Pseudo 2nd Order Research Articles

Superfast adsorption of small and uncharged urea from water using post-sonicated iron-based metal-organic framework

Urea is widely used in fertilizer production for agricultural purposes which risks runoff into soil and water sources. An excess of urea can result in algal or toxic blooms which can poison wildlife or even humans by accumulation in food sources. The removal of urea from water is challenging due to the small size (0.254 nm) and uncharged surface of urea. Intensive research has been conducted on a variety of methods to remove environmental concentrations of urea using adsorbents, but most of them lack effective removal, require long (>2 h) process time, and lack re-generability. Metal-organic frameworks (MOFs) are the new generation of adsorbents with excellent structural and functional group tunability. In this study, we synthesized MIL-100 (Fe), an iron-based MOF, as an efficient adsorbent for the removal of uncharged urea from water. The urea adsorption capacity of MIL-100 (Fe) was tested under varying experimental conditions such as pH (2–10), temperature (25–65 °C), MOF concentration (25–400 ppm), and urea concentration (25–1000 ppm). The results showed the superfast adsorption (more than 85% removal within 2 min) of neutrally charged urea molecules on MIL-100 (Fe). The MOF was able to reach a maximum adsorption efficiency of around 85% with a maximum uptake capacity of 3321 mg/g. The MIL-100 (Fe) showed acceptable re-generability by retaining up to 90% removal efficiency after four regeneration cycles. The urea adsorption followed pseudo 2nd-order adsorption kinetics and dipole-dipole interactions and π-NH bonding were the primary adsorption mechanism.

Biomass - metal oxide nano composite for the decontamination of phenol from polluted environment - parametric, kinetics and isotherm studies

The contamination of aqueous environment by phenol poses a major threat due to its hyper toxic effects and removal of phenol is challenging due to its hydrophilic properties. This research study examines the surface encapsulation of iron oxide (IO) with bio-derived carbon-based date palm (DP) to make date palm-iron oxide (DP-IO) nanocomposite to potentially remediate phenol in aqueous environment. Phenol removal percentage is predominantly influenced by environmental factors, namely pH, nano sorbent loading, temperature, agitation speed, and initial phenol concentration. Under optimum conditions of 30 °C and pH 7.8, 80.30% of phenol was removed using a 0.75 g/L sorbent load with 100 mg/L initial phenol concentration. Langmuir isotherm fitted well (R2 > 0.997), supporting single-layer phenol attachment with maximum bio-sorption capacity of 72.46 mg/g. A pseudo-2nd-order (PSO) kinetic model is identified to be the most appropriate for the DP-IO sorption experiment (R2>0.999). Scanning electron microscopic images, X-ray diffraction observations, FT-IR plots, and thermogravimetric analysis have been used to characterize. The removal mechanism involves unimolecular layer and chemisorption is identified as a rate determining step. The reuse potential proved that the synthesized nanocomposite as a sustainable solution for phenolic wastewater treatment.

Graphene oxide@Fe3O4-decorated iota-carrageenan composite for ultra-fast and highly efficient adsorption of lead (II) from water

The aggravated problem of lead pollution, especially in aquatic environments, necessitates the development of eminent adsorbents that could radically solve this environmental problem. Hence, a new composite was constructed based on iota carrageenan (i.Carr), graphene oxide (GO) and magnetite (Fe3O4) for removing noxious Pb2+ ions. The GO@Fe3O4-i.Carr composite was characterized by VSM, SEM, XPS, XRD, FTIR and Zeta potential. The removal of Pb2+ ions attained a quick equilibrium of almost 30 min with a removal efficiency reaching 93.68 %. The removal of Pb2+ was boosted significantly, in the order of GO@Fe3O4-i.Carr(1:1) > GO@Fe3O4-i.Carr(1:3) > GO@Fe3O4-i.Carr(3:1). Moreover, acquired experimental data fitted the pseudo 2nd order kinetic model and Freundlich isotherm model with a maximal monolayer adsorption capacity reached 440.05 mg/g. Notably, after five adsorption runs, the composite maintained its removal efficiency exceeding 74 %. The assumed adsorption mechanisms of Pb2+ onto GO@Fe3O4-i.Carr were complexation, precipitation, Lewis acid-base, and electrostatic attraction forces. Overall, the GO@Fe3O4-i.Carr composite elucidated the auspicious adsorbent criteria, comprising fast adsorption with high performance, ease-separation and tolerable recyclability, advising its feasible use to decontaminate water bodies from hazardous heavy metals.

