Removal Of Zn Research Articles

Single-stage microwave assisted coconut shell based activated carbon for removal of Zn(II) ions from aqueous solution – Optimization and batch studies

Health and environmental issues associated with heavy metal ions have received serious attention from communities worldwide. This work explores the potential of coconut shell as activated carbon (CSAC), in adsorbing zinc, Zn(II) ions. This adsorbent was prepared via a single-stage microwave irradiation technique under the flow of carbon dioxide, CO 2 gas. CSAC posed BET surface area of 625.61 m 2 /g, 513.25 m 2 /g of mesopores surface area, total pore volume of 0.42 cm 3 /g, and average pore diameter of 4.55 nm. Zeta potential distribution on CSAC was found to be −21 mV. Response surface methodology (RSM) had suggested that the optimum values of variables were 450 W and 3.17 min for radiation power and radiation time respectively, which resulted in 69.65% of Zn(II) removal and 44.32% of CSAC’s yield. Based on F-value, radiation power (473.62) and radiation time (140.50) posed major and moderate effects on Zn(II) removal, respectively. Meanwhile, CSAC’s removal was significantly affected by radiation power (78.84) and less affected by radiation time (7.06). In a batch study, when the initial concentration of Zn(II) was increased, Zn(II) uptakes increased as well. On contrary, Zn(II) removal percentage decreased with the increase of Zn(II)’s initial concentration. Multilayer adsorption of Zn(II) onto CSAC had occurred since this adsorption system followed Freundlich isotherm the best, and the monolayer adsorption capacity, Q m for Zn(II) was revealed to be 7.87 mg/g. The kinetic data of the Zn(II)-CSAC adsorption system was best described by pseudo-first-order (PFO) which indicated the role of physisorption. In the regeneration study, CSAC’s mass and Zn(II) adsorption uptakes had reduced from 100% to 37% and 77%, respectively, after 6 regeneration cycles.

Modification of silica nanoparticles with 1-hydroxy-2-acetonaphthone as a novel composite for the efficient removal of Ni(II), Cu(II), Zn(II), and Hg(II) ions from aqueous media

In this paper, a novel composite based on the formation of Schiff base on silica nanoparticles was facilely synthesized. Firstly, silica nanoparticles, which contain silanol groups (Si-OH), were modified with (3-aminopropyl)trimethoxysilane. Then, the modified silica reacted with 1-hydroxy-2-acetonaphthone to form a novel Schiff base/silica composite. The synthesized composite was characterized using several tools such as XRD, FT-IR, FE-SEM, N2 adsorption/desorption analyzer, and CHN analyzer. The considerable reduction at 2θ = 21.9° in the intensity of the XRD peak of the composite is owing to the formation of the Schiff base. Also, the observed FT-IR bands in the composite at 3440 and 1604 cm−1 are owing to the stretching and bending vibrations of OH and/or CN, respectively. The FE-SEM images confirmed that the silica includes irregular shapes whereas the composite possesses a flaky surface owing to the formation of the Schiff base. Elemental analysis of the composite demonstrated that the % C, % H, and % N are 15.26, 3.24, and 1.65 %, respectively. The BET surface area and total pore volume of the composite were reduced because the formed Schiff base blocks the pores of silica. The synthesized composite was employed for the efficient removal of Ni(II), Cu(II), Zn(II), and Hg(II) ions from aqueous media. The maximum uptake capacity of the composite toward Cu(II), Hg(II), Zn(II), and Ni(II) ions is 68.630, 50.942, 45.126, and 40.420 mg/g, respectively. The adsorption processes of the studied metal ions were spontaneous, chemical, and well described using the pseudo-second-order kinetic model and Langmuir equilibrium isotherm. The synthesized composite can be successfully regenerated and utilized various times in the removal of studied metal ions from aqueous media.

