Mechanical performance and Taguchi optimization of kenaf fiber/cement-paperboard composite for interior application

Demand for particleboards keeps increasing and as such more trees are fell for its production, engendering deforestation. For the purpose of reducing falling of trees, this study, focused on recycling of waste paper in the development of paperboard as alternative to particleboards used for furniture and interior household applications. Kenaf fiber (KF) was blended at varying proportions of 0, 1, 2, 3, 4, and 5 wt.% with 20 wt.% constant cement and 20 wt.% constant coconut shell powder while the remaining was paper pulp. Board specimen developed were cured for 14, 28, and 90 days and mechanical properties were examined. Results obtained showed that fiber dosage improved bond strength and screw holding strengths as compared with the control mix. Similarly, modulus of rupture was enhanced with KF loading as compared with control mix while 1 to 3 wt.% KF spawned enhancement of modulus of elasticity. However, 4 and 5 wt.% KF led to a reduction in the modulus. Infusion of the fiber enhanced tensile strength from 1 to 3 wt.% content. 14-day and 28-day curing periods were observed to improve properties while the 90-day curing period is detrimental to all properties. Optimization via signal-to-noise ratio revealed an optimum mix of 2 wt.% obtained for fiber and an optimum curing duration of 28 days.

     

Use of O2 consumption and CO2 production in kinetic cells to delineate pyrite oxidation-carbonate buffering and microbial respiration in unsaturated media

Identifying zones of sulphide oxidation and carbonate buffering is important in the development of a management plan for mine waste-rock piles. In this study, we used a kinetic cell technique to measure rates of O2 consumption and CO2 production in low sulphide (<0.12 wt.% S), low inorganic carbon (<0.20 wt.% C(inorganic)), gneissic waste rock and associated organic-rich lake sediment (0.7 wt.% C(organic)), and forest soil (1.4 wt.% C(organic)) collected from the Key Lake uranium mine in Saskatchewan, Canada. Solid chemistry, stable carbon isotope, pore water sulphate concentration data, and stoichiometric considerations indicated that O2 consumption and CO2 production were constrained by microbial respiration in the lake sediment and forest soil and by pyrite oxidation-carbonate buffering in the gneissic waste rock. Mean ratios of molar CO2 production to O2 consumption rates were 0.5 for lake sediment, 0.7 for forest soil, and 0.2 for gneissic waste rock. The different O2/CO2 ratios suggested that O2-CO2 monitoring may provide a practical tool for identifying the zones of microbial respiration and pyrite oxidation-carbonate buffering in mine waste-rock piles. Rates of O2 consumption and CO2 production were about one order of magnitude greater in lake sediment than in gneissic waste rock, indicating that microbial respiration would exert a control on the distribution of O2 and CO2 gas in waste-rock piles constructed upon the dewatered lake sediments.     

Alkali borosilicate glass by fly ash from a coal-fired power plant

The possibility of using coal fly ash as a silica source for alkali borosilicate glass was investigated. Alkali borosilicate glasses were prepared from the coal fly ash mixed with 30 wt.% reagents composed of Na(2)O and B(2)O(3) by susceptor-induction heating. Their densities ranged from 2.24 to 2.55 g cm(-3) and decreased as the amount of B(2)O(3) addition increased. However, the Vickers microhardness showed a different tendency with the density since the glass network connectivity improved by boron anomaly, which was identified by a nuclear magnetic resonance analysis. The Vickers microhardness of the glass product, with the addition of 15 wt.% B(2)O(3) and 15 wt.% Na(2)O, was about 4030 MPa. Furthermore, the changes in microstructure were consistent with those in the chemical stability by the toxicity characteristic leaching procedure (TCLP).     

