Simulated Tap Water Research Articles

Assessing the photo-activation efficiency of aminopolycarboxylate iron complex mixtures for effective sulfamethoxazole degradation in a pilot-scale UVA-LED photoreactor

This study focused on the degradation of antibiotic sulfamethoxazole (SMX), through the UVA-LED photo-activation of aminopolycarboxylate-based iron complexes in a pilot-scale photoreactor. Fe3+-EDDS, Fe3+-NTA, and a combination of both complexes Fe3+-EDDS and Fe3+-NTA were studied in simulated tap water (TW) and simulated secondary effluent (SE) from a municipal wastewater treatment plant (MWWTP). In TW, 40% SMX degradation was reached after 60 min, with different concentration profiles due to absorption characteristics of each complex. Combining Fe3+-EDDS and Fe3+-NTA an initial rapid SMX degradation was observed followed by a slower phase, improving SMX degradation with respect to each complex separately. In SE and despite presenting similar kinetics, SMX degradation was lower than in TW, due to the presence of organic matter in the water matrix. Moreover, the Fe3+-EDDS and Fe3+-NTA mixture improved SMX degradation with increasing iron concentration. This improvement was attributed to reduced dissolved organic carbon (DOC) from NTA and the lower molar absorption coefficient of Fe3+-NTA. Higher EDDS ratios led to faster complex degradation but did not significantly enhance SMX removal. Conversely, higher NTA ratios reduced SMX degradation. In summary, this study revealed a synergistic effect between Fe3+-EDDS and Fe3+-NTA in SMX degradation. Considering the cost difference between EDDS and NTA, using both compounds offers technical and economic advantages. All treatments reduced chronic toxicity in Selenastrum capricornutum.

Spatio-temporal variation characteristics of stable isotopes of tap water and its potential as a proxy for surface water in Sichuan, China

The stability and safety of tap water are essential for human health and economic and social development. The stable isotopes can be used to reveal characteristics of tap water and link it with its source. In this paper, 1556 tap water samples were collected from Sichuan, China and the stable isotope ratios for these samples were determined. The δ2H ranges from −126.4 ‰ to −26.4 ‰, and the range of δ18O is −17.04 ‰ to −2.08 ‰, reflecting the tap water sources are affected by complex spatial features and changing meteorological elements. Stable isotopes in tap water usually reach the maximum values in summer, indicating that heavy isotope enrichment is easily achievable by the large amount of evaporation from water sources during the summer season. By using spatial interpolation and isoscapes, we can find that there is a strong correlation between both simulated tap water δ2H and river water δ2H, with the maximum difference not exceeding 10.0 ‰, while the overall mean relative error is 6 %. Consequently, it is feasible to use tap water isotopes as a proxy for surface water isotopes in representative watersheds where surface water is the main source of water. The study shows the variation characteristics and influencing factors of tap water isotopes and enriches the isotope database of tap water in China. Meanwhile, the utilize of stable isotopes in tap water as a proxy for surface water expands the application field of tap water stable isotopes and opens new perspectives for indirectly obtaining isotope data of surface water.

Metal-organic frameworks as solid-phase microextraction adsorbents for the determination of triacetone triperoxide by gas chromatography-mass spectrometry