Modeling, optimization and comparative study on abatement of fluoride from synthetic solution using activated laterite soil and fly ash

The supply of potable water by proper treatment of fluoride laden ground water is a challenging task. Batch experiments were executed with activated laterite soil and fly ash individually for removal of fluoride. The process parameters such as particle size (100–620 μm), dose of adsorbent (10–60 g/L), initial concentration of fluoride (2–12 mg/L), agitation speed (20–120 rpm), contact time (0.5–10 h) and pH (4.5–9.5) were investigated and it was observed that activated laterite soil had better fluoride removal efficiency than fly ash. At pH 4.5, contact time 10 h, particle size 100 μm, adsorbent dose 60 g/L, initial concentration of fluoride 12 mg/L, and agitation speed 120 rpm, maximum removal efficiencies of fluoride using activated laterite soil and fly ash were found as 85.91 ± 0.62% and 77.1 ± 0.39%, respectively. Kinetic study was performed and Pseudo 2nd order kinetic model was found to fit the kinetic data best. The Freundlich isotherm model fit the equilibrium data fairly well. The values of adsorption equilibrium constant as used in Freundlich isotherm model vis-à-vis adsorption capacity (KF) for activated laterite soil and fly ash were obtained as 0.1331 and 0.0772 ((mgg−1)(Lmg−1)1/n). A thermodynamic analysis was conducted to examine the process behaviour. In order to determine whether the adsorbent may be used for further cases, regeneration of the adsorbents was also done. Generally, two types of adsorption mechanisms happen like electrostatic attraction and ion exchange. The electrostatic force of attraction favours the adsorption of negatively charged fluoride ions on positively charged adsorbent surfaces. In ion exchange, fluoride ions are exchanged by hydroxyl and hydronium ion. Based on experimental data, Multi-Gene Genetic Programming (MGGP) model could accurately predict the removal efficiency of fluoride under various operating situations. Finally, using Genetic Algorithm (GA) optimization the maximum output values for both adsorbents were estimated as 99.14% and 99.02%.

Towards sustainable water purification: MOFs as a promising solution to eliminate toxic water pollutant resorcinol

Abstract Water pollutants especially alcoholic based aromatic compounds are documented as emergent water pollutants and caused serious health problems for all living organisms. It is a major challenge for all researchers to synthesize effective adsorbents to eliminate these water pollutants. For this purpose, two MOFs were synthesized and characterized using SEM, FTIR, EDX and PXRD techniques. These MOFs exhibited excellent adsorption capacity for resorcinol and adsorption process was spontaneous, endothermic and proceeds with physiosorption as confirmed using thermodynamics data (∆H ads = 30.473 kJ/mol). Furthermore, separation-factor value was in the range of 0.0238–0.1312 for 30–100 ppm resorcinol concentration which represents that adsorption process was favorable. Langmuir and Pseudo 2nd order Models were best described which represented that chemisorption process also favored due to presence of –OH group and N-atom between adsorbent and adsorbate as well as monolayer adsorption-process is proceeded. Moreover, ion-exchange and electrostatic-interactions are the major interactions which are responsible for adsorption of resorcinol. Along with electrostatic-interactions, ion-exchange, hydrogen-bonding and π–π stacking/interactions are also accountable for adsorptive elimination of resorcinol. In summary we can conclude that MOFs are considered outstanding adsorbents for elimination of water pollutants to purify water, as water is very important for healthy life.

