Removal of Ni(II) from aqueous solution by adsorption onto hazelnut shell activated carbon: equilibrium studies

Valorisation of hazelnut by-products: current applications and future potential

Hazelnut is one of the most widely consumed nuts around the world. Considering the nutritional value of hazelnuts, a wide range of hazelnut-based food products are available in the market such as oil, chocolate, confectionery, etc. Nevertheless, the processing of hazelnuts generates a large number of by-products and waste. The most valuable by-products of the hazelnut industry are shell, skin, and meal. These by-products are rich in bioactive compounds, protein, dietary fibre, mono- and polyunsaturated fatty acids, vitamins, minerals, phytosterols, and squalene. The current utilisation of hazelnut by-products is mostly limited to animal feed supplementation of hazelnut meal and skin and use as a low-value heat source for the shells. However, disposing of these by-products or using them as a low-value heat source or animal feed supplementation results in significant waste of a natural resource rich in nutritional components. Consequently, valorising hazelnut by-products as bioactive ingredients in diverse fields such as food, pharmaceuticals and cosmetics has stimulated interest among scientists, producers, and consumers. This review provides an overview of current scientific knowledge about the main and most valuable hazelnut by-products and their actual valorisation, with a focus on their chemical composition to inspire new applications of these valuable resources and fully exploit their potential.

Removal of hexavalent chromium ions using micellar modified adsorbent: isothermal and kinetic investigations

Hexavalent chromium is a very poisonous oxyanion and has had a negative impact on human health. This study assessed the viability of removing chromium(vi) using micellar modified adsorbents. In this study, chromium(vi) was removed from locally accessible wheat bran using separate applications of anionic sodium dodecyl sulfate (SDS) and cationic cetyltrimethylammonium bromide (CTAB) surfactants. The initial chromium content (5–12 ppm), pH (2–12), adsorbent dose (1–6 g/100 mL), agitation time (15–240 min), agitation speed (50–300 rpm), and temperature (15–50 °C) were all varied in the adsorption investigation. Pseudo first-order and second-order kinetic models were utilized to analyze the kinetic investigation. To determine thermodynamic parameters, the van't Hoff relationship was used. The maximum result for chromium(vi) uptake was obtained as 87.7%, 83.5% and 98.9% for WB, SDS-mWB, and CTAB-mWB, respectively, at an agitation time of 240 min (i.e., 4 h), temperature (i.e., 25–30 °C), agitation speed (150 rpm). However, both WB and CTAB-mWB derives metal ion removal at lower pH levels (2–4), whereas SDS-mWB requires a pH between 4 and 6 for maximum percentage removal of Cr(vi). The equilibrium data of WB and SDS-mWB were modeled by the Langmuir adsorption isotherm, while the data of CTAB-mWB fitted well in the Freundlich isotherm model. The kinetic analysis of WB, SDS-mWB, and CTAB-mWB revealed that the pseudo-second-order kinetic model provides a thorough explanation for each of these adsorbents. It was found that CTAB-mWB can preferably be used for the removal of chromium(vi) due to its high affinity with adsorbate molecules and adsorption capacity.

In this investigation, anionic sodium dodecyl (SDS) and cationic cetyltrimethylammonium bromide (CTAB) surfactants were separately applied to locally accessible wheat bran to remove chromium(vi).

Highly Effective Adsorption Process of Ni(II) Ions with the Use of Sewage Sludge Fly Ash Generated by Circulating Fluidized Bed Combustion (CFBC) Technology

Recently, more and more attention has been paid to the removal of nickel ions due to their negative effects on the environment and human health. In this research, fly ash obtained as a result of incineration of municipal sewage sludge with the use of circulating fluidized bed combustion (CFBC) technology was used to analyze the possibility of removing Ni(II) ions in adsorption processes. The properties of the material were determined using analytical methods, such as SEM-EDS, XRD, BET, BJH, thermogravimetry, zeta potential, SEM, and FT-IR. Several factors were analyzed, such as adsorbent dose, initial pH, initial concentration, and contact time. As a result of the conducted research, the maximum sorption efficiency was obtained at the level of 99.9%. The kinetics analysis and isotherms showed that the pseudo-second order equation model and the Freundlich isotherm model best suited this process. In conclusion, sewage sludge fly ash may be a suitable material for the effective removal of nickel from wastewater and the improvement of water quality. This research is in line with current trends in the concepts of circular economy and sustainable development.