Triacetone triperoxide (TATP) is a high-power explosive which is often used by criminals. The detection of TATP is of great significance for solving the explosion cases. However, the preconcentration and analysis of trace levels of TATP still pose challenges for analytical researchers. In this study, metal-organic frameworks (MOFs), including IRMOF-8, MOF-5, UIO-66, ZIF-8, and MIL-101(Cr), were immobilized on a stainless steel wire using a physical adhesive method as a solid-phase microextraction (SPME) fiber coating. The prepared fibers with a controllable thickness were used for the extraction of TATP followed by gas chromatography-mass spectrometry (GC-MS) analysis. Under the identical experimental conditions, the IRMOF-8-coated fiber exhibited higher extraction efficiency for TATP than the other fibers. The IRMOF-8-coated fiber was then characterized using scanning electron microscopy and thermogravimetric analysis. The results indicated that the IRMOF-8-coated fiber not only had good thermal and chemical stabilities but also afforded a high TATP extraction efficiency. Under the same extraction conditions, the extraction efficiency of the IRMOF-8-coated fiber was 2–8 times higher than those of commercial fibers. The limit of detection was 13 ng/mL, and linearity was observed in the range of 50–5000 ng/mL with a correlation coefficient greater than 0.998. The intraday repeatability (n = 6), interday repeatability (n = 3), and fiber-to-fiber reproducibility (n = 3), were 4.1 %, 4.8 %, and 8.0 %, respectively. The recoveries of TATP from the simulated tap water and soil samples were 87.32–90.57 % and 88.76–100.93 %, respectively, with relative standard deviations lower than 11.11 % (n = 3). The above method was successfully applied for the detection of TATP transferred from a finger to a paper surface, demonstrating its good application prospects in the analysis of trace TATP.

Aspartame-Sweetened Tap Water: Transformation Products and 2,6-Dichloro-1,4-Benzoquinone Formation.

Aspartame (APM), a dipeptide of aspartic acid (ASP) and phenylalanine (PHE), is a widely used artificial sweetener in beverages. It is unclear whether residual chlorine in tap water can react with APM to form disinfection byproducts (DBPs). Therefore, we investigated the formation of DBPs from the reaction of APM with residual chlorine in authentic tap water. APM and a commercial sweetener (CS) packet containing APM were studied under authentic and simulated tap water conditions. Eight chlorinated products of APM were detected using solid-phase extraction (SPE) and high performance liquid chromatography quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS). These new chloro-products were tentatively identified based on accurate masses, isotopic patterns of 35,37Cl, and MS/MS spectra. Furthermore, we identified APM as a precursor to 2,6-dichloro-1,4-benzoquinone (DCBQ). DCBQ significantly increased to 2.3-12 ng/L with the addition of APM or CS in tap waters collected from different locations compared to 1.4-1.8 ng/L in the same tap water samples without sweetener. DCBQ and two of the chlorinated transformation products were identified in cold prepared tea containing APM. DCBQ formation was eliminated when the residual chlorine in tap water was reduced by ascorbic acid or boiling prior to the addition of APM or CS. This study found that eight new DBPs and DCBQ were produced by the reactions of residual chlorine with APM and CS. These findings show an unintended exposure source of emerging DBPs via APM sweetened beverages.

Assessment of new immobilized photocatalysts based on Rose Bengal for water and wastewater disinfection

The aim of this study was to evaluate the water disinfection capability of new immobilized photocatalysts based on the organic photosensitizer Rose Bengal (RB) supported on glass wool and with two different photocatalyst load (RB_GW_0.22 and RB_GW_0.02). Tests were carried out under different operating conditions in a solar simulator at 30 W/m2 average UV-A irradiation. Isotonic water (IW) (with 9 g/L NaCl), simulated tap water (STW) and simulated urban wastewater effluent (SUWWE) spiked with Escherichia coli and Enterococcus faecalis (106 CFU/mL initial concentrations) were used as water model microbial strains. The mere effect of only irradiance was also investigated as reference of the photocatalytic performance over both bacteria. Results showed that RB_GW_0.22 presented high inactivation for E. faecalis, reaching 6 Log Reduction Value (LRV) in 2 min in IW and STW at pH 5 and 6 in comparison with only irradiance (60 min). In SUWWE, the effect of RB_GW_0.22 was also better for E. faecalis inactivation (60 min), compared to that produced in E. coli (120 min) and without the presence of the photocatalyst (where total inactivation was not achieved after 120 min of treatment). Ecotoxicity (ISO 11348–3:2007) and phytotoxicity (EN ISO 18763:2020) tests of the treated water were also assessed and results showed any significant effect, concluding that the use of RB_GW_0.22 is a promising solar photocatalytic treatment for urban wastewater reclamation and reuse.

