Increase In Adsorption Capacity Research Articles

Evaluation of Fenton-like reaction for sorption and degradation of kasugamycin in the presence of biochar.

Although the use of biochar as an adsorbent for the removal of various pollutants from wastewater is well established, the use of biochar/modified biochar for the scavenging of antibiotics from aqueous media in the Fenton-like system receives less attention. The highest kasugamycin (KSM) adsorption capacity (5.0mgg-1) was obtained from the pristine biochar at the lowest initial pH of 3 in Fenton-like system. The Fenton-like system improved the KSM adsorption capacity of pristine biochar by 222.2%, 169.9%, and 159.9% at 25°C, 35°C, and 45°C comparing to control, respectively, and it also increased adsorption capacity by 97.4%, 63.8%, and 56.8% comparing to modified biochar. The amounts of biochar applied and the Fenton-like system affected KSM mineralization and degradation. The KSM degradation products had a significant amount of small molecular organic matter (m/z 384) and a tetrahydropyran structure that was difficult to degrade. The highly efficient degradation of KSM in Fenton-like system can be attributed to the generation of large amounts of hydroxyl radical (·OH) and functional groups (C=C, C=O, etc.).

Pyrolysis of sawdust in a horizontal tube furnace: Effects of temperature and heating rate on product composition

The abundant sawdust waste from the timber production industries in Malaysia can be a potential biomass feedstock for pyrolysis process. However, the understanding of product composition and bio-oil quality from sawdust pyrolysis remains limited in Malaysian’s context. In this study, pyrolysis of sawdust was conducted in a horizontal tube furnace to investigate the effects of temperatures (400-550 °C) and heating rates (10-20 °C/min) on the composition of products, quality and properties of bio-oil. According to Gas chromatography (GC) analysis, phenol group appears to be the major compound in the bio-oil. The chemical components of bio-oil were found to be richer at lower reaction temperatures (400-450 °C), where it showcased the presence of phenols, ketones, carboxylic acids, furans, aldehydes, alkenes, alcohols, ether and amine. At increased reaction temperatures (500–550 °C), the process favoured the production of catechol (17%). The yield of bio-char decreased with increasing temperatures and heating rates due to the loss of volatile matter, and 400 °C proved to be the optimum temperature for maximum biochar yield. The biochar also displays porous structure, with increased adsorption capacity. Since the pyrolysis of sawdust could produce phenolic compounds, it appears to be a potential feedstock for biomass pyrolysis.

The Adsorption Process and Mechanism of Benzo[a]pyrene in Agricultural Soil Mediated by Microplastics.

The coexistence of microplastics and benzo[a]pyrene (BaP) in the environment, and their interactions within agricultural soils in particular, have garnered widespread attention. This study focused on the early-stage interactions between microplastics and BaP, aiming to uncover their initial adsorption mechanisms. Despite the significant environmental toxicity of both pollutants, research on their mutual interactions in soil is still limited. This study conducted adsorption thermodynamics and kinetics experiments to explore the effects and mechanisms of various microplastics (polyethylene (PE), polystyrene (PS), and polyvinyl chloride (PVC)) on the adsorption of BaP. Using advanced techniques such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy, this study explored the surface characteristics of microplastics and their interactions with BaP. The results demonstrated that PVC microplastics exhibited the highest adsorption capacity for BaP, which was primarily due to π-π interactions and increased hydrophobicity. In the soil-microplastic blend systems, BaP was predominantly found on microplastics, enhancing the soil's adsorption capacity for BaP, particularly PVC, which showed an adsorption capacity 3.69 times greater than that of soil alone. Density functional theory (DFT) simulation calculations indicated that the binding energy of BaP for PVC pretreated with soil was -59.16 kJ/mol, whereas it was -53.02 kJ/mol for untreated PVC, -39.35 kJ/mol for PE, and -48.84 kJ/mol for PS. These findings suggest that soil pretreatment enhances the adsorption stability of PVC for BaP, further elucidating the potential mechanisms behind the increased adsorption capacity in the soil-microplastic system. These findings confirm that microplastics serve as effective vectors for organic pollutants such as BaP, significantly influencing their environmental behavior in soils, and provide essential theoretical support for assessing the environmental toxicity and migration behaviors of microplastics and associated organic contaminants.

