Increase In Adsorption Capacity Research Articles

Physical and Chemical Characteristics and Functional Properties of Carbon Nitride Materials Obtained by Template Synthesis

The preparation, structure, and functional properties of carbon nitride such as its photocatalytic, catalytic, and adsorption activities have been examined. The template synthesis of g-C3N4 allows increasing its dispersion, specific surface area, and spatial ordering, leading to enhanced photocatalytic activity of such materials in the photoreduction of carbon dioxide and larger catalytic activity in the Knoevenagel condensation as well as in the oxidation of betulin (as a support for nanodispersed ruthenium) compared with the bulk analog. Increased adsorption capacity for H2 and CO2 is found in the case of non-stoichiometric carbon nitride.

Unique and efficient adsorbents for highly selective and reverse adsorption and separation of dyes via the introduction of SO3H functional groups into a metal-organic framework.

In this study, an unsaturated Cu-based MOF, HKUST (Cu3(BTC)2), was fabricated and modified with sulfonate groups in two steps, leading to the construction of a novel sulfo-functionalized MOF. The prepared framework was utilized in the adsorption and separation of various organic dyes (MB, Er, FS, and MV). The adsorption process represented intriguing features due to the introduction of the SO3H functional groups into the framework. Such an attractive feature has rarely been depicted in previous works. In addition to the substantially increased adsorption capacity of the modified framework compared with that of pristine MOF, a reverse and selective phenomenon was perceived in the cases of FS and MV. The sulfo-functionalized MOF could adsorb MV with high adsorption capacity but barely adsorbed FS, and the opposite condition was observed for pristine MOF. In addition, the prepared framework showed high selectivity in a mixed solution of dyes. On the other hand, the modified framework had no role in the first step of the adsorption and separation process and showed the same behavior as pristine MOF. Furthermore, the sulfonate functional groups could not be directly incorporated into HKUST. The experimental data followed the pseudo-second-order kinetics and the Langmuir isotherm model. Thermodynamic studies demonstrated an exothermic spontaneous mechanism for the dye adsorption process. The prepared adsorbents were capable of being recycled for four sequential cycles. Hereupon, this study presents a notably efficacious approach for the reverse performance of frameworks for the dye adsorption and separation process.

Indigo Carmine and 2,6-Dichlorophenolindophenol Removal Using Cetyltrimethylammonium Bromide-Modified Palm Oil Fiber: Adsorption Isotherms and Mass Transfer Kinetics.

In the present work, the usefulness of cetyltrimethylammonium bromide-modified palm oil fiber (CTAB-modified POF) for the removal of indigo carmine (IC) and 2,6-dichlorophenolindophenol (2,6-DCPIP) from aqueous solutions was investigated. Raw, NaOH-treated, and CTAB-modified POF were characterized by Fourier-transform infrared (FT-IR) spectroscopy, elemental analysis, thermogravimetric-hyperdifferential scanning calorimetric (TG-HDSC) analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The adsorption studies of IC and 2,6-DCPIP were performed in batch mode using CTAB-modified POF. The results showed that equilibrium was attained after a contact time of 30 minutes for IC and 20 minutes for 2,6-DCPIP. The maximum capacity of adsorption was obtained at pH = 2. The capacity of adsorption considerably increased with modified biosorbents and with increasing initial concentration of dyes. The ionic strength favors the increasing adsorption capacity of IC and does not affect the adsorption capacity of 2,6-DCPIP. The percentage of adsorption increased with increasing mass of the biosorbents. The nonlinear regression of adsorption isotherms showed that Freundlich (r2 = 0.953; χ2 = 4.398) and Temkin (r2 = 0.986; χ2 = 1.196) isotherms are most appropriate to describe the adsorption of IC and 2,6-DCPIP on CTAB-modified POF, respectively. The maximum adsorption capacities determined by the Langmuir isotherm were 275.426 and 230.423 μmol·g−1 for IC and 2,6-DCPIP, respectively. The linear regression of adsorption kinetics was best described by the pseudo-second-order model (R2 ≥ 0.998). The diffusion mechanism showed that external mass transfer is the main rate controlling step. Desorption of the two dyes is favorable in the alkaline medium.

