Concentration Of Dye Solution Research Articles

A facile method for studying competitive sorption from binary mixtures of dyes

Textile industry produces a great variety of effluents, rich in dyes, which have to be treated, in order to eliminate (or to decrease to secure levels) the contents of these environmentally harmful substances. The first step is the quantitative determination of dye concentrations in the effluent. In this manuscript, we propose a simple method to determine dye concentrations in solutions with two different dyes: acid blue 260, AB, and methyl orange, MO. It was demonstrated that correlating the apparent molar absorptivity of one of the dyes with the concentration of the other dye, a numerical method can be used to determine both dye concentrations and relative errors, using a single value of absorbance for each dye. The method was applied to the sorption of AB and MO on crosslinked chitosan, C-CHIT, and the more effective sorption of AB could be characterized by the determination of different isotherm parameters, estimation of Gibbs free energy of adsorption, as well as competitive sorption by itself.

Sustainable and efficient removal of cationic, anionic and neutral dyes from water by pre-deposited vinasse biochar membrane

This study demonstrated a simple and sustainable approach for removing dyes from water through a new pre-deposited vinasse biochar (PDVB) membrane, which was developed by single-step deposition of vinasse biochar powder on a filter paper support via vacuum pumping. The PDVB membrane combined advantages of adsorption and membrane filtration processes in one-stage. Performance of the PDVB membranes with water-wettable surface was examined on methylene blue (as a model dye) solution as functions of pyrolysis temperature, amount of biochar on the membrane unit area, solution pH, initial concentration and temperature of dye solution in a dead-end filtration mode. The best performance (removal efficiency >99%, flux: 8017 L/(m2.h)) was obtained at a wide pH range (2−11) by using membrane (7.95 mg biochar/cm2, derived from pyrolysis of vinasse at 900 °C). Moreover, initial dye concentration and solution temperature had no considerable effect on membrane performance, which was stable even after ten cycles of filtration-regeneration by ethanol-washing. At pH 2, the membrane was also quite good at removing Congo red (anionic dye) with efficiency of 98%, which decreased when increasing pH from 2 to 11. Behavior of membrane towards dyes with different characteristics was explained by considering high surface area (756 m2/g) of the biochar and phenomenon, including aromatic stacking and electrostatic-attraction between dye molecule and biochar surface. All findings and application to a real textile industry effluent demonstrated that developed membrane was easy-to-use and sustainable material for effective treatment of water and wastewater containing dyes with different molecular weights and ionic characteristics.

Fabrication of antireflective coatings on cotton surface using dye-loaded nanoparticles for eco-friendly textile inkjet printing

Colored cellulose textiles extensively enriched human-beings' modern lives, but the problem of dye pollution has been a long-plagued trouble and still poses an alarming threat to environment and human beings. In view of this problem, herein, multi-color antireflective nanoparticles inspired by biology were prepared using dye adsorption method. Then, it was applied in cotton inkjet printing to realize the improvement of dye utilization efficiency. Results shows that, cationic poly(styrene-butyl acrylate-vinylbenzyl trimethylammonium chloride) (PSBV) nanoparticles exhibited high dye capacity. The dye-adsorbed nanoparticles possessed uniform spherical structure with an average size at about 90 nm and a surface potential over −30 mV. Turbiscan Lab measurement and high-speed camera system show that the dye-adsorbed nanoparticles possessed good stability and satisfactory jetting performance. Moreover, after the inkjet printing on cotton fabrics, the reflectance was significantly reduced with higher color strength in comparison to the same concentration of dye solution. Moreover, owing to the reaction between the nanoparticles and -OH groups on cotton fibers, durable patterns were obtained. This work provides a potential method on the preparation and application of dye/polymer nanoparticles in textile coloration for improved cleanliness and efficiency.

Quantification of indigo on denim textiles as basis for jeans recycling

Concepts for circularity of post-consumer textile wastes have to consider the presence of dyes in the respective feedstock. Denim textiles form an important group of products which almost exclusively have been dyed with indigo, thus fibre-to-fibre recycling will allow reuse of the dye. Such an approach will require an appropriate analytical method to quantify the indigo content on a textile material. The alkaline Fe(II)-complex with triethanolamine as ligand allows rapid and time stable reduction of the indigo dye into its soluble leuco-form. After desorption of the indigo leuco-dianion quantification of the dye concentration can be achieved by photometry at 410 nm. The measurement of the dye concentration in solution makes the method independent of the uneven dye distribution in denim, which consists of ring-dyed warp and white weft yarn. This uneven dye distribution in denim textiles makes common methods of colour measurement unsuitable for indigo quantification in denim wastes. The presented technique thus will be an essential tool for any approach to recycle denim textiles including valuable indigo dye therein.