A comparative study of photocatalytic degradation of airborne styrene using TiO2 and ZnO nanoparticles immobilized on activated carbon

Background: With the growth of industries and advancing civilization, controlling air pollution from both human and natural sources has become a major concern. Styrene, a volatile organic compound (VOC), is recognized as a hazardous and toxic atmospheric contaminant. Methods: In this study, the removal of Styrene vapors using ZnO and TiO2 nanoparticles coated on activated carbon (AC) was investigated and the styrene removal capacity of AC-ZnO and AC-TiO2 catalysts was compared. The coated adsorbents were characterized using a field emission scanning electron microscope (FESEM), X-ray diffraction patterns (XRD), and the Brunauer–Emmett–Teller (BET) method. All laboratory-scale experiments were conducted at ambient temperatures. Styrene concentrations of 50, 100, and 300 ppm were tested at an input flow rate of 0.03, and 0.06 m3 /h. Results: The AC-TiO2 catalyst had a styrene removal efficiency (RE) of 81%, as compared to 74% efficiency for the AC-ZnO catalyst, this is at a flow rate of 0.06 m3 /h and a concentration of 50 ppm. The results indicated that increasing styrene concentrations reduced breakthrough time but increased adsorption capacity. Also, by increasing the inflow rate, the adsorption capacity decreased. At all concentrations and flow rates, the adsorption capacity of the AC-TiO2 catalyst was higher than the AC-ZnO catalyst. Conclusion: According to the results, it can be concluded that the AC-TiO2 catalyst is more effective in the removal of Styrene vapor from the air as compared to the AC-ZnO catalyst.

Efficient Photocatalytic Reduction of Hexavalent Chromium by NiCo2S4/BiOBr Heterogeneous Photocatalysts

For typical Cr(VI)-containing industrial wastewater, more efficient water treatment technologies need to be used to ensure that Cr(VI) concentrations are reduced to safe levels before discharge. Photocatalytic technology is highly efficient, environmentally friendly, and has been extensively used to address this demand. Herein, heterogeneous NiCo2S4/BiOBr photocatalysts with different ratios were prepared using a solvothermal method. When compared with pure NiCo2S4 and BiOBr, the NiCo2S4/BiOBr-30 had significantly increased adsorption capacity and visible-light-driven photocatalytic reduction activity for Cr(VI) removal. The improved adsorption performance of the NiCo2S4/BiOBr-30 was mainly due to its increased specific surface area, and the enhanced photocatalytic performance of the NiCo2S4/BiOBr-30 could be attributed to the improved separation and transfer of photogenerated carriers at the interface. Lastly, a possible enhanced photocatalytic Cr(VI) reduction mechanism of the NiCo2S4/BiOBr heterostructure was developed.

Microcrystalline cellulose modified chitosan aerogels to enhance Congo Red dye adsorption

Carbohydrate based aerogels were synthesized via a straightforward procedure including freeze-drying of chitosan (Ch) hydrogels of different concentrations cross-linked with glutaraldehyde and incorporating microcrystalline cellulose (MCC) powder to enhance mechanical strength and modify adsorption properties. The increase in Ch content and the incorporation of MCC resulted in samples that exhibited higher densities, lower swelling degrees and accessible porosities while demonstrated improved stabilities. These aerogels were evaluated as adsorbents of the textile dye Congo Red (CR) by isothermal and kinetic studies. Even when relatively simple theoretical models were used to predict these results, in order to eliminate modeling bias, a validation method based on error functions in addition to the more commonly used R2, was applied. Equilibrium adsorption capacities obtained in kinetic studies increased 150 % changing Ch concentration from 4 % to 5 %, and 196 % adding 50 % by weight of MCC. The adsorption tests for initial concentrations of CR below 100 mg/L demonstrated that the aerogels exhibited increased adsorption capacity for higher Ch content or incorporation of MCC. Thermodynamic studies indicated enhanced adsorption at higher temperatures. These environmentally friendly aerogels demonstrated comparable or superior adsorption capacities to other bio-based materials, offering a simple, economical, and effective solution for pollutant removal.

