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Cocos nucifera, commonly known as coconut is rich in coir dust (CCD) at its outer surface, which is a very significant agri waste used as biosorbent for wastewater treatment. The current work addresses use of CCD for removal of hazardous Sunset Yellow dye (SY) FCF widely used as coloring agent in food industry, from wastewater. The uptake capacity in batch and column mode is 82 mg/g and 160 mg/g respectively. Characterization study including SEM, FTIR and BET results also supported the adsorption process. The comparative analysis with other natural biosorbents showed best results of biosorption with CCD. The output was better at high pH (10) and lower concentration of dye (5 mg/L). The kinetic study suggested pseudo second order rate revealing both adsorbate-adsorbent interdependency. The presence of covalent bonding or valence forces between the interfaces, suggested chemisorption as the rate limiting mechanism with valence forces, hydrogen bonding and pi-pi stacking being the chief forces responsible in binding of the dye molecules to the surface. The isotherm supported Langmuir model with monolayer and uniform adsorption at the interfaces. The interference test confirmed slight decrease in percent adsorption with interference from chloride and sulfate as dominating ions. The techno-economic feasibility highly recommended in field application of the substitute (net profit value, 1.256 Rs/m3, input cost, 0.052 Rs/m3). The industrial sample analysis with lab to land approach justified sustainability and commercial viability of the present work. HIGHLIGHTS: Facile removal of a food dye (sunset yellow, FCF) using Coconut coir dust (CCD). Uptake capacity in batch and column mode is 82 mg/g and 160 mg/g respectively. Chemisorption as the rate limiting mechanism with valence forces, hydrogen bonding and pi-pi stacking being the chief forces. Better uptake efficiency is seen at higher pH (10) and lower concentration (5mg/L). NOVELTY STATEMENT: Indiscriminate use of dyes in multidimensional industries including food industry makes water bodies unsafe. To address the issue, we have investigated efficient removal of toxic food dye (Sunset Yellow FCF) using coconut coir dust (CCD) which is a naturally available agri waste. Current protocol demonstrates the removal of dye in batch mode encompassing several batch parameters like dose, pH, concentration and time. The uptake capacity obtained in batch mode is highly significant with percent removal of 71% (82 mg/L) which is highly appreciable for a biosorbent material. Column uptake capacity with remarkable value of 160 mg/L was calculated using Thomas model rate equation in order to explore the maximum viable efficiency to extend the research for a possible pilot-scale and field application studies. The mechanism of biosorption is governed by the surface active forces including covalent forces, hydrogen bonding and pi-pi stacking. Since several agricultural/non-agricultural biomasses are available for wastewater treatment, a comparative research analysis of the removal efficiency with three other natural bio sorbents were experimented for removal of food dye and the results showed the highest uptake for CCD than others. The current study advances the understanding of coconut coir's efficacy in dye removal by comprehensively analyzing physicochemical parameters and conducting column studies to simulate real-world applications. Additionally, it investigates ion interference and validates findings with real wastewater scenarios, enhancing the authenticity and significance of the research. Thus the process firmly stands as low-cost, environment friendly substitute, and does not generate harmful by products. The uniqueness of the work lies in the fact that it is one of the best substitute compared to the other conventional methods of treatment available with a net profit value of 1.256 Rs/m3 and operating cost of 0.052 Rs/m3.The work also meets few principles of green chemistry/engineering and serves as a sustainable protocol to a great extent. [ABSTRACT FROM AUTHOR]

This work presents some preliminary results on the direct use of untreated biomass from agricultural activities as adsorbents for water treatment. Waste was also used to produce activated carbons (ACs) by chemical activation with KOH. The efficacy of agricultural waste such as stubble, sawdust from Teak (Tectona Grandis), fibers from Imbondeiro (Adansonia digitata L.), bamboo flowers, and other regional plants were tested on methylene blue (MB) removal from the aqueous phase. Adsorption studies were conducted in a batch system and the influence of kinetics, pH, and temperature was evaluated. The adsorption performance of the natural adsorbents was significantly high concerning MB. In particular, Imbondeiro presented a maximum removal capacity of 188.3 mg per gram. This amount was similar to or even higher than the values obtained on ACs produced by their predecessors at 873 K. The studies were finished by constructing slow filters containing natural adsorbents or ACs. The maximum amounts of MB removed on a continuous flux were lower than those obtained for a diversity of untreated biomass types on a batch system. However, these amounts were comparable to the published results obtained on a diversity of untreated biomasses in batch mode. [ABSTRACT FROM AUTHOR]

Agricultural wastes are potential sustainable adsorbents since they are available in large quantities, are low-cost, and may require little or no treatment, in some cases. In this study, several fruit peels, such as banana, orange, and pomegranate, were collected from local markets and prepared by a simple and eco-friendly method and used as natural adsorbents for the removal of both anionic (Reactive Red 120 (RR120), Reactive Black 5 (RB5), Remazol Brilliant Blue R (RBBR)) and cationic Methylene Blue (MB) dyes found in wastewaters. Many industries, such as leather and textiles, can release huge amounts of synthetic dyes into the wastewater during dyeing processes. These are one of the most important pollutants of water pollution as they cause enormous damage to the water body and also affect the health of organisms due to their toxicity and carcinogenicity. The search for a sustainable and at the same time efficient material for the removal of a wide variety of dyes is the innovation of this work. These peels were prepared by washing, drying, grinding, and finally sieving, under natural sustainable conditions. Porosometry (BET analysis), FTIR, SEM/EDS, and XRD techniques were used to characterize the fruit peels before and after the adsorption process. Factors affecting the adsorption of dyes (adsorbent dosage, pH solution, initial concentration of dyes, contact time, and temperature) were investigated. According to the results, in terms of the effectiveness of fruit peels as (natural) adsorbent materials, for anionic dyes, 5.0–6.0 g/L of banana or orange dry peels was sufficient to remove near or even more than 90% anionic dyes at pH 2.0, and 4.0 g/L was sufficient to remove 98% of cationic MB dye at pH 9.0. Similar amount of pomegranate peels had lower efficiency for anionic dyes (50–70%), while cationic MB was still efficiently removed (98%) at pH 9.0. Moreover, the adsorption process in all cases was found to better fit to pseudo-second-order model, in comparison to pseudo-first-order model. According to isotherms, Freundlich model fitted better in some cases to the equilibrium data, while the Langmuir model in others. Finally, this study demonstrates the viability of reusing the banana, orange, and pomegranate peel adsorbents for eight, four, and five cycles, showing a gradual reduction of around 50% of their effectiveness. [ABSTRACT FROM AUTHOR]

