Photocatalytic Oxidation of Reactive Red 22 in Aqueous Solution Using La2Ti2O7 Photocatalyst

This study was focused on the application of a highly doped layered perovskite, La₂Ti₂O₇, as the photocatalyst for the photocatalytic decomposition of an azo dye, Reactive Red 22 (RR22). The temporal behavior of the photocatalytic decomposition of RR22 in aqueous solution by the UV/La₂Ti₂O₇ with a batch photoreactor operated in a recirculation mode was studied under various operating conditions including solution pH, light intensity, and La₂Ti₂O₇ loading. The decomposition of RR22 in aqueous solution by La₂Ti₂O₇ photocatalytic process was found to be feasible. An empirical kinetic equation was developed for modeling the photocatalytic decomposition of RR22 in aqueous solution using UV/La₂Ti₂O₇ photocatalytic processes.     

The Oxidation of Di-(2-Ethylhexyl) Phthalate (DEHP) in Aqueous Solution by UV/H2O2 Photolysis

The oxidation of di-(2-ethylhexyl) phthalate (DEHP) in solution using UV/H₂O₂ and direct UV photolysis are analyzed in this study. It was found that DEHP was 100% removal in the solution by 180-min UV/H₂O₂ treatment and 73.5% removal by 180-min direct UV photolysis. The effect of different factors, such as DEHP concentration, H₂O₂ concentration, and UV light intensity, on photochemical degradation was investigated. The degradation mechanism of DEHP and the acute toxicity of intermediates were also studied. The photochemical degradation process was found to follow pseudo-first-order kinetics. The results of our study suggested that the concentration with 40 mg/L H₂O₂ and 5 μg/mL DEHP in the solution at pH 7 with 10.0?×?10^?6 Einstein l^?1?s^?1 UV was the optimal condition for the photochemical degradation of DEHP. The photochemical degradation with UV/H₂O₂ can be an efficient method to remove DEHP in wastewater.     

Diazinon Accumulation and Dissipation in Oryza sativa L. Following Simulated Agricultural Runoff Amendment in Flooded Rice Paddies

Flooded post-harvest rice paddies were examined as systems for reducing diazinon (organophosphate insecticide) concentrations in stormwater runoff. Two paddies were cultivated in Oryza sativa L. and amended with a 3-h simulated stormwater diazinon runoff event. Initial diazinon adsorption peaked at 347 and 571 μg kg^?1 (3% mass load reduction) for mean above-ground plant tissue concentrations in each pond, respectively. Subsequent senescence of above-ground tissue showed significant decreases in tissue mass (r ²?=?0.985) and adsorbed diazinon mass (90?±?4% and 82?±?1%) within 1 month of amendment. There were no corollary increases in water column diazinon concentrations. Furthermore, control O. sativa tissue placed within the treatment ponds had below-detectable levels of diazinon throughout the decomposition phase, suggesting a lack of within pond transference of dissipated diazinon. This study shows the relative effectiveness of diazinon adsorption by post-harvest rice plants and a potential mitigation strategy of senescence and pesticide degradation for contaminated tailwater.     

Decomposition of Gaseous Acetone in an Annular Photoreactor Coated with TiO2 Thin Film

Photocatalytic decomposition of gaseous acetone was studied with a fixed-bed annular reactor using TiO₂ as the photocatalyst. The relation of UV light intensity to the reaction rate was found to be roughly first-ordered. The decomposition of acetone was obviously enhanced with increasing retention time. Removal of acetone was slightly increased with the relative humidity for experiments conducted with relative humidity below 20%. However, the removal of acetone was decreased drastically with relative humidity for experiments conducted with relative humidity greater than 20%. Decomposition of acetone was promoted considerably with increasing oxygen concentration for experiments conducted with oxygen less than 200,000 ppmv, yet the decomposition of acetone was kept relatively constant for experiments conducted with oxygen above 200,000 ppmv. Based on the mass balance for carbon species, the amount of organic intermediates formed for experiments conducted under various conditions were found to be minimal. Experimental results for the decomposition of gaseous acetone by UV/TiO₂ process can be adequately described by the developed two-site Langmuir–Hinshelwood (L–H) kinetic model.     