Development of dried uncharred leaves of Ficus benjamina as a novel adsorbent for cationic dyes: Kinetics, isotherm, and batch optimization

Adsorption is one of the efficient techniques for removing dyes from wastewater. The present work proposes the development of a biowaste-based low-cost, renewable, and porous adsorbent derived from the leaves of Ficus benjamina (FB). The dry leaves of FB are non-edible, and non-medicinal, producing a large amount of waste yearly. The adsorbent was employed for the removal of the cationic dyes rhodamine B (RhB), malachite Green (MG), crystal violet (CV), and methylene blue (MB). The adsorbent was characterized by FTIR, FESEM, EDAX, and BET analysis. The pore size, volume, and surface area were 2 nm, 0.035 cc g−1, and 24.2 m2 g−1, respectively. The batch adsorption studies were done by optimizing parameters like pH, the weight of FB, time of equilibration, and concentration of dye solution. Studies indicated that the maximum pH of adsorption for dyes depends on the pKa values of cationic dye. The optimum adsorption pH for RhB, and MG, were 2, 4, and 6 for CV and MB. The adsorption data were modeled using the non-linear Langmuir, Freundlich, Temkin, and Sips adsorption isotherm. The Freundlich and Sips isotherm showed better fitting of the data indicating the formation of a multilayer of the dyes on the surface. Adsorption kinetics was pseudo-second order highlighting the adsorption mechanism as a two-body interaction. Our studies indicated the maximum adsorption capacities of 9.92 mg g−1 for RhB, 11.01 mg g−1 for CV, 39.62 mg g−1 for MG, and 25.43 mg g−1 for MB. Thermodynamic studies at three different temperatures, 298, 308, and 318 K, show cationic dyes adsorption on adsorbent to be spontaneous and endothermic. Activation energies of RhB, MG, CV, and MB were found to be 90.14, 51.94, 58.74, and 24.22 kJ mol−1, respectively, indicating chemisorption. Our studies indicated that the pulverized dry leaves of FB could serve as a good batch adsorbent for the cationic dyes in wastewater.

Molecular structure tuning impact on optical linearity and nonlinearity of novel push-pull conjugated organic systems for photonic applications

In the present work, we have designed and synthesized push-pull conjugated (symmetric d-π-A-π-D type) organic chromophores 2-(2,6-bis((E)-2-(anthracen-9-yl) vinyl)-4H-pyran-4-ylidene)malononitrile (M2) and 2-(2,6-bis((E)-2-(pyren-1-yl) vinyl)-4H-pyran-4-ylidene) malononitrile (M3). These chromophores are the derivatives of 2-(2, 6-dimethyl-4H-pyran-4-ylidene) malononitrile (DPM) with DPM acting as an electron acceptor unit whereas anthracene and pyrene substituents are represented as the electron donor units in M2 and M3 respectively. The structural and photophysical properties of these compounds have been analyzed using IR, NMR, UV–Vis absorption and emission spectroscopies. We comparatively investigated the third-order NLO properties of these novel compounds in CHCl3 for different dye solution concentrations and various laser powers. Moreover, the effect of substitution (electron acceptor unit anthracene and pyrene) on the nonlinear optical properties have been discussed based on the structural modification. The quantum chemical calculations (DFT) were performed to obtain optimized geometry, frontier molecular orbitals, natural bond orbitals (NBO), and NLO parameters of these compounds. The time-dependent density functional theory (TD-DFT) was employed for insight into the electronic structure, photophysical, and NLO properties of these compounds. Experimental results have been supported by the obtained theoretical results.

Removal of Brilliant Green Dye from Water Using Ficus benghalensis Tree Leaves as an Efficient Biosorbent.