Metal-organic frameworks/alginate composite beads as effective adsorbents for the removal of hexavalent chromium from aqueous solution

Industrial waste discharge comprising heavy metals into potable water bodies induces many health hazards. This study investigates the role of metal-organic frameworks (MOFs) doped alginate beads (MOFs@ABs) as potential adsorbents for Cr(VI). Effects of pH, stirring rate, temperature, initial chrome concentration, and particles dosage on Cr(VI) adsorption are studied to evaluate adsorption ability of UiO-66@ABs for Cr(VI) removal from aqueous solution. The adsorption kinetics follows pseudo second order and the equilibrium isotherm is consistent with Langmuir isotherm model. The maximum adsorption capacity of UiO-66@ABs calculated from the model conforms to the experimental results. The desorption experiment of Cr(VI) adsorbed UiO-66@ABs (82%) demonstrates satisfactory regeneration efficiency. Based on our findings and comparative controlled experiments, the superiority of UiO-66@ABs promises their potential application in Cr(VI) removal from wastewater.

Use of sulfuric acid-carbonization materials from grape pulp for the removal of hexavalent chromium (Cr(VI)): mechanism and characterization

This study investigated the reduction of hexavalent chromium (Cr(VI)) with sulfur dioxide (SO₂) and adsorption of Cr(VI) onto dried grape pulp carbonized with sulfuric acid. Cr(VI) reduction capacities of SO₂ were determined. The filtrate was titrated with NaOH solution after shaking and filtering the carbonized material to retain unreacted sulfuric acid (H₂SO₄). Simple washing recovered 25-38% of the experimental acid at low concentrations. The carbonized material was washed twice with distilled water and then dried at 105 °C and weighed. The carbonized material had a yield of 56.6% (grape pulp/sulfuric acid ratios of 1:2), and the lower the H₂SO₄ content, the better the yield, suggesting that the higher the acid content, the lower the Cr(VI) content per unit grape pulp. Cr(VI) reduction capacities were 219.5, 195.3, and 190.9 mg Cr(VI)/g-H₂SO₄ for the grape pulp/sulfuric acid ratios of 1:1, 1:2, and 1:3, respectively. Novelty statement: A carbonaceous material was obtained from grape pulp by carbonizing with concentrated sulfuric acid. The main objective of this study was to evaluate gas, liquid, and solid products or co-products obtained during carbonization process for hexavalent chromium treatment in aqueous solutions. In this context, (a) hexavalent chromium reduction capability of the gas evolved during carbonization was determined, (b) characterization of unreacted acid recovered by washing the carbonized product left after carbonization step was done, (c) carbonaceous adsorbent obtained was characterized and (d) hexavalent chromium adsorption characteristics of carbonaceous material obtained was determined.HIGHLIGHTSReduction and adsorption mechanisms of hexavalent chromium were investigated.A waste recycling method was proposed.The effects of sulfuric acid on carbonization were assessed.The structures and chemical compositions of a carbonized material were evaluated.The carbonized material is a cost-effective porous adsorbent for a clean environment.