Combined use of a transformed red mud reactive barrier and electrokinetics for remediation of Cr/As contaminated soil

A reactive barrier (RB) of transformed red mud (TRM), a by-product of the refinement of bauxite in alumina production, was placed adjacent to the anode of an electrokinetic (EK) system with the aim of enhancing removal of chromium or arsenic, added singly to a low permeability clayey soil, and favouring entrapment. The innovative study focused on evaluation of the synergic interaction between the EK system and the RB, and of the efficiency when compared to traditional EK remediation (control tests). The results obtained underlined the successful outcome of treatment of the Cr(VI)-contaminated soil. In presence of the TRM RB, 19.4% wt. of total Cr content was detected in the anolyte and 20.6% wt. trapped in the anodic RB after 6 d, versus 6.6% wt. in the anolyte and 8.8% wt. in the soil adjacent to the anode following the control run without RB. On increasing duration of treatment up to 12 d, 60.8% wt. of total initial Cr was found in the anolyte and 25.5% wt. trapped in the RB, versus 9.1% wt. and 5.3% wt., respectively, after a control run of the same duration. Finally, on increasing the mass of TRM in the RB, 60.6% wt. of initial Cr content was found to have accumulated in the RB, with Cr being completely absent from the anodic chamber. Conversely, combined treatment was much less effective on As contaminated soil, at least under the operative conditions applied. Low initial As concentration and interference with iron oxides in the soil were likely the reasons underlying low efficiency while attempting As decontamination.     

Enhancement of p,p'-DDT photodegradation on soil surfaces using TiO2 induced by UV-light

Enhancement of p,p'-DDT photodegradation on soil surfaces using TiO2 induced by UV-light was mainly investigated in this work. After being spiked with p,p'-DDT, soil samples loaded with different doses of TiO2 (0%, 0.5%, 1%, 2%, and 3% wt) were exposed to UV-light irradiation for 24 h. The results indicated that the photodegradation of p,p'-DDT followed the pseudo-first-order kinetics. TiO2 accelerated the photodegradation of p,p'-DDT significantly as indicated by the half-life reduction from 23.3 h to 10.4 h, corresponding to the TiO2 content from 0% to 3% respectively. In addition, the effects of soil pH, photon flux and humic substances on p,p'-DDT degradation were investigated. The photodegradation rate increased with the increase of the soil pH and photon flux. The humic substances (2% wt) inhibited the p,p'-DDT photodegradation by reducing the amount of light available to excite the p,p'-DDT and TiO2 or by quenching radicals capable of oxidizing p,p'-DDT. p,p'-DDE, p,p'-DDD and DDMU were main degradation intermediates and they were further degraded in the presence of TiO2.     

The promoter effect and a rate expression of the catalytic incineration of (CH3)2S2 over an improved CuO-MoO3/gamma-Al2O3 catalyst

The CuO-MoO3/gamma-Al2O3 catalyst, confirmed previously as having good activity in the catalytic incineration of (CH3)2S2, was employed as the principal catalyst in this study. With the aim of improving catalyst activity and resistance to deactivation by sulfur compounds, a promoter was added either before adding the precursors of Cu and Mo or together with Cu and Mo onto the gamma-Al2O3. Promoters included transition metals and elements from groups IA-VIIA in the chemical periodic table. Experimental results reveal Cr2O3 as the most effective promoter, with an optimal composition of 5 wt.% Cu, 6 wt.% Mo and 4 wt.% Cr (designated as Cu(5)-Mo(6)-Cr(4)/gamma-Al2O3). Knowing that higher acidity can improve activity, we further investigated the effect of acid treatment on the performance of the Cu(5)-Mo(6)-Cr(4)/gamma-Al2O3 catalyst. Experimental results indicate the H2SO4-treated catalyst (Cu(5)-Mo(6)-Cr(4)/sulfated-gamma-Al2O3) has a better activity and durability. A study for finding an appropriate rate expression for the catalytic incineration of (CH3)2S2 by Cu(5)-Mo(6)-Cr(4)/sulfated-gamma-Al2O3 was carried out in a differential reactor. The results show that the Mars-Van Krevelen model is applicable to this destructive oxidation reaction. Results additionally reveal that competitive adsorption of CH4 reduces conversion of (CH3)2S2.     