Synthesis and characterization of Ag‐loaded p‐type TiO2 for adsorption and photocatalytic degradation of tetrabromobisphenol A

A p-type TiO2 with Ti vacancies (D-TiO2 ) was synthesized by a facile solvothermal treatment, and Ag/TiO2 with different Ag loading amount was prepared through a photo-reduction deposition method. The samples were characterized through scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The adsorption and photocatalytic characteristics of tetrabromobisphenol A (TBBPA) on D-TiO2 and Ag/TiO2 were investigated. The adsorption of TBBPA on Ag/TiO2 was significantly enhanced and was five times greater than that of pure TiO2 . The increase in pH significantly inhibited the adsorption of TBBPA. The 2%-Ag/TiO2 nearly completely degraded TBBPA in 10min under UV-Vis light (λ>360nm), and the apparent reaction rate constant (kapp ) reached 0.63min-1 . The significantly enhanced UV-Vis light catalytic properties of the Ag/TiO2 in comparison with that of TiO2 were attributed to the increased adsorption capacity and electron transfer ability of the Ag/TiO2 . Free radical trap experiments results showed that holes and superoxide radicals play a major role in the catalytic degradation of TBBPA by Ag/TiO2 . Moreover, the Ag/TiO2 catalyst exhibits high stability during TBBPA degradation even after three cycles. PRACTITIONER POINTS: Ti-defected TiO2 and Ag/TiO2 were synthesized using a solvothermal and photo-reduction deposition, respectively. Ag/TiO2 exhibited outstanding adsorption and photocatalytic activity for TBBPA removal under UV-Vis light. Holes and superoxide radicals play a major role inthe photocatalytic degradation of TBBPA.

Zinc Oxide Nanoparticles for Removal of Arsenic from Water

Removal of arsenate, As(V) from water was achieved using zinc oxide nanoparticles. The nanoparticles were synthesised from zinc acetate dihydrate and sodium hydroxide (NaOH) using the wet chemical sol-gel method. Different synthesis parameters were explored; including different ratios of Zn:NaOH and calcination temperatures. The synthesised samples were subsequently characterised and tested to investigate the adsorption capabilities of ZnO towards As(V). The colourimetric approach was utilised to analyse the samples’ performance. The particles had a relatively large average size as tested by the nanoparticle size analyser and the X-Ray Diffraction (XRD) characterisation of the samples confirmed the formation of ZnO. The peaks were narrow with high intensity, which indicates a larger crystal size and stable crystallinity. The samples showed a linear trend of increased adsorption capacity with the contact time. However, as indicated by the XRD and nanoparticle size analyser results, the particles had agglomerated and this has caused the total surface area to shrink. In summary, ZnO nanoparticles were successfully synthesised and were successful in adsorbing As(V) with different percentages for each sample. The adsorption trend was clear with respect to the changing parameters.

Comprehensive understanding the promoting effect of Dy-doping on MnFeOx nanowires for the low-temperature NH3-SCR of NOx: An experimental and theoretical study

Recently, Mn-based catalysts doped/modified by rare earth elements for the selective catalytic reduction (SCR) of NOx with NH3 are becoming a new research hotspot. In current work, Dy-doped MnFe oxides with the morphology of one-dimensional nanowire are successfully prepared by using electrospinning method for the first time, and the catalytic performances for the NH3-SCR of NOx are investigated in detail. It is found several positive factors are introduced due to the doping of Dy with an appropriate amount, such as the enhanced surface Mn4+ concentration and surface chemical adsorption of oxygen, the increased adsorption capacity for NH3 and NO. Theoretical calculation reveals that the Dy-doping causes the larger depletion of electron density of mainly O atoms on the surface of MnFeDy than that of MnFe case, which energetically favors the adsorption of NH3 and NO molecules. Our results fully confirm that Dy is an effective doped element of Mn-based catalysts for developing SCR catalysts with excellent low-temperature de-NOx performance.