Optimization of Ni(II) adsorption onto Cloisite Na+ clay using response surface methodology

The aim of this study was to investigate the adsorption of Ni(II) from aqueous solutions onto Cloisite Na⁺ clay. The effects of the initial concentration of Ni(II), adsorbent dose, pH, and temperature on adsorption capacity were studied using response surface methodology. A second-order regression model was determined based on the experimental results. Analysis of variance used to evaluate the individual and combined effects of process variables showed that initial Ni(II) concentration and adsorbent dose were more significant than solution pH and temperature. Moreover, the interaction effects of the initial concentration of nickel and the adsorbent dose, as well as the solution pH and adsorbent dose were significant. High coefficient of determination (R² = 0.93) and low probability values signify the validity of the model for predicting the adsorption capacity of Cloisite Na⁺ for Ni(II) ions. The optimal conditions for pH and adsorbent dose were found to be 6.9 and 0.21 g/L, respectively at a constant temperature of 25 °C and initial Ni(II) concentration of 50 mg/L. Under these conditions, the adsorption capacity of clay was found to be 31.43 mg/g. Moreover, the adsorption isotherms results indicated that these data could be best fitted to the Langmuir isotherm model (R² = 0.99). The Langmuir maximum adsorption capacity was estimated to be 32.05 mg/g for an adsorbent dose of 0.2 g/L at pH 7 and 25 °C. In conclusion, the results showed that Cloisite Na⁺ clay can be utilized as an effective adsorbent for the removal of Ni(II) from aqueous solutions.

An overview of chlorophenols as contaminants and their removal from wastewater by adsorption: A review

In this review article, a significant number of published articles (over three decades) were consulted in order to provide comprehensive literature information about chlorophenols, their sources into the environment, classification, and toxicity, various wastewater treatment methods for their removal as well as the characteristics of their adsorption by various adsorbents. Organizing the scattered available information on a wide range of potentially effective adsorbents in the removal of chlorophenols is the principal objective of this article. Various adsorbents such as natural materials, waste materials from industries, agricultural by-products and biomass-based activated carbon in the removal of various chlorophenols have been compiled and discussed here. Crucial factors like temperature, solution pH, contact time and initial solution concentration are also reported and discussed here. The π-π dispersion interaction mechanism, hydrogen bonding formation mechanism, and the electron donor-acceptor complex mechanism were proposed for the chlorophenols adsorption onto various adsorbents with the help of current literature. Conclusions have been drawn proposing a few suggestions for future research on mitigating the effect of chlorophenols in the environment.

Surveying the efficiency of Platanus orientalis bark as biosorbent for Ni and Cr(VI) removal from plating wastewater as a real sample

Heavy metals make up one of the most important pollutants in industrial wastewater. For wastewater, adsorbent materials developed from suitable biomass can be effective in removing the heavy metal ions. In this study, the powder of the bark of Platanus orientalis was used as a biosorbent to remove Cr(VI) and Ni from a nickel-chromium plating wastewater as a real sample for the first time. Two different adsorbents were used in analyzing the data: modified and non-modified bark. The extent of adsorption was dependent on the pH (in the range of 1.5, 3, 5, 7, and 9), the time of contact (in the range of 30, 60, 90, 120 min), and the adsorbent dosage (different doses of 0.5, 1, 1.5, 2 g L^-1). The concentration of unabsorbed metals was measured by inductively coupled plasma-optical emission spectroscopy (ICP-OES, Model Thermo iCAP 6000). The maximum removal of Cr(VI) was obtained 89.6% for non-modified bark and 90.7% for modified bark both at pH of 5 in 2 g L^-1 of adsorbent dosage in 300 min. While, the maximum Ni removal was obtained 74.5 and 56.5% for non-modified and modified bark, respectively, at pH 3 in 2 g L^-1 adsorbent dosage in 90 min. Based on the results, Freundlich isotherm appears better fitted in adsorption with a better correlation coefficient (R² = 0.998) than that of Langmuir model with a correlation coefficient of R² = 0.996. The q_max for Ni₁ and Ni₂ were 126.58 and 285.714 mg g^-1 and the q_max for Cr₁ and Cr₂ were 13.423 and 19.920 mg g^-1, respectively. The FTIR studies indicated that S-O stretching group from sulfonate, surface O=H stretching, and also aliphatic C-H stretching are responsible for the adsorption. The SEM results obviously show the difference between the biomass surface before and after loading of ions. Ultimately, the present study concluded that P. orientalis could be a cheap and efficient biosorbent to adsorb and remove Cr(VI) and Ni from the plating wastewater; however, it seems more efficient for Cr(VI) with an average removal power of 90.15% than Ni with an average removal power of 65.75%.