Matrine and oxymatrine in corroborant plant extracts and fertilizers: HPLC/MS-MS method development and single-laboratory validation

A reversed phase high-performance liquid chromatographic method (HPLC/MS-MS) has been developed and validated for detection of alkaloids matrine and oxymatrine in fertilizer with labeled enhancer plant defense activities. The analytical method was validated statistically. The results show a strong matrix effect, requiring quantification by standard addition method. The regression lines showed r² > 0.994. Recoveries ranging from 97 to 104% were obtained for the fortification level of 0.01% wt wt^?1 and the relative standard deviations ranged from 3 to 4% (n = 10). The limits of detection were below 0.0001% wt wt^?1, while the limits of quantification did not exceed 0.0004% wt wt^?1. The method is currently applied in ICQRF Laboratory of Catania on fertilized and corroborant plant extract collected in the Italian market in the frame of MIPAAF institutional quality control activity, with the aim to dectect these unpermitted active substances.     

Lead concentrations in birds of prey in Britain

This paper reports on lead (Pb) concentrations in the livers of 424 individuals of 16 raptor species found dead and sent for analysis to the Institute of Terrestrial Ecology, Monkswood, from the early 1980s to the early 1990s. Elevated Pb concentrations in liver (>20 ppm dry wt), within the range associated with Pb poisoning mortality in raptors, were recorded in one peregrine (4% of species sample) and one buzzard (2% of species sample). These birds are likely to have ingested lead gunshot in the flesh of their prey. Another one each of these species had liver Pb concentrations of 15-20 ppm dry wt, reflecting unusually high absorption of Pb. No individuals of any other species had >15 ppm dry wt liver Pb, although some had 6-15 ppm. The source of Pb in these birds was unknown, but it could have resulted from high Pb concentrations in prey items, including some containing lead shot. Median liver Pb concentrations were generally very low (ranging from <0.07 to 1.61 ppm dry wt for species with sample sizes exceeding 10). In sparrowhawks, for which a large sample was available, liver Pb concentrations in all but one individual were low (<2.6 ppm dry wt). Pb concentrations in juveniles were significantly lower than in adults, and were lowest in recently fledged birds.     

Nickel speciation of residual oil fly ash and ambient particulate matter using X-ray absorption spectroscopy

The chemical speciation of Ni in fly ash produced from approximately 0.85 wt % S residual (no. 6 fuel) oils in laboratory (7 kW)- and utility (400 MW)-scale combustion systems was investigated using X-ray absorption fine structure (XAFS) spectroscopy, X-ray diffraction (XRD), and acetate extraction [1 M NaOAc-0.5 M HOAc (pH 5) at 25 degrees C]-anodic stripping voltammetry (ASV). XAFS was also used to determine the Ni speciation of ambient particulate matter (PM) sampled near the 400-MW system. Based on XAFS analyses of bulk fly ash and their corresponding acetate extraction residue, it is estimated that > 99% of the total Ni (0.38 wt %) in the experimentally produced fly ash occurs as NiSO4.xH2O, whereas > 95% of the total Ni (1.70 and 2.25 wt %) in two fly ash samples from the 400-MW system occurs as NiSO4.xH2O and Ni-bearing spinel, possibly NiFe2O4. Spinel was also detected using XRD. Acetate extracts most of the NiSO4.xH2O and concentrates insoluble NiFe2O4 in extraction residue. Similar to fly ash, ambient PM contains NiSO4.xH2O and NiFe2O4; however, the proportion of NiSO4.xH2O relative to NiFe2O4 is much greater in the PM. Results from this and previous investigations indicate that residual oil ash produced in the 7-kW combustion system lack insoluble Ni (e.g., NiFe2O4) but are enriched in soluble NiSO4.xH2O relative to fly ash from utility-scale systems. This difference in Ni speciation is most likely related to the lack of additive [e.g., Mg(OH)2] injection and residence time in the 7-kW combustion system.     

Promotional effect of ZrO2 and WO3 on bimetallic Pt-Pd diesel oxidation catalyst

Environmental Science and Pollution Research - Diesel oxidation catalysts Pt-Pd-(y)ZrO2-(z)WO3/CeZrOx-Al2O3 with total Pt &amp; Pd loading of only 0.68 wt.% were prepared and investigated for...     