The process of removing pollutants from wastewater is a significant challenge for many countries due to the high cost of current technologies and the continuous increase in water consumption. Several methods are used to treat wastewater, but their efficiency varies according to the quality of the treated effluent and the technology used. In this study, seven natural waste materials: Moringa leaves, Chitosan, Opuntia, Pomegranate peel, Lupin straw, Sugarcane bagasse, and tea were prepared, characterized, and utilized as bio-coagulants for domestic wastewater treatment. Jar test experiments were carried out for the bio-coagulants using the coagulation/flocculation procedure. The optimum dose and time were tested for the bio-coagulants and the experiments were performed at pH 7.5 and at 25 °C. The presence of surface functional groups such as -COOH, -C]N and -OH and the formation of surface adsorbents were characterized using Fourier transform infrared (FT-IR) spectroscopy and electron microscopy (SEM) analysis. All bio-coagulants were effective in removing contaminants from wastewater. The tested bio-coagulants removal efficiency increased with increasing doses until equilibrium was reached. The maximum removal percentage of Moringa, Chitosan, Opuntia, Pomegranate, Lupin, Sugarcane bagasse, and tea waste residue was observed at the optimal dose of 0.8 g/L. Pomegranate showed the highest pollutant removal efficiency. Chitosan and Lupin showed moderate efficiency for chemical oxygen demand (COD), biological oxygen demand (BOD5), total suspended solids (TSS), phosphate (PO4), ammonia (NH3), nitrate (NO3), turbidity, total Kjeldahl nitrogen (TKN), total nitrogen (TN), and total organic carbon (TOC). The highest adsorption capacities achieved for Opuntia in terms of TSS, COD, BOD5, PO4, NH3, NO3, TKN, TN, and TOC were 367.42, 625, 450, 82, 3.5, 3.83, 10.43, 8.21, 18.64, and 231.66 mg/g, with corresponding average removal efficiency of 85%, 88.25%, 88.07%, 90.32%, 90.29%, 93.82%, 90.23%, 92.23%, and 95.69%, respectively, due to the presence of cracked texture with porous adsorption sites. The research work suggested that the materials could be considered eco-friendly, low-cost, and effective bio-coagulants for wastewater treatment. [ABSTRACT FROM AUTHOR]

AbstractIn this study, the adsorption properties of an amphiphilic cationic drug imipramine hydrochloride (IMP) on natural and recycled adsorbents, such as bentonite (BENT), Fuller’s earth (FE), and the eggshell (ES) in the aqueous medium has been aimed to report by means of absorption spectrophotometry. The adsorption of IMP has also been studied in the presence of cationic (dodecyl trimethylammonium bromide; DTAB) and anionic (sodium dodecyl sulfate; SDS) surfactants to clearly understand and identify the adsorption characteristics of IMP in different environments. Therefore, the association of IMP with surfactants has also been conducted using both absorption spectrophotometry and surface tension measurements to gain more information on the adsorption characteristics of IMP on BENT, FE, and ES. Micellar binding constants of IMP to SDS and DTAB micelles were calculated using the Benesi–Hildebrand Equation to ensure a more particular comparison of the effect of surfactants on the adsorption features of IMP. Additionally, the interfacial parameters Gibbs surface excess (Γmax) and the minimum area occupied by IMP (Amin) were estimated in the case of DTAB and SDS. Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherm equations were applied to the adsorption of IMP on natural adsorbents. Depending on their structure, the presence of surfactants in the environment diminished or completely inhibited the adsorption of IMP on all-natural adsorbents studied with the exception of IMP adsorption on FE in the presence of SDS monomers in the medium where the adsorption quantity increased significantly. [ABSTRACT FROM AUTHOR]

This work presents some preliminary results on the direct use of untreated biomass from agricultural activities as adsorbents for water treatment. Waste was also used to produce activated carbons (ACs) by chemical activation with KOH. The efficacy of agricultural waste such as stubble, sawdust from Teak (Tectona Grandis), fibers from Imbondeiro (Adansonia digitata L.), bamboo flowers, and other regional plants were tested on methylene blue (MB) removal from the aqueous phase. Adsorption studies were conducted in a batch system and the influence of kinetics, pH, and temperature was evaluated. The adsorption performance of the natural adsorbents was significantly high concerning MB. In particular, Imbondeiro presented a maximum removal capacity of 188.3 mg per gram. This amount was similar to or even higher than the values obtained on ACs produced by their predecessors at 873 K. The studies were finished by constructing slow filters containing natural adsorbents or ACs. The maximum amounts of MB removed on a continuous flux were lower than those obtained for a diversity of untreated biomass types on a batch system. However, these amounts were comparable to the published results obtained on a diversity of untreated biomasses in batch mode.