Effects of Dissolved Water Constituents on the Photodegradation of Fenitrothion and Diazinon

The photochemical degradation of two widely used organophosphorothioate insecticides, fenitrothion and diazinon, was investigated in aqueous solutions containing three separate dissolved constituents commonly found in natural waters (NO₃⁻, CO₃²⁻ and dissolved organic matter (DOC)). The effect of these constituents on pesticide photodegradation was compared to degradation in “constituent-free” pure water. Solutions were irradiated in an Atlas solar simulator fitted with a UV-filtered Xenon arc lamp with light irradiances (500 W m⁻²) measured using a spectral radiometer to allow derivation of quantum yields of degradation. Fenitrothion absorbs light within the solar UV range (λ, 295–400 nm) and underwent direct photolysis in pure water whereas diazinon (λ _max ∼250 nm) showed no observable loss over the experimental period. However, photodegradation conforming to pseudo-first-order kinetics was observed for both chemicals in the presence of the dissolved constituents (at concentrations typically observed in natural waters), with the rates of photodecay observed in the order of NO₃⁻ > CO₃²⁻ ≅ DOC, with the highest rates observed in the 3 mM NO₃⁻ solutions (k _Fen = 0.155 ± 0.041 h⁻¹; k _Dia = 0.084 ± 0.0007 h⁻¹). For diazinon this rate was comparable to fenitrothion photolysis in pure water (k _fen 0.072 ± 0.0078 h⁻¹), highlighting the importance of NO₃⁻ on a non-photolabile pesticide, with indirect photodegradation probably attributable to the light-induced release of aqueous hydroxyl radicals (^·OH) from NO₃⁻. Suwannee river fulvic acid (serving as DOC) did not statistically affect the rate of photodecay for fenitrothion relative to its photolysis in MilliQ water, although measured rates in DOC solutions were slightly lower. However, measurable rates of photodecay were apparent for diazinon in the DOC solutions, indicating that fulvic acid, possibly in the form of “excited” triplet-state-DOC plays a role in diazinon transformation. Hydrolysis was not apparent for fenitrothion (in buffered solutions of pH 5–9) but was notable for diazinon at the lower pHs of 5 and 3 (k _Dia-hyd 0.3414 h⁻¹ at pH 3 and 0.228 h⁻¹ at pH 5), resulting in the formation of the degradate, 2-isopropyl–6-methyl–4-pyrimidinol. This work highlights the importance of dissolved constituents on abiotic photodegradation of pesticides and it is recommended that these constituents be incorporated into laboratory-based fate-testing regimes.     

Photodecomposition of an acaricide,fenazaquin, in aqueous alcoholic solution

Fenazaquin (I) is a new acaricide of the quinazoline class. The photodecomposition of I was studied in aqueous methanolic and 2-propanolic solution under UV light (30 h) and sunlight (70 h) separately. The photolytic half-lives in aqueous methanolic solution were found to be 17.1 h (UV) and 38.1 h (sunlight), whereas these were 12.9 h (UV) and 29.2 h (sunlight) for aqueous 2-propanolic solution; all followed a first-order reaction kinetics. Six photoproducts were obtained: beta-phenyl (p-tert-butyl) ethyl alcohol (II), 4-hydroxyquinazoline (III), p-tert-butyl vinyl benzene (IV), 2,4-dihydroxyquinazoline (V), phenyl (p-tert-butyl) acetic acid (VI), and 2-methyl-2-[4'-(2' '-hydroxyethyl)phenyl]propanoic acid (VII). Compounds VI and VII could be isolated only from aqueous 2-propanolic solution under sunlight irradiation. The major degradation products are formed as a result of cleavage of the ether bridge linking the quinazoline and phenyl ring systems of the molecule, oxidation of the tert-butyl substituent, and oxidation of the heterocyclic portion of the quinazoline ring. A probable mechanism of formation of the photoproducts is also suggested.     

