Corncob as an effective, eco-friendly, and economic biosorbent for removing the azo dye Direct Yellow 27 from aqueous solutions

Potential of Capparis decidua plant and eggshell composite adsorbent for effective removal of anionic dyes from aqueous medium

The presence of hazardous dyes in wastewater poses significant threats to both ecosystems and the natural environment. Conventional methods for treating dye-contaminated water have several limitations, including high costs and complex operational processes. This study investigated a sustainable bio-sorbent composite derived from the Capparis decidua plant and eggshells, and evaluated its effectiveness in removing anionic dyes namely tartrazine (E-102), methyl orange (MO), and their mixed system. The research examines the influence of initial concentration, contact time, pH, adsorbent dosage, and temperature on the adsorption properties of anionic dyes. Optimal removal of tartrazine (E-102), methyl orange (MO), and their mixed system was achieved at a pH of 3. The equilibrium was achieved at 80 min for MO and mixed systems, and 100 min for E-102. The adsorption process showed an exothermic nature, indicating reduced capacity with increasing temperature, consistent with heat release during adsorption. Positive entropy values indicated increased disorder at the solid-liquid interface, attributed to molecular rearrangements and interactions between dye molecules and the adsorbent. Isotherm analysis using Langmuir, Freundlich, Temkin, and Redlich-Peterson models revealed that the Langmuir model best fit the experimental data. The maximum adsorption capacities of 50.97 mg/g, 52.24 mg/g, and 56.23 mg/g were achieved for E-102, MO, and the mixed system under optimized conditions, respectively. The pseudo-second-order kinetic model demonstrated the best fit, indicating that adsorption occurs through physical and chemical interactions such as electrostatic attraction, pore filling, and hydrogen bonding. Hence, the developed bio-sorbent could be a sustainable and cost-effective solution for the treatment of anionic dyes from industrial effluents.

Ecofriendly Approach on the Removal of Reactive Orange 107 from Aqueous Solutions Using Cladophora Species as a Novel Biosorbent

The efficiency of Cladophora species for the removal of Reactive Orange 107 (RO107) from the aqueous solution was evaluated through batch adsorption studies by optimising various process parameters such as pH (3-8), dye concentration (100-500 mg/l), biosorbent concentration (100-500 mg/l), temperature (25-45 °C) and contact time (12-108 h). The results revealed that the optimum conditions for RO107 decolourisation (87%) was found on 72 h of incubation with 100 mg/l dye concentration amended with 200 mg/l biosorbent at pH 6 at 25 °C. The mechanism of dye adsorption was evaluated using isotherms, kinetics and thermodynamic models. The experimental data fitted well with Langmuir isotherm and pseudo-second-order kinetic models. Thermodynamic studies revealed that the adsorption process was endothermic, spontaneous and feasible in nature. Recovery of RO107 from the Cladophora sp. was maximum when 0.1 M HNO3 was used as an eluent. UV-Visible, FT-IR and SEM analyses reveal the interaction between the biosorbent-adsorbate and confirm the process of decolourisation by Cladophora sp. In order to evaluate the nature of the untreated and treated dye solutions, toxicological studies were conducted and the results revealed that the treated dye solution was non- toxic as compared with untreated dye solution. The results of the docking study proved that there was a substantial binding energy between RO107 and the protein (Cytochrome C6) of Cladophora sp. Hence, Cladophora sp. proves to be a promising biosorbent to decolourise RO107 and its potential can be explored in the textile sectors.

Straw-derived biochar for the removal of antibiotics from water: Adsorption and degradation mechanisms, recent advancements and challenges

