02 mg/g of kaolin-only pellets. XRD, TGA-DSC, EDX and SEM analysis were used to characterize the adsorbent. XRD analysis showed that the raw adsorbent contained phases of CaCO3 and kaolinite, whereas the calcined material comprised Ca(OH)2 and metakaolinite. Batch experiments were carried out with CKE3 for adsorbent dosage, pH, contact time, and initial fluoride concentration. An adsorbent dosage of 4 g was capable of resulting in a 53% removal of fluoride for a 5 mg/L solution after 60 min of contact time. Pseudo-first-order and pseudo-second-order kinetic models were applied in the study, and pseudo-second-order exhibited the best fit. The isotherm data were studied for Langmuir and Freundlich models, and the results were satisfactorily fitted with Langmuir isotherm.

Efficient adsorption of acid orange 7 from wastewater using novel bio-natural granular bentonite-sawdust-corncob (GBSC): Mixture optimization, adsorption kinetic and regeneration

The removal of dyes from industrial wastewater is one of the most environmental challenges that should be addressed through sustainable technologies. In this study, a novel green and cost-effective granular from bentonite and bio-wastes of sawdust and corncob (GBSC) was prepared for sustainable treatment of acid orange 7 (AO7) dye wastewater. The d-optimal mixture method was employed to determine the optimum combination of the GBSC in terms of dye adsorption and structure stability. Characterizations of the GBSC were investigated using SEM, XRD, FTIR and BET analyses and compared with bentonite powder (BP), modified bentonite powder (MBP), and granular modified bentonite (GMB). According to the results, a mixture of bentonite 60 wt%, sawdust 20 wt% and corncob 20 wt% at 550 °C yielded the optimal combination of the GBSC which resulted to the highest adsorption capacity 135.22 mg/g, the lowest mass loss 3.1% and maximum crushing strength 12.275 N. The kinetic and isotherm of the adsorption data were fitted well by the pseudo-second-order model and Langmuir isotherm. Our finding suggested a green circular economy model by utilizing agriculture wastes (sawdust and corncob) to synthesize GBSC for sustainable dye wastewater treatment, which offers a cost-effective adsorbent (0.907 $/g) with high regeneration (4 times reusability with 40.5% removal rate) to keep them in circulation for as long as possible.

Adsorption parameters optimization of spent coffee ground biochar for methylene blue removal using response surface methodology

This study investigates the potential of spent coffee ground biochar (SCGB) as a sustainable and cost-effective adsorbent for the removal of methylene blue (MB), a hazardous dye commonly used in the textile and printing industries. A response surface methodology (RSM) approach with central composite design (CCD) was employed to systematically investigate the effects of key process parameters, including adsorbent dosage, solution pH, contact time and temperature, on MB removal efficiency. The analysis revealed that adsorbent dosage and temperature as critical factors influencing MB removal, with a linear model providing a strong correlation. Optimal conditions for MB removal were determined to be 0.99 g of SCGB, 30 min of contact time, 30 °C temperature, and a solution pH of 7. Under these conditions, MB removal reached 99.99%, with a desirability of 1.000. The experimental results closely matched the predicted values, differing by only 0.02%, thus validating the accuracy of the model. Kinetic studies indicated a rapid adsorption process, well-described by both pseudo-first and pseudo-second order models. Isotherm analysis confirmed the applicability of the Freundlich model, suggesting favorable adsorption with increasing MB concentration. The high adsorption capacity of SCGB is attributed to its carbonaceous and porous structure, highlighting its potential as an effective adsorbent for dye removal in wastewater treatment applications.

Boosted adsorptive removal of eosin yellow dye from aqueous solution with C–ZnO nanoparticles: optimization of process parameters

This study investigates the effectiveness of ultrasound-aided sorption using carbon–doped zinc oxide nanoparticles (C–ZnO NPs) for the removal of eosin yellow dye (EY) from wastewater. Raman spectroscopy was employed to confirm the successful carbon doping in the ZnO lattice, while field emission scanning electron microscopy (FESEM) was used to observe the morphology of the C–ZnO NPs, revealing uniform pseudo-spherical grains with diameters ranging from 20 to 35 nm. The impact of important parameters such as EY base concentration (50–200 mg/L), C–ZnO NPs dose (0.125–1.0 g/L), initial solution pH (2.0–10.0), and reaction time (1–30 minutes) on EY dye removal was investigated to assess the adsorptive potential of C–ZnO NPs. The highest sorption efficiency of 95.90 ± 0.96 % for EY dye was achieved within 20 minutes using C–ZnO NPs dose of 0.50 g/L, a solution pH of 4.0, and at an EY base concentration of 50 mg/L. The adsorption followed pseudo-second-order kinetics and Langmuir isotherm, with a sorption capacity of 232.59 ± 1.36 mg/g. Sono-assisted adsorption outperformed with a performance of 98.96% ± 0.85% as compared with conventional methods like magnetic stirring and overhead stirring, which had a performance of 73.24% ± 1.90% and 78.06% ± 2.0% respectively. C–ZnO is found to be a cost-effective adsorbent due to its low production cost of 31.0 $/kg and high reusability. As a result, this work emphasizes the prospective use of C–ZnO NPs as adsorbent for EY removal from wastewater on account of high sorption efficiency, superior adsorptive performance over ZnO NPs, and its cost effectiveness.