Color removal from wastewater using a synthetic high-performance antifouling GO-CPTMS@Pd-TKHPP/polyether sulfone nanofiltration membrane

Modified graphene oxide with 5,10,15,20-tetrakis-(4-hexyloxyphenyl)-porphyrin and palladium (II) (signified by GO-CPTMS@Pd-TKHPP) prepared as a novel antifouling polyether sulfone (PES) blended nanofiller membrane. The membrane efficiency has been analyzed such as pure water flux (PWF), hydrophilicity, and antifouling features. By increasing of modified graphene oxide percentage from 0 to 0.1 wt.% in the polymer matrix, the PWF was incremented from 14.35 to 37.33 kg/m²·h at 4 bar. The membrane flux recovery ratio (FRR) has been investigated by applying powdered milk solution; the FRR results indicated that the 0.1 wt.%-modified graphene oxide membrane showed a positive effect on fouling behavior with Rir and FRR value 8.24% and 91.76%, respectively. The nanofiltration membrane performance was assessed applying the Direct Red 16 dye rejection. It was demonstrated that the optimal membranes (0.1 wt.%-modified graphene oxide) had notable dye removal (99.58% rejection). The results are also verified by measuring the scanning electron microscopy (SEM), water contact angle (WCA), and atomic microscopy analysis (AFM).

     

The sorption of hydrogen sulfide from hot syngas by metal oxides over supports

Six 5 wt.% metal sorbents including Mn, Fe, Cu, Co, Ce and Zn supported on gamma-Al2O3, prepared by the incipient wetness impregnation method with calcination at 700 degrees C for 2 h, have been investigated for sorption of hydrogen sulfide in the temperature range of 500-700 degrees C. The sorption experiments were conducted in a fixed-bed reactor in terms of breakthrough curves and characterized by X-ray powder diffraction. The results reveal that the copper and manganese sorbents exhibit the best performance because they provide nearly 100% utilization, but the copper sorbent has a lower sulfur sorption capacity compared with the manganese sorbent. The zinc and cerium sorbents are not good candidates attributed to the vaporization of zinc and unexpected product for cerium. Effects of support materials on 5 wt.% manganese were also investigated by using gamma-Al2O3, SiO2 and TiO2 in this study. Five weight percent Mn/gamma-Al2O3 shows the best performance among support candidates. On the basis of XRPD and BET surface area analysis, TiO2 appears a huge loss in BET surface area associated with a significant formation of rutile form.     

Hydrocarbons in Sand Crabs (Emeritaanaloga) from Southern California (U.S.A.)

$\text{Emerita}$$\text{analoga}$ (Crustacea:Hippidae) from three southern California (U.S.A.) beaches contained 0.9 to 24.1 μg/g dry wt saturated hydrocarbons, and 3.6 to 21.4 μg/g dry wt unsaturated hydrocarbons. Major constituents were (in wt. % total): n-alkanes (13.1%), heneicosapentaene plus heneicosahexaene (1.0%), squalene (5.1%), and unidentified polyenes (7.8%). Crabs from beaches exposed to small boat traffic and natural oil seepage were slightly and severely tainted, respectively, with petroleum hydrocarbons. Animals from San Nicolas Island (85 km offshore) contained only biogenic compounds.     

One-part alkali-activated slag binder for cemented fine tailings backfill: proportion optimization and properties evaluation

In this study, a one-part alkali-activated slag (AAS) composed of ground-granulated blast furnace slag, desulfurized gypsum, and hydrated lime is proposed as alternative to cement for the production of cemented fine tailings backfill (CFTB), which is an environmentally friendly binder consisting of 93.72 wt.% industrial solid waste. Results show that AAS with 67.83 wt.% slag, 25.92 wt.% desulfurized gypsum, and 6.25 wt.% hydrated lime yields the highest strength, which is 1.7–3.2 times that of ordinary Portland cement (OPC). Aside from calcium silicate hydrate gel, appreciable quantity of ettringite characterized by interlocking needles structure and high bound water is also produced during the AAS hydration process. In addition, the hydration heat of the AAS binder is 48% less than that of OPC. Moreover, CFTB made of AAS provides better workability than that of CFTB with OPC up to 20 h. The findings of this study will contribute to the production of more cost-effective, durable, and environmental-friendly cemented fine tailings backfill.