The presence of dyes in water stream is a major environmental problem that affects aquatic and human life negatively. Therefore, it is essential to remove dye from wastewater before its discharge into the water bodies. In this study, Banyan (Ficus benghalensis, F. benghalensis) tree leaves, a low-cost biosorbent, were used to remove brilliant green (BG), a cationic dye, from an aqueous solution. Batch model experiments were carried out by varying operational parameters, such as initial concentration of dye solution, contact time, adsorbent dose, and pH of the solution, to obtain optimum conditions for removing BG dye. Under optimum conditions, maximum percent removal of 97.3% and adsorption capacity (Qe) value of 19.5 mg/g were achieved (at pH 8, adsorbent dose 0.05 g, dye concentration 50 ppm, and 60 min contact time). The Langmuir and Freundlich adsorption isotherms were applied to the experimental data. The linear fit value, R2 of Freundlich adsorption isotherm, was 0.93, indicating its best fit to our experimental data. A kinetic study was also carried out by implementing the pseudo-first-order and pseudo-second-order kinetic models. The adsorption of BG on the selected biosorbent follows pseudo-second-order kinetics (R2 = 0.99), indicating that transfer of internal and external mass co-occurs. This study surfaces the excellent adsorption capacity of Banyan tree leaves to remove cationic BG dye from aqueous solutions, including tap water, river water, and filtered river water. Therefore, the selected biosorbent is a cost-effective and easily accessible approach for removing toxic dyes from industrial effluents and wastewater.

Removal of Food Dye Tartrazine (E102) from Aqueous Solution using ZnO and CuO-TiO2 as Photocatalysts

Tartrazine dye has a major role in food as well as in other industrial products, like cosmetics, personal care products, pharmaceutical products and many more, therefore it is the cause of many environmental pollutions particularly water pollution. Its removal from water bodies is almost impossible with traditional techniques, because of heterogeneity in its composition. This investigation was carried out to examine the photo-catalytic degradation of food dye tartrazine (E102) from its aqueous solution, using ZnO (zinc oxide) and mixed CuO-TiO2 (copper oxide-titanium dioxide) as photo-catalysts at room temperature. The influence of several parameters, such as pH of medium, time of irradiation, concentration of dye solution and amount of catalyst was investigated. Kinetic analysis was also carried out using Langmuir – Hinshelwood approach. Maximum Photo-Catalytic Degradation (PCD) of E102 was observed to be at pH 1. Similarly significant rise in the degradation of E102 was observed with the time of irradiation, concentration of dye solution and amount of catalyst. From the results obtained it was observed that ZnO and CuO-TiO2 are effective photo-catalysts for the removal of E102 from its aqueous solution. However ZnO was observed to be more effective than CuO-TiO2 in the degradation of E102 from aqueous solution.

Treatment of Water Containing Dyes Using Cellulose Aerogels

Abstract In recent years, there has been an interest in the study of new methods for the removal of dyes from water due to its large-scale use in different industries, for example, for paper printing, textile, leather, pharmaceutical, food or technological applications. It is estimated that more than 700 thousand tons of about 10 000 different types of dyes are produced annually. Most of them are synthetic origin and can generate adverse effects, for example, teratogenic, mutagenic and carcinogenic action. Dyes are mainly applied in the textile industry, and they are usually classified into anionic (acid dyes), cationic (basic dyes) and non-ionic (disperse dyes) dyes. The direct discharge of dyes into the environment can cause various damages to plants and animals: dyes can block the penetration of sunlight, reduce the photosynthetic efficiency of aquatic plants and ultimately destroy the ecological balance of the aquatic ecosystem. This study determined the adsorption efficiency of congo red, methylene blue, rhodamine B and naphthol green B dyes used in textile industry by using the aerogel – an adsorbent synthesized from paper waste. Total carbon was selected as indicator of dye concentration in solution. An increase in fibre content from 3 % to 5 % contributes to the improvement of adsorption properties. The decrease in congo red concentration after an adsorption process was 31.0 % and 38.0 % respectively; the decrease in methylene blue was 2.49 % and 8.15 %; the decrease in naphthol green B was 28.04 % and 34.14 % and the decrease in rhodamine B was 1.28 % and 4.13 %.