Cost-efficient removal of organics from Bayer liquor by tricalcium aluminate hexahydrate: Insights into the organic micelle and multilayer adsorption

The existence state and effective removal of organics from Bayer liquor have troubled the alumina industry for six decades. This study delved into the aggregation behavior and micellization of organics in Bayer liquor. Tricalcium aluminate hexahydrate (3CaO·Al2O3·6H2O, TCA) was then employed as a cost-effective adsorbent to remove organics by regulating the aggregation behavior of organics. Sodium dodecylsulfate (SDS), acting as a research object of organics, aggregated into inhomogeneous and large micelles (>3080.00 nm) with an extremely low critical micelle concentration (CMC) of 0.14 mmol·L−1 in the sodium aluminate solution (CNa2O = 2.42 mol·L−1, αK = 3.0, I ≥ 4.84 mol·L−1) at 298 K. Decreasing temperature facilitated the formation of these large micelles and the micellar size reached 2.20 μm in length. The solvated Ca2+ (Ca(OH)+) of TCA, acting as counterions with a content exceeding 11.97 wt%, initially induced the formation of micelles and then enlarged their size. Furthermore, these large micelles exhibited a preferential aggregation at the active concave of TCA. As a result, the interaction among inhomogeneous micelles, solvated Ca2+ (Ca(OH)+), and special active concave collectively contributed to the maximum organic carbon adsorption capacity of 32.46 mg·g−1 (equivalent to 64.92 mg·g−1 of SDS) at 298 K. These results open up new perspectives for understanding the existence state of the anionic organics in sodium aluminate solutions, as well as a cost-effective and eco-friendly approach to removing organics from Bayer liquor.

Remediation of cationic dye from aqueous solution through adsorption utilizing natural Haloxylon salicornicum: An integrated experimental, physical statistics and molecular modeling investigation

Wastewater emanating from declining industrial processes often presents a vexing challenge due to its intricate composition replete with hazardous chemicals. The quest for environmentally sustainable methods to remediate such wastewater has led to the exploration of biomaterials as adsorbents and co-substrates within diverse treatment systems. In this study, we harnessed the abundant and cost-effective adsorbent, Haloxylon salicornicum (HS), as a potent agent for the removal of the pernicious triphenylmethane dye, crystal violet, from aqueous mediums. The adsorbent was characterised using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), while Brunauer-Emmett-Teller (BET) analysis yielded a specific surface area (SBET) of 85.23 m2 g−1, highlighting its advantageous mesoporous structure for adsorption. Comprehensive investigations were conducted across various operational parameters, encompassing initial dye concentration, contact time, HS adsorbent dosage, initial pH, and temperature, with a keen focus on their influence on dye removal efficiency. The results unveiled several key trends, demonstrating that elevated initial dye concentration, prolonged contact time, and higher initial pH levels substantially enhanced the efficiency of dye removal, while ionic strength and temperature exhibited comparatively modest impacts. The kinetics of dye adsorption were rigorously examined, revealing a closer adherence to the pseudo-second-order model in comparison to the PFO model, thereby offering deeper insights into the adsorption dynamics. To further unravel the intricate mechanism underpinning the adsorption of CV on HS, we employed a single-layer model linked to SLMRG. In conjunction, DFT calculations, encompassing COSMO-RS, NCI, Molecular Dynamics (MD) simulations and QTAIM calculations, were applied to probe the interactions between adsorbed CV and the adsorbent-molecules, providing compelling evidence of robust binding interactions. These theoretical insights were subsequently aligned with empirical observations, affirming a significant relation between the theoretical and experimental data. This multifaceted study not only advances our understanding of CV removal using HS but also underscores the robustness of this adsorbent within the context of wastewater treatment. Furthermore, it demonstrates the synergy of empirical investigations and theoretical modeling in unraveling the intricacies of adsorption processes.

Sustainable industrial process design for derived CO2 adsorbent from municipal solid wastes: Scale-up, techno-economic and parametric assessment

Climate change and carbon emissions attributed to anthropogenic activities is getting alarming dimensions. On the other hand, the overwhelming progress of industrialization and urbanization contributed to an explosion in the municipal solid waste (MSW), as one of the other global challenges. However, developing a cost-effective adsorbent with appealing textural properties for CO2 capture is still one of the main challenges. Lately, carbon-based solid waste materials of biogenic origin have received a major interest to this end, owing to the renewability, availability and low-cost. Routinely, academic research mainly focuses on lab-scale development of activated carbons derived from waste materials. However, there is a significant gap concerning the industrial production of activated carbon from such materials. Accordingly, in this work, an industrial plant has been designed for producing activated carbon derived from digestate of MSWs in the industrial scale by presenting all scale-up details, engineering assumptions and process specifications. The results indicated that the plant has a potential to process 90,273 ton MSW annually, which consumes 1367.8 MWh net electricity and 20,134.4 GJ net heat, also produces 4788.10 ton CO2 adsorbent, per year. The economic assessment specified that the plant capital cost is around $14.112 million with the net price of 0.61 $/kg for produced activated carbon. Further, the sensitivity analysis and parametric study determined that the sample level in the drum is the determinative parameter on the energy consumption and net price of adsorbent. Finally, Response Surface Methodology was employed to maximize the plant profitability concerning the designing factors.