Insects are a readily available source of chitosan due to their high reproductive rates, ease of breeding, and resistance to changes in their ecosystem. This study aimed to extract chitosan from several widespread insects: Blaps lethifera (CS-BL), Pimelia fernandezlopezi (CS-PF), and Musca domestica (CS-MD). The study was also extended to using the obtained chitosans in removing methylene blue dye (MB) from wastewater. The source of the chitosan, the initial concentration of MB dye, and the reaction time were chosen as the working parameters. The experiments were designed using a central composite design (CCD) based on the dye removal efficiency as the response variable. The experimental work and statistical calculation of the CCD showed that the dye removal efficiency ranged from 35.9% to 88.7% for CS-BL, from 18.8% to 47.1% for CS-PF, and from 10.3% to 29.0% for CS-MD at an initial MB concentration of 12.79 mg/L. The highest methylene blue dye removal efficiency was 88.7% for CS-BL at a reaction time of 120 min. This indicates that the extraction of chitosan from insects (Blaps lethifera) and its application in dye removal is a promising, environmentally friendly, economical, biodegradable, and cost-effective process. Furthermore, the CCD is a statistical experimental design technique that can be used to optimize process variables for removing other organic pollutants using chitosan. [ABSTRACT FROM AUTHOR]

Natural zeolite is among the low-cost materials that can be used to remove contaminants in biogas. The cleaning of biogas increases its energy density and reduces possible negative effects. The current study aimed to upgrade biogas using natural zeolites. The activation of natural zeolite was done using sodium hydroxide. The adsorbent samples were characterised using an XRF machine, while the biogas samples were analysed using Shimadzu gas chromatography and a portable digital gas detector. The effect of zeolite-to-water ratio on the carbonation process was investigated. In addition, the effects of biogas flow rate, adsorbent dose and contact time on the dry adsorption process were studied. The maximum CO2 uptake of zeolite was 4.8 and 0.2 mmol/g by dry adsorption and wet carbonation process, respectively. The results indicate that surface adsorption favoured by a low Si2O3/Al2O3 ratio was more prominent than carbonation that requires high basic oxides. The results showed that an increase in the dose of activated clay from 2.5 to 35 g increased the removal efficiency of CO2 from 11.2% to 79.8%, while the CO2 uptake decreased from 4.8 to 2.5 mmol/g. Furthermore, the experimental data fitted best to pseudo-first-order kinetics and the Bohart-Adams model for the breakthrough curve. [ABSTRACT FROM AUTHOR]

Oil-contaminated water is among the most significant environmental challenges from various industries and manufacturing processes. Oily water poses a severe environmental threat and is toxic to many forms of life. This study aims to investigate the potential of natural adsorbents, namely animal bones (ABs) and anise residues (ARs), for removing oil from water using a batch adsorption process. The effects of adsorbent dosage (0.2–2 g), oil concentration (200–1000 mg/L), and contact time (30–120 min) on the adsorption process were evaluated. This study is the first to employ ABs and ARs as adsorbents for oil removal, and their efficacy for this purpose has not been previously reported. The results indicate that ABs exhibit superior oil removal capacity compared to ARs. Specifically, ABs removed 45 mg/g of oil from water, while ARs removed only 30 mg/g of oil. Furthermore, ABs achieved a percentage removal rate of 94%, whereas ARs had a percentage removal rate of 70%. The adsorbents were characterised using Fourier transform infrared (FTIR) spectrometry, contact angle measurements before and after adsorption, and thermogravimetric analysis (TGA). In addition to the experimental analysis, several kinetic and adsorption models were employed to investigate the adsorption process. The pseudo-first-order and pseudo-second-order models were used to represent the kinetics of the reaction, while the Langmuir and Freundlich isotherm models were used to represent the adsorption isotherm. Marquardt's percent standard deviation (MPSD) error function was used to confirm the fit of the experimental data with the isotherm model, in addition to the correlation coefficient R2. The isotherm studies indicated that the experimental data of the two adsorbents used with the Langmuir isotherm model were consistent with one another. The kinetics study demonstrated that the adsorption process using the two adsorbents adheres to a pseudo-second-order kinetics model. [ABSTRACT FROM AUTHOR]

This study investigated the adsorption capacity of Remazol Black B (RBB) from aqueous solutions using a pumice stone as a cheap, high-frequent, and available adsorbent. The raw pumice was modified using five acids: Acetic, Sulfuric, Phosphoric, Nitric, and Hydrochloric acid. Fourier transform infrared spectrograph (FTIR), x-ray fluorescence (XRF), and scanning electron microscopy (SEM) were used to analyze the morphological and chemical properties of raw and modified adsorbents. The adsorption capacity equilibrium was investigated using the Langmuir, Freundlich, Temkin, and Dubinin – Radushkevich isotherms. The results indicated that the data are well-fitted with Langmuir isotherm. The maximum adsorption capacity was observed when pumice modified with H2SO4 (qm = 10.00 mg/g) was used, and the RBB removal efficiency was higher than that for raw pumice (qm = 5.26 mg/g). Also, the results were best fitted with pseudo-second-order kinetic. The experiments indicated that increasing the RBB concentration reduces the efficiency of adsorbents while increasing the contact time and adsorbent doses improved the RBB removal efficiency. Accordingly, it can be concluded that pumice stone modified with various acids can be considered a cheap adsorbent with high efficiency in removing RBB from industry effluent.

The storage of food grains against the fungal infection has been a great challenge to the farmers, but nanotechnology provides a solution to address this problem. The application of nanotechnology for the storage of food grains replaces synthetic fungicides in agriculture. Inorganic nanoparticles such as silver and zinc oxide are well-known for their antifungal activity. Green synthesized nanoparticles show enhanced antimicrobial activity than the chemically synthesized nanoparticles. Extracts and essential oils derived from plants exhibit very good antifungal properties. The synthesized nanoparticles can be impregnated in packaging materials, which are used to store food grains. Natural materials are having advantages like non-toxicity and easier to degrade and are suitable for food safety. This overview discusses the nanomaterials-mediated protection of food materials from mycotoxin and its releases into the open environment. [ABSTRACT FROM AUTHOR]