Revisiting the effect of boiling on halogenated disinfection byproducts, total organic halogen, and cytotoxicity in simulated tap water

Boiling is a widely adopted household tap water treatment method because of its ability to inactivate chlorine-resistant pathogenic bacteria, and to reduce certain groups of disinfection byproducts (DBPs). From a more comprehensive point of view, this study revisited the effect of boiling on four groups of 17 aliphatic DBPs and six groups of 44 aromatic DBPs in both simulated chlorinated and chloraminated tap water samples, with a special focus on the changes of total organic halogen (TOX) and cytotoxicity. Results showed that the concentrations of aliphatic DBPs substantially decreased during boiling via volatilization (trihalomethanes and chloral hydrate) and hydrolysis (haloacetamides) in chlorinated and chloraminated tap water samples. The concentrations of aromatic DBPs during boiling generally followed an increasing trend due to decarboxylation of polycarboxylic precursors in chlorinated tap water samples, and showed a first increasing and then decreasing trend in chloraminated tap water samples. A sharp decreasing of TOX occurred in the heating process of tap water samples from room temperature to 100 °C, and a relatively gentle decreasing was kept in the prolonged boiling process till 5 min. The most abundant DBP group in the tap water samples without boiling was trihalomethanes, and was replaced by haloacetic acids with boiling for 5 min. Continuous boiling for 5 min substantially reduced the cytotoxicity of chlorinated and chloraminated water samples by 52.6% and 21.3%, respectively. Reduction of cytotoxicity matched well with the reduction of TOCl (r = 0.907, P < 0.01), TOBr (r = 0.885, P < 0.01) and TOX (r = 0.905, P < 0.01), suggesting that the cytotoxicity reduction during boiling was mainly ascribed to the reduction of halogenated DBPs. Therefore, boiling of tap water to 100 °C was strongly recommended to reduce the potential health risks induced by tap water ingestion.

Inhibiting the increase of antibiotic resistance genes during drinking water distribution by superior microbial interface using Fe modified granular activated carbon

The effects of biological activated carbon treatment using Fe2O3-modified granular activated carbon in inhibiting antibiotic resistance genes in simulated drinking water distribution systems was compared with unmodified granular activated carbon as a reference. Fe2O3-modified biofiltration resulted in a sustained inhibition of resistance genes during drinking water chlorination and distribution (relative abundance in simulated tap water after the modified and unmodified filtration was 1.31% and 9.40%, respectively). A new electron transfer pathway occurring in attached biofilms on Fe2O3-modified granular activated carbon surface, which was identified using X-ray photoelectron spectroscopy and the phenanthroline spectrophotometric method, enhanced the extracellular electron transfer rate and weakened the pressure of organic micropollutants on microorganisms. Hence, the relative abundance of resistance genes (36.32%) and integron (8.79%) on modified carbon was considerably lower than that on unmodified carbon (115.59% and 13.85%, respectively). Meanwhile, the secreted extracellular polymeric substances on modified carbon presented higher flocculating efficiency and better mechanical stability, resulting in the suspended extracellular polymeric substances in downstream water exhibiting stronger electrostatic repulsion. The particle-attached biofilms in downstream distribution systems consistently failed to form larger aggregates, inhibiting horizontal gene transfer, and overall microbial metabolism. Based on network analysis, 11 OTUs in the water samples from raw water to simulated tap water formed an extremely interrelated module with no links to target resistance genes and integron. Therefore, a range of microbial variations triggered by the microbial interface on modified carbon successfully controlled the transfer of antibiotic resistance genes-associated risk from biological activated carbon effluent to tap water. Our findings revealed that enhancing the microbial interface using Fe2O3-modified granular activated carbon is a promising option for inhibiting the antibiotic resistance genes increase in tap water.