Antibiotics, a kind of containments with the properties of widely distributed and difficult to degrade, has aroused extensive attention in the world. As a prevalent agricultural waste, straws can be utilized to prepare biochar (straw-derived biochar, SBC) to remove antibiotics from aquatic environment. To date, although a number of review papers have summarized and discussed research on biochar application in wastewater treatment and soil remediation, there are few reviews on SBC for antibiotic removal. Due to the limitations of poor adsorption and degradation performance of the pristine SBC, it is necessary to modify SBC to improve its applications for antibiotics removal. The maximum antibiotic removal capacity of modified SBC could reach 1346.55 mg/g. Moreover, the adsorption mechanisms between modified SBC and antibiotics mainly involve π-π interactions, electrostatic interactions, hydrophobic interactions, and charge dipole interactions. In addition, the modified SBC could completely degrade antibiotics within 6 min by activating oxidants, such as PS, PDS, H2O2, and O3. The mechanisms of antibiotic degradation by SBC activated oxidants mainly include free radicals (including SO4•-, •OH, and O2•-) and non-free radical pathway (such as, 1O2, electrons transfer, and surface-confined reaction). Although SBC and modified SBC have demonstrated excellent performance in removing antibiotics, they still face some challenges in practical applications, such as poor stability, high cost, and difficulties in recycling. Therefore, the further research directions and trends for the development of SBC and biochar-based materials should be taken into consideration.

Maize cob (Zea mays) as natural biomass sorbent for crude oil biosorptive removal from contaminated seawater: Taguchi process optimization and biosorptive removal mechanism

Crude oil pollution poses a serious threat to the aquatic environment. Hence, there is an increasing interest in developing an efficient cleaner process technique for oil spill cleanup via agricultural biomass waste-organic sorbent utilization. This work evaluated the effects of independent biosorptive removal at three varying levels (initial concentration of crude oil (Z1, 7.8-15.6 g/L), seawater-oil temperature (Z2, 25-45 °C), sorbent dose (Z3, 1-3 g), and sorbent particle size diameter (Z4, 1.18-4.72 mm)) on the biosorptive removal efficiency and biosorptive capacity performance of maize cob sorbent for crude oil biosorptive removal from seawater. Experiments were designed based on Taguchi orthogonal array experimental design (L9(34)) to study the effects and process optimization. The results revealed that the maize cob sorbent's crude oil biosorptive removal efficiency is related to Z1, Z3, and Z4, while the biosorptive capacity is related to Z1 and Z3. The optimum biosorptive removal efficiency and the biosorptive capacity values were 96.53% and 12.64 g/g, respectively, achieved at optimum factors of Z1 (7.8 g/L), Z3 (3 g), and Z4 (1.18 mm), as well as at Z1 (15.6 g) and Z3 (1 g). The isotherm and kinetic data, respectively, followed the Langmuir isotherms and the pseudo-second-order kinetics with a maximum monolayer biosorptive capacity of 23.31 g g-1. The mechanism of biosorptive crude oil removal was by physical sorption and film diffusion control. Therefore, the maize cob represents an inexpensive and effective natural sorbent for oil spill removal from water bodies.

Selective Adsorption of Direct Group Anionic Dyes on Layered Double Hydroxide-Chitosan Composites

In this research, the potential of M2+/Al intercalated chitosan has been evaluated and good ability to reduce dyes in an aqueous solution. M2+/Al intercalated chitosan was prepared by anion exchange method and coprecipitation in a nitrogen atmosphere. Selectivity adsorption was studied to maintain the ability of M2+/Al intercalated chitosan for particle size of direct dyes (direct green, direct red, and direct yellow). To evaluate the adsorption process, M2+/Al intercalated chitosan was conducted with kinetic, isotherm, and thermodynamic parameters. The kinetic data fitted well by pseudo-second order and isotherm fitted Langmuir isotherm with qmax obtained 294.11 and 322.58 mg/g for Zn/Al-chitosan and Mg/Al-chitosan, respectively. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Azo dyes degradation by microorganisms - An efficient and sustainable approach

Synthetic aromatic compounds consisting of various functional groups are known as dyes. These colored compounds are often discharged in effluents, and they are very dangerous to aquatic life. Basically, the dye industry started by using natural plant and insect sources, and then suddenly turned into artificial manufacturing. Natural equilibrium of our environment gets changed by the reduction in photosynthetic activity due to the dyes. In China 900,000 tons of all kinds of dyes are usually produced, which are used in many industries like food, textile, food, paper and leather. Untreated wastewater contaminates aquatic bodies by causing eutrophication, change in water color, oxygen depletion which affect aquatic organisms to a great extent. Dye wastewater is now the key environmental pollution form. In recent eras an extensive study line has been developed to explore the dye decolorization and biodegradation under both aerobic as well as anaerobic conditions. In this review, the chemistry, toxicity and microbial biodegradation/decolorization are presented. Some recent studies along with the new techniques and methodologies of remediating the dye pollution are also discussed to provide the bases of their handling. Overall, efficient and high biodegradation potential make microbes an impending foundation for green chemistry to eradicate toxic dyes from industrial wastewater.