The Adsorption Equilibrium and Kinetic Studies for The Removal of Crystal Violet Dye (Methyl Violet 6b) from Aqueous Solution Using Avocado Pear Seed Activated Carbon

In this study, adsorption equilibrium and kinetic studies for the removal of crystal violet (CV) from an aqueous solution were investigated using a batch adsorption process. The activated carbon was prepared by carbonizing the avocado pear seed at a carbonization temperature of 500OC for 1hr and was impregnated with a 30% concentration of aqueous HCl solution which was further activated in a muffle furnace at a temperature of 500OC for 1hr. The avocado pear seed activated Carbon obtained was characterized using proximate analysis, Fourier Transform Infra-Red Spectrophotometer (FT-IR) analysis and Scanning Electron Microscope (SEM) analysis. The effect of various adsorption parameters such as contact time (15-150 min), initial dye concentration (25-150 mg/L), adsorbent dosage (1-9 g), particle size and pH of dye solution were investigated. The adsorption equilibrium data were fitted into different isotherm models and the Langmuir model exhibited the best fit which implied that the adsorption of CV dyes onto avocado pear seed activated carbon was monolayer and the adsorbent surface was homogeneous and also; adsorption energy was uniform for all sites and there was no transmigration of adsorbate in the plane of the surface. The kinetic studies revealed that the adsorption data fitted well to the pseudo-second-order model with a high correlation coefficient of 0.977 when compared to other models, thus; signifying that the adsorption’s mechanism was chemisorption. APSAC shows a much better adsorption capacity for CV dye removal having a maximum adsorption capacity of 3.3254 mg/g and percentage removal of 99.995 %. Hence, APSAC can be used as an effective and low-cost adsorbent for the removal of CV dye from an aqueous solution.

Complexes of terpyridine scaffold as efficient photocatalysts for the degradation of methylene blue pollutant in wastewater effluents

In the present protocol, a series of varyingly substituted terpyridine-based ligands have been designed and synthesized. The synthesized ligands were coordinated with different transition metal cations. Their complexation with Fe(II), Co(II) and Zn(II) led to interesting coordination compounds which for the first time, were evaluated for their photocatalytic potential against the degradation of methylene blue. Almost all the tested complexes 1–9 exhibited fascinating photocatalytic properties. However, noteworthy, photocatalytic results revealed that zinc complexes 1 ([Zn (4′-(p-tolyl)-2,2′:6′,2″-terpyridine)(SO4)2−]), 4 ([Zn (N,N-Dimethyl-4-(2,2′:6′,2″-terpyridin-4′-yl)aniline)(SO4)2−]) & 7 ([Zn (N,N-Diphenyl-4-(2,2′:6′,2″-terpyridin-4′-yl)aniline)(SO4)2−]) have high potential against the degradation of methylene blue followed by iron complexes 3 ([Fe(4′-(p-tolyl)-2,2′:6′,2″-terpyridin)2](PF6)2), 6 ([Fe(4′-(N,N-Dimethyl-4-(2,2′:6′,2″-terpyridin-4′-yl)aniline)2]2PF6) &9 ([Fe(N,N-Diphenyl-4-(2,2′:6′,2″-terpyridin-4′-yl)aniline)2]2PF6) and then cobalt complexes 2 (Co(4′-(p-tolyl)-2,2′:6′,2″-terpyridin)2](PF6)2), 5 ([Co(4′-(N,N-Dimethyl-4-(2,2′:6′,2″-terpyridin-4′-yl)aniline)2]2PF6) &8 ([Co(N,N-Diphenyl-4-(2,2′:6′,2″-terpyridin-4′-yl)aniline)2]2PF6). Among all the complexes, maximum degradation efficiencies were observed for complex 1 (67.31 %) and complex 7 (65.91 %). The optimized photocatalytic conditions were found to be 10 mg/L of initial concentration of dye solution, 20 mg of catalyst dose, pH = 4 and irradiation time of 40 min. At optimized conditions complex 7 was found to be more efficient photocatalyst with rate constant value of 0.011 min−1 as compared to the rate constant value of 0.009 min−1 for complex 1. Both complexes followed the pseudo-first order kinetics model. The reusability test indicated only 8.62 % and 7.01 % loss of photocatalytic activity for complex 1 and complex 7, respectively, up to four cycles of photodegradation reflecting that these catalysts can be used again and again. This study suggested the remarkable potential of terpyridine metal complexes for the environmental remediation to remove harmful pollutants from aqueous bodies.