Unraveling sorption of nickel from aqueous solution by KMnO4 and KOH-modified peanut shell biochar: Implicit mechanism

Nickel-containing wastewater is a serious hazard to water environment, so that it is a burning issue to find an efficient and environment-friendly adsorbent. The conventional biochar could not effectively adsorb nickel (Ni(II)), so our study focuses on exploring the adsorption of chemically modified biochar to Ni(II). In this study, the biochar derived from waste peanut shell was modified by KMnO₄ and KOH (MBC). And a series of experiment were carried out to evaluate the sorption ability and explore adsorption mechanism of modified biochar to Ni(II). The results showed the adsorption ability of MBC to Ni(II) reached 87.15 mg g^-1. And the reaction process was spontaneous and endothermic chemisorption. Meanwhile, the analysis of FTIR and XPS visually revealed that the amine groups in the modified biochar could form NH₂Ni with Ni(II) by complexation, while the hydroxyl could form nickel hydroxide and complexed nickel oxide by co-precipitation and complexation. This research showed this novel MBC is a promising adsorbent and has a fantastic prospect in the application of nickel-containing wastewater.

Biosorption of Cd(II) and Cs(I) from aqueous solution by live and dead cells of Saccharomyces carlsbergensis PTCC 5051

The biosorption characteristics of Cd(II) and Cs(I) using live and dead cells of Saccharomyces carlsbergensis PTCC 5051 as biosorbents have been investigated in the present research. The influence of different experimental parameters such as initial pH (pHi), shaking rate, sorption time and initial metal concentration was evaluated. The optimum pH was obtained as 4 for Cd(II) and 7 for Cs(I). The experimental adsorption data were fitted to the Langmuir linear equation adsorption model. The highest metal uptake values of 0.593 and 0.473 mmol g^-1 were calculated for Cd(II) and Cs(I), respectively. The results of Fourier transform infrared analysis suggested the involvement of amine, carboxyl and hydroxyl groups during the biosorption process and also indicated that more functional groups were involved in the biosorption process of live adsorbents, compared with those linked to dead biomass. The results showed that the biomass of S. carlsbergensis PTCC 5051 is a suitable biosorbent for the removal of Cd(II) and Cs(I) from the aqueous solutions.

Ni2+ and Co2+ adsorption using Tectona grandis biochar: kinetics, equilibrium and desorption studies

In this research, the potential of a relatively new adsorbent prepared from Tectona grandis leaves by pyrolysis for heavy metal removal from aqueous solution was studied. Adsorption behavior of the pyrolytic biochar was investigated with respect to Ni²⁺ and Co²⁺ removal with its affinity examined through batch studies and the mechanism elucidated using different empirical isotherm and kinetic models. A significantly higher efficiency of 92.46% and 91.21% was achieved at a weakly acidic pH of 6 and 5, dose of 3 g L^-1 and 2 g L^-1 for Ni²⁺ and Co²⁺ removal, respectively. Pseudo-second-order kinetics and Langmuir isotherm model best represented the adsorption process for both Ni²⁺ and Co²⁺. Thermodynamic analysis proved the endothermic and spontaneous nature of the process. Desorption studies revealed hydrochloric acid to have a high potential toward eluting the adsorbed metal ions. The well-organized microporous structure, the significant surface area value along with the presence of relative functional groups together with its high adsorption capacity for Ni²⁺ and Co²⁺, revealed the significant adsorptive potential of biochar of teak leaves powder for metal ion removal.