Irradiated fig pomace pyrochar as a promising and sustainable sterilized sorbent for water pollutant removal

Irradiated fig pomace pyrochar (IrrPyrFP) is noteworthy as a novel sterilized low-cost sorbent of BTEX, pesticides, and Pb2+ ions. It was produced by applying pyrolysis treatment followed by gamma irradiation modification in order to obtain a highly efficient and sterile sorbent.The characterization of fig pomace before and after pyrolysis, as well as before and after irradiation of the obtained pyrochar, was done using SEM, FTIR, and elemental analysis, while its sorption ability was tested through the removal of examined pollutants by batch sorption experiments. The obtained results suggest that IrrPyrFP could play a significant role in the control of environmental pollutants, as indicated by the maximum adsorption capacities: 42 mg g−1 for BTEX, 0.625 mg g−1 for malathion, 0.495 mg g−1 for chlorpyrifos and 255 mg g−1 for Pb2+. A kinetic study showed that the removal process by IrrPyrFP mainly follows pseudo 2nd kinetics order, while the sorption equilibriums were estimated using the Langmuir and Freundlich model. Overall, the findings of this work suggest that pyrolysis and activation by irradiation of waste biomass is a promising way to produce sterile efficient sorbents for waste-water treatment based on green chemistry. Additionally, the demonstrated application of fig pomace promotes the potential of using this biomass for continual and economical waste management in the rising fig industry.

Understanding the sorption behavior of tri, tetra and hexavalent f cations on metal–organic framework (MOF), ZIF-67: experimental and theoretical investigation

ABSTRACT Metal–organic frameworks (MOFs) are a class of compounds with modern-age technological importance due to diverse structural topologies, porosity, and modularity. ZIF-67 has been synthesized for efficient extraction of f cations in different oxidation states (UO2 2+, Th4+ and Eu3+) from aqueous pH medium exhibiting the trend in sorption efficiency as: Kd Th(6.19 × 103) > Kd U (5.20 × 103) > Kd Eu (1.58 × 103) in accordance to their chemical potential. Langmuir isotherm was found to be predominate with sorption capacity 85.9 mg g−1, 137.4 mg g−1 and 50.6 mg g−1 for U, Th and Eu, respectively. The sorption predominantly proceeded via pseudo 2nd order rate kinetics with rate constants: k2 U ~0.089 g mg−1 min−1, k2 Th ~0.011 g mg−1 min−1 and k2 Eu ~0.04 g mg−1 min−1. The processes were found to be spontaneous as revealed from negative ΔG values; and endothermic in nature (ΔHU ~10.5 kJ mol−1; ΔHTh ~12.8 kJ mol−1; ΔHEu ~8.3 kJ mol−1). The sorption proceeded via the formation of an inner sphere complex as indicated from their enhancement in the entropy values on sorption due to the release of water molecules. The Density Functional Theory (DFT) predicted selectivity using binding energy (ZIF-67-Eu3+ ~ -60.90 eV, ZIF-67-Th4+ ~ -70.78 eV, ZIF-67-Th4+ ~ -69.52 eV) is in line with the experimental selectivity of Th4+ > UO2 2+ > Eu3+. Total density of states (TODS) and Projected density of States (PODS) were estimated in order to understand the interaction between the ZIF-67 and f cations.

Sustainable approach for adsorptive removal of cationic and anionic dyes by titanium oxide nanoparticles synthesized biogenically using algal extract of Spirulina

