Fly Ash Adsorption Research Articles

Penurunan Kadar COD Air Limbah Domestik Menggunakan Fly Ash dengan Metode Adsorpsi

Domestic wastewater was collected from a drainage system on Soekarno Hatta Street, Kalibalau Kencana, Kecepatan District, Bandar Lampung City, with a high Chemical Oxygen Demand (COD) content of 4,867 mg/L. If the wastewater is discharged directly into water bodies, it can reduce the availability of dissolved oxygen, potentially disrupting the survival of aquatic organisms. This research aims to determine the effect of contact time on the reduction of COD levels in domestic wastewater, the effect of fly ash adsorbent both activated and non-activated on the reduction of COD values, and its impact on other parameters according to domestic wastewater quality standards. Fly ash was activated using 6M NaOH and heated at 160°C for 1 hour. The adsorption process was carried out with varying contact times of 30, 60, 90, 120, and 150 minutes, using both activated and non-activated adsorbents with masses of 1.5 and 3 grams. The results of this study showed that the adsorption test with the activated adsorbent with masses of 1.5 and 3 grams reached optimum times of 90 and 60 minutes, respectively, with percentage reductions of 98.78% and 99.03%. In contrast, for the non-activated adsorbent with masses of 1.5 and 3 grams, optimum times occurred at 150 minutes, with percentage reductions of 95.64% and 90.79%, respectively.

Measuring concrete air-entraining admixture adsorption on coal ash using three-phase equilibrium and fluorescence-based methods

This manuscript presents two novel methods of evaluating the adsorption of air-entraining admixtures (AEAs) by coal ashes used in cementitious mixtures. A developed three-phase equilibrium (TPE) method measures fly ash adsorption capacity accounting for carbon adsorption, Ca2+ interactions with AEA, and the equilibrium between the two. A fluorescence-based method (FBM) was also developed, utilizing a non-ionic NP-10 surfactant as a representative for AEA. This study verifies the applicability and accuracy of the TPE and FBM methods using seven class C and F coal ashes with a wide range of loss on ignition values, varying from 0.2 to 15.6 %, and three commercial AEAs. Verified with foam index test results, the TPE method was applicable to all tested AEAs and coal ashes. The results were consistent between the FBM and TPE methods when comparing rosin- and fatty acid-based AEAs, but less consistent when using a sulfonate-based AEA. These findings help us understand the applicability and limitations of the TPE and FBM methods and provide two methods for quantifying adsorption in fly ash samples.

Decoration of Chitosan-Benzaldehyde/Algae/Coal Fly Ash Adsorbent for Brilliant Green Dye Removal: Box–Benken Design Optimization and Mechanism Approach

Decoration of Chitosan-Benzaldehyde/Algae/Coal Fly Ash Adsorbent for Brilliant Green Dye Removal: Box–Benken Design Optimization and Mechanism Approach

A thorough investigation into the adsorption behavior of sophorolipid-modified fly ash towards compound pollution of lead and tetracycline

Heavy metal ions and antibiotics were simultaneously detected in authentic water systems. This research, for the first time, employed synthesized sophorolipid-modified fly ash(SFA) to eliminate tetracycline(TC) and lead(Pb2+) from wastewater. Various characterization techniques, including SEM-EDS, FTIR, XPS, BET, and Zeta, were employed to investigate the properties of the SFA. The results showed that the sophorolipid modification significantly improved the fly ash's adsorption capacities for the target pollutants. The static adsorption experiments elucidated the adsorption behaviors of SFA towards TC and Pb2+ in single and binary systems, highlighting the effects of different Environmental factors on the adsorption behavior in both types of systems. In single systems, SFA exhibited a maximum adsorption capacity of 128.96 mg/g for Pb2+ and 55.57 mg/g for TC. The adsorption of Pb2+ and TC followed pseudo-second-order kinetics and Freundlich isotherm models. The adsorption reactions are endothermic and occur spontaneously. SFA demonstrates varying adsorption mechanisms for two different types of pollutants. In the case of Pb2+, the primary mechanisms include ion exchange, electrostatic interaction, cation-π interaction, and complexation, while TC primarily engages in hydrogen bonding, π-π interaction, and complexation. The interaction between Pb2+ and TC has been shown to improve adsorption efficiency at low concentrations. Additionally, adsorption-desorption experiments confirm the reliable cycling performance of modified fly ash, highlighting its potential as a cost-effective and efficient adsorbent for antibiotics and heavy metals.