Synthesis of biochar from residues after biogas production with respect to cadmium and nickel removal from wastewater

The objective of the study was to investigate the ability of biochars prepared under different temperatures (400 °C and 600 °C) from the residue of biogas production (RBP) for the adsorption of cadmium (Cd(II)) and nickel (Ni(II)) ions from aqueous solution. Furthermore, the RBP biochars adsorption capacity was compared with adsorption capacity of biochar produced from wheat straw at 600 °C (BCS600). The kinetics of the adsorption, the sorption isotherms, the influence of solution pH and the interfering ions (chlorides and nitrates) were investigated. The desorption of Cd(II) and Ni(II) by hydrochloric and nitric acid from biochars was also investigated. The different types of feedstock used for biochar (BC) preparation (RBP and biomass) determined the physico-chemical properties of biochars and hence their adsorption abilities. Generally, biochars produced from RBPs (regardless of temperature) had the greater capacity to adsorb Cd(II) and Ni(II) than the biochar produced from wheat straw. Of the tested models (Freundlich and Langmuir), the Langmuir model was demonstrated to be the best to describe the sorption of Cd(II) and Ni(II). For the kinetic study, the adsorption process proceeded the fastest for BCU400 than BCU600. Furthermore, BCU600 was the most resistant to the influence of interfering ions on adsorption. For the desorption study, BCU400 was characterized by the highest reproducibility of the surface. The comparison of the results obtained in each adsorption step between RBP biochars and BCS600 suggested that the residue from biogas production could be successfully applied for the removal of Cd(II) and Ni(II) ions from aqueous solutions.

Synthesis of the modified nanofiber as a nanoadsorbent and its dye removal ability from water: isotherm, kinetic and thermodynamic

In this paper, poly(vinyl alcohol) (PVA) nanofiber was prepared and modified by diethylenetriamine (DETA) and ethylenediamine (EDA) in the presence of glutaraldehyde (GA). Dye removal ability of the modified nanofiber (PVA/DETA/EDA/GA) as a nanoadsorbent from water was studied. Fourier transform Infrared (FTIR) and scanning electron microscopy (SEM) were used to investigate the characteristics of the modified nanofiber. Direct Red 23 (DR23) and Direct Blue (DB78) were used. The effect of operational parameters such as pH, initial dye concentration, contact time, temperature and adsorbent dosage on dye removal was studied. The dye adsorption isotherms, kinetics and thermodynamics were investigated. The maximum dye adsorption capacity of the modified nanofiber was 370 and 400 mg/g for DR23 and DB78, respectively. Four isotherms, the Langmuir, the Freundlich, Tempkin and a modified Langmuir-Freundlich model were used. Dye adsorption on the modified nanofiber followed the Langmuir isotherm and pseudo-second kinetic order. Thermodynamic data showed that dye removal was a spontaneous, endothermic and physisorption process.

State of the science review: Potential for beneficial use of waste by-products for in situ remediation of metal-contaminated soil and sediment

Metal and metalloid contamination of soil and sediment is a widespread problem both in urban and rural areas throughout the United States (U.S. EPA, 2014). Beneficial use of waste by-products as amendments to remediate metal-contaminated soils and sediments can provide major economic and environmental advantages on both a site-specific and national scale. These waste by-products can also reduce our need to mine virgin materials or produce synthetic materials for amendments. Waste by-products must not be hazardous or pose unacceptable risk to human health and the environment, and should be a suitable replacement for virgin and synthetic materials. This review serves to present the state of science on in situ remediation of metal-contaminated soil and sediment and the potential for beneficial usage of waste by-product materials. Not all unintended consequences can be fully understood or predicted prior to implementing a treatment option, however some realized, and potentially unrealized, benefits and unintended consequences are explored.