Effects of Silver on the Photocatalytic Degradation of Gaseous Isopropanol

Water, Air, & Soil Pollution - The decomposition of gaseous isopropanol (IPA) by UV/TiO2 process in an annular photoreactor was studied under various conditions such as UV light intensity and...     

Management strategy,uptake and translocation of nitrogen in tidal flooded rice ecosystem

Abstract

Enhancing rice yield is a great challenge for rice growers in the tidal flooded ecosystem, where poor agronomic management is one of the major constrains. Improve management practice (IMP) was compared with traditional farmers’ practice (TFP) in evaluating rice productivity, nutrient uptake, translocation and farm income in tidal flooded ecosystem. Results revealed that, IMP significantly produced higher number of panicles m^?2, more grain panicle^?1 and better grain filling. The rice cultivars produced 2.0 to 2.5 t grain ha^?1 with TFP, while 3.0 to 4.0 t ha^?1 with IMP. In different rice cultivars, the grain yield in IMP increased 12 to 60% over TFP. Similarly, the grains in IMP treatment absorbed 21.41 to 57.03?kg N ha^?1 whereas only 15.85 to 46.94?kg N ha^?1 in TFP plot. However, higher nitrogen (N) transfer from shoot to grain in IMP also suggests that the amount of N in soil was too low to meet the plant demand in TFP. Although, the IMP involved additional cost, but it gave significantly higher gross return (438 to 954?US$ha^?1) and margin (397 to 913?US$ha^?1) which added farm income upto 225?US$ha^?1 over TFP. Hence, it could be concluded that IMP is a potential option for increasing grain yield and farm income during aman season in the tidal flooded ecosystem.     

阿特拉津在土表的紫外光降解行为研究

本文研究了阿特拉津在土壤表面的紫外光光解的动力学,并研究了各种因素对光解的影响。实验表明,土壤粒度、湿度、pH值、有机质、腐殖酸和表面活性剂都影响阿特拉津在土壤中的降解。在紫外光辐射下,阿特拉津在土壤表面降解速率常数为(0.09~0.17)/min,光解深度为0.1~0.3mm,半衰期为4~8min。     

Biotisch und abiotisch gesteuerter Abbau von organischer Substanz im Boden

Biotic and abiotic decomposition of organic matter in soils The problem area of organic matter decomposition in soils by biotic, abiotic and photochemical mechanisms is tested under administration of uniformly ¹⁴C-labelled wheat straw, humic of fulvic acids; furthermore by the use of conventional methods. In four separate test runs, based on Hapludalf-Ah soil, formed in loess, as well as on Ah soil of a spodic Dystrochrept in pleistocene sand, measurements over years - altogether 57 measurement cycles - revealed similar decomposition rates of ¹⁴C fulvic and 14C humic acid. The approximate magnitudes of turnover were: biotic: abiotic (Hg-sterilization): biotic + UV-irradiation: abiotic + UV-irradiation = 100:20:70:50. The sterilized samples continued to release CO₂. Biotic + UV showed losses, compared with biotic, by partial UV sterilization. Abiotic + UV indicated increasing CO₂ release, compared with abiotic only, due to additional photochemical decomposition. In a larger program with radioactive as well as conventional methods of CO₂ measurement decomposition rates in different soils were tested under biotic, abiotic and photochemical condition in presence of metal ions, such as iron, aluminium, copper, zinc, lead and mercury. The impact by the added metals can be summerized as follows: Calcium and aluminium are favoring the organic matter decomposition under biotic conditions, while mercury, lead, copper, zinc and iron are rather inhibitive. Contrary, under biotic/steril conditions copper and especially mercury, further zinc and lead, at lower extent also calcium, impede CO₂ liberation. Since there are but small differences among the various test soils, soil own parameters seem to exert under abiotic conditions low importance only. Under UV irradiation calcium had in the biotic milieu high, in the steril/abiotic milieu a lower increasing effect upon COz liberation. Also iron indicates a stimulating effect under contemporary UV irradiation, which at lower level applies to lead and mercury too, particularly in connection with the sandloess Hapludalf of Harburg. Based on the observed CO₂ release also under abiotic/steril conditions final tests were conducted with calcinated quartzsand in contrast to soil, otherwise again under biotic, abiotic, as well as biotic or abiotic + UV conditions. Also in these calcinated sands ¹⁴CO₂ release from the ¹⁴C labelled straw continued. Addition of increasing amounts of aluminiumlactate causes decreasing ¹⁴CO₂ rates. An even stronger inhibition was produced by addition of zinclactate.     