Worldwide, dyes are significant pollutants present in water because of their huge consumption for industrial purposes. These dyes as pollutants cause serious health issues in human beings and cause the loss of aquatic biodiversity. So, remediation of pollutants like dyes from wastewater is the need of the hour. In the present study, we greenly synthesized Spirulina-mediated titanium oxide nanoparticles (STONPs) for the adsorptive remediation of methyl orange (MO) (anionic) and malachite green (MG) (cationic) dyes. The characterization of STONPs was performed by Field emission scanning electron microscopy (FESEM) with EDX, FT-IR, XRD, Zeta Potential and particle size analyzer, Raman spectroscopy, and UV–vis. The various parameter effects like pH, nano-adsorbent dose, the concentration of dye, contact time, and temperature were also examined. Adsorption isotherms like Langmuir, Freundlich, and Temkin, and Kinetics models like Elovich Model, Pseudo 1st, intraparticle diffusion model (IPDM), Pseudo 2nd order, and the thermodynamic model were applied for a stronger interpretation. The q max attained utilizing the Langmuir adsorption model was 272.4795 mg g−1 and 209.6436 mg g−1 for MO and MG correspondingly. The regeneration study of synthesized nanomaterials up to five cycles was also done. We found that greenly synthesized STONPs have great potential for adsorptive remediation for both MG and MO dyes.

Fabrication of nanoclay embedded adsorptive electrospun nanofiber membrane for removal of trace organic molecules

This study aims to fabricate nanoclay (NC) embedded polyacrylonitrile (PAN) adsorptive electrospun nanofibers (Ads-ESNs) as high performance membranes for organic micropollutants (OMPs) removal. Ads-ESN were tested using a comprehensive protocol included adsorption in batches (static) and during filtration (dynamic). The filtration performance of Ads-ESNs was tested using gravity driven membrane (GDM) filtration using methylene blue (MB) as an adsorbate of similar characteristics to OMPs. The characterization was carried using SEM-EDS, FTIR and BET N2 adsorption/desorption technique. Addition of NC increased fiber diameters from 164 to 355 nm and surface areas from 12.9 to 45.9 m2/g. Accordingly, Ads-ESNs had 7 times higher adsorption capacity than PAN-ESN with isotherms fitting to Langmuir model (R2 = 0.9511–0.9899). The kinetics showed that adsorption in Ads-ESNs followed pseudo 1st and 2nd order indicating the occurrence of physisorption and chemisorption mechanisms simultaneously. pH and temperature effect were investigated and the results showed that highest adsorption occurred at pH 7 and 25 °C. The GDM system was operated at constant permeate flow rates of 1.0, 2.0 and 4.0 mL/min at 50mbar. MB rejection was over 90% at 1.0 and 2.0 mL/min of flow rates indicating the effect of applying lower flow rate and higher contact time. The adsorption capacities of Ads-ESN were different at static and dynamic adsorption due to different equilibrium states achieved at both adsorption modes. The fabricated Ads-ESNs showed outstanding removal performance for trace organic molecules even after four adsorption+filtration/regeneration cycles. Overall, this study demonstrated the potentials of combining membrane filtration and adsorption in a single-step process at same entity.

Photocatalytic Degradation Studies of Organic Dyes over Novel Cu/Ni Loaded Reduced Graphene Oxide Hybrid Nanocomposite: Adsorption, Kinetics and Thermodynamic Studies.

Nowadays, for environmental remediation, photocatalytic process involving graphene-based semiconductors is considered a very promising oxidation process for water treatment. In the present study, nanocomposite (Cu/Ni/rGO) has been synthesized by Dypsis lutescens leaf extract. Characterization of the sample was carried out by UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Different parameters like contact time, nanocatalyst amount, dye concentration, effect of temperature. and pH factor were optimized to examine the maximum removal efficiency for dyes rhodamine B and alizarine R with and without visible light source. In both cases, i.e., with or without light, maximum removal was observed at 20 mg of nanocatalyst for 5 ppm concentration of both dyes at 45 °C temperature and pH 10 for rhodamine B and pH 4 for alizarine R, respectively with a 20 min contact time. Maximum removal of dyes 93% rhodamine B and 91% alizarine R were observed under a tungsten lamp as compared to without a tungsten lamp, i.e., 78% of RhB and 75% of AR from mixture solution of these dyes. To assess the rate of reaction, spontaneity, and nature of reaction thermodynamics, kinetics and adsorption isotherms were studied. Thermodynamic values indicated that both dyes depicted endothermic and spontaneous degradation processes. Isotherm data fitted best to a Freundlich isotherm, while results of kinetic studies of both dyes followed the pseudo 2nd order kinetic equation. In the end, scavenging radical studies concluded that hydroxyl radicals were the main active specie involved in the photocatalytic degradation process, and regeneration experiments resulted that Cu/Ni/rGO nanocomposites were re-utilized for about four times.