Study on the adsorption performance of fly ash loaded on nano-FeS for chromium-containing wastewater treatment

In view of the problems caused by chromium-containing wastewater, such as environmental pollution, biological toxicity, and human health risks. Based on fly ash adsorption and nano-FeS reduction characteristics, fly ash loaded nano-FeS composite (nFeS-FA) was synthesized using mineral supported modification technology and ultrasonic precipitation method. The effect of adsorbent dosage, initial pH, contact time, and initial concentration of the solution on the adsorption of Cr(VI) and total Cr by nFeS-FA was investigated. The characteristics of Cr(VI) and total Cr adsorption by nFeS-FA were studied using adsorption isotherms, adsorption kinetics principles, as well as XRD, TEM, SEM-EDS, and BET analysis. The results demonstrated that under the conditions of nFeS-FA of 8 g/L, initial pH of 4, contact time of 150 min, and initial concentration of the solution at 100 mg/L, nFeS-FA achieved removal efficiency of 87.85 % for Cr(VI) and 71.77 % for total Cr. The adsorption of Cr(VI) and total Cr by nFeS-FA followed the Langmuir model and pseudo-second-order kinetic model, indicating monolayer adsorption with chemical adsorption as the dominant mechanism. XRD, TEM, SEM-EDS, and BET revealed that the flaky nano-FeS was uniformly distributed on the surface of fly ash, exhibiting good dispersion and thereby increasing the specific surface area. During the adsorption experiments, nFeS-FA reacted with Cr(VI), and the generated Fe3+ mainly existed as FeOOH precipitation, while S2− reacted with Cr(III) to produce Cr2S3 precipitation. Therefore, nFeS-FA exhibited excellent adsorption performance towards Cr(VI) and total Cr. It can serve as a technological reference for the remediation of heavy metal chromium pollution in the field of water treatment.

The efficient uptake of uranium by amine-functionalized β-cyclodextrin supported fly ash composite from polluted water

A novel polyethyleneimine/polydopamine-functionalized β-cyclodextrin supported fly ash adsorbent (PEI/PDA/β-CD/FA) had been synthesized to uptake uranium from polluted water. At pH = 5.0 and T = 298 K, the uranium uptake efficiency and capacity of PEI/PDA/β-CD/FA reached to 98.7 % and 622.8 mg/g, respectively, which were much higher than those of FA (71.4 % and 206.7 mg/g).The excellent uranium uptake properties of PEI/PDA/β-CD/FA could be explained by three points: (1) using β-CD as a supporting material could effectively avoid the aggregation of FA and improve the hydrophily of FA; (2) the unique cavity structure of β-CD could form chelates with uranyl ions; (3) the formation of PEI/PDA co-deposition coating on FA further enhanced the affinity of FA to UO22+. With the presence of interfering ions, the uptake efficiency of PEI/PDA/β-CD/FA for uranium was still up to 94.5 % after five cycles, indicating the high selectively and recoverability of PEI/PDA/β-CD/FA. In terms of the results of characterizations, uranium was captured by PEI/PDA/β-CD/FA via electrostatic attraction, hydrogen bond, coordination and complexation. To sum up, PEI/PDA/β-CD/FA was expected to be used for actual sewage treatment owing to its excellent uranium uptake efficiency/capacity, selectivity, cycle stability and feasibility of actual application.