Metanil Yellow dye adsorption using green and chemical mediated synthesized manganese ferrite: An insight into equilibrium, kinetics and thermodynamics

Green Manganese Ferrite (GMF) and Chemical mediated Manganese Ferrite (CMF) were designed and prepared via in situ co-precipitation method and their adsorption potential was compared using the model dye, Metanil Yellow (MY). Previously, an extract of aquatic macrophyte and metal chloride were employed for the development of ecofriendly GMF. Alternatively, CMF has been synthesized through chemical co-precipitation from metal chloride precursors. Several characterization methods, including PSA, BET, TGA, DSC, FTIR, SEM, VSM, EDX, and XRD, were analyzed to reveal the structural and functional properties of the as-synthesized GMF and CMF. Their MY adsorption performances were tested as the function of the operational conditions such as initial solution pH, temperature, nanocomposite dosage, and dye concentration in a batch mode of operation. The pseudo-second order MY adsorption process fits best in Langmuir model which yielded the maximal monolayer adsorption capacity (q_max) of 391.34 mg/g for GMF and 271.89 mg/g for CMF. This outperformance of GMF over CMF was observed due to the augmentation of specified surface functional moieties derived from the phyto-constituents of macrophages. Further, the thermodynamic studies confirmed the chemisorptive and exothermic nature of adsorption processes. Conclusively, with the ease of regeneration and reuse potential, GMF and CMF could be viable contenders for scale up and industrial applications.

Sodium hydroxide pre-treated Aspergillus flavus biomass for the removal of reactive black 5 and its toxicity evaluation

The present study was focused on the removal of Reactive Black 5 (RB5) from aqueous solution using pre treated Aspergillus flavus as a biosorbent. Pre-treatment of fungal biomass with 0.1 M sodium hydroxide facilitated the removal of dye effectively when compared to untreated fungal biomass. Optimum biosorption conditions for RB5 removal was determined as a function of dye concentration (50-400 mg/L), biosorbent concentration (100-500 mg/L), incubation time (1-7hrs), pH (3-8) and temperature (20-50 °C). At the optimum conditions, the maximum removal efficiency of RB5 achieved by NaOH pretreated A. flavus was 91%. The dye removal was studied kinetically and it obeys the pseudo-second order model and the experimental equilibrium data well fitted the Langmuir isotherm indicating monolayer adsorption of dye molecules on the biosorbent. The thermodynamic parameters such as a change in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were calculated and negative values of ΔG suggested that the dye removal process was spontaneous at all temperatures. Furthermore, the values of ΔH revealed that the adsorption process was endothermic. Recovery of RB5 from the fungal biomass was effective using 0.1 M Na₂CO₃ as an eluent. The interaction of adsorbate with biosorbent was analyzed using UV-Vis and FT-IR spectroscopy, SEM and XRD analyses. Phytotoxicity and microbial toxicity studies revealed the non-toxic nature of the treated dye solution. Hence, the fungal biomass pretreated with NaOH was efficient in decolorizing RB5 as well as composite raw industrial effluent generated from dyeing industries.

Integration of green economy concepts for sustainable biosurfactant production - A review

The link between increasing global population, food demand, industrialization, and agricultural waste is strong. Decomposing by-products from food cycles can introduce harmful toxic heavy metals, active degrading microbes, and enzymes to the environment. Additionally, high greenhouse gas emissions from the decomposing wastes contribute to global change and a high carbon economy. The bioeconomy and circular economy of biosurfactant production utilize these cheap feedstocks and promote waste to valuable product initiatives. Waste reduction, reuse, and recycling in an integrating green economy bioprocess ensure the sustainability of novel, cost-effective, safe, and renewable health-grade biosurfactants. This work reviews green economy concepts integration with sustainable biosurfactant production and its application in health-related industries. Benefits from recent advances in the production, characterization, and health-wise classification of biosurfactants were further discussed, including its limitations, techno-economic assessment, market evaluations, possible roadblocks, and future directions.