Ternary Ag-deposited TiO2/palygorskite composites with synergistic effect for enhanced photocatalytic activity

Ternary Ag-deposited TiO2/palygorskite (AgTP) composites were facilely prepared by a one-step method. The crystal phases, morphology and photoelectric performances were characterized, and the results indicated that Ag-deposited TiO2 nanoparticles with size of 12–15 nm were adequately immobilized on the palygorskite fibers surface. Compared with anatase TiO2 and TiO2/palygorskite, the AgTP composites exhibited enhanced photocatalytic activity in degradation of methylene blue. Especially, the optimal sample (6.0AgTP) showed the highest photocatalytic activity, achieving 99.48% and 95.27% degradation efficiency after 60 min of UV–vis (350 ≤ λ ≤ 780 nm) or 210 min of visible-light (λ ≥ 420 nm) irradiation, respectively. Trapping tests with different scavengers revealed that not superoxide radicals but hydroxyl radicals and photogenerated holes were highly responsible for the degradation process. The enhanced photocatalytic activity was ascribed to the synergetic effect of palygorskite support effects (provide large surface area, optimize nanoparticles dispersibility and increase adsorption capacity), surface plasmon resonance of Ag, and efficient separation of charge carriers.

Synergistic Adsorption and Photocatalytic Activity under Visible Irradiation Using Ag-ZnO/GO Nanoparticles Derived at Low Temperature

Ag-ZnO/graphene oxide (AG-ZnO/GO) nanocomposite was synthesized via facile aqueous solution reactions at low temperature in order to improve the photocatalytic activity for cationic dye removal under visible light irradiation. Analytical techniques were carried out in order to determine the abilities including structure, state of elements, morphology, and surface area of synthesized materials. Ag-ZnO/GO nanocomposite presented an extremely high removal rate of methylene blue (MB) not only under UV light (over 99% removal) but also under visible light (85% removal) during the same irradiation time. In this study, initial process parameters of catalyst dosage, MB concentration, and pH of the solution were also examined for MB removal efficiency effects. The proposed mechanisms for the increased removal of MB by Ag-ZnO/GO nanocomposite under visible irradiation include increased photocatalytic degradation, mainly due to increased charge transfer capacity by lowering band gap energy; minimized recombination of the excited electron-hole pairs of ZnO with the addition of Ag into the ZnO crystal lattice; and an increased adsorption capacity with the addition of GO with high surface area and semiconductor function with zero band gap energy.

The effect of support on the structure and photocatalytic activity of ternary ZnO-ZnFe2O4/palygorskite composite photocatalysts

The ternary ZnO-ZnFe2O4/palygorskite composite photocatalysts were fabricated via a solvothermal method followed by thermal treatment. The structure, morphology and photoelectric performances of samples were characterized, and the results indicated that ZnO/ZnFe2O4 nanoparticles with size of 25–30 nm were adequately anchored on the palygorskite fibers surface. Compared with ZnO, ZnFe2O4, ZnO/ZnFe2O4 and ZnO/palygorskite, the ZnO-ZnFe2O4/palygorskite composite photocatalysts exhibited significantly improved photocatalytic activity in degradation of methylene blue (MB). Especially, the optimal photocatalyst (ZF1.5) displayed the highest photocatalytic activity, achieving 99.68% and 99.48% degradation efficiency after 90 min of UV–vis (350 ≤ λ ≤ 780 nm) and 100 min of visible-light (λ ≥ 420 nm) irradiation, respectively. The photocatalysis degradation process matched well with the Langmuir-Hinshelwood kinetics. The obtained improvement of photocatalytic activity was ascribed to the synergetic effect of superior visible-light utilization; effective charge carrier separation and palygorskite support effect (optimize nanoparticles dispersibility, developed mesoporous structure, enlarge specific surface area and increase adsorption capacity).