Ni (II) adsorption onto Chrysanthemum indicum: Influencing factors, isotherms, kinetics, and thermodynamics

The study explores the adsorption potential of Chrysanthemum indicum biomass for nickel ion removal from aqueous solution. C. indicum flowers in raw (CIF-I) and biochar (CIF-II) forms were used as adsorbents in this study. Batch experiments were conducted to ascertain the optimum conditions of solution pH, adsorbent dosage, contact time, and temperature for varying initial Ni(II) ion concentrations. Surface area, surface morphology, and functionality of the adsorbents were characterized by Brunauer, Emmett, and Teller (BET) surface analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR). Adsorption kinetics were modeled using pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion, Bangham's, and Boyd's plot. The equilibrium data were modeled using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) isotherm models. Experimental data provided the best fit to pseudo-second-order kinetic model and Langmuir isotherm model for the adsorption of Ni(II) ion on both CIF-I and CIF-II with maximum adsorption capacities of 23.97 and 44.02 mg g(-1), respectively. Thermodynamic analysis of the data proved the process to be spontaneous and endothermic in nature. Desorption studies were conducted to evaluate the possibility of reusing the adsorbents. Findings of the present study provide substantial evidence for the use of C. indicum flower as an eco-friendly and potential adsorbent for the removal of Ni(II) ions from aqueous solution.

Adsorptive removal of nickel(II) ions from aqueous environment: A review

Among various methods adsorption can be efficiently employed for the treatment of heavy metal ions contaminated wastewater. In this context the authors reviewed variety of adsorbents used by various researchers for the removal of nickel(II) ions from aqueous environment. One of the objectives of this review article is to assemble the scattered available enlightenment on a wide range of potentially effective adsorbents for nickel(II) ions removal. This work critically assessed existing knowledge and research on the uptake of nickel by various adsorbents such as activated carbon, non-conventional low-cost materials, nanomaterials, composites and nanocomposites. The system's performance is evaluated with respect to the overall metal removal and the adsorption capacity. In addition, the equilibrium adsorption isotherms, kinetics and thermodynamics data as well as various optimal experimental conditions (solution pH, equilibrium contact time and dosage of adsorbent) of different adsorbents towards Ni(II) ions were also analyzed. It is evident from a literature survey of more than 190 published articles that agricultural solid waste materials, natural materials and biosorbents have demonstrated outstanding adsorption capabilities for Ni(II) ions.

Synthesis of a functionalized fibrous adsorbent of high uptake capacity: a study on Pb(ii) uptake and simple acidic site model development

Development and exposure of acidic functional groups on lignocellulose biomaterials through destruction of lignin barrier by acid treatment.

A review on progress of heavy metal removal using adsorbents of microbial and plant origin

Heavy metals released into the water bodies and on land surfaces by industries are highly toxic and carcinogenic in nature. These heavy metals create serious threats to all the flora and fauna due to their bioaccumulatory and biomagnifying nature at various levels of food chain. Existing conventional technologies for heavy metal removal are witnessing a downfall due to high operational cost and generation of huge quantity of chemical sludge. Adsorption by various adsorbents appears to be a potential alternative of conventional technologies. Its low cost, high efficiency, and possibility of adsorbent regeneration for reuse and recovery of metal ions for various purposes have allured the scientists to work on this technique. The present review compiles the exhaustive information available on the utilization of bacteria, algae, fungi, endophytes, aquatic plants, and agrowastes as source of adsorbent in adsorption process for removal of heavy metals from aquatic medium. During the last few years, a lot of work has been conducted on development of adsorbents after modification with various chemical and physical techniques. Adsorption of heavy metal ions is a complex process affected by operating conditions. As evident from the literature, Langmuir and Freundlich are the most widely used isotherm models, while pseudo first and second order are popularly studied kinetic models. Further, more researches are required in continuous column system and its practical application in wastewater treatment.