Are Disinfection Byproducts (DBPs) Formed in My Cup of Tea? Regulated, Priority, and Unknown DBPs

Globally, tea is the second most consumed nonalcoholic beverage next to drinking water and is an important pathway of disinfection byproduct (DBP) exposure. When boiled tap water is used to brew tea, residual chlorine can produce DBPs by the reaction of chlorine with tea compounds. In this study, 60 regulated and priority DBPs were measured in Twinings green tea, Earl Grey tea, and Lipton tea that was brewed using tap water or simulated tap water (nanopure water with chlorine). In many cases, measured DBP levels in tea were lower than in the tap water itself due to volatilization and sorption onto tea leaves. DBPs formed by the reaction of residual chlorine with tea precursors contributed ∼12% of total DBPs in real tap water brewed tea, with the remaining 88% introduced by the tap water itself. Of that 12%, dichloroacetic acid, trichloroacetic acid, and chloroform were the only contributing DBPs. Total organic halogen in tea nearly doubled relative to tap water, with 96% of the halogenated DBPs unknown. Much of this unknown total organic halogen (TOX) may be high-molecular-weight haloaromatic compounds, formed by the reaction of chlorine with polyphenols present in tea leaves. The identification of 15 haloaromatic DBPs using gas chromatography-high-resolution mass spectrometry indicates that this may be the case. Further studies on the identity and formation of these aromatic DBPs should be conducted since haloaromatic DBPs can have significant toxicity.

Thin-film nanocomposite NF membrane with GO on macroporous hollow fiber ceramic substrate for efficient heavy metals removal

The ceramic membrane has been widely used in the wastewater treatment based on the chemical resistance and superior separation performance. A robust and defect-free thin-film nanocomposite (TFN) nanofiltration (NF) membrane on the macroporous hollow fiber ceramic (HFC) substrate was novelly developed for heavy metals removal. Before interfacial polymerization (IP), the aqueous solution of graphene oxide (GO) grafted with ethylenediamine (EDA) was deposited on the HFC substrate by vacuum filtration. Then, a thin polyamide (PA) film was fabricated by EDA and 1,3,5-trimesoyl chloride (TMC), followed by heat treatment. The effects of GO content and EDA concentration on the performance of the NF membrane have been systematically investigated. The results showed that when the GO content was 0.015 mg·mL−1 and the EDA concentration was 0.75 wt.%, the as-prepared eGO3/PA-HFC membrane had a rejection rate of 94.12% for MgCl2 and a pure water flux of 18.03 L·m−2·h−1. Additionally, the removal ability of eGO3/PA-HFC membranes for heavy metal ions was satisfactory (93.33%, 92.73%, 90.45% and 88.35% for Zn2+, Cu2+, Ni2+ and Pb2+, respectively). The study explored further that it was efficient and stable for heavy metal ions removal during 30 h in the simulated tap water and mining wastewater, which indicated that the eGO/PA-HFC membrane has great application potential in wastewater treatment.

Identification, formation and control of polar brominated disinfection byproducts during cooking with edible salt, organic matter and simulated tap water

Edible salt is essential to the health of humans and serves as a seasoning universally. Besides chloride, edible salt also contains other anions such as bromide, fluoride, sulfate, and carbonate due to incomplete removal during raw salt refinement. In a household cooking (e.g., soup making) process, a chlorine/monochloramine residual in tap water could react with bromide in edible salt and organic matter in food (e.g., rice, wheat) to form numerous brominated disinfection byproducts (Br-DBPs) at significant levels, which might induce adverse health effects to human beings. In this study, we solicited 20 edible salts of different types (i.e., sea salts, well and rock salts, lake salts, and bamboo salts) from nine countries and determined their bromide levels to be 67–375 mg/kg, with an average level of 173 mg/kg. A total of 25 polar Br-DBPs were detected and identified with structures/formulae in cooking water samples using ultra performance liquid chromatography/electrospray ionization-triple quadruple mass spectrometry (UPLC/ESI-tqMS) and high-resolution mass spectrometry. Effects of cooking conditions (e.g., disinfectant type and level, edible salt dose, organic matter type and dose, sequence and time interval of adding organic matter and salt, etc.) on the formation of polar Br-DBPs were investigated, and optimized cooking conditions with minimized formation of polar Br-DBPs were determined. Further aided with an Hep G2 cell cytotoxicity assay, it was found that the overall cytotoxicity of chlorinated and chloraminated cooking water samples prepared after cooking condition optimization was reduced by 57% and 22%, respectively, compared with those prepared before cooking condition optimization.