Effect of Ammonia Modification on Activated Carbons for the Removal of Acidic Anthraquinone Dyes

Abstract The objective of this research is to study the retention of two acidic anthraquinone dyes by Coconut-shell-based activated carbon. Ultimately, this work allows the valorization of this new material as an adsorbent. The effect of ammonia modification on the adsorption capacity of activated carbon towards remazol brilliant blue R19 (RB19) and acid blue 25 (AB25), has been studied. Coconut-shell-based activated carbon material was modified under ammonia flow at 900 and 1000 °C. The adsorption rates and isotherms of RB19 and AB25 on the resultant materials were then tested. The results show that ammonia modification remarkably increases the adsorption capacities of the activated carbons to RB19 and AB25, by a factor of 2–3 after treatment at 1000 °C (From 0.22 mmol g−1 and 1.04 mmol g−1 to 0.76 mmol g−1 and 2.19 mmol g−1 on AC and AC-O-N-1000, respectively). The increased adsorption capacity is attributed to the introduction of basic nitrogen-containing functional groups and enhanced pore development by ammonia modification. The collected experimental kinetic and isotherm data are well compatible with the intraparticle diffusion kinetic model and the Langmuir isotherm model. According to these results, the adsorption affinity is homogeneous in terms of surface functional groups and the surface bears a finite number of identical adsorption sites.

Superior Mesoporosity of Lipid-Free Spent Coffee Ground Residues.

As part of the biorefinery concept for spent coffee grounds (SCG), production of activated carbon (AC) was investigated from the degreased coffee grounds (DCG) left behind after oil extraction (primarily for biodiesel). The oils were extracted through conventional solvent extraction with GC/GC-MS confirming the oil was comparable to oils produced industrially. More significantly, analysis showed the DCG AC to have a four-fold increase in mesoporosity compared with the SCG AC with mesopore volumes of 0.6 and 0.15 cm3 g-1 , respectively. Adsorption trials showed a ten-fold increase in capacity for AuIII from 8.7 to 88.6 mg g-1 with subsequent experiments confirming that DCG AC displayed standard behavior for mesoporous materials of increasing adsorption capacity with decreasing pH. This raises the potential for valorization of SCG into a functional material for water remediation without the need for templating agents or expansion pretreatments with the added bonus of an additional material being produced simultaneously.

Dispersive Magnetic Solid-Phase Extraction Coupled to Direct Analysis in Real Time Mass Spectrometry for High-Throughput Analysis of Trace Environmental Contaminants.

Coupling dispersive magnetic solid-phase extraction (DMSPE) to direct analysis in real time mass spectrometry (DART-MS) with a newly developed metal iron probe enables high-throughput, sensitive detection of herbicides such as triazine in environmental waters. Magnetic graphene oxide was used as a dispersive sorbent because it increased adsorption capacity in the DMSPE process. The planar structure and excellent thermal conductivity of graphene oxide facilitated the desorption and ionization of target analytes in DART-MS analysis. The iron probe, which is designed to fit into the moving trail of the DART interface, served as the sorbent collector as well as the support for the magnetic graphene oxide after DMSPE, and was put directly into the DART system. The ratio of magnetic core to graphene oxide in the nanoparticles and other key parameters in DMSPE and DART-MS procedures were systematically investigated and optimized. In addition, the presence of water on the sorbent proves to have a significant effect on DART-MS analysis. No organic solvents are used in this method, and the reusable iron probe is of low cost. Under the optimal conditions, limits of detection were found in the range of 1.6-152.1 ng/L for the triazines. Recovery and reproducibility were found to be in the ranges of 87.5-115.0% and 1.9-10.2%, respectively, for the six herbicides studied. The analytical performance of the DMSPE-DART-MS method indicated that applications for trace analysis of other compounds in liquid samples are also possible.

Adsorption of Serum Albumin onto Octacalcium Phosphate in Supersaturated Solutions Regarding Calcium Phosphate Phases.