Evaluation of a sand filter material for road runoff treatment– pilot-scale field trial focused on copper and zinc removal

Abstract The effects of stormwater discharges on receiving aquatic environments and the need for their purification were highlighted by an EU court in May 2020. The ruling stated the need for removal of dissolved pollutants, which justifies field studies for development of far-reaching methods for runoff treatment. In this study, a standard sand was used as medium for road runoff filtration and removal of dissolved and particle-bound (<0.45 μm) zinc (Zn) and copper (Cu). Data included 24 road runoff events, mimicking the flow variations and pollutant emissions over a seven-month period. The findings showed that sand can be used to remove Zn and Cu from road runoff in a gravity fed treatment system at a surface load ranging from 16.8 to 201 L m−2 h−1. The removal of total Zn and Cu was 93 and 67%, respectively. Dissolved Zn was efficiently removed by the sand (87%), however not Cu (19%). The sand efficiently removed total suspended solids (TSS) from the maximum occurring 443 mg L−1 to below 5 mg L−1. No head loss due to the TSS loadings was observed. The sand's potential to remove the investigated metals was shown, but in the longer term, effluent concentrations may exceed permitted values.

Removal of Zn2+ from Aqueous Solution Using Biomass Ash and Its Modified Product as Biosorbent.

To study the removal effect of bottom ash of biomass power plants and its modified products on zinc (Zn2+) in aqueous solution, a series of indoor experiments is carried out. The aim of this work is to explore a method to improve the ability of biomass ash to remove Zn2+ from aqueous solution and obtain its adsorption characteristics of Zn2+ in aqueous solution; on this basis, the feasibility of its application in the treatment of Zn2+-contaminated wastewater is analyzed. The mesoporous siliceous material is used to modify the biomass, and the modified material is functionalized with 3-aminopropyltriethoxysilane. The results show that the specific surface area of modified biomass ash is nine times that of the material before modification. The adsorption capacity of Zn2+ on the material increases with the increase of pH, and pH 6 is the optimum pH to remove Zn2+ from the aqueous solution. The Langmuir model and Freundlich model can show better fits for biomass ash and the modified material, respectively. Thermodynamic analysis results show that the adsorption of Zn2+ is spontaneous and endothermic in nature. The adsorption of Zn2+ onto biomass and modified biomass ash follow pseudo-first-order and pseudo-second-order kinetics, respectively.

Simultaneous removal of Zn(II) ions and pathogens from pharmaceutical wastewater using modified sugarcane bagasse as biosorbents

Sugarcane bagasse (SCB) was developed into biosorbents by base (BSB), acid (ASB), and acid-base (A-BSB). The biosorbents were deployed to remediate pharmaceutical wastewater that was laden with Zn(II) ions and pathogens. The wastewater was characterised and revealed an increased Zn(II) ions concentration of 10.41 mg/l, total bacterial count (TBC) of 1.3 × 103 CFU/ml, and total coliform count (TCC) of 6 × 102 CFU/ml. These pollutants are hazardous to human and aquatic lives if discharged into the ecosystem without treatment. The developed biosorbents were characterised by FTIR, XRD, SEM with EDX mapping, and BET. The FTIR spectra showed peaks of the carboxylic groups present in lignin and hemicellulose which have good biosorbent properties. The XRD revealed the effect of the chemical modification of the SCB by changing the compound composition from sucrose to cellulose. The BET of the A-BSB gave the highest surface area and pore volume of 5.339 × 102 m2/g and 2.722 × 10−1 cc/g respectively, while the pore size of 2.105 nm was the lowest. Therefore, A-BSB exhibited optimum 99% removal of Zn(II) ions, and antimicrobial capacity of 100% removal for both TBC and TCC at 120 min, 40 °C, and 0.5 g dosage. The A-BSB is the most suitable adsorbent among the developed biosorbents for pharmaceutical wastewater treatment, as the findings from the kinetics study recommended chemisorption. Hence, the chemical modification of SCB was a promising low-cost adsorbent for Zn(II) ions and pathogens' removal from aqueous solutions.

Highly Active and Selective Sites for Propane Dehydrogenation in Zeolite Ga-BEA.