In this study, adsorption of the heavy metal ions (Pb(II), Cu(II) and Cd(II)) from water by peanut shells (PS), sawdust (S) and commercial activated carbon (AC) were comparatively studied. Thus, the relationship between different adsorption parameters and different heavy metal ion removal rates was investigated. The adsorption capacity of the three adsorbents for heavy metal ions increased with an increase in temperature, pH value, contact time, adsorbent dosage, and heavy metal ion concentration, however, it decreased with an increase of adsorbent particle size. All the adsorption processes are better described by Langmuir isotherm or Freundlich isotherm. Thus, the results show good agreement with pseudo-second-order kinetics and the adsorption processes are spontaneous heat absorption processes. Herein, all adsorbents have higher affinity for Pb(II) ions, and hence possess higher removal rates. In addition, heavy metal ions were desorbed significantly at acidic conditions in the desorption experiments. The results demonstrate that PS can be used as a green adsorbent instead of AC for the adsorption of heavy metal ions from the water. [ABSTRACT FROM AUTHOR]

Among the low-cost adsorbent are agricultural residues, which can be used in natura or modified forms. This work evaluated the adsorption of Ni2+, Cu2+, and Cr3+ in mono- and multi-component aqueous solutions using passion fruit peels in natura (Nat-PF) and physicochemically modified (Mod-PF). The adsorption was investigated by kinetic and isotherm models. A comparative investigation was conducted to analyze the effect of the experimental conditions by statistical test, adsorption capacity ratio, selectivity of adsorbate, and distribution coefficient. In both adsorbents, the process occurs in monolayer by chemosorption. Equilibrium was reached after 30 min, with highest adsorption capacity for Cu2+ as 0.495 mg g−1, for Cr3+ as 0.483 mg g−1, and for Ni2+ as 0.464 mg g−1. The adsorption in Mod-PF was less affected in multi-component solutions, reducing the adsorption capacity by 0.06–0.15 times when compared to monocomponent solutions, while in Nat-PF a reduction of more than half of adsorption capacity was obtained. The modifications imposed on the biomass led to a change in its adsorptive selective, being Cr3+ > Cu2+ > Ni2+ for Nat-PF and Cu2+ > Ni2+ > Cr3+ for Mod-PF. [ABSTRACT FROM AUTHOR]

This study investigated the use of different natural raw soil materials as low-cost adsorbents for the removal to remove As(V) and Pb(II) from aqueous systems. It deals with the effect of different soil textures, sandy loam, loam, and loamy sand, on adsorption efficiency. Fourier-transform infrared spectroscopy (FTIR) was used to carry out the comprehensive characterization of materials, as well as scanning electron microscopy (SEM), X-ray diffraction (XRD), and liquid nitrogen porosimetry or the Brunauer–Emmett–Teller (BET). Studies were performed in a batch system; the initial concentration of examined heavy metals was 100 μg·L–1, pH varied in the range of 4–6, and the adsorbent dosage was 5–20 mg/10 mL. Sandy loam was the most efficient adsorbent for As(V) separation, with a maximum removal efficiency of 47.5%, while the loam was the most efficient for Pb(II) separation, with a maximum removal efficiency of 94.2%. The removal efficiency was affected mainly by the adsorbent characteristics. Performed kinetic studies revealed two steps of adsorption for both investigated ions. Obtained results indicate that natural sorbents used in this work present environmentally sustainable material for As(V) and Pb(II) removal, on the one hand, and the basis for further studies on the simultaneous removal of heavy metals from water and their reduced mobility in soil, on the other. [ABSTRACT FROM AUTHOR]

Abstract Natural adsorbents are a good alternative to remove antibiotic residues from wastewater. In this study, the adsorption capacity of sulfamethoxazole (SMX) onto sugarcane bagasse (SB) and corn cob (CC) in a continuous fixed-bed was compared. Brunauer Emmett Teller, Fourier transform infrared (FTIR), Boehm titration, and point of zero charge (pHpzc) were used to characterize both adsorbents. The adsorption capacity (qe) and the removal percentage of SMX (% R) were investigated at different different flow rates (2, 5, and 7 mL min− 1) and adsorbent masses (4 and 6.4 g), and a constant initial concentration of 5 mg L− 1. The results of the characterization showed that SB has a morphology with more dispersed particles and a specific surface higher than CC (2.6 > 1.2 m2 g− 1). Boehm titration indicates that both the surface of SB and CC have a greater amount of acid groups, which is in agreement with FTIR and pHpzc results. The continuous fixed-bed experiments showed that % R and qe of SMX are higher with SB in all the tests. The highest qe and maximum % R was 0.24 mg g− 1 and 74% with SB, and 0.15 mg g− 1 and 65% using CC. In most cases, the qe of both adsorbents decreased with the increase of flow rate and bed height. An analysis suggests that hydrogen bonds could be the main factor favoring the SMX adsorption with SB. Finally, the intraparticle diffusion was the rate-controlling step, predominating the pore-volume diffusion resistance.

Insects are a readily available source of chitosan due to their high reproductive rates, ease of breeding, and resistance to changes in their ecosystem. This study aimed to extract chitosan from several widespread insects: Blaps lethifera (CS-BL), Pimelia fernandezlopezi (CS-PF), and Musca domestica (CS-MD). The study was also extended to using the obtained chitosans in removing methylene blue dye (MB) from wastewater. The source of the chitosan, the initial concentration of MB dye, and the reaction time were chosen as the working parameters. The experiments were designed using a central composite design (CCD) based on the dye removal efficiency as the response variable. The experimental work and statistical calculation of the CCD showed that the dye removal efficiency ranged from 35.9% to 88.7% for CS-BL, from 18.8% to 47.1% for CS-PF, and from 10.3% to 29.0% for CS-MD at an initial MB concentration of 12.79 mg/L. The highest methylene blue dye removal efficiency was 88.7% for CS-BL at a reaction time of 120 min. This indicates that the extraction of chitosan from insects (Blaps lethifera) and its application in dye removal is a promising, environmentally friendly, economical, biodegradable, and cost-effective process. Furthermore, the CCD is a statistical experimental design technique that can be used to optimize process variables for removing other organic pollutants using chitosan.