Investigation of Release Kinetics of DOX from Polydopamine Nanocapsules Prepared by Hard Template Method

AbstractDevelopment of smart drug delivery systems (DDSs) for effective delivering drugs to targeted areas and achieving controlled drug release (CDR) is critical for cancer chemotherapy. The purpose of this study is synthesis of polydopamine (PDA) nanocapsules and analyze the adsorption and release properties of doxorubicin (DOX). PDA nanocapsules are manufactured using hard template approach. The influence of various parameters such as pH, adsorption time, and initial DOX content on the adsorption and release process is investigated. The resulting adsorption isotherm is consistent with the Langmuir isotherm, indicating that DOX adsorption on PDA nanocapsules is homogenous, uniform, and monolayer. PDA nanocapsules have an adsorption capacity of 689.6 mg g−1 under alkaline conditions, which is attributed to phenol group deprotonation mechanism and electrostatic repulsion. The adsorption kinetics are more consistent with the pseudo‐second‐order model. Furthermore, raising initial concentration of DOX results in a greatly increased adsorption capacity due to a larger driving force. Among the several parameters that can influence the pace and degree of DOX loading and release, local pH is regarded as a significant environmental component in the processes. Thus, pH‐responsive PDA nanocapsules have a significant potential for usage in locations with aberrant pH level, such as cancer tissue.

Development and Performance of ZnO/MoS2 Gas Sensors for NO2 Monitoring and Protection in Library Environments

The presence of harmful oxidizing gases accelerates the oxidation of cellulose fibers in paper, resulting in reduced strength and fading ink. Therefore, the development of highly sensitive NO2 gas sensors for monitoring and protecting books holds significant practical value. In this manuscript, ZnO/MoS2 composites were synthesized using sodium molybdate and thiourea as raw materials through a hydrothermal method. The morphology and microstructure were characterized by X-ray diffraction analysis (XRD), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The ZnO/MoS2 composite exhibited a flower-like structure, with ZnO nanoparticles uniformly attached to the surface of MoS2, demonstrating advantages such as high specific surface area and good uniformity. The gas sensitivity of the ZnO/MoS2 nanocomposites reached its peak at 260 °C, with a sensitivity value around 3.5, which represents an improvement compared to pure ZnO, while also enhancing sensitivity. The resistance of the ZnO/MoS2 gas sensor remained relatively stable in air, exhibiting short response times during transitions between air and NO2 environments while consistently returning to a stable state. In addition to increasing adsorption capacity and improving light utilization efficiency, the formation of hetero-junctions at the ZnO-MoS2 interface creates an internal electric field that effectively promotes the rapid separation of photo-generated charge carriers within ZnO, thereby extending carrier lifetime.

Adsorption properties of alkali-activated stone wool

Alkali-activated materials are actively studied as adsorbents for toxic metals, nutrients, and dyes from wastewater. They are produced using an environmentally friendly process from low-cost aluminosilicate precursors, and thus have significant potential for fostering the development of clean technology. One of the potential precursors is stone and glass wool, for which alkali activation has been successfully demonstrated in construction products. In this study, alkali-activated stone wool was assessed for adsorption for the first time. Stone wool manufactured without organic resin (SW) and another stone wool with organic resin being removed by heat treatment (SW-O) were alkali activated using NaOH, Na2CO3, NaAlO2, or Na silicate solution, and characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetry–mass spectrometry, and potentiometric titrations to understand the surface properties affecting adsorption. Comparative adsorption experiments were conducted using methylene blue (MB), cobalt (Co(II)), arsenite (As(III)), and NH4+ at 100 mg × L−1 concentration, 1 g × L−1 adsorbent dose, 24 h contact time, and pH of 7. The raw stone wools demonstrated almost no adsorption, whereas the alkali-activated stone wools adsorbed up to 78, 42, 3, and 18 mg × g−1 of MB, Co(II), As(III), and NH4+, respectively. The samples prepared with the SW Na silicate demonstrated higher adsorption capacities for MB and Co(II). For As(III), an adsorption capacity was similar regardless of the mixture. The highest adsorption capacity for NH4+ was achieved with SW-O NaOH. The increased adsorption capacities were related to the increase in the specific surface area, more negative zeta potential, formation of tobermorite-like structures, and an increase in the quantity of surface OH groups. The varying adsorption levels of specified contaminants are possibly governed by their speciation at pH 7, aqueous radii, and the adsorption mechanism. This study demonstrated that stone wool-based adsorbents could have practically relevant potential for wastewater treatment.