Tea Waste Products: A New Low-Cost and Green Adsorbent Alternative for Rhodamine-B Dye Removal

Tea waste products were thrown out without any intention to utilize their potential benefits. This waste will help to improve industries to absorb rhodamine-B (RhB) dye pollutants currently used by various industries. This study evaluated the application of tea waste products to remove Rh-B from aqueous systems by investigating adsorption kinetics in a batch process. The ability and mechanism of Indonesian black and green tea in RhB adsorption were determined by optimizing temperature, pH, contact time, and concentration of dye solution. Achievement of equilibrium attained at 40 min for black tea (BT) and green tea (GT). Subsequently, the adsorption capacity reached optimum at 80 and 70 °C for GT, and the maximum adsorption capacities for BT and GT were 22 and 47 mg/g, respectively, at pH 2.5. The absorption of RhB in both bio-sorbents was an exothermic process that well fit the Langmuir model and a pseudo-second-order reaction. The presented R2 values from the Langmuir isotherm are 0.9967 (BT) and 0.9979 (GT). The separation factor was determined as 0.026 (BT) and 0.055 (GT). Thermodynamic studies were carried out to calculate free energy, enthalpy, and entropy changes. The result showed that the removal study of BT and GT is 59.06 and 60.25%, respectively, using 10% acetic acid. Study comparisons were carried out on both teas with other bio-sorbents for more improvement. These results show that tea waste products can be used as alternative adsorbents to absorb RhB from wastewater.

A Sustainable Approach to Study on Antimicrobial and Mosquito Repellency Properties of Silk Fabric Dyed with Neem (Azadirachta indica) Leaves Extractions

The present research work was conducted on developing sustainable production of mulberry filament silk fabric dyed with different extracted dye solutions based on extraction ratios of 1:4, 1:6, 1:8, and 1:10 from neem (Azadirachta indica) leaves. The research work focused on evaluating the antimicrobial and mosquito repellent properties of dyed silk fabric. In the experiment, the samples were dyed using the exhaust method at different dye bath concentrations i.e., 15 g/L, 20 g/L, and 25 g/L in the presence and absence of mordant at 80 °C maintaining 1:60 dyeing liquor ratio. The absorbance of the extracted dye solutions was determined with a UV/VIS spectrophotometer, which detected the highest absorbance of 7.73 at the peak 490 nm of λmax of 1:4 extracted dye solution. Fourier transform infrared (FTIR) spectroscopy was used to investigate the chemical structure of dyed fabrics; however, no chemical changes or bond formation occurred; instead, dye particles were deposited on the fabric layer, indicating the presence of bioactive components. Allergy test was also performed to confirm allergic reactions of neem extract on human skin. The antimicrobial activity of extracted dye solutions and dyed samples was estimated against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria using the agar diffusion method and mosquito repellency of fabrics were examined by the cage method. The results emphasized that dyed fabric with the highest concentrated dye solution, 1:4 extraction, and highest dye bath concentration, 25 g/L along with mango bark mordant solution, possesses the highest antimicrobial activity in terms of an inhibition zone of 0.67 mm against Gram-negative bacteria and 0.53 mm against Gram-positive bacteria obtained after incubation, and the highest mosquito repellent of 75% due to the absorption of active bio constituents. The experimental results also determined that the dyed fabric with 1:4 extracted dye solution exhibited good antimicrobial (inhibition zone, 0.65 mm against E. coli and 0.52 mm against S. aureus) and mosquito repellent property (66.67%). The experimental study also revealed that Potassium dichromate mordant reduced the antimicrobial (inhibition zone, 0.05 mm against E. coli and no inhibition against S. aureus) and mosquito repellent action (33.33%). In conclusion, the data revealed that the increase in the extraction ratio of dye solution and dye bath concentration has no impact on the silk fibroin; it only impacts what is deposited on the fabric layer that improves its antimicrobial and mosquito repellency. The current research showed that neem leaves were found to have a beneficial effect in controlling microorganisms and mosquitoes through a sustainable approach.