Potential of microwave-assisted hydrothermal modification for enhanced fly ash adsorption capacity toward to heavy metals: A comprehensive investigation of adsorbent characterization, isotherms, kinetics, and thermodynamics

ABSTRACT Heavy metal contamination is a major concern, and the adsorption process is regarded as one of the most efficient water remediation processes to deal with it. Herein, we modified fly ash by a microwave-assisted hydrothermal process to enhance its adsorption capacity and tested the material toward Cd(II) and Cu(II). Characterization of the adsorbents was performed by several techniques in detail to elucidate considerable structural changes such as cracking of spherical morphology, increase in surface area and changing of the chemical composition. Then batch adsorption was performed under different conditions to investigate the equilibrium, kinetics, and thermodynamics of the process. NaOH-modified fly ash considerably has a higher adsorption performance than that of the as-received sample for both ions. The highest adsorption capacity of modified fly ash was achieved as 133.8 and 95.7 mg/g for Cd(II) and Cu(II), respectively. The kinetics and isotherms could be perfectly reflected by a pseudo-second-order rate equation and the Freundlich model, while thermodynamics confirmed the endothermicity of the process.

Study on the adsorption performance of modified high silica fly ash for methylene blue.

Presently, there are several issues associated with solid waste fly ash, such as its accumulation and storage, low comprehensive utilization rate, lack of high-value utilization technology, environmental risk and ecological impact. Thus, based on the high silica content and adsorption characteristics of fly ash, two novel adsorbents, namely mesoporous silica-based material (MSM) and sodium dodecyl sulfate-modified fly ash (SDS-FA), were prepared using an ultrasound-assisted alkali fusion-hydrothermal method and surface modification method. Furthermore, effects of adsorbent dosage, initial pH, contact time, and initial concentration of the solution on the adsorption of the organic pollutant methylene blue (MB) by fly ash, MSM, and SDS-FA were investigated to select the optimal modified high silica fly ash adsorbent. Based on the adsorption isotherms and adsorption kinetics, together with SEM, XRD, FTIR and BET analyses, the adsorption mechanism of MSM for MB was revealed. The results showed that under the conditions of an adsorbent dosage of 2 g L-1, initial pH of 9, contact time of 150 min, and initial concentration of 100 mg L-1, MSM and SDS-FA exhibited removal efficiencies of 92.69% and 84.64% for MB, respectively, which were significantly higher than that of fly ash alone. The adsorption of MB by MSM and SDS-FA followed the Langmuir model and pseudo-second-order kinetics, indicating monolayer adsorption with chemical adsorption as the dominant mechanism. The mechanism of the adsorption of MB by MSM is mainly the result of the synergistic effect among its increased specific surface area, hydrogen bonding, ion exchange, and electrostatic interactions. After five cycles of adsorption-desorption process, the removal efficiency of MSM for MB consistently remained above 80%. Therefore, MSM can serve as a valuable reference for the resource utilization of fly ash and remediation of dye-polluted wastewater.

ADSORPTION OF REMAZOL BRILLIANT BLUE DYE USING PALM OIL SHELL FLY ASH HCl ACTIVATED

Remazol Brilliant blue is an azo dye that is widely used in textile dyeing. The most appropriate handling method to be used in overcoming problems caused by textile dye waste is adsorption. Fly ash is an adsorbent that can be used to overcome this problem. Chemical activation was carried out using 1 M HCl solution. Besides that, physical activation was also carried out at 500°C for 1 hour. Research is needed to determine the optimum conditions for fly ash in dye adsorption to produce high adsorption efficiency. XRF characterization showed that palm shell fly ash was dominated by CaO of 71.064% and SiO2 of 15.734%. Characterization using FTIR shows the presence of Si-O groups in Fly ash. To analyze the surface morphology of the fly ash adsorbent, an SEM test was carried out and it was known that the surface morphology of the fly ash adsorbent after chemical and physical activation showed pore formation. Characterization using Surface Area Analyzer showed a surface area of 13.6153 m2/g. optimum absorption conditions at pH 6 with an adsorption capacity of 15.84 mg/g. optimum contact time of 60 minutes with an adsorption capacity of 15.54 mg/g. The optimum adsorbent mass is 0.5 g with an adsorption capacity of 9.54 mg/g and the optimum adsorbent concentration is at 200 ppm with an adsorption capacity of 69.08 mg/g. In this study the adsorption model used is the Freundlich isotherm. Based on the research result, it is known that fly ash is a suitable adsorbent for dye adsorption which is characterized by high color removal efficiency. Further characterization regarding the initial conditions of fly ash is needed as a comparison for fly ash after activation

Experimental Investigation of Removal of SO3 from Flue Gas with Modified Fly Ash Adsorbents.