A Thermogravimetric Analysis of Biomass Conversion to Biochar: Experimental and Kinetic Modeling

This study investigates the pyrolytic decomposition of apple and potato peel waste using thermogravimetric analysis (TGA). In addition, using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), the influence of pyrolysis temperature on the physicochemical characteristics and structural properties of biochar was studied. The degradation of biomass samples was studied between 25 °C and 800 °C. Although apple and potato peel decomposition present similar thermogravimetric profiles, there are some differences that can be evidenced from DTG curves. Potato peel showed one degradation peak in the range 205–375 °C with 50% weight loss; meanwhile, the apple peel exhibited two stages: one with a maximum at around 220 °C and about 38% weight loss caused by degradation of simple carbohydrates and a second peak between 280 °C and 380 °C with a maximum at 330 °C, having a weight loss of approximately 24%, attributed to cellulose degradation. To gain more insight into the phenomena involved in biomass conversion, the kinetics of the reaction were analyzed using thermal data collected in non-isothermal conditions with a constant heating rate of 5, 10, 20, or 30 °C /min. The kinetic analysis for each decomposed biomass (apple and potato) was carried out based on single-step and multi-step type techniques by combining the Arrhenius form of the decomposition rate constant with the mass action law. The multi-step approaches provided further insight into the degradation mechanisms for the whole range of the decomposition temperatures. The effect of temperature on biomass waste structure showed that the surface morphologies and surface functional groups of both samples are influenced by the pyrolysis temperature. A higher pyrolysis temperature of 800 °C results in the disappearance of the bands characteristic of the hydroxyl, aliphatic, ether, and ester functional groups, characteristic of a porous surface with increased adsorption capacity. Therefore, this study concludes that biomass waste samples (apple and potato) can produce high yields of biochar and are a potential ecological basis for a sustainable approach. The preliminary adsorption tests show a reasonably good nitrate removal capacity for our biochar samples.

High-performance activated carbon from coconut shells for dye removal: study of isotherm and thermodynamics.

This study investigates the production of high-performance activated carbon (AC) from coconut shells (CS) through acid and base activation processes, along with pre- and post-functionalization of the biochar, aiming to effectively remove dyes from aqueous solutions. The resulting AC exhibited outstanding adsorption capabilities, with the Langmuir model providing a good fit to the experimental data. Maximum adsorption capacities were observed at different temperatures: 805 mg g-1 at 298 K, 904 mg g-1 at 318 K, and 1000 mg g-1 at 338 K for NaOH-activated AC, and 252 mg g-1 at 298 K, 295 mg g-1 at 318 K, and 305 mg g-1 at 338 K for H2SO4-activated AC. The presence of active sites and functional groups on the surface of AC facilitated dye adsorption. The influence of various parameters, including adsorbent dosage, dye concentration, pH, and temperature, on the adsorption process were also examined, identifying the ideal conditions for dye removal. Thermodynamic analysis confirmed the endothermic nature of the adsorption process, with higher temperatures leading to increased adsorption capacities. Overall, the research highlights the potential of various activation routes for the production of high-value AC as a sustainable and effective adsorbent for dye removal from wastewater.

Improving the pore properties of porous aromatic frameworks in two aspects via partition strategy

Microporous solids are famous for their high surface area and pore size at the molecular scale, which are crucial for the applications of adsorption, separation and catalysis. An ideal porous solid would simultaneously have a high surface area and nanopores with the desired opening size. However, due to the uncontrollable reaction process of porous organic frameworks (POFs), the acquisition of such a solid is still technically limited. Herein, we reported a simple but platform-wide pore partition strategy to improve the porosity of porous aromatic frameworks (PAFs) in two aspects. This strategy was achieved by introducing a partition unit with flexible linkage to segment the original voids of PAFs into multiple micropore domains. The obtained partitioning PAFs have 130%-217% increments in surface area due to the creation of extra accessible surfaces while the pores are segmented into smaller ones. Notably, the partitioning PAFs showed significantly increased adsorption capacity for CO2 due to their improved surface area. At the same time, the narrowed pore size allowed selective capture of dye molecules by their size differences. Similar to their parent PAFs, the partitioning PAFs retained their high stability in harsh environments. A simple and universal pore partition strategy will be an important step in improving PAF porosity to desired functions.