A highly selective Ga-modified zeolite BEA for propane dehydrogenation has been synthesized by grafting Ga on Zn-BEA followed by removal of Zn in the presence of H2. A propene selectivity of 82% at 19% propane conversion illustrates the high selectivity at 813 K. The kinetic model of the catalyzed dehydrogenation including the elementary steps of propane adsorption, first and second C-H bond cleavage, and propene and H2 desorption demonstrates that the propane dehydrogenation rate is determined by the first C-H bond cleavage at low pC3H8, while at high pC3H8, the rate is limited by the desorption of H2. The active sites have been identified as dehydrated and tetrahedrally coordinated Ga3+ in the *BEA lattice. The low selectivity toward aromatics is concluded to be associated with the high Lewis acid strength of lattice Ga3+ and the low Brønsted acid strength of the hydrated Ga sites.

Molecular characterization and optimization of streptomyces albogriseolous NGP2 and its prospects on heavy metals degradation

The biosorbing ability of actinomycetes from the marine sediments of South Indian Coastal region, Chennai, Tamilnadu, India was examined and identified as Streptomyces albogriseolous NGP 2 (JX843531) by 16S rRNA gene sequence analysis. The isolate showed the potential metal removing capacity by incubating it with various concentrations of heavy metals such as Copper (Cu), Zinc (Zn), Chromium (Cr) and Cadmium (Cd). Simultaneously, various optimization properties such as pH, initial metal concentration and contact time were analyzed. The pH 7.0 was recorded as an optimum for the removal of Cr and Zn, for Cd and Cu it was recorded as 6.0. The biosorption of the heavy metals Cu and Zn by the strain was found to be highest and recorded as 92% and 90.6% respectively, while the lowest sorption was found for Cd (85 %) at 30 mg/l concentration. The effectiveness of the removal of heavy metals was best studied by Langmuir and Freundlich adsorption isotherm models. The regression Coefficients also significantly expressed in the removal process. The results revealed that the isolate has the potential capability for the removal of heavy metals.

A Comparison Study for The Performance of Polyethersulfone Ultrafiltration Mixed Matrix Membranes in The Removal of Heavy Metal Ions from Aqueous Solutions

Polyethersulfone (PES) ultrafiltration membrane blending NaX zeolite crystals as a hydrophilic additive was examined for zinc (II) and lead ions Pb (II) removal from aqueous solutions. The effect of NaX zeolite content on the permeation flux and removal efficiency was studied. The results showed that adding zeolite to the polymer matrix enhanced the permeation flux. The permeation flux of all the zeolite/PES matrix membranes was higher than the pristine membrane. No significant improvement was observed in the removal of Zn (II) ions using all prepared membranes as the removal percentage did not raise above 29.2%. However, the removal percentage of Pb (II) ions was enhanced to 97% using a membrane containing 0.9%wt. zeolite. Also, it was found that this membrane has a higher ion exchange capacity than the other prepared membranes. Two isotherm models (Langmuir model, and Freundlich model) were employed in the analysis of the ion exchange equilibrium data. The experimental data best fitted the Langmuir model with R2 of 0.889 than the Freundlich model.

Characterization of Cu(II) and Zn(II) Sorption onto Zeolite

In this study, a batch sorption study approach was combined with an instrumental analytical approach of atomic absorption spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) for the sorption of copper and zinc ions from aqueous solution on zeolites. Both copper and zinc are biogenic elements; nevertheless, many industrial processes produce an excessive amount, which is why their efficient removal from water must be studied. Two types of zeolites, Zeolite Micro 20 (Z-M20) and Zeolite Micro 50 (Z-M50), were used. The results showed that the maximum sorption capacities for removal of Cu and Zn were 1.06 for CuSO4, 42.35 for Cu(NO3)2, 1.15 for ZnSO4 and 2.29 for Zn(NO3)2 adsorption onto Z-M20 and 0.45 for CuSO4, 1.67 for Cu(NO3)2, 0.39 for ZnSO4 and 1.51 for Zn(NO3)2 adsorption onto Z-M50. The maximum sorption capacities are higher for sulfates and the sorbent with smaller particle size. The sorption capacities of Cu and Zn for corresponding anion and particle size differ only up to 5–15%. Using XRD and XPS analyses before and after the sorption process, it was found that the content of both Cu and Zn in the surface layer and the bulk are the same for sorption onto sorbent with smaller particle size, but are higher in the surface layer than in the bulk for sorption onto sorbent with larger particle size. One of the main findings of this study is that a zeolite with smaller particles takes Cu and Zn by the whole particle, while with bigger particles, Cu and Zn concentrate in the surface of the particle. The results of the study may be used as an indicator for sorption efficiency of the studied zeolites for their application in the treatment of copper and zinc contaminated effluents.