The removal of nonconventional pollutants in coal-fired power plants, such as SO3, has been receiving more and more attention. However, due to its unique nature, it is difficult to remove SO3 effectively with the widely used wet flue gas desulfurization systems. Nowadays, dry-sorbent injection technology has become a promising method for SO3 emission control in coal-fired power plants. The removal characteristics of SO3 from flue gas with modified fly ash adsorbents were investigated in a fixed-bed reactor. Factors affecting the adsorption efficiency of SO3 were studied, including modification method, modified fly ash adsorbent particle size, reaction temperature, and flue gas component. Combined with adsorbent characterization analysis, the adsorption kinetics of SO3 by modified fly ash adsorbents were carried out with four different adsorption kinetics models. The results show that the SO3 adsorption efficiency of the fly ash samples increases after modification; the best SO3 removal performance of fly ash was achieved when 1.5 mol/L NaOH solution was used, with the highest SO3 adsorption efficiency of up to 98.3%. The modified fly ash adsorbent particle size, water vapor content, and the addition of NO have little effect on the adsorption efficiency of SO3. As the reaction temperature increases from 250 to 450 °C, the SO3 adsorption efficiency first increases and then decreases, with an optimal reaction temperature of 350 °C. The addition of SO2 would compete with SO3 for adsorption and inhibit the uptake of SO3 by the adsorbent. Adsorption kinetics data show that external mass transfer and chemical adsorption are the main critical mechanisms affecting the adsorption efficiency of the modified fly ash adsorbent in the SO3 removal process compared to internal diffusion.

Efektivitas Fly Ash Sebagai Adsorben Dalam Menurunkan Chemical Oxygen Demand (COD) pada Air Limbah Pulp and Paper

This study aims to determine the characteristics of fly ash as an adsorbent that has been activated and to determine the optimum conditions of fly ash adsorbent to reduce the COD value of pulp and paper wastewater. The characteristics of water content, ash and iodine number were tested. The quality of fly ash adsorbent is done by determining the optimum pH, mass and time. The variations of pH 4,5,6,7,8,9 and 10, mass 0.5 g, 1 g, 1.5 g, and 2 g and contact time variations are 5 minutes, 15 minutes, 30 minutes, 45 minutes and 60 minutes. This research method uses experimental method with Complete Randomized Design analysis by conducting Anova test and Duncan's further test. The results showed that the test results of the characteristics of water content, ash and iodine number have met SNI 06-3730-1995 regarding technical activated charcoal. The optimum conditions obtained during adsorption consisting of optimum pH was found at pH 4 with % Removal COD as much as 18.1%, the optimum mass obtained was 1 gram with % Removal COD as much as 24.8%, while the optimum time obtained was 15 minutes with % Removal COD as much as 20.38%. The adsorption results show that the decrease in COD of pulp and paper wastewater is still not effective in accordance with PermenLH No. 5 of 2014.

Sulphuric Acid-Modified Coal Fly Ash for the Removal of Rhodamine B Dye from Water Environment: Isotherm, Kinetics, and Thermodynamic Studies