Biochar Derived from Sesbania sesban Plant as a Potential Low-Cost Adsorbent for Removal of Methylene Blue

In this study, biochar made from the Sesbania sesban plant, under slow pyrolysis at 300°C was used to adsorb methylene blue (MB) in aqueous solution. The biochar properties were clarified by diverse analytical methods such as FTIR, SEM, and BET. The results indicated that the surface of biochar was relatively smooth, had porous texture, and stacked evenly. In addition, the biochar had a large specific surface area of 561.8 m2/g and the pHpzc value was 6.9. The effect of adsorbent dosage, initial pH, contact time, and concentration of dye solution on biochar were investigated. The optimum conditions for MB adsorption were found at the MB concentration of 50 mg/L, initial pH of 11, biochar mass of 0.6 mg, and contact time of 30 min. Under these optimal conditions, MB dye removal efficiency was above 90%. Adsorption isotherm data were fitted with the Langmuir isotherm model (R2=0.897) suggesting the adsorption was monolayer, and its maximum adsorption capacity was about 6.6 mg/g. The adsorption kinetic models showed that the linear pseudo-second-order by R2=0.999 was well fitted. The results indicated the enormous potential of Sesbania sesban plant to produce biochar as a low-cost and rather high-effective adsorbent for dye removal from wastewater as well as water quality improvement.

Dye Elimination by Surface-Functionalized Magnetite Nanoparticles: Kinetic and Isotherm Studies

In the present manuscript, uncoated and citric acid-coated magnetic nanoparticles were synthesized and characterized using various techniques. The manuscript mainly focuses on the adsorption study of the citric acid-modified magnetic nanoparticles for dye adsorption from the solution. The effect of several factors, including adsorbent amount, adsorption time, and dye solution concentration, were examined. Additionally, kinetic and isotherm studies confirmed that the adsorption process followed pseudo-second-order kinetics and the Langmuir isotherm model. The desorption study was also scrutinized. The coated magnetite nanoparticles show better adsorption capacity than uncoated magnetite nanoparticles.

Synthesis of Starch-Grafted Polymethyl Methacrylate via Free Radical Polymerization Reaction and Its Application for the Uptake of Methylene Blue.

In this research, a new biodegradable and eco-friendly adsorbent, starch-grafted polymethyl methacrylate (St-g-PMMA) was synthesized. The St-g-PMMA was synthesized by a free radical polymerization reaction in which methyl methacrylate (MMA) was grafted onto a starch polymer chain. The reaction was performed in water in the presence of a potassium persulfate (KPS) initiator. The structure and different properties of the St-g-PMMA was explored by FT-IR, 1H NMR, TGA, SEM and XRD. After characterization, the St-g-PMMA was used for the removal of MB dye. Different adsorption parameters, such as effect of adsorbent dose, effect of pH, effect of initial concentration of dye solution, effect of contact time and comparative adsorption study were investigated. The St-g-PMMA showed a maximum removal percentage (R%) of 97% towards MB. The other parameters, such as the isothermal and kinetic models, were fitted to the experimental data. The results showed that the Langmuir adsorption and pseudo second order kinetic models were best fitted to experimental data with a regression coefficient of R2 = 0.93 and 0.99, respectively.

Adsorption efficiency of date palm based activated carbon-alginate membrane for methylene blue.

In the current study, activated carbon (AC) was prepared from date palm using single step activation using boric acid as an activating agent. The synthesized AC was incorporated with alginate (AC-alginate (AC-alg)) to prepare membrane for adsorption of methylene blue (MB) in batch adsorption study. The prepared membrane was characterized using different types of analytical techniques such as FTIR, SEM, and TGA analysis. Adsorption of methylene blue dye from aqueous solution was carried out using AC-alg membrane in batch investigation. Various experimental parameters effecting the adsorption of MB on membrane such as initial pH of dye solution, contact time, concentration of dye solution and temperature were optimized to get maximum adsorption efficiency. Kinetics, isotherm and thermodynamics study was performed for dye adsorption. Pseudo-second order kinetic model and Langmuir adsorption isotherm were well fitted to the experimental data. The maximum adsorption capacity for MB adsorption was 666mg/g found by Langmuir adsorption isotherm. Thermodynamic study revealed that the adsorption of MB on AC-alg membrane is spontaneous and an exothermic process. The experimental result confirmed that AC-alg membrane is a suitable and easily recoverable adsorbent to be used for efficient removal of MB and MB like other dyes.