GREEN WASTE DERIVED ALKALI FOR REMEDIATION APPLICATION IN HEAVY METALS CONTAMINATED GROUNDWATER AND ITS KINETICS EVALUATION

The production of high purity alkali that can be sourced from green wastes (plantain peels) as an alternative remediation option that is effective, efficient, environmental friendly and less expensive for the treatment of heavy metal contaminated groundwater constitutes the focus of this study. High purity alkali was produced from plantain peels using standard methods to give a yield of 89.72%, with the potash predominantly potassium carbonate. Groundwater was contaminated with 5% Zn, Cu, Pb, Mn, Ni and Fe from their respective metal salts by 10% simulation. pH and heavy metal analysis were done using standard methods. Heavy metals contaminated groundwater was treated by precipitation with the alkali produced after appropriate optimization process. Optimization of pH for effective remediation showed optimum precipitation efficiency at a pH of 10 for all metals. Treatment of the simulated groundwater gave remediation efficiencies of 88.24%, 91.05%, 85.45% and 90.44% for Zn, Cu, Ni and Mn removal respectively, after 12hours treatment period at pH ranges of 8.1-10. While those of Pb and Fe were found as 89.77% and 95.15% respectively, after same treatment period at pH ranges of 7.85-10; which were within the minimal pH values required for metal precipitation. Precipitation processes all followed zero order kinetics with zero order rate constants of 1.242 µg/lhr-1, 0.933 µg/lhr-1, 0.493 µg/lhr-1 0.608 µg/lhr-1, 0.157 µg/lhr-1 and 3.411 µg/lhr-1 for the removal of Zn, Cu, Pb, Mn, Ni and Fe respectively from the treated groundwater. Half life for the remediation processes were found as 6hours 24minutes, 6hours 21minutes, 7hours 22seconds, 6hours 22minutes 12 seconds, 6hours 44minutes 24 seconds and 6hours 24minutes 22 seconds for the removal of Zn, Cu, Ni, Mn, Pb, and Fe respectively from the treated groundwater. The time required for complete precipitation and removal of the metals to zero metal concentration was found to be 12 hours 48minutes 36 seconds, 12 hours 42minutes, 14 hours 36 seconds, 12 hours 43minutes 48 seconds, 13 hours 30minutes and 12 hours 48minutes 36 seconds for Zn, Cu, Ni, Mn, Pb, and Fe respectively. Significant differences at 95% confidence limit (p ≤ 0.05) were statistically observed when the initial metal concentrations were compared to residual metal concentrations left after treatment, showing the efficacy of the treatment process. The use of potash alkali locally sourced from green waste in wastewater remediation for heavy metals is seen to be quite fast, cost effective, efficient and viable, thus providing a viable alternative for remediation experts in this regard.

Fabrication of feldspar-based geopolymers from perlite toward decontamination of heavy metals from aqueous solution: Hydrolysis process, characterizations, kinetic and isotherm studies

Nowadays, alkali-activated materials have widely attracted great attention in the adsorption process. The present study describes a novel approach for fabricating feldspar-based geopolymers and investigates their applications for the adsorption of heavy metals. The processes involved for this purpose are i)- using perlite as the precursor, ii) extraction of silicate (water glass) by NaOH solution, iii) fabrication of feldspar-based geopolymers and iv) employing heavy metals pollution to find out the possible potential in the adsorption process. The structure of the raw perlite and synthesized compounds were identified through XRD, XRF, FT-IR, SEM, and BET analyses. The XRD characterization clarified the formation of albite (a plagioclase feldspar mineral) as the only common mineral in the fabricated adsorbents. BET results indicated an increase in the surface area of samples after hydrolysis. The experiment results demonstrated the adsorption ability of TTA (hydrolyzed by tartaric acid) and TSU (hydrolyzed by sulfuric acid) samples for the removal of Cd(II), Co(II), and Zn(II) from an aqueous solution. The maximum adsorption capacity of Cd(II), Co(II), and Zn(II) ions onto the TTA sample was 50.251, 36.764, and 39.525 mg/g, respectively; while this amount for TSU adsorbent was 52.63, 24.449, and 20.161 mg/g, respectively. In addition, isotherm and kinetic studies confirmed that the adsorption process was done chemically and desirably. Considering this paper’s results, the newly fabricated geopolymeric feldspars from low-cost perlites can be used for heavy metals adsorption.