Influences of ultra‐violet (UV)‐blue light radiation on the growth of cotton. II. Photosynthesis,leaf anatomy,and iron reduction

Cotton (Gossypium hirsutum L.) plants grown under low pressure sodium lamps (LPS) developed chlorosis which was similar in appearance to iron‐stress induced chlorosis, while plants under cool white fluorescent lamps (CWF) at the same level of photosynthetically active radiation (PAR) developed normally. These illumination sources differ in spectral irradiance; CWF lamps emit ultra violet (UV), whereas LPS lamps do not. Ultraviolet radiation is capable of reducing Fe³⁺ to Fe²⁺ through a chlorotic leaf which may be important in establishing an active iron fraction in the leaf. Root reduction of Fe³⁺ to Fe²⁺ was lacking in Fe‐stressed cotton under LPS light, but was present under CWF light. Net photosynthesis, photosynthetic electron transport, and leaf chlorophyll content were lower under LPS than CWF light in most of the growing media studies (soil or solutions with nitrate‐ or ammonium‐nitrogen supplied). Chloroplast ultrastructure and leaf thickness were also altered by LPS irradiance. Electron microscopic studies with plants grown in nutrient solutions for 4 weeks suggested that chioroplastic granal disorganization was more directly associated with diminished iron supplies than with light source. However, plants grown in soil for 6 weeks under LPS light had granal disorganization similar to that found in iron‐stressed plants. These studies suggest an important role for UV radiation in influencing the activity of iron in plants.     

No UV enhancement of litter decomposition observed on dry samples under controlled laboratory conditions

In field studies, various workers have observed a stimulation of organic matter breakdown by visible light and UV radiation. We aimed to confirm the involvement of UV radiation under controlled laboratory conditions and quantify the magnitude of any stimulation. Grass and pine foliage samples were oven-dried and continuously exposed to UV radiation at room temperature for up to 60 days. A range of UV flux densities was established using shading to different levels. After UV exposure under air-dry conditions, samples were rewetted and incubated in the dark with microbial inoculums to investigate whether UV exposure had rendered samples more susceptible to subsequent microbial decomposition.However, we found no weight loss associated with different UV flux densities. The same finding held true for grass and pine litter samples. Similarly, microbial decomposition of either grass or pine litter was not enhanced by prior UV exposure. These findings suggest that UV-induced photooxidation of dry materials cannot be responsible for the observed apparent enhancement of weight loss of litter samples under UV exposure in the field.     

2,4-D丁酯的水解与光解特性研究

通过室内模拟试验,研究2,4-D丁酯在不同pH值和温度下的水解动态和在有机溶剂中的光解特性。结果表明,2,4-D丁酯的水解与光解均符合一级动力学方程。在pH7以下的缓冲溶液中,2,4-D丁酯的水解反应十分缓慢,但在碱性溶液中其水解速率加快。25℃下2,4-D丁酯在pH5、7和9的缓冲溶液中的水解半衰期分别为23.5、5.8d和10.7min。2,4-D丁酯的水解速率随温度升高而增加,在温度为15、25℃和35℃的pH7缓冲溶液中的水解半衰期分别为21.5、5.8、3.9d,平均温度效应系数为2.57。2,4-D丁酯水解反应的活化能与温度之间无明显相关性,而活化熵与温度呈显著相关性。2,4-D丁酯的水解主要由活化熵所驱动。采用GC-MS技术对2,4-D丁酯水解产物进行鉴定,确定水解产物主要是2,4-二氯苯氧乙酸和2,4-二氯苯酚。2,4-D丁酯在正己烷中光解速率比在甲醇中快,在丙酮中几乎不发生光解,其光解速率随浓度的升高而减慢。     