Octacalcium phosphate (OCP) has been shown to enhance new bone formation, coupled with its own biodegradation, through osteoblasts and osteoclast-like cell activities concomitant with de novo hydroxyapatite (HA) formation and serum protein accumulation on its surface. However, the nature of the chemical environment surrounding OCP and how it affects its metabolism and regulates protein accumulation is unknown. The present study examined how the degree of supersaturation (DS) affects the bovine serum albumin (BSA) adsorption onto OCP in 150 mM Tris-HCl buffer at 37 °C and pH 7.4, by changing the Ca2+ ion concentration. The amount of BSA adsorbed onto OCP increased as the DS increased. In addition, the amount of newly formed calcium phosphate, which could be OCP, was increased, not only by increases in DS, but also at lower equilibrium concentrations of BSA. The increased adsorption capacity of BSA was likely related to the formation of calcium phosphate on the adsorbed OCP. Together the results suggested that the formation of new calcium phosphate crystals is dependent on both the DS value and the adsorbate protein concentration, which may control serum protein accumulation on the OCP surface in vivo.

Adsorption behavior of three triazole fungicides on polystyrene microplastics.

Environmental pollution caused by microplastics (MPs) and pesticides has become a global challenge, and increasing evidence shows that MPs can adsorb organic pollutants which may affect their distribution and bioavailability. As widely used pesticides, triazole fungicides with potential environmental and human safety risks often coexist with MPs in the environment. Understanding the adsorption behavior is the basis of risk assessment of co-exposure of MPs and triazole fungicides. In this study, the adsorption behavior of three commonly used triazole fungicides on polystyrene (PS) was studied using adsorption test. The influences of PS particle size and environmental factors on adsorption capacity were evaluated, and the adsorption mechanisms were discussed. Results suggested that the adsorption kinetics and isotherm conformed to the Pseudo-second-order and Freundlich model, respectively. The order of adsorption and desorption capacity was hexaconazole (HEX) > myclobutanil (MYC) > triadimenol (TRI), which was positively correlated with LogKow of pesticides. To a certain extent, the decrease in PS particle size and change in solution pH value and increase in salt ion strength all contribute to increasing adsorption capacity. The main mechanisms of adsorption were hydrophobic and electrostatic interactions. MPs can adsorb and may become the source and sink of triazole fungicides in aqueous environments. Our results demonstrate that more attention should be given to the combined water pollution risk of MPs and triazoles fungicides.

Nanostructured Membrane of Sodium Montmorillonite Reinforced Cellulose Acetate for Adsorption of Ca(II) and Mg(II) Ions in Hard Water

Permanent hard water softening was conducted with the use of cellulose acetate (CA)/sodium montmorillonite (Na+-MMT) nanostructured membranes. Fabrication of the nanostructured membranes with various Na+-MMT loading (0%, 5%, 10%, 15%) was made possible by electrospinning technique, which was carried out at 25°C, 30 kV applied voltage, needle size of 25G and a tip to collector distance of 18 cm. The effect of Na+-MMT content on the morphology of the fiber was examined with the use of Scanning Electron Microscope (SEM). It was determined that increasing the Na+-MMT loading decreases the average fiber diameter. The molecular structure of the blend nanostructured membranes were investigated using Fourier Transform Infrared (FTIR) Spectroscopy and the existence of CA and Na+-MMT in the electrospun nanostructured membrane was confirmed. Better adsorption performance was observed for the blend with 15% Na+-MMT as compared to pure CA and maximum uptake rate was attained at 7 hours for pure CA and only 5 hours for CA/Na+-MMT (85%/15%) blend. Increasing the initial hard water concentration increases the driving force for diffusion and in turn increases adsorption capacity of both pure CA and the CA/Na+-MMT (85%/15%) blend. More so, the results of the experiment best fitted the pseudo-second order kinetic model and the Freundlich isotherm model. Integration of Na+-MMT in CA increases the surface area for adsorption of the nanostructured membrane, and thus, could be used as an effective adsorbent for hard water softening.