Conversion of haloacid disinfection byproducts to amino acids via ammonolysis

Haloacetic acids (HAAs) are the major disinfection byproducts (DBPs) that are formed during chlorination of drinking water. In this paper, the conversion of HAAs to amino acids (e.g., glycine) via ammonolysis was studied. First, a new and sensitive method for detecting glycine was developed by setting selected ion recording m/z 76 in positive electrospray ionization mass spectrometry coupled with ultra performance liquid chromatography. Second, among the mono-HAAs under the same test conditions, iodoacetic acid (49.3%) showed a considerably higher conversion to glycine during ammonolysis than chloroacetic acid (4.2%) and bromoacetic acid (27.7%). The conversion of iodoacetic acid to glycine increased with increasing temperature, increasing reaction time, or decreasing the ratio of (NH4)2CO3 to NH3·H2O in the aminating agent. Hydrolysis of iodoacetic acid to glycolic acid was also observed during ammonolysis, and it accounted for at most 50% of the iodoacetic acid conversion. The conversion to amino acids and the hydrolysis were the two major pathways during ammonolysis of HAAs. Third, compared with the iodoacetic acid sample and the simulated tap water sample without ammonolysis, the developmental toxicity of the corresponding samples with ammonolysis decreased by up to 10.4% and 32.1%, respectively. The ammonolysis was thus demonstrated to be a detoxification process for both individual HAAs and DBP mixture in chlorinated tap water. In practice, the ammonolysis of haloacid DBPs in tap water may be realized by simply adding an appropriate amount of an aminating agent during cooking.

Functionalized polymer-iron oxide hybrid nanofibers: Electrospun filtration devices for metal oxyanion removal

Via a single-pot electrospinning synthesis, we developed a functionalized polymer-metal oxide nanofiber filter for point of use (POU) water treatment of metal oxyanions (e.g., arsenate and chromate). Polyacrylonitrile (PAN) functionalization was accomplished by inclusion of surface-active, quaternary ammonium salts (QAS) [cetyltrimethylammonium bromide (CTAB) or tetrabutylammonium bromide (TBAB)] that provide strong base ion exchange sites. Embedded iron oxide [ferrihydrite (Fh)] nanoparticles were used for their established role as metal sorbents. We examined the influence of QAS and Fh loading on composite properties, including nanofiber morphology, surface area, surface chemical composition, and the accessibility of embedded nanoparticles to solution. Composite performance was then evaluated using kinetic, isotherm, and pH-edge sorption experiments with arsenate and chromate, and benchmarked to unmodified PAN nanofibers and freely dispersed Fh nanoparticles. We also assessed the long-term stability of QAS in the composite matrix. For composites containing QAS or Fh nanoparticles, increasing QAS/Fh nanoparticle loading generally yielded increasing metal oxyanion uptake. The optimized composite (PAN 7 wt%, Fh 3 wt%, TBAB 1 wt%) exhibited two distinct sites for simultaneous, non-competitive metal binding (i.e., iron oxide sites for arsenate removal via sorption and well-retained QAS sites for chromate removal via ion exchange). Moreover, surface-segregating QAS enriched Fh abundance at the nanofiber surface, allowing immobilized nanoparticles to exhibit reactivity comparable to that of unsupported (i.e., suspended or freely dispersed) nanoparticles. To simulate POU application, the optimized composite was tested in a dead-end, flow-through filtration system for arsenate and chromate removal at environmentally relevant concentrations (e.g., μg/L) in both idealized and simulated tap water matrices. Performance trends indicate that dual mechanisms for uptake are maintained in kinetically limited regimes. Although chromate removal via ion exchange is more susceptible to interfering counter-ions, arsenate removal in simulated tap water indicates that ∼130 g of the composite could produce an individual's annual supply of drinking water (assuming an influent contaminated with 100 μg As/L, which is 10 times the current MCL).