Spectroscopic Investigation on the Interaction of Direct Yellow-27 with Protein (BSA)

Direct yellow 27 (DY-27) interaction with bovine serum albumin (BSA) was investigated using multi-spectroscopic techniques to understand the toxicity mechanism. Fluorescence quenching of BSA by DY-27 was observed as a result of the formation of a BSA-DY27 complex with a binding constant of 1.19 × 10⁵M^-1and followed a static quenching mechanism with a quenching constant K_svof 7.25 × 10⁴M^-1. The far UV circular dichroism spectra revealed the conformational changes in the secondary structure of BSA in the presence of DY-27. The calculated average lifetime of BSA is 6.04 ns and is nearly constant (5.99 ns) in the presence of dye and supports the proposed quenching mechanism. The change in free energy (ΔG) was calculated to be -28.96 kJ mol^-1and confirmed the spontaneity of the binding process. Further, docking studies have been conducted to gain more insights into the interactions between DY-27 and serum albumin.

Adsorption of anionic dyes from textile wastewater utilizing raw corncob

Toxic dyes are irrefutable effluent components of textile wastewater, so they have become a major economic and health concern. With the purpose of efficient removal of textile dyes, multiple nature-inspired adsorbents have been applied. Herein, raw corncob is proposed as a novel highly efficient, low-price, and abundantly attainable adsorbent with the potential for uptake of methyl red and methyl orange. Multiple experiments were carried out to optimize parameters including pH, primary concentration, adsorbent dosage, temperature, and contact time. The adsorption was raised with the mounting of the contact time and it was alleviated with the addition of initial concentration. The foremost uptake of dye was apperceived at an acidic medium pH 4 for methyl red and pH 1 for methyl orange. Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy were employed to characterize the surfaces of corncobs. The well-fitted Langmuir and Freundlich models (methyl red: R² = 0.9956 and methyl orange: R² = 0.9883) confirmed the homogeneous monolayer adsorption process on the raw corncob surface. The obtained results disclose that corncob is an effectual biosorbent for eliminating anionic dyes without the necessity for any prior modifications.

Gibberellic Acid Production from Corn Cob Residues via Fermentation with Aspergillus niger

Following numerous biotechnological innovations, a variety of agricultural by-products can now be employed as low-cost substrates for the production of secondary metabolites, such as antibiotics, phytohormones, biofuels, pesticides, and organic acids. As an example, gibberellin (GA) growth phytohormones can be obtained by such means, wherein gibberellic acid (GA3) is of great interest worldwide in the agricultural sector. The central aspect of this research therefore focused on the bioconversion of agricultural by-products, such as corn cob, to obtain GA3 phytohormone via solid-state fermentation (SSF) with Aspergillus niger. The chemical characterization of the obtained material showed that the corn cob possessed glucose, mannose, arabinose, and lignin contents of 34, 26, 8, and 16%, respectively. Our results also indicated an appreciable carbon content (47%), in addition to the mineral elements of nitrogen (4%), potassium (1.2%), iron (0.03%), sodium (0.01%), calcium (0.06%), and Al (0.02%). Following SSF for 11 d in the presence of A. niger at pH 5, 30°C, and 24% sample consistency, a GA3 production of >6.1 g·kg−1 was obtained. This value is higher than those previously reported for different by-products of the food industry, such as coffee husk, wheat bran, cassava, pea pods, and sorghum straw (i.e., 0.25–5.5 g·kg−1) following SSF. The production of GA3 from corn cob residues not only contributes to reducing the negative impact of agricultural by-products but also represents a new source of a key raw material for phytohormone production, thereby contributing to the development of processes to convert agricultural residues into biologically active compounds of commercial interest.