Removal of Cr(VI) from aqueous solution using amine-impregnated crab shells in the batch process

To increase adsorption capacity of Cr(VI) ions in aqueous solution, crab shells was chemically modified by means of copolymerization method using tri-ethyl amine and epichlorohydrine. Functional groups of chemically modified adsorbents were analyzed by Fourier Transform Infrared (FT-IR) and surface condition was confirmed by the SEM (scanning electron microscopy) and EDX (energy dispersive X-ray). It was found that the amino, amide and hydroxyl groups play an important role in adsorption of Cr(VI) ions. The adsorption capacity for Cr(VI) ions of the amine-impregnated crab shells was about 36.865 mg/g-dry mass and higher than that of virgin adsorbents (16.564 mg/g-dry mass) at initial solution pH 2.0. Langmuir and Freundlich models were used to fit the equilibrium data and the Langmuir isotherm model well fit the data. The maximum adsorption capacity (qm) for Cr(VI) ions was calculated as the 41.412 mg/g-dry mass. Also, the pseudo-second-order kinetic model well fit the experimental data better than that of the pseudo-first-order. In addition, the adsorption capacity of Cr(VI) decreased as the temperature rose, indicating the exothermic nature of the adsorption process. Furthermore, adsorption capacity of Cr(VI) for reused amine-impregnated crab shells can be still maintained at 33.653 mg/g level until the 2nd cycle. It was concluded that the adsorption process using amine-impregnated crab shells could be applied to the removal system of Cr(VI) ions from aqueous solution and it could sufficiently replace the commercial ion-exchange resins.

Removal of emulsified and dissolved diesel oil from high salinity wastewater by adsorption onto graphene oxide

Large quantities of oily wastewaters are produced globally from oil extraction and refining industries containing low concentrations of dissolved and finely emulsified oils. These waters are difficult to treat within a small footprint as often necessary, especially on offshore sites, and often contain high salinity making many treatment methods ineffective. In this study the use of graphene oxide (GO) as an adsorbent is investigated using diesel as a representative oil. GO demonstrated a high adsorption capacity of 1335 mg/g according to the Freundlich isotherm and based on theoretical surface area was likely due to limited multi-layer adsorption. Increasing salinity to 1% increased adsorption capacity by 75%, remaining constant thereafter, confirming the suitability for the material for saline produced water remediation. Adsorption was extremely rapid, reaching more than 90% of the equilibrium capacity within 4 min, and was represented best by a pseudo-second order kinetic model. Fixed bed column tests confirmed the ability for excellent removal capacities under a short contact time and good regeneration, indicating the potential of GO for industrial oil-water emulsion separation applications. Based on careful analysis of isotherm and kinetic data, in conjunction with theoretical considerations, a rapid multi-layer physisorption mechanism, influenced by GO agglomeration, is proposed.

Reduced graphene oxide-loaded-magnetite: A Fenton-like heterogeneous catalyst for photocatalytic degradation of 2-methylisoborneol

A reduced-graphene-oxide-loaded magnetite (rGOF) composite was successfully synthesized by co-precipitation method for photocatalytic degradation of an odorous water contaminant 2-methylisoborneol (MIB). This heterogeneous Fenton-like catalyst degraded the recalcitrant MIB under both UV and solar light irradiations at neutral pH without the addition of other chemicals. Bare magnetite (Fe3O4) degraded only 22.5% of MIB because of rapid charge recombination. In comparison, the degradation efficiency increased to 99% for 10% (by weight) reduced graphene oxide (rGO) loading in magnetite. The addition of the rGO not only increased the adsorption capacity by increasing surface area but also increased the photodegradation efficiency synergistically by separating the electron–hole pairs, indicated by the photoluminescence spectra. The reduction in aggregation of Fe3O4 nanoparticles was explained by the increase in d-spacing and with FE-SEM images. The impedance and photocurrent data also proved the transfer of electron in presence of light in the hybrid composite. The rGOF composite presented excellent ferromagnetism, which made its recovery very easy. The recycled composite showed significantly high photocatalytic activity even after the fifth cycle with increased adsorption capacity of the recycled composite. Degradation mechanism and degradation pathway have been proposed and intermediates were identified.