An impact of poultry farms on the environment caused by ammonia emission from chicken manure has been studied. A negative impact minimisation method by adding natural sorbents to the bedding composition has been proposed. The optimum natural adsorbents compositions (clinoptilolite and palygorskite) for adding to the bedding as well as the optimum mixture ratio of these adsorbents to chicken manure mass have been determined. The optimum conditions for obtaining granulated organic-mineral fertiliser of prolonged action based on this composition have been studied. In the result of the research data analysis a technological scheme for organic-mineral fertiliser production based on chicken manure and a mixture of natural adsorbents have been proposed.

Oil-contaminated water is among the most significant environmental challenges from various industries and manufacturing processes. Oily water poses a severe environmental threat and is toxic to many forms of life. This study aims to investigate the potential of natural adsorbents, namely animal bones (ABs) and anise residues (ARs), for removing oil from water using a batch adsorption process. The effects of adsorbent dosage (0.2–2 g), oil concentration (200–1000 mg/L), and contact time (30–120 min) on the adsorption process were evaluated. This study is the first to employ ABs and ARs as adsorbents for oil removal, and their efficacy for this purpose has not been previously reported. The results indicate that ABs exhibit superior oil removal capacity compared to ARs. Specifically, ABs removed 45 mg/g of oil from water, while ARs removed only 30 mg/g of oil. Furthermore, ABs achieved a percentage removal rate of 94%, whereas ARs had a percentage removal rate of 70%. The adsorbents were characterised using Fourier transform infrared (FTIR) spectrometry, contact angle measurements before and after adsorption, and thermogravimetric analysis (TGA). In addition to the experimental analysis, several kinetic and adsorption models were employed to investigate the adsorption process. The pseudo-first-order and pseudo-second-order models were used to represent the kinetics of the reaction, while the Langmuir and Freundlich isotherm models were used to represent the adsorption isotherm. Marquardt’s percent standard deviation (MPSD) error function was used to confirm the fit of the experimental data with the isotherm model, in addition to the correlation coefficient R2. The isotherm studies indicated that the experimental data of the two adsorbents used with the Langmuir isotherm model were consistent with one another. The kinetics study demonstrated that the adsorption process using the two adsorbents adheres to a pseudo-second-order kinetics model.

Extraction of Copper ion from its water solutions using plant waste (compost), sludge and Bentonite metal as cheap natural adsorbed materials. It was found that Copper ion extraction was based on concentration of Copper and amount of the adsorbed materials. Highest amount of adsorption was obtained at 180 µg Cu ml-1 as Bentonite, plant waste and sludge respectively. Thermal equilibrium of the system was studied by Langmuir equation, R² gave a good linear relationship in succession. Maximum regulatory capacity and regulatory capacity at equilibrium is 1.0, 0.99 and 0.96 to plant waste, sludge and Bentonite respectively, as the preference coefficient constant calculated by the Langmuir equation indicate that adsorption is preferable and irriversible for plant waste and sludge while not preferentially and reversible for bentonite. ΔG adsorption reactions were automatic for the Bentonite metal, while for plant waste and sludge non-spontaneous reaction and needs extra activation energy. It is clear from the above that the use of natural materials in the extraction of copper ion is a very effective method and it is an inexpensive and friendly methods envirooment. [ABSTRACT FROM AUTHOR]

Newly designed mesoporous brushite-metakaolin-based geopolymer materials were examined with an idea for using this material as a potential adsorbent for Pb(II) removal from aqueous solutions. As a starting component for geopolymer synthesis, a natural raw kaolinite clay with the addition of 2 wt.%, 4 wt.%, 6 wt.%, 8 wt.%, and 10 wt.% of pure brushite was used. Phase, structural, morphological, and adsorption properties of newly synthesized mesoporous brushite-metakaolin geopolymer materials were examined in detail by the means of XRPD, FTIR, SEM-EDS, BET/BJH, and ICP-OES methods. The ICP-OES results showed that the synthesized material samples with 2 wt.%, 4 wt.%, and 6 wt.% of brushite possess significant adsorption properties and the mechanisms of the adsorption process can be attributed to chemisorption. The most notable result is that brushite-metakaolin-geopolymer with 2 wt.% of brushite have the best efficiency removal, more than 85% of Pb(II). [ABSTRACT FROM AUTHOR]

Endocrine-disrupting chemicals (EDCs) are pollutants with adverse effects even at very low concentrations; they remain a major concern for water quality. There is a strong link between environmental matrices such as water, soil, and human health. This implies that releasing these pollutants into the environment gets to the human system through contaminated air, water, and food. EDCs pose adverse effects on the endocrine systems of humans and wildlife and act as agents that interrupt metabolism, transport, synthesis, secretion, or elimination of natural blood-borne hormones present in the human body, which are responsible for the development, reproduction, and homeostasis process. The molecular group known as an endocrine disruptor is extremely heterogeneous, including the usage of synthetic chemicals in industrial solvents, lubricants and their by-products (such as 1,2-dichloroethane, 17α-ethinylestradiol, 17β-estradiol, 2,4-dichlorophenol, acetaminophen, amoxicillin, antiretroviral, benzotriazole, bisphenol A, carbamazepine, ciprofloxacin, diclofenac, ibuprofen, ketoprofen, naproxen, paracetamol, phenol, tetracycline, metformin, etc. discussed in this work). Natural chemicals in food can also act as endocrine disruptors and some of these chemicals are toxic. Contaminants in water influence all living beings; therefore, to prevent health complications, improve water quality and make it safer in the ecosystem, water must be purified. The complex nature of EDCs has necessitated the development of suitable, robust, and more versatile removal techniques capable of producing the desired result in a very cost-effective manner. The first part of this review addresses source and occurrence of EDCs, available EDC treatment technologies and their drawbacks, and followed by the recent advances in sequestrating EDCs using natural, synthetic (metal–organic frameworks, nanoparticle/nanomaterials), and agricultural waste adsorbents. Influence of different operational parameters on the adsorptive removal of EDCs, mechanism of EDCs sequestration and thermodynamic studies were also discussed. We concluded by providing some useful insights, challenges, and future prospects to foster better efficiency of these adsorbents for EDCs removal to meet various industrial applications. [ABSTRACT FROM AUTHOR]