Tuning crystallization for controlled morphology of Zeolite A by an eco-friendly sonochemical precursor-less method

This study describes the sustainable synthesis of zeolite 4A from industrial solid residues without the addition of chemical precursors, as well as the optimization of its structural and morphological control using a central composite design. High-modulus silicate and aluminate are extracted from fly ash and red mud by low-temperature alkali fusion (350 °C) followed by ultrasonication. The transformation of colloidal aluminosilicate sol into a stable crystal of zeolite 4A by the hydrothermal method was studied to observe morphological changes and hypothesize a crystal growth mechanism. A total of 20 experiments were conducted to optimize high-quality truncated edge cubic zeolite 4A formation. A pure zeolite 4A (85% of crystallinity, 79.825 m2/g of specific surface area, uniform pore size distribution of 3.69 nm) is obtained under the optimized conditions of FA/RM extract = 1.02, crystallization temperature = 90 °C, crystallization time = 10.25hrs. The surface morphology of zeolite 4A appears in three distinct forms: sharp edge cube when FA/RM extract is greater than 1.02 (Run 19), truncated edge cube when FA/RM extract is equal to 1.02 (Run 2), and rounded edge cube when FA/RM extract is less than 1.02 (Run 18). Based on the ANOVA and desirability function results, we can infer that our anticipated model is a fit and the desired goal of maximum crystallinity was achieved with 95% confidence. The optimized zeolite 4A shows a higher hardness removal capacity of Ca2+(184.6 Ca2+mg/g in just 15 min) and Mg2+ (253.94 mg Mg2+/g in 5 h) for moderately hard pond water than commercial one. The kinetic and thermodynamic study reveals a better fit for the pseudo 2nd order kinetic model with a faster exchange rate of Ca2+(1.5 × 10−2 g.mg−1. min−1) than Mg2+ (7.4 × 10−5 g mg−1. min−1) and cation exchange is a spontaneous endothermic process.

Removal of methylene blue in aqueous solution using nanosilica based sorbent from volcanic ash

In this study, a mesoporous nano-SiO2 from Taal volcanic ash was successfully synthesized via sol–gel precipitation method and used effectively as adsorbent of methylene blue in aqueous solution. The silica rich volcanic ash from Taal contains 43.5% SiO2 which is the precursor of nano-SiO2 and characterized using scanning electron microscope (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRD) and Brunauer, Emmett and Teller (BET). The synthesized nano-SiO2 have an average size of 45 nm, surface area of 181.66 m2/g, pore size of 16–25 nm with purity greater than 99.9%. Characteristics bands at 3410 cm−1 attributed to OH- stretching of silanol groups, and a sharp peak at 1067 cm−1 and 801 cm−1 indicating siloxane (-Si-O-Si-) functional groups. XRD analysis revealed an amorphous nature of nano-SiO2 with crystallite size of 2.96 nm. A ∼99.9 % maximum removal was reached at pH 8, adsorbate concentration of 25 mg/L, adsorbent dose of 1.87 g/L at 22.89 min contact time and found to be reusable even after 5 cycles. Adsorption was best explained by Langmuir model having 65.5 mg/g maximum monolayer adsorption capacity. Kinetic studies showed a pseudo 2nd order with R2 of 99.9%.