Interactions between N fertilization, grass clipping addition and pH in turf ecosystems: Implications for soil enzyme activities and organic matter decomposition

Turf has been acknowledged as an important ecosystem with potential for soil C sequestration. As a major process dictating soil C storage, organic matter decomposition has received little attention in turf systems. Given that soil enzyme-catalyzed biochemical reactions are the rate limiting steps of organic matter decomposition, we examined the activities of oxidative and hydrolytic soil enzymes and their relations with soluble organic compounds and soil C and N mineralization in two turf chronosequences with contrasting soil pH and in response to N fertilization and grass clipping addition. In comparison with turf ecosystems under acidic soil, phenol oxidase activity was about two-fold greater in turf ecosystems under alkaline soil and positively correlated to about two-fold differences in soluble phenolics and dissolved organic C between alkaline and acidic soils. However, the activities of hydrolytic enzymes including cellulase, chitinase, and glucosidase were lower in alkaline soil. It appears that the high concentration of soluble phenolics inhibited the activities of hydrolytic enzymes that in turn limited the decomposition of dissolved organic C and resulted in its accumulation in alkaline soil. Nitrogen mineralization was comparable between alkaline and acidic soils, but CO₂ evolution was about two-fold greater in alkaline soil, possibly due to considerable abiotic carbonate dissolution. We observed that mineral N input at 60 mg N kg⁻¹ soil had very minor negative effects on the activities of both phenol oxidase and hydrolytic enzymes. Grass clipping addition did not affect the activity of phenol oxidase, but increased the activities of soil chitinase, cellulase, glucosidase, and glucosaminidase by up to 20% and also soluble phenolics in soil by about 10%. Our results suggest that soil phenol oxidase might regulate the activities of hydrolytic soil enzymes via its control on soluble phenolics and function as an ‘enzymatic latch’ to hold soil organic C in highly managed turf ecosystems. While soil pH is important to affect phenol oxidase activity and therefore decomposition, management practices, i.e., N fertilization and grass clipping addition may indirectly affect the decomposition through enhancing turfgrass productivity and thus soil C input.     

Separating cellular metabolism from exoenzyme activity in soil organic matter decomposition

Soil organic matter (SOM) decomposes both inside and outside of cells. Cellular metabolism and extracellular depolymerization normally operate simultaneously in soil but are difficult to separate in practice. To learn more about the extracellular component of SOM decomposition, we sterilized a semiarid annual grassland soil to inhibit cellular metabolism, and then assayed cell viability, exoenzyme activities, and pathways of carbon dioxide (CO₂) emission. Chloroform (CHCl₃) fumigation was intended to disrupt cellular activities while leaving biochemical processes intact. Gamma (γ) irradiation and autoclaving were intended to disrupt both cellular and extracellular biochemical processes while leaving abiotic processes intact. We measured the potential activities of eight enzymes (six hydrolytic, two oxidative) and CO₂ emission induced by seven substrates (glucose, three amino acids, three tricarboxylic acid [TCA] cycle intermediates). We found that all three sterilization techniques clearly disrupted cellular metabolism. Chloroform and irradiation decreased cultivable cell counts by 2–3 orders of magnitude, inhibited CO₂ emission pathways associated with glucose and amino acids, and decreased the hydrolytic activities of α-glucosidase and xylosidase by 72–82%. The other hydrolytic enzymes (β-glucosidase, cellobiohydrolase, NAGase, phosphatase) were less sensitive to both CHCl₃ and irradiation. All hydrolytic activities that we assayed were inhibited by autoclaving, indicating that biochemical reactions and other extracellular processes drive hydrolytic SOM decomposition. Oxidative activities, on the other hand, did not stop after autoclaving or even combusting at 500 °C. This supports other studies which have found that mineral catalysts partly drive oxidative SOM decomposition. Unexpectedly, CO₂ emission from TCA intermediates decreased by only 26–47% after sterilization suggesting that the required dehydrogenase enzymes for decarboxylation are still active when cells are dead but relatively intact. Because CHCl₃ had slightly smaller effects on exoenzyme activities compared to irradiation, and because it may be continuously applied, limiting the potential for recolonization and regrowth (unlike irradiation), we suggest it is an adequate and more accessible method for separating the activity of exoenzymes from cellular metabolism under realistic soil conditions.     