Extraction of Value-Added Minerals from Various Agricultural, Industrial and Domestic Wastes

Environmental pollution is one of the major concerns throughout the world. The rise of industrialization has increased the generation of waste materials, causing environmental degradation and threat to the health of living beings. To overcome this problem and effectively handle waste materials, proper management skills are required. Waste as a whole is not only waste, but it also holds various valuable materials that can be used again. Such useful materials or elements need to be segregated and recovered using sustainable recovery methods. Agricultural waste, industrial waste, and household waste have the potential to generate different value-added products. More specifically, the industrial waste like fly ash, gypsum waste, and red mud can be used for the recovery of alumina, silica, and zeolites. While agricultural waste like rice husks, sugarcane bagasse, and coconut shells can be used for recovery of silica, calcium, and carbon materials. In addition, domestic waste like incense stick ash and eggshell waste that is rich in calcium can be used for the recovery of calcium-related products. In agricultural, industrial, and domestic sectors, several raw materials are used; therefore, it is of high economic interest to recover valuable minerals and to process them and convert them into merchandisable products. This will not only decrease environmental pollution, it will also provide an environmentally friendly and cost-effective approach for materials synthesis. These value-added materials can be used for medicine, cosmetics, electronics, catalysis, and environmental cleanup.

Solvent-Dependent Spectral Properties in Diverse Solvents, Light Harvesting and Antiviral Properties of Mono-Azo Dye (Direct Yellow-27): A Combined Experimental and Theoretical Study

In this paper, we have discussed for the first time a detailed electronic absorption study of the mono-azo dye Direct Yellow 27 [C[Formula: see text]H[Formula: see text]N4Na2O9S3] (DY-27) with five different homogeneous media by applying experimental and theoretical techniques along with some new characteristics of DY-27 in the field of solar cells as well as antiviral activities. A clear absorption band in the UV-visible region was observed, although the absorption maxima lie in the visible region. The electronic absorption transitions observed in our study were fully spin and symmetry allowed transitions with [Formula: see text]–[Formula: see text] character. Time-dependent density functional theory (TD-DFT) analysis has been done for understanding the electronic and the charge transfer performance. Moreover, the impacts of polar protic and polar aprotic solvents in the structural variation of DY-27 have been reported here. Further, applications of the dye in the field of solar cell, as well as antiviral activity, were performed using molecular modeling approaches. The dye exhibited a D–[Formula: see text]–A–A structure with a high light-harvesting efficiency (LHE) and good injection efficiency acts as an effective dye sensitized solar cell (DSSC). Molecular docking studies of the dye DY-27 performed with M-protease of the different corona viruses, MERS, SARS-CoV-1 and SARS-CoV-2 indicated comparable binding energies with the controlled inhibitors and best interactions are observed for the SARS-CoV-1.

Removal of Methylene Blue from Aqueous Solutions by Using Nance (Byrsonima crassifolia) Seeds and Peels as Natural Biosorbents

Contamination of effluents with chemicals is a serious problem that impacts human health. Methylene blue is a cationic dye found frequently in industrial and urban sewages. In this work, dried grinded seeds and peels of nance were used as biosorbents in aqueous solutions at pH 7 and 10 (simulating urban and textile effluents) finding that Langmuir and Freundlich isotherms adequately described the sorption. Adsorption efficiencies were larger than 98% in all cases and slightly lower at pH 7 due to the closeness with the point of zero charge (pzc) of seeds and peels of nance (5.96 and 3.42, respectively). In all cases, Langmuir adsorption was favorable (RLa < 1), and Gibbs free energy of adsorption was negative indicating spontaneity, and since these values were larger than −80 but lower than 0 kJ/mol, the MB removal process was mainly due to physical interactions, a characteristic of physical adsorption. No significant differences were found amongst bulk mass transfer coefficients for the adsorption of both sorbents, indicating that both bioadsorbents had the same hydrodynamic and driving forces as well as depicted similar MB-adsorbent affinities. Interaction of MB with adsorbents was corroborated by FTIR spectroscopy, and the sorption was evidenced by scanning electron microscopy and image analysis which indicated that both adsorbents had fractal structures.