Application for Reprocessing Cattle, Chicken, and Fish Bones in the Removal of Zn (II) and Cr (VI) from Wastewater Using Batch Adsorption System

Application for Reprocessing Cattle, Chicken, and Fish Bones in the Removal of Zn (II) and Cr (VI) from Wastewater Using Batch Adsorption System

A “Turn-On” fluorescent probe for detection and removal of Zn2+ in aqueous and its application in living cells

Using 3-hydroxy-2-naphthoic acid hydrazine and 4-(diethylamino) salicylaldehyde.as raw materials, compound L with an acylhydrazones structure was synthesized. The structure of compound L was characterized by nuclear magnetic resonance spectroscopy, X-ray single crystal diffraction, Fourier transform infrared spectroscopy, and mass spectrometry. The results show that Compound L can quickly and selectively recognize zinc ions in the H2O/DMSO (V:V = 3:7) solvent system. After that, the spectral performance of probe L was studied by fluorescence spectroscopy and UV–vis spectroscopy. The results show that the combination with Zn2+ can significantly enhance the fluorescence intensity of probe L while being almost unaffected by other coexisting ions. After that, Job’s curve method, nuclear magnetic titration analysis, and mass spectrometry were used to study the binding mechanism of probe L and Zn2+. The results showed that probe L coordinated with Zn2+ is 1:1. The linear equations of different concentrations of Zn2+ and fluorescence intensity were obtained by fitting, and the detection limit of probe L for Zn2+ was determined to be 6.75 × 10-9 mol/L. The experimental study of standard addition and recovery showed that probe L could be used for the quantitative detection of Zn2+ in natural water samples. After that, we prepared L-doped sodium alginate hydrogel (SAL). The research results show that SAL has obvious adsorption capacity for Zn2+ in solution, and the color change before and after adsorption can be easily distinguished by the naked eye under ultraviolet light. SEM-EDS study showed that the microscopic morphology and composition of SAL changed significantly before and after adsorption. This fluorescent probe can be used for detection and removal of Zn2+ in aqueous solution. Also, probe L is effective for sensing for zinc (II) in living tumor cells. Overall, this work allows us to obtain a great potential to be applied to detect and remove Zn2+.

Immobilization of heavy metals by microbially induced carbonate precipitation using hydrocarbon-degrading ureolytic bacteria

Crude oil contamination introduces multiple threats to human health and the environment, most of which are from toxic heavy metals. Heavy metals cause significant threats because of their persistence, toxicity, and bio-accumulation. Biomineralization, performed through many microbial processes, can lead to the immobilization of heavy metals in formed minerals. The potential of the microbially carbonate-induced precipitation (MICP) in removal by biomineralization of several heavy metals was investigated. A collection of diverse 11 bacterial strains exhibited ureolytic activity and tolerance to heavy metals when growing in Luria-Bertani (LB) and urea medium. Determination of the minimum inhibitory concentrations (MIC) revealed that heavy metal toxicity was arranged as Cd > Ni > Cr > Cu > Zn. Three hydrocarbon-degrading bacterial strains (two of Pseudomonas aeruginosa and one of Providencia rettgeri) exhibited the highest tolerance (MIC > 5 mM) to Cu, Cr, Zn, and Ni, whereas Cd exerted significantly higher toxicity with MIC <1 mM. At all MICP conditions, different proportions of calcium carbonate (calcite) and calcium phosphate (brushite) were formed. Pseudomonas aeruginosa strains (QZ5 and QZ9) exhibited the highest removal efficiency of Cr (100%), whereas Providencia rettgeri strain (QZ2) showed 100% removal of Zn. Heavy metal complexes were found as well. Cd removal was evidenced by the formation of cadmium phosphate induced by Providencia rettgeri bacterial activity. Our study confirmed that hydrocarbon-degrading ureolytic bacteria not only can tolerate heavy metal toxicity but also have the capability to co-precipitate heavy metals. These findings indicate an effective and novel biological approach to bioremediate petroleum hydrocarbons and immobilize multiple heavy metals with mineral formation. This is of high importance for ecological restoration via stabilization of soil and alleviation of heavy metal toxicity.