Rietveld refinement, Morphological, Optical and Photocatalytic Dye Degradation Studies of Pristine and Sr-Doped SnS2 Hexagonal Nanoplates

In the present study, SrxSn1-xS2 hexagonal nanoplates have been synthesized via a cost-effective hydrothermal route and characterized by XRD, UV-DRS, PL, SEM, EDXS, Zeta potential, and dye degradation. The XRD pattern confirms the structure and FESEM corroborates the hexagonal nanoplate morphology of all the synthesized samples while EDX ascertains the Sr presence in doped samples. The optical band gap energy (Eg) of the samples has been estimated using UV-DRS and is found in the visible region. The negative surface charge is ascertained using the Zeta potential (ζ) analyzer. The dye degradation efficiency of pristine and SrxSn1-xS2 is tested on RhB under a visible lamp of 250W for 120min and found highest for x = 0.06 sample (90.93 %). The adsorption kinetics follows the pseudo 2nd order model whereas photodegradation kinetics follows 1st order kinetics model. Further isotherms processes studied in the dark follow the Langmuir model.

Fluorescence sensing and adsorption kinetics of Gd-doped AgInS2 I-III-VI quantum dots – A case study of Ag+ ions interactions

The poor fluorescence properties of magneto-fluorescent paramagnetic-ion (Gd, Mn, or Co) doped I-III-VI quantum dots (QDs) at higher paramagnetic-ion doping concentrations have limited their use in magnetic-driven water-based applications. This work presents, for the first time, the use of stable magneto-fluorescent Gd-doped AgInS2 QDs at high Gd mole ratios of 16, 20, and 30 for the fluorescence detection and adsorption of Ag+ ions in water environments. The effect of pH, initial concentration, contact time, and adsorbent dosage were systematically evaluated. The AgInS2 QDs with the least Gd mole ratio (16) exhibited the best fluorescence characteristics (LOD = 0.88, R2 = 0.9549) while all materials showed good adsorption properties under optimized conditions (pH of 2, initial concentration of 30 ppm, contact time of 10 min and adsorbent dosage of 0.02 g) and a pseudo 2nd order reaction was followed. The adsorption mechanism was proposed to be a combination of ion-exchange, electrostatic interaction, complexation, and diffusion processes. Application in environmental wastewater samples revealed complete removal of Ag + ions alongside Ti2+ Pb2+, Ni2+, Cr3+, and Zn2+ ions.

Biosorption Potential of Desmodesmus sp. for the Sequestration of Cadmium and Lead from Contaminated Water

Industrialization, urbanization, and natural processes have potentially accelerated the pace and level of heavy metals in the aquatic environment. Recently, modern strategies for heavy metal treatment in wastewater have received the specific attention of the scientific community. The present study aimed to assess the amorphous biomass of Desmodesmus sp. as a low-cost adsorbent to remove the cadmium (Cd) and lead (Pb) from aqueous solutions. It involved the optimization of pH, contact time, initial concentration of metal ions, and the dosage of biosorbent. Data collation revealed that an optimum contact time for both metals was 60 min, with an adsorption capacity of 63% for Cd and 66% for Pb. Different models were applied to the equilibrium data. The pseudo 2nd order described the best adsorption of Cd and Pb. The equilibrium data were computed with various isotherms. Langmuir isotherms better suit the adsorption of the above-mentioned metals. Hence, the maximum adsorption capacity of Desmodesmus sp. for Cd and Pb was 64.1 and 62.5 mg/g, respectively. The mechanism of biosorption was validated through a comparative FT-IR and Scanning Electron Microscopy of raw and metal-loaded algal biomass based on cell morphological changes. In order to study the reusability of adsorbent, adsorption-desorption of Cd and Pb ions was repeated three times using HCl. These results did not noticeably change in adsorption capacity during the three cycles. Using HCl (0.1 M), desorption of both metals was achieved up to 90% in three cycles. This work presented a long-term bioremediation approach for heavy metal pollutants in wastewater. This research could be seen as an interdisciplinary approach to large-scale heavy metal remediation. In addition, growing microalgae in wastewater produces animal feed and biodiesel. When compared to other conventional methods for environmental remediation and the manufacture of valuable products, the use of microalgae is a more efficient and cost-effective method.