Impregnating Activated Carbon with Iron Salts to Increase Hydrogen Sulfide Removal

Hydrogen sulfide (H₂S) emissions from landfills negatively impact surrounding communities. In addition to an unpleasant, rotten-egg odor, inhalation of the gas can cause respiratory distress and irritation. Peak emissions are released from C&D landfills through the decomposition of gypsum drywall. Current removal technologies are costly and often ineffective. The goal of this research was to develop a cost-effective mat geared toward H₂S removal. Preliminary research revealed an increase in adsorption capacity through the addition of iron salts, FeCl3 and FeSO4, to activated carbon at a 5:1 carbon to iron ratio. To evaluate the effect of heat treatments on iron oxide formation, and subsequent adsorption capacity, samples were divided into heat treatment groups of 250ºC, 450ºC, and 650ºC. Samples were flushed with 100 ppm of H₂S under N₂ at 250 ml/min for two hours. Over this time duration, samples subjected to higher temperature heat treatments showed increased adsorption capacity. All heat treated samples demonstrated higher adsorption compared to the baseline non-heat treated samples. Additional research will be conducted to assess the effect of heat treatments above 650ºC.

Arsenic variability and groundwater age in three water supply wells in southeast New Hampshire

Three wells in New Hampshire were sampled bimonthly over three years to evaluate the temporal variability of arsenic concentrations and groundwater age. All samples had measurable concentrations of arsenic throughout the entire sampling period and concentrations in individual wells had a mean variation of more than 7 μg/L. The time series data from this sampling effort showed that arsenic concentrations ranged from a median of 4 μg/L in a glacial aquifer well (SGW-65) to medians of 19 μg/L and 37 μg/L in wells (SGW-93 and KFW-87) screened in the bedrock aquifer, respectively. These high arsenic concentrations were associated with the consistently high pH (median ≥ 8) and low dissolved oxygen (median <0.1 mg/L) in the bedrock aquifer wells, which is typical of fractured crystalline bedrock aquifers in New Hampshire. Groundwater from the glacial aquifer often has high dissolved oxygen, but in this case was consistently low. The pH also is generally acidic in the glacial aquifer but in this case was slightly alkaline (median = 7.5). Also, sorption sites may be more abundant in glacial aquifer deposits than in fractured bedrock which may contribute to lower arsenic concentrations.Mean groundwater ages were less than 50 years old in all three wells and correlated with conservative tracer concentrations, such as chloride; however, mean age was not directly correlated with arsenic concentrations. Arsenic concentrations at KFW-87 did correlate with water levels, in addition, there was a seasonal pattern, which suggests that either the timing of or multiple sampling efforts may be important to define the full range of arsenic concentrations in domestic bedrock wells.Since geochemically reduced conditions and alkaline pHs are common to both bedrock and glacial aquifer wells in this study, groundwater age correlates less strongly with arsenic concentrations than geochemical conditions. There also is evidence of direct hydraulic connection between the glacial and bedrock aquifers, which can influence arsenic concentrations. Correlations between arsenic concentrations and the age of the old fraction of water in SGW-65 and the age of the young fraction of water in SGW-93 suggest that water in the two aquifers may be mixing or at least some of the deeper, older water captured by the glacial aquifer well may be from a similar source as the shallow young groundwater from the bedrock aquifer. The contrast in arsenic concentrations in the two aquifers may be because of increased adsorption capacity of glacio-fluvial sediments, which can limit contaminants more than fractured rock. In addition, this study illustrates that long residence times are not necessary to achieve more geochemically evolved conditions such as high pH and reduced conditions as is typically found with older water in other regions.