Resource Recycling of Red Soil to Synthesize Fe2O3/FAU-type Zeolite Composite Material for Heavy Metal Removal.

Heavy metal-polluted water is of great concern to human health and the eco-environment. In situ water remediation techniques enabled by highly efficient adsorption materials are of great importance in these circumstances. Among all the materials used in water remediation, iron-based nanomaterials and porous materials are of great interest, benefiting from their rich redox reactivity and adsorption function. Here, we developed a facile protocol to directly convert the widely spread red soil in south China to fabricate the Fe2O3/faujasite (FAU)-type zeolite composite material. The detailed synthesis procedure and synthesis parameters, such as reaction temperature, reaction time, and the Si/Al ratio in the raw materials, have been carefully tuned. The as-synthesized composite materials show good adsorption capacity for typical heavy metal(loid) ions. With 0.001 g/mL Fe2O3/FAU-type zeolite composite material added to different heavy metal(loid)-polluted aqueous solutions (single type of heavy metal(loid) concentration: 1,000 mg/L [ppm]), the adsorption capacity was shown to be 172, 45, 170, 40, 429, 693, 94, and 133 mg/g for Cu (II), Cr (III), Cr (VI), As (III), Cd (II), Pb (II), Zn (II), and Ni (II) removal, respectively, which can be further expanded for heavy metal-polluted water and soil remediation.

High efficient removal of lead(II) and cadmium(II) ions from multi-component aqueous solutions using polyacrylic acid acrylonitrile talc nanocomposite

This study is interested in the removal of Pb(II), Cd(II), Co(II), Zn(II), and Sr(II) onto polyacrylic acid acrylonitrile talc P(AA-AN)-talc nanocomposite. P(AA-AN)-talc was fabricated using γ-irradiation-initiated polymerization at 50 kGy. Different analytical tools were used to investigate the functional groups, morphology, particle size, and structure of this composite. The ability of P(AA-AN)-talc to capture (Pb2+, Cd2+, Co2+, Zn2+, and Sr2+) as multi-component aqueous solutions was performed by a batch method. Saturation capacity and the effect of (agitating time, pH, initial metal concentrations, and temperature) were investigated. The distribution coefficients at different pHs have order: Pb2+ > Cd2+ > Co2+ > Zn2+ > Sr2+. The saturation capacity decreases by increasing heating temperatures. Reaction kinetic obeys the pseudo-second-order model. Sorption isotherms are more relevant to a Langmuir isotherm, and the monolayer sorption capacity is closed to saturation capacity. Thermodynamic parameters (∆G˚, ∆H˚, and ∆S˚) were endothermic and spontaneous. P(AA-AN)-talc is used for loading and recovery of studied cations in the column system. The study confirms that P(AA-AN)-talc is a promised composite for the sorption of the studied ions from aqueous solutions and should be considered as potential material for decontaminating these ions.Graphical abstract

Metal Removal Kinetics, Bio-Accumulation and Plant Response to Nutrient Availability in Floating Treatment Wetland for Stormwater Treatment