Among the wide variety of dyes present in the environment, cationic dyes are more toxic and have complex structure. The adsorption process of rhodamine B dye was successfully carried out by sulphuric acid-treated inexpensive modified fly ash (MFA) adsorbent via batch experiments. The nature of the adsorbent was characterized by techniques, namely, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The maximum removal efficiency of RhB dye was found to be 99.78% by using 0.5 g of adsorbent dosage in 50 mg/L of dye concentration. The SEM images displayed the porous nature of the adsorbent where the EDS analysis displays the elemental compositions present in the adsorbent. XRD pattern shows the crystallinity nature of the adsorbent. Among the batch study parameters, effect of pH plays an important role in the adsorption process. The pH of 4 was found to be an ideal setting for the efficient removal of the dye RhB. The preferable elimination ability was found by keeping the dosage at 5 g/L, contact time 120 min, and dye concentration at 50 mg/L. Adsorption capacity was found to be 36.36 mg/g. This shows the ability of the MFA for the removal of wastewater contaminants. This adsorption process is well suited for the Freundlich isotherm, which displaces the process as a multilayer adsorption. Studies in kinetics and thermodynamics demonstrate that the process was well suited for its exothermic nature and pseudo-second-order. Thermal regeneration studies were carried out, and the adsorbent was effectively recycled and utilized up to four more times with minimal loses in its effectiveness. Therefore, from these obtained results, it is clear that the MFA is an effective adsorbent for the effective removal of dyes from wastewater.

Study of the removal of Pb(ii) and Ni(ii) from aqueous solution by new nano-Mg(OH)2/fly ash adsorbent materials

Adsorption mechanism of composite powder.

Efektivitas Penggunaan Fly Ash Batubara sebagai Koagulan dan Adsorben dalam Menurunkan Chemical Oxygen Demand (COD) dan Total Suspendedd Solid (TSS) Limbah Cair Industri Pulp and Paper

The content of Al and Fe in coal fly ash has underpinned several studies on the use of coal fly ash as a coagulant and adsorbent. Coal fly ash coagulant was activated with H2SO4. While coal fly ash adsorbent is activated with HCl. This study aims to compare the effectiveness of the coagulant or as adsorbent, to determine the optimum concentration of coagulant/ adsorbent addition, and to determine the effectiveness of fly ash as a coagulant/ adsorbent in reducing COD and TSS in Pulp and Paper wastewater. This research used 2 treatments, activating coal fly ash with 2M H2SO4 and 4M HCl, and then comparing the effect of fly ash coagulants and adsorbents in reducing COD and TSS wastewater. The results showed that coagulant reduced COD by 53.23% and TSS by 60.1%, more effective than adsorbent which only reduced COD by 6.38%, and increased TSS value by 7.2%. However, it has not yet below the quality standards. Numerical analysis using 3rd order polynomials shows that doses of 41,000-42,000 ppm of coagulant can reduce COD below the quality standard. This concludes is coal fly ash coagulant is effective in reducing COD and TSS of pulp and paper wastewater, with the optimal dose to reduce COD below the quality standard, is 41,000 - 42,000 ppm.

Adsorption of Heavy Metals Fe and Mn in Acid Mine Drainage from Coal Mining Waste Using Calcium Oxide and Fly Ash

Acid mine drainage for Fe and Mn metals have a negative impact on the environment. This study studies the use of calcium oxide and fly ash as adsorbents, used to absorb Fe and Mn metals contained in acid mine drainage. This study aims to analyze the effectiveness of Calcium Oxide and fly ash as adsorbents, that an adsorbent of Fe and Mn metals in acid mine drainage. The method used is experimental with a laboratory scale, the test is carried out by adsorption using a batch system. Magnetic stirrer is used as a stirring medium in the adsorption process. Calcium oxide with various doses (0.1; 0.2; 0.3 grams) and fly ash with various doses (10; 14; 17 grams) were mixed with 250 ml acid mine drainage, then stirred at a speed of 150 rpm and (30; 60; 90 minutes) stirring time. The characterization of the adsorbent was carried out by SEM testing. The results show that fly ash adsorbent has a better adsorption effectiveness than calcium oxide. The effectiveness of Fe is 85.35% and Mn 78.14%. While calcium oxide has the effectiveness of Fe 72.91% and Mn 61.81%. SEM testing of holes that increase and enlarge after adsorption, as well as the filling of the cavity by the material indicates the success of the adsorption process.