Phosphorus recovery and recycling from model animal wastewaters using materials prepared from rice straw and corn cobs

Anthropogenic loss of phosphorus to surface waters not only causes environmental problems but depletes valuable phosphorus reserves. In this study, magnesium amended biochars and magnesium silicate, synthesized from corn cobs and rice straw, respectively, were evaluated for phosphorus uptake including the effects of pH and alkalinity. The overall goal was to close the phosphorus loop by recovering phosphorus from animal waste and reusing it as fertilizer. After phosphorus uptake, spent materials were tested for phosphorus release using modified soil tests representing different soil pH and alkalinity conditions. In experiments using model animal wastewaters containing both ammonia and bicarbonate alkalinity, dissolved phosphorus was removed by struvite (MgNH₄PO₄·6H₂O) formation, whereas in deionized water, dissolved phosphorus was removed by adsorption. Alkalinity in the model animal wastewaters competed with phosphate for dissolved or solid-associated magnesium, thereby reducing phosphorus uptake. Spent materials released significant phosphorus in waters with bicarbonate alkalinity. This work shows that abundant agricultural wastes can be used to synthesize solids for phosphorus uptake, with the spent materials having potential application as fertilizers.

Unleashing the Biological Potential of Fomes fomentarius via Dry and Wet Milling

Fomes fomentarius, usually referred to as tinder conk, is a common wood-based fungus rich in many interesting phytochemicals and with an unique porous structure. Dry or wet ball milling of this sponge on a planetary mill results in small particles with sizes in the range of 10 µm or below. Suspended in water and without preservatives or other stabilizers, the resulting micro-suspensions are sterile for around six days, probably due to the increased temperatures of around 80 °C especially during the wet milling process. The suspensions also exhibit excellent antioxidant activities as determined in the DPPH, ferric reducing antioxidant potential (FRAP) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. In the DPPH assay, IC₅₀ values of 0.02–0.04% w/v and 0.04% w/v were observed for dry and wet milled samples, respectively. In the FRAP assay, IC₅₀ values of <0.02% w/v and 0.04% w/v were observed for dry and wet milled samples, respectively. In contrast, the ABTS assay provided IC₅₀ values of 0.04% w/v and 0.005% w/v, respectively. Notably, this activity is mostly—albeit not exclusively—associated with the highly porous particles and their large surfaces, although some active ingredients also diffuse into the surrounding aqueous medium. Such suspensions of natural particles carrying otherwise insoluble antioxidants on their surfaces provide an interesting avenue to unleash the antioxidant potential of materials such as sponges and barks. As dry milling also enables longer storage and transport, applications in the fields of medicine, nutrition, agriculture, materials and cosmetics are feasible.

Enhancement in xylonate production from hemicellulose pre-hydrolysate by powdered activated carbon treatment

Xylonic acid can be produced with high-yield from hemicelullosic xylose, which accounts for 25% of the total sugars in lignocellulosic material. The key barrier associated with efficient bio-oxidation of hemicellulosic xylose to xylonic acid is the serious foam formed in downstream air-aerated and agitated bioreaction process, which caused by the high viscosity of concentrated pre-hydrolysate. Powdered activated carbon treatment can selectively absorb the non-sugar compounds with relatively low losses of xylose, which is beneficial for the valuable xylose derivatives production. In this present study, powdered activated carbon was employed for treating the concentrated pre-hydrolysate from diluted acid pretreated corncob. The results indicated that the powdered activated carbon treatment significantly reduced the viscosity of concentrated pre-hydrolysate and the other non-sugar compounds, which enabled scale-up lignocellulosic xylonic acid production using the air-aerated and agitated bioreactor.

Enhancement of Cadmium Adsorption Capacities of Agricultural Residues and Industrial Fruit Byproducts by the Incorporation of Al2O3 Nanoparticles