Electrochemical and Quantum Chemical Studies of 1, 2, 3-Benzotriazole as Inhibitor for Copper and Steel in Simulated Tap Water

Electrochemical and Quantum Chemical Studies of 1, 2, 3-Benzotriazole as Inhibitor for Copper and Steel in Simulated Tap Water

Effect of Inclusions on Corrosion and Dissolution of Metallic Ions of Stainless Steel 304 in Simulated Tap Water

Effect of Inclusions on Corrosion and Dissolution of Metallic Ions of Stainless Steel 304 in Simulated Tap Water

Preparation of polyaniline-coated polystyrene nanoparticles for the sorption of silver ions

Polyaniline-coated polystyrene (PS/PANI) beads with an average diameter of approximately 310nm were prepared from styrene and divinylbenzene via emulsion polymerization and subsequent oxidative polymerization of aniline. The sorption capacity of the polymer beads towards silver ions in aqueous solution increased substantially as the pH increased, up to a pH of 7, owing to more free amine and imine groups. The FE-SEM images and XRD data indicated that silver ions were reduced to form silver nanoparticles on the polymer beads. The kinetics of silver ion uptake by PS/PANI particles in a 160ppm silver nitrate solution could be described by a pseudo-second order model. Even though the sorption isotherm correlated to the Freundlich model much better than the Langmuir model, the Langmuir model-based maximum sorption (320mgg−1) was closer to the experimentally obtained value of 330mgg−1. This study reveals that PS/PANI beads can be readily prepared in large quantities and employed as one of most efficient sorbents of silver ions in the aqueous phase. The high sorption capacity of the polymer nanoparticles was illustrated not to be affected by common alkali and alkaline earth metal ions in a simulated tap water. The PS/PANI nanoparticles were stable enough not to show any significant loss in sorption efficiency even after fourth cycle of adsorption-desorption.

Application of freeze desalination for chromium (VI) removal from water

Chromium (VI) is a highly toxic metal ion found in the priority list of pollutants, which is also often abundant in areas having low access to high-tech solutions for chromium (Cr) removal. This study was initiated to investigate the capacity of home-use refrigerators to generate fresh water free from Cr(VI) by melting ice produced from Cr(VI) polluted water. Simulated tap water samples as well as deionized water to which different concentrations of Cr(VI) were added were frozen in a closed freezer unit. The effects of initial concentration, time of ice nucleation, fraction of ice volume, and influence of co-occurring ions were evaluated in relation to the quality of the produced ice. The physicochemical characteristics of the produced ice cubes were also evaluated. A high total water recovery of up to 85% was achieved. Chromium removal ranged from 57.4 to 80% for simulated tap and from 93 to 97% for deionized water spiked with Cr. The energy consumption estimation basing form the refrigerator amounted to 0.076kWh. Freeze desalination was found to be relatively viable desalination technology in terms of quality of water produced, easiness for safe water production, and amount of energy consumed, especially where high-tech solutions for Cr(VI) removal are not available.

NOM and alkalinity interference in trace-level hexavalent chromium analysis

Three analytical methods were evaluated for hexavalent and trivalent chromium analyses in the presence of natural organic matter (NOM) and alkalinity. Each method was tested using a simulated tap water with 1μgL−1 Cr(VI) and 0.8μgL−1 Cr(III) and several concentrations of NOM and/or alkalinity. An ion chromatograph with post column reaction cell conforming to USEPA Method 218.7 could accurately quantify Cr(VI) in the presence of up to 8mgCL−1 NOM and up to 170mgL−1 as CaCO3 alkalinity, and no oxidation of chromium was observed when 0.8μgL−1 Cr(III) was also present. A high-performance liquid chromatography coupled with inductively coupled plasma (HPLC–ICPMS) method and a field speciation method were also evaluated. Each of these methods was unaffected by the presence of alkalinity; however, the presence of NOM created issues. For the HPLC–ICPMS method, as the concentration of NOM increased the recovery of Cr(VI) decreased, resulting in a ‘false negative’ for Cr(VI). However, for the field speciation method, Cr(III) was complexed by NOM and carried through the ion exchange column, resulting in a ‘false positive’ for Cr(VI).