Removal of cadmium ion from wastewater by carbon-based nanosorbents: a review

A green environment and a healthy life are dream projects of today's science and technology to save the world. Heavy metal ions in water affect both environment and human health. Cadmium has been identified as one of the heavy metals that causes acute or chronic toxic effects if ingested. Increasing use of cadmium in different technological fields has raised concern about its presence and removal from water/wastewater. Researchers have made many systematic efforts to remove heavy metals from water to reduce their impact on human beings and the environment. Adsorption is one of the best methods to remove heavy metals from water among the different proposed methods. This study explores carbon-based nanosorbents which have been proved as effective adsorbents for removal of cadmium ions from water. The adsorption efficiency of carbon-based nanosorbents is the main criterion to rank and select them for removal of cadmium ions from water. Toxicity, reusability and environmentally friendly characteristics of sorbents are also taken considered while ranking the suitable carbon-based nanosorbents for removal of cadmium ions from water.

Laccase immobilized manganese ferrite nanoparticle: synthesis and LSSVM intelligent modeling of decolorization

Laccase was immobilized onto manganese ferrite nanoparticle (MFN) and dye decolorization from single and binary systems was studied. The characteristics of laccase immobilized manganese ferrite nanoparticle (LIMFN) were investigated using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Direct red 31 (DR31), Acid blue 92 (AB92) and Direct green 6 (DG6) were used. A least square support vector machine (LSSVM) was developed to predict the decolorization efficiency of various single and binary systems based on the obtained laboratory data under different experimental conditions. Statistical and graphical quality measures were also employed to evaluate the performance and accuracy of the developed intelligent models. It is shown that the predictions of the designed LSSVM models are in close agreement with the experimental data. The effects of LIMFN dosage, pH and dye concentration on dye decolorization from single and binary systems were evaluated. Decolorization kinetics followed Michaelis-Menten Model.

Synthesis of magnetic carbon nanotube and photocatalytic dye degradation ability

In this paper, magnetic carbon nanotube (M-CNT) was synthesized. The photocatalytic dye degradation ability of M-CNT in the presence of hydrogen peroxide (H2O2) from colored wastewater was studied. Manganese ferrite (MnFe2O4) was synthesized in the presence of multiwalled carbon nanotube. Direct Red 23 (DR23), Direct Red 31 (DR31), and Direct Red 81 (DR81) were used as anionic dyes. The characteristics of M-CNT were investigated using Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). The photocatalytic dye degradation using M-CNT was studied by UV-vis spectrophotometer and ion chromatography (IC). The effects of M-CNT dosage, initial dye concentration, and salt on the degradation of dye were evaluated. Formate, acetate, and oxalate anions were detected as dominant aliphatic intermediates. Inorganic anions (nitrate and sulfate anions) were detected and quantified as the mineralization products of dyes during the degradation process. The results indicated that the M-CNT could be used as a magnetic catalyst to degrade anionic dyes from colored wastewater.

Direct dyes removal using modified magnetic ferrite nanoparticle

The magnetic adsorbent nanoparticle was modified using cationic surface active agent. Zinc ferrite nanoparticle and cetyl trimethylammonium bromide were used as an adsorbent and a surface active agent, respectively. Dye removal ability of the surface modified nanoparticle as an adsorbent was investigated. Direct Green 6 (DG6), Direct Red 31 (DR31) and Direct Red 23 (DR23) were used. The characteristics of the adsorbent were studied using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effect of adsorbent dosage, initial dye concentration and salt was evaluated. In ternary system, dye removal of the adsorbent at 90, 120, 150 and 200 mg/L dye concentration was 63, 45, 30 and 23% for DR23, 97, 90, 78 and 45% for DR31 and 51, 48, 42 and 37% for DG6, respectively. It was found that dye adsorption onto the adsorbent followed Langmuir isotherm. The adsorption kinetic of dyes was found to conform to pseudo-second order kinetics.