Evaluation of phosphorus mobilization potential in rewetted fens by an improved sequential chemical extraction procedure

After rewetting of peatlands, phosphorus (P) pore‐water concentrations were up to three orders of magnitude greater than under pristine conditions. It was hypothesized that different mobilization processes such as ion‐exchange reactions, biotic/abiotic redox reactions, acidification and ongoing anaerobic decomposition of particulate organic matter by hydrolytic cleavage and fermentation might be responsible. To identify P pools in peat samples of varying degrees of decomposition, we modified and improved a sequential chemical extraction method that allowed conclusions on potential mobilization mechanisms in rewetted peatlands. The results indicated that the earlier drainage of rewetted fens strongly increased the P mobilization potential in the upper decomposed peat layers. Accordingly, the amount of P bound to redox‐sensitive (bicarbonate/dithionite soluble) compounds (BD‐P) was, on average, one order of magnitude greater in decomposed peat of rewetted fens (5.4–14.3 μmol P g^?1 dry matter or DM) than in underlying less‐decomposed peat layers (0.2–1.9 μmol P g^?1 DM) or slightly decomposed peat derived from pristine fens (0.4–2.0 μmol P g^?1 DM). The BD‐P fraction found in the upper very decomposed peat layers appears to be most important for P mobilization in rewetted fens and accounted for 85% of the variability of P mobilization rates. Despite uncertainties regarding P diagenetic processes in peat, as well as the development of microbial decomposition processes, in the long‐term, high pore‐water P concentrations can be expected in rewetted fens for decades to come.     

effects of diazinon on some population parameters of moina macrocopa (cladocera)

The effects of the organophosphate insecticide diazinon on selected population parameters of the freshwater cladoceran Moina macrocopa were studied. Survivorship and average longevity were affected by exposure to 1.00 μg L^-1 or higher concentrations. Exposure to diazinon had no effect on the time of first reproduction, but animals did not reproduce in 10.00 μg L^-1 and the number of offspring produced by a female during her entire life span was reduced in 1.00 μg L^-1. The intrinsic rate of population growth and the generation time were not significantly affected by exposure to diazinon.     

Processes controlling the production of aromatic water-soluble organic matter during litter decomposition

Dissolved organic matter (DOM) plays a fundamental role for many soil processes. For instance, production, transport, and retention of DOM control properties and long-term storage of organic matter in mineral soils. Production of water-soluble compounds during the decomposition of plant litter is a major process providing DOM in soils. Herein, we examine processes causing the commonly observed increase in contribution of aromatic compounds to WSOM during litter decomposition, and unravel the relationship between lignin degradation and the production of aromatic WSOM. We analysed amounts and composition of water-soluble organic matter (WSOM) produced during 27 months of decomposition of leaves and needles (ash, beech, maple, spruce, pine). The contribution of aromatic compounds to WSOM, as indicated by the specific UV absorbance of WSOM, remained constant or increased during decomposition. However, the contribution of lignin-derived compounds to the total phenolic products of ¹³C-labelled tetramethylammonium hydroxide (¹³C-TMAH) thermochemolysis increased strongly (by >114%) within 27 months of decomposition. Simultaneous changes in contents of lignin phenols in solid litter residues (cupric oxide method as well as ¹³C-TMAH thermochemolysis) were comparably small (−39% to +21% within 27 months). This suggests that the increasing contribution of lignin-derived compounds to WSOM during decomposition does not reflect compositional changes of solid litter residues, but rather the course of decomposition processes. In the light of recently published findings, these processes include: (i) progressive oxidative alteration of lignin that results in increasing solubility of lignin, (ii) preferential degradation of soluble, non-lignin compounds that limits their contribution to WSOM during later phases of decomposition.     