Boiling of Simulated Tap Water: Effect on Polar Brominated Disinfection Byproducts, Halogen Speciation, and Cytotoxicity

Tap water typically contains numerous halogenated disinfection byproducts (DBPs) as a result of disinfection, especially of chlorination. Among halogenated DBPs, brominated ones are generally significantly more toxic than their chlorinated analogues. In this study, with the aid of ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry by setting precursor ion scans of m/z 79/81, whole spectra of polar brominated DBPs in simulated tap water samples without and with boiling were revealed. Most polar brominated DBPs were thermally unstable and their levels were substantially reduced after boiling via decarboxylation or hydrolysis; the levels of a few aromatic brominated DBPs increased after boiling through decarboxylation of their precursors. A novel adsorption unit for volatile total organic halogen was designed, which enabled the evaluation of halogen speciation and mass balances in the simulated tap water samples during boiling. After boiling for 5 min, the overall level of brominated DBPs was reduced by 62.8%, of which 39.8% was volatilized and 23.0% was converted to bromide; the overall level of chlorinated DBPs was reduced by 61.1%, of which 44.4% was volatilized and 16.7% was converted to chloride; the overall level of halogenated DBPs was reduced by 62.3%. The simulated tap water sample without boiling was cytotoxic in a chronic (72 h) exposure to mammalian cells; this cytotoxicity was reduced by 76.9% after boiling for 5 min. The reduction in cytotoxicity corresponded with the reduction in overall halogenated DBPs. Thus, boiling of tap water can be regarded as a "detoxification" process and may reduce human exposure to halogenated DBPs through tap water ingestion.

Date Palm leaves Fiber Utilization as sorbent for Crude Oil Spill Cleanup and the Temperature Effect

Crude oil spill are a global concern due to the environmental and economic impact as well as harm the beauty of the polluted sites. Date Palm leaves fiber (DPLF) as a natural agricultural fiber, which is environmentally materials, biodegradable, renewable, abundant, and cheap. A hollow cellulosic material like DPLF is a potential sorbent to counter the oil spill pollution. The oil sorption capacity (OSC) of fresh and weathered oils into DPLF as a sorbent was studied. The effects of contact time and temperature on sorption were studied in simulated tap water as well as salty water. The OSC increases with increasing the contact time. The DPLF has given oil sorption capacity of 4.534-7.985 g oil/g sorbent for a contact time of 5-90 min for fresh oil (tap water, at room temperature). This OSC are considered to be good for a sorbent considering it is locally available and not expensive. Fresh oil is having higher OSC at room temperature at all the experimental times (5-120 min). At lower temperature, e.g. 15 °C the adsorption of oil having greater role in increasing OSC, since at low temperature the oil having high viscosity and that will increase the adherence of oil onto the surface of the fibers and within the capillary during drainage. At room temperature and little higher e.g. 25 &amp; 30 °C , the oil will have less viscosity and more diffusion and that will increase the absorption within the internal capillary and lumens of the fibers and that increase the OSC. There is decrease in viscosity at higher temperature e.g. 45 &amp; 60 °C that will increase the diffusion in the oil and increase the segmental mobility of the fibers as well as increasing the penetration of oil into the pores and lumens of the fibers. That will increase the OSC, but much oil will come out during the drainage time (5 min).

Recycling of process water in sulphide flotation: Effect of calcium and sulphate ions on flotation of galena

The effects of major components of calcium and sulphate species present in recycled process water on galena flotation has been investigated through Hallimond flotation, zeta-potential, diffuse reflectance FTIR spectroscopy and XPS measurements using pure galena mineral. The significance of process water species in flotation has been understood using deionised water, process water and simulated tap water containing equivalent calcium and sulphate ions concentration as in process water.Hallimond flotation indicated marginally lower recoveries of galena in the presence of calcium and sulphate ions using potassium amyl xanthate as collector. Zeta-potential shows the adsorption of calcium ions whereby the potential are seen to increase while sulphate ions have no significant effect. FTIR and XPS studies revealed surface calcium carbonate and/or calcium sulphate species in process water which affected xanthate adsorption. Presence of surface oxidised species such as sulfoxy, hydroxyl species on galena at pH 10.5 in deionised and process water was also revealed.