Optimization of Mesoporous Silica Nanoparticles of Silymarin through Statistical Design Experiment and Surface Modification by APTES

ABSTRACT: The major goal of this study was to create surface-modified mesoporous silica nanoparticles (MSN) of Silymarin, which has a short half-life and requires regular dosing due to first-pass metabolism. MSN was prepared by cost effective Sol-Gel method, functionalized by (3-Aminoprpyl) triethoxysilane (3-APTES). Evaluated and compared the Silymarin-loaded MSN and APTES functionalized MSN for drug loading, in-vitro dissolution, particle size, surface morphology, surface area, pore size and volume. The percent drug loading and encapsulation efficiency of APTES-functionalized MSN were found to be 92.50±0.72 % percent and 93.20±0.13 %, respectively, which showed a higher value in APTES-functionalized MSN as compared to Silymarin-loaded MSN. Drug release of APTES-functionalized MSN was 92.15 0.03%, which was more as compared to silymarin-loaded MSN. XRD showed that after functionalization silymarin changed from crystalline to amorphous form. SEM indicates that MSN was formed in a spherical shape with particle size of 196.7nm. The BET analysis proved that the nanoparticles had a larger surface area, which was reduced after drug loading and functionalization. Also, the pore size was increased and the pore volume was reduced after functionalization, indicating the incorporation of silymarin. The results suggested that the functionalization might successfully increase adsorption capacity, larger surface area, and increased encapsulation. Mesoporous silica nanoparticles also showed a greater impact on dissolution.

Advanced biopolymer-based Ti/Si-terephthalate hybrid materials for sustainable and efficient adsorption of the tetracycline antibiotic

This study involves the synthesis of an organic-inorganic hybrid material consisting of Ti/Si-terephthalate (Ti-TPA-Si) in a 1:1:1 ratio using sol-gel method and its reaction with cellulose and chitosan (Ti-TPA-Si-C and Ti-TPA-Si-CS). Characterization techniques such as XRD, FTIR, SEM, EDS, XPS, BET, TGA, and DTA were used. The incorporation of biopolymers (cellulose and chitosan) into the Ti/Si-terephthalate structure improved the morphology and textural properties of the hybrid materials, leading to increased adsorption capacity and sustainability. Adsorption experiments reveal that Ti-TPA-Si, Ti-TPA-Si-C, and Ti-TPA-Si-CS hybrid materials exhibit a high affinity towards tetracycline, achieving remarkable adsorption efficiencies of 88.27, 89.60, and 88.98 %, respectively. Isotherm studies indicate that the adsorption process follows both Langmuir (R2 = 0.971, 0.990, and 0.994) and Dubinin-Radushkevich (R2 = 0.922, 0.965, and 0.949) isotherm models. According to the Langmuir model, the maximum adsorption capacity (qm) of Ti-TPA-Si, Ti-TPA-Si-C, and Ti-TPA-Si-CS adsorbents was found to be 24.10, 33.56, and 26.59 mg/g, respectively. Kinetic studies indicate that the adsorption process follows both pseudo-second-order (R2 = 0.998, 0.984, and 0.989) and intra-particle diffusion (R2 = 0.995, 0.994, and 0.988) models. Thermodynamic studies reveal that adsorption processes are spontaneous and endothermic in nature. Reusability studies demonstrate their potential for repeated use without significant loss in performance.

Highly porous carbon with rich inherent groups for ultrahigh adsorption of organic dyes from wastewater

Activated carbon from renewable biomass or its waste to purify various dyeing wastewater from textile industry is highly desired. In this work, porous activated carbon was prepared by using silk waste as precursor via a simple one-step carbonization process. The obtained SWC-1-800 had ultrahigh adsorption for anionic dye AR73 and cationic dye MB owing to its ultrahigh specific surface area (2774 m2 g−1) and rich functional groups. SWC-1-800 had an increased adsorption capacity reaching 1310 and 928 mg g−1 for AR73 and MB respectively as the initial concentration up to 1000 mg L−1. Moreover, the adsorption capacity was stable under a wide range of Na+ and SDS concentration. By adjusting the temperature and pH value, the maximum adsorption capacity reached 1337 and 1000 mg g−1 for AR73 and MB respectively, keeping the removal rate of AR73 and MB more than 80 % after 5 adsorption cycles. Besides, SWC-1-800 demonstrated quite good adsorption ability for many other kinds of dyes, which adsorption capacity as high as 1998 mg g−1 (Rh B). The adsorption mechanism was further proposed according to the structural characteristics, inherent functional groups and adsorption properties. Using silk waste-derived carbon to effectively absorb the harmful dyes in the wastewater shows dual value for cleaner production via a “waste-waste to clean products” model, which has great application potential in dyeing wastewater purification.