The applications of natural products in aquaculture to improve fish production and modulate toxic undesired effects of heavy metals represent a global environmental demand. In this study, fish diets supplemented with natural zeolite (Clinoptilolite) were evaluated for their ability to improve growth and alleviate the deleterious effects of lead acetate in Nile tilapia (Oreochromis niloticus). Four main experimental groups were used: one control group that fed on diets supplemented with 0% zeolite and three treatment groups received 1%, 3% and 5% zeolite. After 45 days of feeding, zeolite treatments resulted in a positive effect on weight gain (WG) with a significant reduction in water ammonia levels. Following feeding experiment, the control group was divided into two groups. All zeolite-treated groups and one of the control groups (Control +ve) were subjected to lead (Pb) toxicity for additional 21 days, while the other control received no Pb (Control -ve). Exposure to Pb significantly decreased protein and albumin on one hand and increased glucose, cholesterol, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) on the other. Elevation of hepatic catalase (CAT), superoxide dismutase (SOD) and total antioxidant capacity (TAC) were also detected. In contrast, zeolite feeding before and during Pb exposure showed an increase in protein and albumin levels, and a decrease in glucose, cholesterol, ALT, AST, CAT, SOD and TAC levels. Moreover, zeolite decreased Pb residues in muscles and increased it in kidneys. All in all, the data presented indicate that zeolite can improve the growth performance in Nile tilapia and increases fish resistance to undesired effects associated with Pb toxicity. [ABSTRACT FROM AUTHOR]

Pharmaceutical pollutants are one of the most important issues concerning human life due to the introduction of these pollutants into the food cycle and resulting in drug resistance which leads to environmental hazards. Thus investigation and pollution control of pharmaceuticals is essential. Aqueous media should be free of such contaminants before entering the environment. Adsorption is an effective and efficient method for removing pharmaceutical pollutants from aqueous solutions which have been given a comprehensive review in this paper, reporting the performance of different adsorbents such as activated carbon, silicagel, clays, zeolits, graphene nanoplates, polymers, clay-polymer nanocomposites and biochars. Removal efficiencies of 70-100% for activated carbon, 87-99% for clay and 98-100% for biochars are reported. Adsorption mechanisms of some antibiotics on various adsorbents are also discussed.

Natural adsorbents are a good alternative to remove antibiotic residues from wastewater. In this study, the adsorption capacity of sulfamethoxazole (SMX) onto sugarcane bagasse (SB) and corn cob (CC) in a continuous fixed-bed was compared. Brunauer Emmett Teller, Fourier transform infrared (FTIR), Boehm titration, and point of zero charge (pHpzc) were used to characterize both adsorbents. The adsorption capacity (qe) and the removal percentage of SMX (% R) were investigated at different different flow rates (2, 5, and 7 mL min− 1) and adsorbent masses (4 and 6.4 g), and a constant initial concentration of 5 mg L− 1. The results of the characterization showed that SB has a morphology with more dispersed particles and a specific surface higher than CC (2.6 > 1.2 m2 g− 1). Boehm titration indicates that both the surface of SB and CC have a greater amount of acid groups, which is in agreement with FTIR and pHpzc results. The continuous fixed-bed experiments showed that % R and qe of SMX are higher with SB in all the tests. The highest qe and maximum % R was 0.24 mg g− 1 and 74% with SB, and 0.15 mg g− 1 and 65% using CC. In most cases, the qe of both adsorbents decreased with the increase of flow rate and bed height. An analysis suggests that hydrogen bonds could be the main factor favoring the SMX adsorption with SB. Finally, the intraparticle diffusion was the rate-controlling step, predominating the pore-volume diffusion resistance. [ABSTRACT FROM AUTHOR]

An impact of poultry farms on the environment caused by ammonia emission from chicken manure has been studied. A negative impact minimisation method by adding natural sorbents to the bedding composition has been proposed. The optimum natural adsorbents compositions (clinoptilolite and palygorskite) for adding to the bedding as well as the optimum mixture ratio of these adsorbents to chicken manure mass have been determined. The optimum conditions for obtaining granulated organic-mineral fertiliser of prolonged action based on this composition have been studied. In the result of the research data analysis a technological scheme for organic-mineral fertiliser production based on chicken manure and a mixture of natural adsorbents have been proposed. [ABSTRACT FROM AUTHOR]

Disposal of untreated wastewater released by industries using dyes , causes serious damage to aquatic life and to the ecosystem in general. Both physical and chemical methods have been used for the removal of these dyes from wastewater ; among them , adsorption has been found to be a very efficient technique. In this study, the ability to simultaneously remove cationic (MB) and anionic dyes (RR120, RB5 and RBBR) from a quaternary mixture solution by using zero-cost materials as banana, orange and pomegranate peels, was investigated. The optimal removal rates were achieved at pH 2.0 and a dose of 6.0 g/L. The comparative results of natural adsorbents on dye removal, separately and simultaneously in solution showed that MB adsorption on banana and orange peels was augmented from 89 to 96 and 43 to 87%, respectively, in the presence of anionic dyes (synergistic effect). On the other hand, a competitive effect was determined, mainly between anionic dyes, resulting in a decrease in their respective percentage. Banana peels were selected as the adsorbent material for further study in a quaternary dye mixture containing all dyes. Parameters affecting dye adsorption such as pH solution, initial concentration of dyes, contact time and temperature were examined. Based on the experimental results, two mechanisms for interactions were proposed: (a) the cationic MB molecules are connected to the negatively charged anionic dyes or (b) electrostatic attractions occurred among cationic MB molecules and negatively charged anionic dyes in the solution enhancing the adsorption efficiency. Kinetic experiments showed that equilibrium for anionic dyes reached at around 180 min (3 h), and for MB was reached much faster, at 30 min; 87% of 20 mg/L was found to be removed in just 5 min. Langmuir isotherm model and pseudo-second-order kinetic model were best fitted to the experimental results. According to thermodynamics the spontaneous nature of their adsorption was confirmed. [Display omitted] • Eco-friendly and cost-effective banana, orange and pomegranate peels are used as natural adsorbents. • Quaternary dye systems are used for first time. • Cationic dye adsorption was augmented in the presence of anionic dyes (synergistic effect). • Two mechanisms for interactions were proposed. [ABSTRACT FROM AUTHOR]