Effects of polyacrylamide,biopolymer and biochar on the decomposition of 14C‐labelled maize residues and on their stabilization in soil aggregates

The efficacy of applying plant residues to agricultural soils as a carbon (C) source for microorganisms and C sequestration is dependent on soil physiochemical properties, which can be improved by aggregation using soil conditioners. However, no attempt has been made to assess the effects of soil conditioners such as biochar (BC), biopolymer (BP) or polyacrylamide (PAM) on plant residue decomposition. We assessed the effects of BC, synthesized BP and anionic PAM on the decomposition of ¹⁴C‐labelled maize residues and on their stabilization in aggregate fractions in sandy and sandy loam soils. Polyacrylamide and BP were applied at 400 kg ha^?1 and BC was applied at 5000 kg ha^?1, and the soils were incubated for 80 days at 22°C. The conditioners improved the physical and biological properties of both soils, as shown by a 24% increase in the 1–2 mm aggregates. Biochar and BP accelerated the decomposition of plant residues as indicated by ¹⁴CO₂ efflux, and resulted in reduced stabilization of residues in both soils relative to that observed in the control and PAM treatments. The reduction in ¹⁴C incorporation and C stabilization in the BC‐ and BP‐treated soils was observed mainly in the < 0.25‐mm aggregates. This was confirmed by reduction of activity of hydrolytic enzymes (β‐cellobiosidase and β‐glucosidase). Decomposition of plant residues in sandy soil was more sensitive to BP and PAM application than that in sandy loam soil. Improved soil structure after applying BC and BP increased aeration and decreased the contact between plant residues and mineral soil particles and consequently accelerated plant residue decomposition and reduced C sequestration.     

Efficient Photocatalytic Reduction of CO<Subscript>2</Subscript> Present in Seawater into Methanol over Cu/C-Co-Doped TiO<Subscript>2</Subscript> Nanocatalyst Under UV and Natural Sunlight

Photocatalytic reduction of CO₂ in seawater into chemical fuel, methanol (CH₃OH), was achieved over Cu/C-co-doped TiO₂ nanoparticles under UV and natural sunlight. Photocatalysts with different Cu loadings (0, 0.5, 1, 3, 5, and 7 wt%) were synthesized by the sol–gel method and were characterized by XRD, SEM, UV–Vis, FTIR, and XPS. Co-doping with C and Cu into TiO₂ remarkably promoted the photocatalytic production of CH₃OH. This improvement was attributed to lowering of bandgap energy, specific catalytic effect of Cu for CH₃OH formation, and the minimization of photo-generated carrier recombination. Co-doped TiO₂ with 3.0 wt% Cu was found to be the most active catalyst, giving a maximum methanol yield rate of 577 μmol g-cat^?1 h^?1 under illumination of UV light, which is 5.3-fold higher than the production rate over C-TiO₂ and 7.4 times the amount produced using Degussa P25 TiO₂. Under natural sunlight, the maximum rate of the photocatalytic production of CH₃OH using 3.0 wt% Cu/C-TiO₂ was found to be 188 μmol g-cat^?1 h^?1, which is 2.24 times higher than that of C-TiO₂, whereas, no CH₃OH was observed for P25.