New biobased chitosan/polyvinyl alcohol/graphene oxide derivatives for the removal of pharmaceutical compounds from aqueous mixtures

The main scope of this study is synthesis, characterization and implementation of new bio-based chitosan derivatives for the removal by adsorption of pharmaceutical mixtures from aqueous matrices. Six different materials of chitosan/polyvinyl alcohol were synthesized using an increasing quantity of graphene oxide and reduced graphene oxide (0.05%, 0.1% and 0.2%). A combination of different groups of pharmaceuticals was used as a model pollutant. Within this context, four non-steroidal anti-inflammatory drugs (diclofenac, ibuprofen, ketoprofen, paracetamol), one anti-epileptic (carbamazepine) and two antihypertensives (valsartan and irbesartan) were selected. The highest adsorption capacity was exhibited by the composites with the highest concentration of GO and rGO (0.2%), while the pollutants that presented the highest adsorption removal were valsartan and diclofenac. The adsorption process was appeared to be finished after 3 h for all compounds of the studied mixture (well-fitted to pseudo-2nd order model). The results indicated that the Langmuir model offered better match for the experimental data, while the adsorption capacity of adsorbents increased with the rise of the temperature. Overall, the highest adsorption capacities achieved at pH 10 (55 °C). Desorption was accomplished by using different aqueous eluents (with pH 2–10) and organic solvents. FTIR, SEM, EDS techniques were used to characterize the composition and morphology, and for the compounds detection the UHPLC system was used.

Characterization and recycling of raw fly ash derived through stems of Sesamum indicum as a proficient adsorbent for chlorazol black E from wastewater

Coal fly ash (CFA) is an anthropogenic industrial byproduct that is expected to increase exponentially to fulfill the needs of energy using coal and agro-waste as a cheap fuel. The disposal of this classified human carcinogen is a major concern in developing and underdeveloped economies due to lack of resources. Recycling and value addition of industrial waste, coherence with sustainable development goals is a viable solution. Zeolitization of coal fly ash is an ideal approach for recycling this waste into superior products to be used in a variety of industrial applications. This study was aimed to recycle CFA to useful zeolites using ultrasound assisted hydrothermal process. Sesamum indicum plant stems based fly ash (rFA) was found to belong to class “F" and has very low moisture and carbon contents. To investigate the morphology and elemental composition of rFA and UHSZ, SEM/EDX was used along with XRD, FTIR and Raman spectroscopy which confirmed the existence of quartz, mullite and anhydrite. SEM/EDX results revealed the presence of Al, Si, S, K, Sb, Mg and Ta in raw ash. Adsorption studies of both rFA and synthesized zeolite(UHSZ) were conducted to determine the quintessential parameters of pH, time, initial dose of adsorbent for optimum results. Fabricated zeolites (2 ​g/100 ​mL) from raw fly ash removed 90–98% of chlorazol black E (DB38) from 100 ​mg/L solution within 40 ​min at pH ​≈ ​7. Both Langmuir and Freundlich isotherms gave best fit, which validated that the adsorption of DB38 to UHSZ was a blended process rather than a simple monolayer adsorption mechanism. Pseudo 1st-order and 2nd-order kinetic models were adopted to fit the obtained kinetic data. The pseudo 2nd-order kinetic model was found to be most related.

Physico-chemical adsorption of cationic dyes using adsorbent synthesis via hydrochloric acid treatment and subcritical method from palm leaf biomass waste

Today, where water resources are polluted rapidly, the need for eco-friendly green methods is gradually increasing. Conversion of waste biomass into functional adsorbents that can be utilized in water treatment is a win-win practice for both recycling and water pollution treatment. In this study, the adsorbent material was obtained from the palm leaf to contribute to sustainable green energy. This cellulose-containing adsorbent material was tested in the removal of Methylene Blue (MB) and Basic Red-18 (BR18). The properties of palm leaf adsorbent were determined. The best removal efficiencies and optimum conditions were determined in the adsorption process. In both dye types; the original pH value, 2 g/L adsorbent dose, 25 mg/L dye concentration, and 120 min were chosen as the optimum conditions since the best removal efficiency was obtained in the experiments performed at 25 °C. At these conditions, the removal efficiencies were found to be 100% and 90% for BR18 and MB, respectively. In addition, adsorption kinetics, isotherms, and thermodynamic data were analyzed. For BR18 and MB, it was found to fit the Langmuir isotherm and pseudo-2nd order. Palm leaf adsorbent was used with an efficiency of over 50% in four consecutive cycles.