Mercury removal from coal combustion flue gas by pyrite-modified fly ash adsorbent.

Pyrite and fly ash have certain advantages in adsorption and mercury oxidation. The pyrite-modified fly ash (PY + AC-FA) mercury adsorbent was prepared by mixing pyrite (PY) with acid-modified fly ash (AC-FA), which has better mercury removal effect than AC-FA. The experimental results of mercury adsorption show the following: when the reaction temperature is 50°C, the best doping proportion of modified fly ash is 20 wt%, the mass proportion of pyrite to acid-modified fly ash is 4:1, and the flue gas flow rate is 1.0 L/min; the adsorbent has the best performance, and the adsorption rate of mercury reaches 91.92%.It was also found that the quasi-second-order kinetic model could describe the entireprocess of adsorption, and its adsorption process was mainly influenced by chemisorption. XRF, BET, SEM, XRD, and TG-DSG were used to characterize these adsorbents, and the mechanism of mercury removal of pyrite-modified fly ash adsorbent is inferred: Hg0 is first adsorbed on the surface of the adsorbent, and then oxidized to HgS by the active component FeS2 in pyrite-modified fly ash.

Preparation of manganese oxide coated coal fly ash adsorbent for the removal of lead and reuse for latent fingerprint detection

Heavy metals are becoming a huge problem in the environment and lead is one of them. Lead is disposed into water systems from huge industries such as paint industry, mining, and electroplating. In this study, manganese oxide coated fly ash (MnO 2 -CFA) was synthesized and characterized. The BET surface area of CFA MnO 2 -CFA was 18.4196 m 2 /g, 3 times more than the raw CFA (5.9231 m 2 /g). Batch adsorption experiments indicated that the uptake of Pb 2+ fitted well in a Elovich kinetics model while the adsorption isotherm best fitted the Langmuir model with a maximum adsorption capacity of 141 mg/g at 40 °C and a pH of 7. Thermodynamic parameters obtained proved that the adsorption of Pb 2+ ions using the MnO 2 -CFA was endothermic and spontaneous. Furthermore, the adsorbent was highly selective towards Pb 2+ in the presence of Mn 2+ , Zn 2 , Ni 2+ and Cd 2+ . The Pb 2+ removal % from a real water sample spiked with 30 mg/L Pb 2+ was found to be 83.33%. The spent adsorbent was further applied in latent fingerprint detection which showed that Pb 2+ -MnO 2 -CFA produced clearer latent finger print (LFP) images compared to MnO 2 -CFA. LFP images were still clear 8 days after application of the spent adsorbent, proving that Pb 2+ -MnO 2 -CFA is a promising labelling agent. • Manganese oxide coated fly ash was synthesized by hydrothermal method. • MnO 2 -CFA surface area (18.4196 m 2 /g) was 3 times more than the raw CFA (5.9231 m 2 /g). • MnO 2 -CFA shows the maximum adsorption capacity of 60.61 mg g −1 (Pb 2+ ) at 50 °C. • Reuse application of Pb 2+ -MnO 2 -CFA spent adsorbent for LFP detection under day light condition.

HISTOLOGY TEST OF TILAPIA (Oreochromis niloticus) ON ADSORBENT PERFORMANCE RESULTS IN LIQUID TREATMENT OF INDUSTRY PULP AND PAPER WASTE