Carbon Dioxide Adsorption by Variation in Operating Parameters of Sound Assisted Fluidization Using Coal Based Fine Activated Carbon

This research delves into the promising domain of CO2 capture through fine solid activated carbon adsorbent, offering a more energy-efficient alternative to traditional adsorption methods. The central challenge addressed here is the utility of cheaper CO2 adsorbent, fine powder materials whose properties can be precisely tailored via molecular-level fictionalization. Equally vital is selecting an optimal fluidizing column configuration that maximizes CO2 interaction with adsorption particles and enhances adsorption efficiency. The proposed solution is a fluidized bed column uniquely equipped with integrated acoustic vibrations to counteract interparticle forces common in fine powders. For adsorption evaluations, sound-assisted fluidized-bed experimentation on a laboratory size was set up. Adsorbent material activated carbon made up of coal underwent rigorous testing between a range of 20 Hz-200 Hz and 20 dB-135 dB. Results reveal the beneficial effects of acoustic enhancement of fluidization quality and adsorption efficiency, increased adsorption capacity, enhanced bed utilization, and accelerated adsorption rates. Extensive research has been conducted on the detailed effects of major operational variables on adsorption performance, notably frequency, sound intensity, and minimum fluidization velocity. The findings highlight the pivotal role of particle size with mean size 75 microns range as a determinant of adsorption capacity at 100 Hz and 125 dB. At the end of experimentation, the adsorbent considered for the experiment is compared to the study adsorption capacity at operating conditions. The research concludes with a discussion on the effects of influencing parameters for adsorption on employing sound vibrations using fluidization technique adsorption for CO2 capture.

Characteristics and adsorption of methylene blue on activated carbon derived from enzyme-pretreated Camellia oleifera shells

Activated carbon is a porous material extensively utilized in water treatment field. In this study, an efficient activated carbon (E-AC) adsorbent was prepared from agricultural by-product Camellia oleifera shells (COS) by enzymatic pretreatment combined with phosphoric acid activation. The enzymatic pretreatment was beneficial for increasing the volume of mesopores and loosening the structure of the synthesized activated carbon, which ultimately led to an increased adsorption capacity of E-AC. The characteristics and adsorption performances of E-AC were thoroughly investigated. The results showed that E-AC exhibited a high adsorption capacity of 1249.01 mg/g on methylene blue (MB), and the adsorption process was a spontaneous endothermic process. The adsorption kinetics aligned closely with the pseudo-second-order kinetic model (R2 > 0.99), and the adsorption mechanisms could be a combination of hydrogen bonding, π-π conjugation, electrostatic attraction, and physical adsorption. Additionally, E-AC exhibited good reusability, with a consistent MB removal rate of 91.14 % even after five cycles. This study offered an approach for obtaining high-quality activated carbon from COS and contributed to sustainable development strategies.

Effects of Sugarcane Bagasse Biochar on Ammonium and Nitrate Adsorption and Leaching in a Japanese Tropical Soil Cropped with Japanese Mustard Spinach (Brassica rapa)