Upcycling Glass Waste into Porous Microspheres for Wastewater Treatment Applications: Efficacy of Dye Removal

Each year about 7.6 million tons of waste glasses are landfilled without recycling, reclaiming or upcycling. Herein we have developed a solvent free upcycling method for recycled glass waste (RG) by remanufacturing it into porous recycled glass microspheres (PRGMs) with a view to explore removal of organic pollutants such as organic dyes. PRGMs were prepared via flame spheroidisation process and characterised using Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and Mercury Intrusion Porosimetry (MIP) analysis. PRGMs exhibited 69% porosity with overall pore volume and pore area of 0.84 cm3/g and 8.6 cm2/g, respectively (from MIP) and a surface area of 8 m2/g. Acid red 88 (AR88) and Methylene blue (MB) were explored as a model source of pollutants. Results showed that removal of AR88 and MB by PRGMs was influenced by pH of the dye solution, PRGMs doses, and dye concentrations. From the batch process experiments, adsorption and coagulation processes were observed for AR88 dye whilst MB dye removal was attributed only to adsorption process. The maximum monolayer adsorption capacity (qe) recorded for AR88, and MB were 78 mg/g and 20 mg/g, respectively. XPS and FTIR studies further confirmed that the adsorption process was due to electrostatic interaction and hydrogen bond formation. Furthermore, dye removal capacity of the PRGMs was also investigated for column adsorption process experiments. Based on the Thomas model, the calculated adsorption capacities at flow rates of 2.2 mL/min and 0.5 mL/min were 250 mg/g and 231 mg/g, respectively which were much higher than the batch scale Langmuir monolayer adsorption capacity (qe) values. It is suggested that a synergistic effect of adsorption/coagulation followed by filtration processes was responsible for the higher adsorption capacities observed from the column adsorption studies. This study also demonstrated that PRGMs produced from recycled glass waste could directly be applied to the next cyclic experiment with similar dye removal capability. Thus, highlighting the circular economy scope of using waste inorganic materials for alternate applications such as pre-screening materials in wastewater treatment applications.

Removal of toxic thymol sulfone phthalein dye from wastewater by using efficient adsorbent NiO nanoparticles

NiONPs was synthesized from Ficus Nitida plant under control conditions and which is considerably efficient for removal of dyes from wastewater. The obtained NiONPs was identified by Fourier transform infrared spectra (FTIR), Scanning electron microscopy (SEM), X-ray diffraction (XRD), Energy dispersive x-ray spectroscopy (EDX), Transmission electron microscopy (TEM) analyses and surface area. The removal of toxic thymol sulfone phthalein (TSP) dye by an efficient adsorbent NiONPs has been investigated spectrophotometrically. Variables such as contact time, initial dye concentration, adsorbent dose, temperature and pH of dye solution were studied. Langmuir and Freundlich isotherm models were used to illustrate the equilibrium of the adsorption. The correlation coefficient values of Langmuir and Freundlich equations were found to be in good agreement. A pseudo-second-order mechanism governs the absorption of TSP onto NiONPs. A spontaneous and exothermic process, adsorption was a spontaneous process. In addition, the thermodynamic parameters have been analyzed, and an appropriate reaction mechanism has been presented and discussed in this paper.

Characterization of the biosynthesized intracellular and extracellular plasmonic silver nanoparticles using Bacillus cereus and their catalytic reduction of methylene blue

The biosynthesis of silver nanoparticles (Ag NPs) has been studied in detail using two different approaches. For the first time, Bacillus cereus is used for one-pot biosynthesis of capsulated Ag NPs, using both intracellular and extracellular approaches. To discriminate between the produced nanostructures by these two approaches, their structures, nanomorphologies, optical properties, hydrodynamic sizes and zeta potentials are studied using different techniques. Fourier-transform infrared spectroscopy was used to identify the bioactive components responsible for the reduction of Ag+ ions into Ag and the growth of stable Ag NPs. Scanning and transmission electron microscopy images displayed spherical and polygon nanomorphology for the intracellular and extracellular biosynthesized Ag NPs. For intracellular and extracellular biosynthesized Ag NPs, a face-centred cubic structure was observed, with average crystallite sizes of 45.4 and 90.8 nm, respectively. In comparison to the noncatalytic reduction test, the catalytic activities of intracellular and extracellular biosynthesized Ag NPs were explored for the reduction of highly concentrated MB dye solution. Extracellular Ag NPs achieved 100% MB reduction efficacy after around 80 min, compared to 50.6% and 24.1% in the presence and absence of intracellular Ag NPs, respectively. The rate of MB reduction was boosted by 22 times with the extracellular catalyst, and by 3 times with the intracellular catalyst. Therefore, the extracellular production process of Ag NPs utilizing Bacillus cereus bacteria might be applied in the industry as a cost-effective way for eliminating the toxic MB dye.