Increasing the quality of food products through the prudent use of natural adsorbents is becoming a topical problem in agriculture in conditions of anthropogenic heavy metal contamination. The purpose of the study is to work out a method for detoxifying heavy metals by using natural adsorbents such as local zeolite and vitamin C as an example of the implementation of standards and requirements for environmental food safety in animal husbandry in the territories with high anthropogenic pollution. Using the analogue method three groups of cows were formed with account of origin, age, body weight and lactation performance. To determine the heavy metal concentration, the spectrophotometric method was applied. It was experimentally established that in order to enhance the quality of dairy products in the territory with the man-made contamination, it is advisable to supplement the diets of lactating cows with zeolite and vitamin C (the recommended doses are 3% and 0.04% of the dry matter norm respectively). Due to the combined use of these natural adsorbents, zinc concentration in the cows' blood decreased 2.04 times, lead - 2.53 times and cadmium - 3.65 times. The cow milk increased in mass fraction of fat by 0.22% and protein - by 0.20%; at the same time zinc concentration lowered 3.47 times, lead - 2.76 times and cadmium - 3.09 times. At that, the content of these toxicants in dairy products was lower than the maximum allowable concentration (MAC). [ABSTRACT FROM AUTHOR]

Access to safe drinking water is not only fundamental to human development and well being but is also recognized as a human right. The provision of safe potable water is considered critical and pivotal to the achievements of overall development, including adequate nutrition, education, gender equality and especially the eradication of poverty in developing countries. Fluoride is one of the water quality parameters of concern, the excess (beyond 1.5 mg/L, the World Health Organization (WHO) guideline value of which contaminates groundwater resources in many parts of the world, and renders it not potable for human consumption, due to the related adverse health effects. Therefore knowledge of its removal, using the best technique with optimum efficiency is needed. Taking the severity of the problem into consideration, the present paper aims to provide a retrospective approach to the use of effective low-cost adsorbents for the removal of fluoride from water. The defluoridation capacity of certain lowcost natural adsorbents like Citron peel, Karanj, Parijaat, Neem, Rice husk, and Tulsi was added in the list and discussed in detail. The effect of contact time, pH and adsorbent dose were investigated. The adsorption isotherm and kinetics were studied conducting Batch and Column experiment. [ABSTRACT FROM AUTHOR]

Highlights • Trends on lignocellulosic materials as adsorbents in multi-element systems. • Effects of metal ion competition on adsorption process in multi-element systems. • Application of multi-element adsorption isotherms on lignocellulosic materials. Abstract In recent years studies demonstrated good efficiency of lignocellulosic materials for adsorption and removal of toxic ions from water, however many of them are related to mono-element adsorption processes, which does not adequately describe a real aqueous system. This critical review article provides recent studies on adsorption processes in multi-element aqueous systems using natural or modified lignocellulosic adsorbents, characteristics of lignocellulosic materials, competition between metal ions in multi-element solutions, main adsorption isotherms for bi-element and multi-element systems and their applications. Trend, evolution and application of lignocellulosic materials in multi-element systems and main factors responsible for adsorption process of metal ions in lignocellulosic materials are also discussed and evaluated. It is evident, from the bibliographical research, that works on mono-element adsorption are abundant, whereas in multi-element systems are scarce. Several studies describing mechanisms of adsorption of toxic ions in lignocellulosic materials have been found, but they have reported several contradictory or non-complementary results, which makes necessary to study in depth how these mechanisms occur. In addition, many studies demonstrated good fits of multi-element isotherms to the experimental data, although some limitations of these models were found in specified cases. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the removal of Cu2+ and Zn2+ in water by means of the adsorption process using three biosorbents derived from jatropha biomass (bark, endosperm and endosperm + seed coat). The experiments were performed in batch and evaluated the effect of solution pH, adsorbent mass, contact time, different initial concentrations of the metals Cu2+ and Zn2+, and the temperature of the solution during the adsorptive process. By kinetics, the adsorption isotherms and thermodynamics the mechanisms that control the adsorptive process were evaluated. The optimal conditions for the realization of the adsorptive process for both metals were: solution pH of 5.0 and 8 g L-1 of adsorbent mass per volume of solution, with a contact time between adsorbent and adsorbate of 60 min. According to the Langmuir model, the maximum adsorption capacities for the bark, endosperm and endosperm + seed coat of Jatropha were, respectively, for Cu2+ 11.541, 20.475 and 22.910 mg g-1, and for Zn2+ 14.852; 15.888 and 14.674 mg g-1, with the predominance of chemisorption in monolayer. The three biosorbents derived from the biomass of Jatropha have potential for the remediation of water contaminated with Cu2+ and Zn2+.

Sorption characteristics of Pb(II) from aqueous solutions through a low-cost adsorbent mixture comprising of Bamboo biochar (BB) and Calcium Sulphate (CS), and a more expensive mixture of Hydroxyapatite (HAP) and Calcium Sulphate (CS), were investigated. The effects of equilibrium contact time, and adsorbate concentration conducted in batch experiments were studied. Adsorption equilibrium was established in 40 (min). The adsorption mechanism of Pb(II) from these two adsorbent mixtures was carried out through a kinetic rate order. A pseudo second-order kinetic model was applied for the adsorption processes. The model yielded good correlation (R2 >0.999) of the experimental data. Adsorption of Pb(II) using (BB&CS) and (HAP&CS) correlated well (R2 >0.99) with both the Langmuir and Freundlich isotherm equations under the concentration range studied. Hence, the effectiveness of an inexpensive natural material (BB&CS) mixture in Pb(II) removal is established, and is promising for use in other heavy metal adsorptions.