This study investigated the dynamics of ammonium-nitrogen (NH4+-N) and nitrate-nitrogen (NO3–-N) adsorption and leaching in a Japanese tropical soil amended with sugarcane bagasse biochars (SBBs) in the presence of plant. Adsorption and column leaching studies were conducted in a laboratory in Japan, and the column study was performed for 21 days. Biochar was produced from sugarcane bagasse at the maximum pyrolysis temperatures of 400°C (SBB400) and 800°C (SBB800) for use in the experiments. Adsorption isotherms for NH4+-N and NO3–-N were developed for soil only, SBB400-amended soil, and SBB800-amended soil. Column leaching study included 6 treatments: fertilizer only, fertilizer and plant, fertilizer and SBB400, fertilizer and SBB400 and plant, fertilizer and SBB800, fertilizer and SBB800 and plant. This study showed that soil and SBBs-amended soils fitted well into the Langmuir adsorption model for NH4+-N and NO3–-N (r2= 0.983–0.994 and 0.956–0.970, respectively). Application of SBBs to soil significantly decreased cumulative NH4+-N leached from the soil (P < 0.05) because of increased adsorption capacity due to high acid functional groups and increased soil water holding capacity (WHC) due to high specific surface areas and pore volumes, regardless of the presence of plant. However, the SBBs application did not affect the adsorption capacity for NO3–-N because of negatively charged surfaces. However, cumulative NO3–-N leached was significantly reduced (P< 0.05) due to increased soil WHC, regardless of the presence of plant. Therefore, more soil water contents retained and less NO3–-N leached from the soil may have contributed to greater plant growth with the SBBs application. This study showed that the SBBs application to soil could enhance adsorption capacity for NH4+-N but not for NO3–-N, nevertheless increase soil WHC and reduce leaching of both NH4+-N and NO3–-N, thus contributed to increased plant growth.

Amphoteric chitosan derivatives for the removal of basic and reactive dyes from aqueous solutions

The present study describes the use of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide and 2-acrylamido-2-methyl-1-propanesulfonic acid as grafting agents to chitosan (CS) natural polymer were examined. Two chitosan derivatives were synthesized in this study, and then added in single-component aqueous solutions in order to study the removal of Methylene Blue (MB) and Remazol Brilliant Blue R (RBBR) dyes, by adsorption, in a more innovative way. The characterization of the chitosan derivatives was achieved via X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Adsorption efficiency of the chitosan derivatives was tested at several pH values (2–12) and for adsorbent’s dosage between 10 and 50 mg per 30 mL effluent. The rising of temperature from 25 to 65 °C led to increased adsorption capacity. Equilibrium data were fitted to both the more common Langmuir and Freundlich isotherm models, as well as the Sips isotherm model. Pseudo 1st and 2nd kinetic order equations and a relatively simple phenomenological kinetic model for adsorption kinetics, were studied as well as the thermodynamic parameters were calculated. The adsorption capacity for CS grafted with [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide (CS-SBMA) was 238.1 and 244.5 mg/g for MB and RBBR removal, respectively, at 25 °C, while for CS grafted with 2-acrylamido-2-methyl-1-propanesulfonic acid (CS-AMPS) the adsorption capacity was 219.5 and 203.9 mg/g for MB and RBBR removal, respectively, at 25 °C.

New silica-based adsorbents for water purification: Removal of short- and long-chain perfluoroalkyl sulfonic acids (PFSA) at sub-nanomolar concentrations

Perfluoroalkyl acids (PFAAs) are widespread in the aquatic environment and also measurable in ground and drinking water. Because of the insufficient PFAA elimination in conventional water treatment processes, e. g. active carbon based methods, consumers in areas with contaminated water supplies are exposed to an elevated health hazard. For this purpose, the applicability of five differentially fluorinated silica-based adsorbents (HSU00107954-958) to remove the potentially human toxic perfluoroalkyl sulfonic acids(PFSAs) perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorobutane sulfonic acid (PFBS) from water was investigated with regard to removal efficiencies (REs) and equilibrium loadings. During the adsorbent screening at nanomolar concentrations (20.0–33.4 nmol L−1) maximum REs of 46.9% for PFBS (HSU00107954), 79.4% for PFHxS (HSU00107954), and between 86.5 to 96.7% for PFOS (HSU00107956, and HSU00107954, respectively) have been achieved. Even at picomolar concentrations (< 400 pmol L−1) HSU00107954 was still able to eliminate PFBS and PFHxS with an efficiency of 46.3–51.2% and 79.1–88.2%, respectively. Analyses of the equilibrium loadings of the functionalized adsorbents in the concentration range 40.1 pmol to 3.34 nmol L−1 resulted in appropriate linearized Freundlich isotherms for all investigated PFSA. Compared to literature-based Freundlich adsorption coefficients (KF) for granular activated carbon (GAC), the determined KF values (nmol(1−n) Ln m−2) of the most efficient adsorbents HSU00107956 and HSU00107954 for each PFSA were significantly 8–10 and 50–60 times higher, respectively. These proven increased adsorption capacities relative to activated carbon possibly indicate specific PFSA selectivities of the functionalized macroporous silica adsorbents.