     

Residues of chlorpyrifos-methyl in balsam fir foliage, forest litter, soil, stream water, sediment and fish tissue after double aerial applications of Reldan

Chlorpyrifos-methyl was applied twice at 70 g A.I./ha by means of a fixed-wing aircraft to a mixed coniferous forest near Allardville, New Brunswick. Residue in balsam fir foliage was highest (1 ppm wet wt) 1 hr after spraying and rapidly declined to about 30% within 1 day, but persisted at a very low level (0.03 ppm wet wt) for 125 days. Current year's foliage contained a higher level of residue than old foliage. Chlorpyrifos-methyl persisted longer in forest litter than in soil. After 125 days, trace amounts (less than 6 ppb wet wt) were still found in litter but were not detected in soil. In stream water the residue dissipated very rapidly; more than 90% disappeared 3 hours after the second application and were not detected after 4 days. Low-level residue (less than 0.1 ppm wet wt) was present in the sediment and persisted for 10 days. Although brook trout and slimy sculpin captured in the stream within 3 days of the second application contained residues (less than 0.05 ppm fresh wt) none were detected in any fish captured, 9 and 47 days later.     

Ozone treatment of soil contaminated with aniline and trifluralin

Column studies were conducted to determine the ability of ozone to degrade aniline and trifluralin in soil. Ozone rapidly degraded aniline from soil under moist soil conditions, 5% (wt). Removal of 77-98% of [UL-14C]-aniline was observed from soil columns (15 ml, i.d. = 2.5 cm), exposed to 0.6% O(3) (wt) at 200 ml/min after 4 min. Initial ozonation products included nitrosobenzene and nitrobenzene, while further oxidation led to CO(2). Ring-labeled-[UL-14C]-trifluralin removal rates were slower, requiring 30 min to achieve removals of 70-97%. Oxidation and cleavage of the N-propyl groups of trifluralin was observed, affording 2,6-dinitro-4-(trifluoromethyl)-aniline, 2,6-dinitro-N-propyl-4-(trifluoromethyl)-benzamine, and 2,6-dinitro-N-propyl-N-acetonyl-4-(trifluoromethyl)-benzamine. Base solutions revealed that trifluralin was similarly oxidized to CO(2), where 72-83% of the activity recovered comprised 14CO(2). Use of ozone-rich water improved contaminant removal in trifluralin-amended soil columns, but did not improve removal in aniline, pentachloroaniline, hexachlorobenzene amended soil columns, suggesting that ozonated water may improve contaminant removal for reactive contaminants of low solubility.     

Organohalogen compounds in human breast milk from Republic of Buryatia, Russia

Human breast milk samples collected during 2003/04 in Buryatia, a Russian autonomous republic, were analyzed in order to assess human exposure to organohalogen compounds including organochlorine pesticides, polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs). When compared with available worldwide data, levels of HCB (23-880 ng/g lipid wt.), PCBs (69-680 ng/g lipid wt.), and HCHs (100-3700 ng/g lipid wt.) were relatively high, indicating elevated human exposure to these organochlorines (OCs) in Buryatia. In contrast to OCs, PBDE concentrations were low (0.46-1.7 ng/g lipid wt.). Out of 14 BDE congeners analyzed, BDE-28, BDE-47, BDE-100, BDE-153, BDE-197, and BDE-207 were detected. Estimated daily intakes (EDIs) of HCHs, HCB, CHLs, and PCBs by infants solely from human milk for 100%, 43%, 34%, and 17% of the samples, respectively, exceeded guideline thresholds. Although high EDIs raise concern for possible toxic effects of OCs, women in Buryatia are recommended to breastfeed due to numerous advantages of breastfeeding for mother and child.     