Pulp and paper industry fly ash is categorized as B3 waste, namely hazardous and toxic waste. Liquid waste produced by the pulp and paper industry contains pollutants that are toxic and can cause pathological and histopathological changes in important tissues such as the gills of fish that live in the waters around the disposal. The purpose of this study was to analyze the histology of tilapia on the performance results of fly ash adsorbents in the management of liquid waste in the pulp and paper industry. The research method has 6 treatments, namely the ratio of fly ash to pulp and paper liquid waste (20 g; 1 L) namely P0: 100 % well water control, P1: lowest liquid waste 5 % + 9.5 % well water, P2: 5 % liquid waste fly ash adsorbent + 95 % well water, P3: 6.25 % liquid waste fly ash adsorbent + 93.75 % well water, P4: 7.5 % liquid waste fly ash adsorbent + 92.5 L of well water, P5: 8.75 % fly ash adsorbent + 91.25 % well water, P6: 10 % fly ash adsorbent + 9 % well water. Water quality measurements such as temperature, NH3, pH and DO were carried out. Observation of gill histology used microtechnical method which includes deparaffinization and histological staining (HE). Analysis was carried out on changes in cell morphology in gill tissue. The results showed that the morphology of gill cells in liquid waste pulp and paper 5 % found gill damage in the form of congestion, secondary lamella fusion, secondary filament rupture and goblet proliferation occurred in the treatment of wastewater treatment while Fly ash adsorbent 5 % damaged gills in the form of congestion and fusion of secondary lamellae. From the results of the Fly ash functions can reduce damage to body organs in fish, especially on the gills so that it can reduce the number of deaths in fish compared to treatment without the use of fly ash.

Fly ash-based adsorbent for adsorption of heavy metals and dyes from aqueous solution: a review

A critical global issue in the 21st century is water shortage, as well as its pollution with noxious metal ions and organic dyes. To extract these pollutants from wastewater, a variety of traditional methods have been employed but they lack reusability/recyclability, are expensive, environmentally unfriendly, unsafe and the remediation process takes a long time. Therefore, to treat these contaminants, nanotechnology (NT) has recently been granted several leeways in terms of making the desirable nanomaterials (NMs) with high surface-to-volume ratios and special surface functionalities. In particular, fly ash (FA) has stood out as one of the greatest exciting new-found affordable and high efficient materials for water decontamination owing to its high porosity, huge surface area, and exceptional features. Hence, this present review study will attempt to compile data from existing literature on the utilization of FA-based adsorbent for the removal of heavy metals (HMs) and dyes from wastewater. Based on the reviewed publications, Langmuir's isotherm models (LIMs) and Freundlich's isotherm models (FIMs) best described the sorption process thus signalling monolayer and multi-layer sorptions. Pseudo-second-order (PSO) model provided the best appropriate means in elucidating the kinetic process and both exothermic and endothermic processes revealed the nature of the thermodynamic process during sorption. Some recommendations in the form of future prospects on how to advance the capacity of the adsorption and effectiveness of FA on the removal of HMs, dyes and other environmental contaminants using innovative technologies such as the nanofiber technology is also been proposed.

Removal of Hazardous Organic Pollutants Using Fly Ash

This study aims to achieve the highest removal efficiency of direct blue dye using a low-cost adsorbent. The adsorption of direct blue 78 dye (DB78) with commercial name (Tubantin blue GLL 300) from a synthetic wastewater using a raw coal fly ash was studied. The ability of coal fly ash (industrial by product) as cost-effective adsorbent to remove dyes from textile wastewater effluent was investigated in detail. A series of batch experiments were conducted in terms of adsorbent dose, contact time, pH, and initial concentration of dye. The raw coal fly ash was characterized by physico-chemical analysis namely; X-ray diffraction (XRD), X-ray fluorescence (XRF) and Brunauer–Emmett–Teller (BET). It was found that the major phases for coal fly ash are quartz and hematite. Loss of ignition percentage and surface area are 36% and 9.6113 m²g^-1 respectively with average particles size 624 nm. The adsorption tests showed that the removal efficiency increases with increasing adsorbent dosage and contact time. Removal efficiency decreases at high initial concentration of direct blue 78 dye. The maximum capacities for dyes removal reached to 99.1% with initial concentration 10 mg/l and fly ash dose 3 g/l. Dyes removal (98.4%) was obtained using initial concentration 20 mg/l and fly ash dose 4 g/l. At higher initial concentration (30 mg/l) using fly ash dose 5 g/l, lower removal efficiency was obtained with 97.2%. The Langmuir isotherm model was shown to have a higher coefficient of determination R² than the Freundlich isotherm model in representing the fly ash adsorption process.