Chemical activation and magnetization of onion waste derived carbon for arsenic removal

Arsenic is a known human carcinogen and its contamination of drinking water has been a global challenge. In this study, magnetic activated carbon (MAC) as an efficient adsorbent material was synthesized by hydrothermal method. Three adsorbent materials MCH, MCH3 and MCNa were synthesized using different chemical activators like HNO3, H3PO4 and NaOH respectively. Structural and morphological features of the adsorbents before and after magnetization were determined by XRD, FTIR, FESEM, EDX and TGA. BJH nitrogen adsorption–desorption isotherm was used to find the surface area and pore size of adsorbents while the surface charge was determined by measuring zeta potential. FESEM images clearly showed the incorporation of magnetite nanoparticles into a porous network. The XRD further confirmed the formation of magnetite nanoparticles within the network of porous carbon with average crystallite sizes of 6.3, 5.8, 5.5 nm for MCH, MCH3 and MCNa respectively. To examine the adsorption behaviour of As(III) onto the MAC, batch adsorption experiments were conducted with the effect of different parameters like initial concentration, temperature, time, amount of adsorbent and pH. The results showed that MCNa is a potential adsorbent for As(III) with removal efficiency of 99%. Overall adsorption process follows pseudo 2nd order kinetics while the Langmuir model was found well applicable to the experimental data. Thermodynamics of adsorption and desorption studies suggest that chemisorption is a predominant adsorption mechanism. Cost-effectiveness, novelty and magnetic recovery are the key features making onion-based MAC a potential adsorbent for the removal of As(III) from contaminated water.

Removal of Malachite Green Dye from Aqueous Solution Using Lemon Leaf Powder as an Adsorbent

The majority of developing nations experience significant water contamination from textile sector wastewater. The use of low-cost, environmentally friendly adsorbents has been researched as a means of addressing problems of water contamination and high costs for waste - water treatment processes. Malachite green is an incredibly dangerous colour that not only damages mammalian cells but also has a key influence in the growth of liver cancers. The life cycle of aquatic creatures, plants, and people is hampered by dye released into bodies of water without sufficient treatment. In this study, the powdered lemon leaves are utilized for removal of the aniline green dye. By using batch-style setting and design of the experiment (the Box– Behnken technique) adsorbent has been investigated & have been developed to evaluate the process's critical factors, including agitation time, size of adsorbent, dosage of adsorbent, pH, initial concentration and temperature. The acquired values were fitted with adsorption isotherms. Malachite green dye sequestration onto Lemon Leaf Powder was chosen using kinetic models. The results of the trials showed that employing powdered lemon leaves, malachite green could be removed to a maximum of 82.21%. Malachite green dye concentration of 50 mg/L, temp of solution 303 K, and dosage of adsorbent 20 g/L are the ideal parameters. Lemon leaf powders have a maximum sorption capacity (qmax) of 8.08 mg/g. The equilibrium was more accurately modelled using the Freundlich isotherm. When compared to other models, the data which fits the pseudo 2nd order kinetics model is better. Previously researchers had proved several low– cost materials such as wheat bran, marina alga, wood apple shell etc In the current work, to remove malachite green dyes the efficacy of citrus lemon leaves is thoroughly done. The operating parameters that are optimized include dye solution concentration, initial solution pH, sorbent dose, and temperature. Studies on thermodynamics have demonstrated that the adsorption process was endothermic & spontaneous.