Amelioration of acidic soil using various renewable waste resources

In this study, improvement of acidic soil with respect to soil pH and exchangeable cations was attempted for sample with an initial pH of approximately 5. Acidic soil was amended with various waste resources in the range of 1 to 5 wt.% including waste oyster shells (WOS), calcined oyster shells (COS), Class C fly ash (FA), and cement kiln dust (CKD) to improve soil pH and exchangeable cations. Upon treatment, the soil pH was monitored for periods up to 3 months. The exchangeable cations were measured after 1 month of curing. After a curing period of 1 month, a maize growth experiment was conducted with selected-treated samples to evaluate the effectiveness of treatment. The treatment results indicate that in order to increase the soil pH to a value of 7, 1 wt.% of WOS, 3 wt.% of FA, and 1 wt.% of CKD are required. In the case of COS, 1 wt.% was more than enough to increase the soil pH value to 7 because of COS's strong alkalinity. Moreover, the soil pH increases after a curing period of 7 days and remains virtually unchanged thereafter up to 1 month of curing. Upon treatment, the summation of cations (Ca, Mg, K, and Na) significantly increased. The growth of maize is superior in the treated samples rather than the untreated one, indicating that the amelioration of acidic soil is beneficial to plant growth, since soil pH was improved and nutrients were replenished.     

Residues of chlorpyrifos‐methyl in balsam fir foliage,forest litter,soil, stream water,sediment and fish tissue after double aerial applications of Reldan®

Abstract

Chlorpyrifos‐methyl was applied twice at 70 g A.I./ha by means of a fixed‐wing aircraft to a mixed coniferous forest near Allardville, New Brunswick. Residue in balsam fir foliage was highest (1 ppm wet wt) 1 hr after spraying and rapidly declined to about 30% within 1 day, but persisted at a very low level (0.03 ppm wet wt) for 125 days. Current year's foliage contained a higher level of residue than old foliage. Chlorpyrifos‐methyl persisted longer in forest litter than in soil. After 125 days, trace amounts (< 6 ppb wet wt) were still found in litter but were not detected in soil. In stream water the residue dissipated very rapidly; more than 90% disappeared 3 hours after the second application and were not detected after 4 days. Low‐level residue (< 0.1 ppm wet wt) was present in the sediment and persisted for 10 days. Although brook trout and slimy sculpin captured in the stream within 3 days of the second application contained residues (< 0.05 ppm fresh wt) none were detected in any fish captured, 9 and 47 days later.     

Exposure to PCBs, through inhalation, dermal contact and dust ingestion at Taizhou, China--a major site for recycling transformers

Air samples containing gaseous and particulate phases were collected from e-waste workplaces and residential areas of an intensive e-waste recycling area and compared with a reference site. The highest total concentration of PCBs was detected at transformer recycling workshops (17.6 ng m(-3)), followed by the residential area (3.37 ng m(-3)) at Taizhou, and the lowest was obtained at the residential area of the reference site, Lin'an (0.46 ng m(-3)). The same trend was also observed with regards to PCB levels in dust samples. The highest average PCBs level of 2824 ng g(-1) (dry wt) was found in the transformer recycling workshops, and was significantly higher than that of residential areas of Taizhou (572 ng g(-1) dry wt) and Lin'an (42.4 ng g(-1) dry wt). WHO-PCB-TEQ level in the workshops of Taizhou was 2216 pg TEQ(1998)g(-1) dry wt or 2159 pg TEQ(2005)g(-1) dry wt, due to the high abundance of PCB 126 (21.5 ng g(-1) dry wt), which contributed 97% or 99% of WHO-PCB-TEQs. The estimated intake of PCBs via dust ingestion and dermal absorption by transformer recycling workers were 77.5×10(-5) and 36.0×10(-5) pg WHO-PCB-TEQ(1998)kg(-1)d(-1), and 67.3×10(-5) and 31.3×10(-5) pg WHO-PCB-TEQ(2005)kg(-1)d(-1), respectively.