In this work, two types of residues (industrial fruit byproducts and agricultural wastes) were studies as promising adsorbents for cadmium uptake. Adsorption experiments using the evaluated biomasses (corn crops CC, palm bagasse PB, orange peels OP, and lemon peels LP) were conducted in batch mode by varying initial solution pH (2, 4, and 6) as well as the particle size (0.355, 0.5, and 1 mm). The optimum operating conditions were defined for further adsorption tests. The biomasses were chemically modified with alumina nanoparticles to evaluate the enhancement in adsorption capacities and how the nature of biomass contributes to successful incorporation of nanotechnology-based materials. The point of zero charges was ranged between 4 and 5 for all biomasses. Simultaneously, the Böehm titration method confirmed the presence of lactonic and carboxylic acid groups on the surfaces of the biomasses. Optimum operating conditions for batch cadmium adsorption experiments were observed at pH 6. Moreover, no significant changes were detected as a function of biomass size. For corn cob and lemon peels, removal percentages at 86 and 88% were reached using particle size = 0.5 mm. For palm bagasse and orange peels, the optimum parameters were 0.355 and 1 mm, respectively. Al2O3 nanoparticles with a crystal size of 58 ± 12 nm were obtained by applying the sol-gel methodology. A higher cadmium removal percentage was detected after using the biomasses modified with the Al2O3 nanoparticles, determining for the agricultural wastes an adsorption capacity of 91% (CC-Al2O3) and 92% (PB-Al2O3). In comparison, the industrial fruit byproducts exhibited a removal percentage of 93% (LP-Al2O3) and 96% (OP-Al2O3). The modification of industrial fruit byproducts (lemon peels and orange peels) showed increases in adsorption efficiencies around 12-6% after incorporating alumina nanoparticles, suggesting that this type of biomass is more suitable for adsorption property enhancement using nanomaterials.

Structures, Properties and Potential Applications of Corncob Residue Modified by Carboxymethylation

In this study, corncob residue (CR) valorization was simply and efficiently realized via carboxymethylation, and its enhanced performance as fillers in urea-formaldehyde (UF) resin was investigated. The structures of corncob residue and carboxymethylated derivative were analyzed by nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), and Raman techniques, respectively. The thermal stability, morphology, viscosity control, and adhesive strength were then investigated to evaluate its performance as fillers in UF resin composite. Similar to commercial flour, carboxymethylated CR could effectively disperse in UF resin. It also exhibited a better initial viscosity control between 30 and 50 °C. The adhesive test analysis showed that the shear strength of resin with carboxymethylated CR addition could reach 1.04 MPa, which was comparable to flour (0.99 MPa) and significantly higher than raw CR (0.45 MPa). Moreover, a low formaldehyde emission was observed.

Biosorptive removal of acid orange 74 dye by HCl-pretreated Lemna sp

Acid orange 74 (AO74) is a chromium-complex monoazo acid dye widely used in the textile industry. Due to being highly toxic and non-biodegradable, it must be removed from polluted water to protect the health of people and the environment. The aim of this study was two-fold: to evaluate the biosorption of AO74 from an aqueous solution by utilizing HCl-pretreated Lemna sp. (HPL), and to examine dye desorption from the plant material. The maximum capacity of AO74 biosorption (64.24 mg g^-1) was reached after 4 h at the most adequate pH, which was 2. The biosorption capacity decreased 25% (to 48.18 mg g^-1) during the second biosorption/desorption cycle and remained essentially unchanged during the third cycle. The pseudo-second-order kinetics model concurred well with the experimental results of assays involving various levels of pH in the eluent solution and distinct initial concentrations of AO74. NaOH (0.01 M) was the best eluent solution. The Toth isotherm model best described AO74 biosorption equilibrium data. FTIR analysis confirmed the crucial role of HPL proteins in AO74 biosorption. SEM-EDX and CLSM techniques verified the effective biosorption/desorption of the dye during the three cycles. Therefore, HPL has potential for the removal of AO74 dye from wastewaters.

Adsorption of Rhodamine B dye from aqueous solution onto acid treated banana peel: Response surface methodology, kinetics and isotherm studies

The adsorption of rhodamine B (RhB) using acid modified banana peels has been examined. Chemical characteristics of the adsorbents were observed in order to determine active functional groups. The major functional groups on the surface were OH, C = O, C = C and C-O-C. Interactions between operational parameters were studied using the central composite design (CCD) of response surface methodology (RSM). The predictions of the model output indicated that operational factors influenced responses at a confidence level of 95% (P<0.05). The optimum conditions for adsorption were pH 2 at a 0.2 g/L dose within 60 minutes of contact time. Isotherm studies were carried out using the optimized process variables. The data revealed that RhB adsorption fitted the Langmuir isotherm equation while the reduction of COD followed the Freundlich isotherm. Kinetic experiments fitted the pseudo second order model for RhB removal and COD reduction. The adsorption mechanism was not the only rate controlling step. Diffusion through the boundary layer described the pattern of adsorption.