In this study, an idea of using multiple layers of adsorbents in adsorption column is proposed for treatment of synthetic wastewater for removal of Cr(VI) ions. In the present study, an effort has been made to study and compare the performance of fixed bed column with single bed adsorbent (RH only) and multi bed adsorbent of Rice Husk (RH), Saw Dust (SD) and Coir Dust (CD) in removal of Cr(VI) from synthetic wastewater and arrive at the parameters of the adsorption column that are useful for process design. From the characterization studies, it has been observed that carbon, aluminium and silica were the major components of the three natural adsorbents studied. It was found that, for better heavy metal removal, natural adsorbents with a percentage of fineness of around 54% could be used in adsorption studies. From the breakthrough curves of single bed and multi bed adsorption columns, it was evident that the multi bed adsorption column performed better. The time taken to achieve the breakthrough point and the exhaustion point in multi bed column is 2.5 times and 1.9 times greater than the time taken by single bed adsorption studies respectively. It was observed that in multi bed adsorption column, at greater bed depths, the significant increase in metal uptake capacity was due to the increase in contact time. Kinetic models viz. Thomas model, Yoon-Nelson model and Bed Depth Service Time model (BDST) were used to predict the performance of the column and sum of squares (SS) error analysis was carried out to test the accuracy of model equations. Higher R2 value and smaller SS value obtained from Thomas model proves that it is suitable to explain the adsorption of Cr(VI) in single and multi bed adsorption column of natural adsorbents. Experimental data fitted well with BDST model where R2 = 0.997. From the cost analysis, multi bed adsorption column was proven to be economical and confirmed that the locally and abundantly available agricultural wastes viz. RH, SD and CD could be used as an alternate to commercially available activated carbon for the removal of Cr(VI) from synthetic wastewater.

In this study, an idea of using multiple layers of adsorbents in adsorption column is proposed for treatment of synthetic wastewater for removal of Cr(VI) ions. In the present study, an effort has been made to study and compare the performance of fixed bed column with single bed adsorbent (RH only) and multi bed adsorbent of Rice Husk (RH), Saw Dust (SD) and Coir Dust (CD) in removal of Cr(VI) from synthetic wastewater and arrive at the parameters of the adsorption column that are useful for process design. From the characterization studies, it has been observed that carbon, aluminium and silica were the major components of the three natural adsorbents studied. It was found that, for better heavy metal removal, natural adsorbents with a percentage of fineness of around 54% could be used in adsorption studies. From the breakthrough curves of single bed and multi bed adsorption columns, it was evident that the multi bed adsorption column performed better. The time taken to achieve the breakthrough point and the exhaustion point in multi bed column is 2.5 times and 1.9 times greater than the time taken by single bed adsorption studies respectively. It was observed that in multi bed adsorption column, at greater bed depths, the significant increase in metal uptake capacity was due to the increase in contact time. Kinetic models viz. Thomas model, Yoon-Nelson model and Bed Depth Service Time model (BDST) were used to predict the performance of the column and sum of squares (SS) error analysis was carried out to test the accuracy of model equations. Higher R² value and smaller SS value obtained from Thomas model proves that it is suitable to explain the adsorption of Cr(VI) in single and multi bed adsorption column of natural adsorbents. Experimental data fitted well with BDST model where R² = 0.997. From the cost analysis, multi bed adsorption column was proven to be economical and confirmed that the locally and abundantly available agricultural wastes viz. RH, SD and CD could be used as an alternate to commercially available activated carbon for the removal of Cr(VI) from synthetic wastewater. [ABSTRACT FROM AUTHOR]

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Wide variety of inorganic compounds such as nutrients and trace metals, organic chemicals, radioactive contaminants and pathogens are commonly present as contaminants in the groundwater. Migration of contaminants in soil involves important mechanisms such as molecular diffusion, dispersion under physical processes, adsorption, precipitation and oxidation - reduction under chemical processes and biodegradation under biological process. Cr (VI) is a major and dangerous contaminant as per the ground water is concerned. There are numerous research work carried out with concentrated efforts by the researchers towards removal of Cr (VI) contaminant from aqueous solutions. There are few studies relevant to Cr (VI) removal with respect to utilization of low cost admixtures and also soil type. In the present study, different low cost admixtures like rice husk (RH), shredded tyre (ST) and fly ash (FA) are used to understand the performance in removal of Cr (VI) from aqueous solution and also two different soil types are used along with the admixture. The results are discussed in terms of sorption capacity and performance of individual admixture and combination of admixture with soil in removal of contaminant. The fly ash, rice husk and shredded tyre admixtures are used and the results revealed that the shredded tyre showed higher performance in removal of contaminant concentration. Also, the soil which has more fine particle content (size

The aim of this work was to evaluate the removal of Cd (II) from water using three biosorbents originated from the biomass of jatropha (bark, endosperm, and endosperm + tegument). For that, batch tests were performed to verify the effect of solution pH, adsorbent mass, contact time, initial concentration of Cd (II), and the temperature of the process. The adsorption process was evaluated by the studies of kinetics, isotherms, and thermodynamics. The ideal conditions of solution pH were 5.5 and 8 g L of adsorbent mass of biosorbents by solution volume, with an equilibrium time of 60 min. According to the Langmuir model, the maximum adsorption capacity for bark, endosperm, and bark + endosperm of jatropha was, respectively, 29.665, 19.562, and 34.674 mg g, predominating chemisorption in monolayers. The biosorbents presented potential for the remediation of waters contaminated with Cd (II). [ABSTRACT FROM AUTHOR]