Preparation of Enteromorpha prolifera-based cetyl trimethyl ammonium bromide-doped activated carbon and its application for nickel(II) removal

Activated carbon was prepared from Enteromorpha prolifera (EP) by H3PO4 activation in the presence of doped cetyl trimethyl ammonium bromide (CTAB), producing EPAC-CTAB. The thermal decomposition process of the activated carbon substrate was identified by thermo-gravimetric analysis. Scanning electron microscope (SEM), N2 adsorption/desorption, Fourier transform infrared spectroscopy (FTIR), Boehm titration, and X-ray Photoelectron Spectroscopy (XPS) were employed to characterize the physicochemical properties of native EPAC and EPAC-CTAB. EPAC-CTAB exhibited smaller surface area (689.0m(2)/g) and lower total pore volume (0.361cm(3)/g) than those of EPAC (1045.8m(2)/g and 1.048cm(3)/g), while the number of acidic groups, oxygen and nitrogen groups on the surface of EPAC-CTAB increased through CTAB doping. The batch kinetics and isotherm adsorption studies of nickel(II) onto the adsorbents were examined and agreed well with the pseudo-second-order model and the Langmuir model. The maximum adsorption capacity determined from the Langmuir model was 16.9mg/g for EPAC and 49.8mg/g for EPAC-CTAB. Under acidic condition, the adsorption of nickel(II) onto EPAC and EPAC-CTAB was hindered due to ion competition and electrostatic repulsion. The results indicated that using CTAB as a dopant for EPAC modification could markedly enhance the nickel(II) removal.

Determination of Adsorption Capacity of Agricultural-Based Carbon for Ni (II) Adsorption from Aqueous Solution

The aim of the study was to prepare potentially cheaper carbon for the adsorptive removal of Nickle [Ni (II)] from aqueous solution. The adsorption capacity of the prepared carbon to remove Ni (II) from aqueous solution was determined and adsorption mechanism was investigated. Rice husk carbon was prepared by incineration in a muffle furnace. The incinerated rice husk carbon (IRHC) was characterised in terms of surface area, micropore area, micropore volume, average pore diameter and surface morphology. Adsorption of Ni (II) by IRHC was examined. The influence of operating parameters, namely, pH, initial concentration and contact time on adsorption of Ni (II) by IRHC was evaluated. Batch adsorption tests showed that extent of Ni (II) adsorption depended on initial concentration, contact time and pH. Equilibrium adsorption was achieved in 120 min, while maximum Ni (II) adsorption occurred at pH 4. Langmuir and Freundlich isotherms were studied and the equilibrium adsorption data was found to fit well with the Langmuir isotherm model. Langmuir constants Q° and b were 14.45 and 0.10, and Freundlich constants Kf and 1/n were 4.0 and 0.26, respectively. Adsorption of Ni (II) by IRHC followed pseudo-second-order kinetics. Being a low-cost carbon, IRHC has potential to be used for the adsorption of Ni (II) from aqueous solution and wastewater in developing countries.

Chemodynamics of methyl parathion and ethyl parathion: adsorption models for sustainable agriculture

The toxicity of organophosphate insecticides for nontarget organism has been the subject of extensive research for sustainable agriculture. Pakistan has banned the use of methyl/ethyl parathions, but they are still illegally used. The present study is an attempt to estimate the residual concentration and to suggest remedial solution of adsorption by different types of soils collected and characterized for physicochemical parameters. Sorption of pesticides in soil or other porous media is an important process regulating pesticide transport and degradation. The percentage removal of methyl parathion and ethyl parathion was determined through UV-Visible spectrophotometer at 276 nm and 277 nm, respectively. The results indicate that agricultural soil as compared to barren soil is more efficient adsorbent for both insecticides, at optimum batch condition of pH 7. The equilibrium between adsorbate and adsorbent was attained in 12 hours. Methyl parathion is removed more efficiently (by seven orders of magnitude) than ethyl parathion. It may be attributed to more available binding sites and less steric hindrance of methyl parathion. Adsorption kinetics indicates that a good correlation exists between distribution coefficient (Kd) and soil organic carbon. A general increase in Kd is noted with increase in induced concentration due to the formation of bound or aged residue.