Floating treatment wetland (FTW) is a recent innovation to remove nutrients from stormwater, but little is known about its effectiveness for metal removal. This study aims to test the hypothesis that the metal removal performance of FTWs will be affected by nutrient (NH3-N, NO3-N, and PO4-P) availability in stormwater. Two experiments were carried out in nutrient-deficient tap water, and two experiments were carried out in nutrient-rich lake water using four native Australian plants, namely Carex fascicularis, Juncus kraussii, Eleocharis acuta, and Baumea preissii. Up to 81% Cu and 44.9% Zn removal were achieved by the plants in 16 days in tap water. A reduction in Cu and Zn removal of 28.4–57.3% and 1.0–19.7%, respectively, was observed in lake water compared with tap water for the same duration. The kinetic analysis also confirmed that plant metal uptake rates slowed down in lake water (0.018–0.088 L/mg/day for Cu and 0.005–0.018 L/mg/day for Zn) compared to tap water (0.586–0.825 L/mg/day for Cu and 0.025–0.052 L/mg/day for Zn). A plant tissue analysis revealed that E. acuta and B. preissii bioaccumulated more than 1000 mg/kg of both metals in their tissue, indicating high metal accumulation capacities. To overcome the slower metal uptake rate problem due to nutrient availability, future studies can investigate multi-species plantations with nutrient stripping plants and metal hyper-accumulator plants.

Response surface methodology adhering central composite design for the optimization of Zn (II) adsorption using rice husk nanoadsorbent

Present study highlights the effectuality of rice husk nanoadsorbent RHN for the removal of Zn (II) from aqueous solution. A peculiar statistical technique central composite design of response surface methodology by using Design-Expert® software version 11 was executed to investigate Zn (II) removal by varying three adsorption parameters such as pH, dose and metal ion concentration. Quadratic model equation and analysis of variance were outlined in the study. Zn (II) removal was found to be 80% at optimum conditions pH 6, dose 0.8 g/L and metal ion concentration 15 mg/L and desirability was near 0.9. To comprehend the nature of adsorption process, linear forms of isotherms were gratified. Langmuir isotherm model was found to be compatible with adsorption data indicating monolayer adsorption on homogeneous active sites of nanoadsorbent with 0.9978 R2. Pseudo-second order kinetic model fitted well to the adsorption data with R2 0.992. Spontaneous and endothermic nature of the process was depicted by thermodynamic study. Adsorption mechanism is reasonably explained by hydrolysis, precipitation, electrostatic interactions and HASB inreaction. The regeneration of RHN was analysed upto three successive cycles.

Improving water quality, growth performance, and modulating some stress physiological biomarkers in Cyprinus carpio using raw date nuclei as a zinc adsorbent agent

Adsorption of heavy metals by affordable adsorbents has recently become one of the most often applied method for removing these metals from contaminated water. The purpose of this study was to evaluate the efficacy of using raw date nuclei (RDN) as a natural and inexpensive adsorbent to remove Zn ions from contaminated water and reduce its impact on water quality, Zn bioaccumulation levels in fish organs, growth performance, and some physiological aspects of common carp (Cyprinus carpio) under sublethal concentrations. Five experimental groups were examined for eight weeks; CNT, control group rearing in clean water; RDN0, fish group rearing in Zn-contaminated water; RDN3, fish group rearing in Zn-contaminated water and treated with 3 g RDN/L; RDN4.5, fish group rearing in Zn-contaminated water and treated with 4.5 g RDN/L; RDN6, fish group rearing in Zn-contaminated water and treated with 6 g RDN/L. Water quality measures were monitored in a continuously manner without removing fish excreta or renewing water. The results showed that sublethal concentration of Zn alone significantly elevated the level of antioxidant biomarkers (SOD, superoxide dismutase; GST, glutathione transferases; GPX, glutathione peroxidase; CAT, catalase and MDA, malondialdehyde), significantly declined fish performance, increased Zn-accumulation in fish organs (gills and flesh) and increased the ammonia secretions in fish ponds compared to the control group. Zn concentrations in RDN-containing aquariums were significantly lower than in RDN-free aquariums, and Zn removal from polluted water was dependent on RDN dosage. Consequently, fish performance and serum bio-indicators enhanced in the presence of RDN in a fish group reared under sublethal Zn concentrations. In conclusion, although Zn caused toxicity in C. carpio at sublethal levels, treating Zn-contaminated water with RDN at a dosage of 6 g per liter effectively prevented oxidative stress and the harmful impacts of Zn exposure.

Effectiveness of Wheat Straw Biochar in Aqueous Zn Removal: Correlation with Biochar Characteristics and Optimization of Process Parameters

Effectiveness of Wheat Straw Biochar in Aqueous Zn Removal: Correlation with Biochar Characteristics and Optimization of Process Parameters