Effects of pore structure and electrolyte on the capacitive characteristics of steam- and KOH-activated carbons for supercapacitors

Four kinds of activated carbons (denoted as ACs) with specific surface area of ca. 1050 m² g⁻¹ were fabricated from fir wood and pistachio shell by means of steam activation or chemical activation with KOH. Pore structures of ACs were characterized by a t-plot method based on N₂ adsorption isotherms. The amount of mesopores within KOH-activated carbons ranged from 9.2 to 15.3% while 33.3–49.5% of mesopores were obtained for the steam-activated carbons. The pore structure, surface functional groups, and raw materials of ACs, as well as pH and the supporting electrolyte were also found to be significant factors determining the capacitive characteristics of ACs. The excellent capacitive characteristics in both acidic and neutral media and the weak dependence of the specific capacitance on the scan rate of cyclic voltammetry (CV) for the ACs derived from the pistachio shell with steam activation (denoted as P-H₂O-AC) revealed their promising potential in the application of supercapacitors. The ACs derived from fir wood with KOH activation (denoted as F-KOH-AC), on the other hand, showed the best capacitive performance in H₂SO₄ due to excellent reversibility and high specific capacitance (180 F g⁻¹ measured at 10 mV s⁻¹), which is obviously larger than 100 F g⁻¹ (a typical value of activated carbons with specific surface areas equal to/above 1000 m² g⁻¹).     

Dry matter partitioning and quality of Miscanthus,Panicum, and Saccharum genotypes in Arkansas,USA

The partitioning and quality of aboveground biomass have important ramifications for crop management and biomass conversion. In preliminary studies, Saccharum sp. × Miscanthus sp. hybrids exhibited stubble cold tolerance in west-central Arkansas, unlike Saccharum sp. × Saccharum spontaneum hybrids. The objective was to examine foliar and stem quality of the C₄ grasses Miscanthus sinensis (‘Gracillimus’), Miscanthus x giganteus (Q42641, proprietary), Panicum virgatum (‘Alamo’), and two F₁ hybrids of Saccharum sp. × Miscanthus sp. (US84-1028 and US84-1058) in a field study during 2004 (plant cane) and 2005 (first stubble) near Booneville, AR. Switchgrass produced more stems m^?2 than the other entries both years, and there was little difference in stem number among other entries. Clone US84-1028 yielded more dry mass m^?2 than other entries in plant cane, while switchgrass, US84-1028, and M. x giganteus did not differ in first stubble. Clone US84-1028 also had more stem dry mass and leaf dry mass than other entries both yr. Tissue N concentrations were low for these entries, but leaves contained about twice the N of stems (≤15.2 and 7.8 g kg^?1, respectively). Leaves represented as much as one-third of total biomass, and had large cellulose (≤482 g kg^?1) and lignin (167 g kg^?1) concentrations. The competitively high biomass yield of this small sample of sugarcane alleles should encourage the expansion of the crop beyond its current production regions. Sugarcane and M. x giganteus should be examined in higher-input temperate systems because of their bioenergy potential.     

Preparation and characterization of composite electrodes of coconut-shell-based activated carbon and hydrous ruthenium oxide for supercapacitors

The relationship between the structure-specific capacitance (F g⁻¹) of a composite electrode consisting of activated coconut-shell carbon and hydrous ruthenium oxide (RuO_x(OH)_y) has been evaluated by impregnating various amounts of RuO_x(OH)_y into activated carbon that is specially prepared with optimum pore-size distribution. The composite electrode shows an enhanced specific capacitance of 250 F g⁻¹ in 1 M H₂SO₄ with 9 wt.% ruthenium incorporated. Chemical and structural characterization of the composites reveals a homogeneous distribution of amorphous RuO_x(OH)_y throughout the porous network of the activated carbon. Electrochemical characterization indicates an almost linear dependence of capacitance on the amount of ruthenium owing to its pseudocapacitive nature.     

The capacitive characteristics of activated carbons—comparisons of the activation methods on the pore structure and effects of the pore structure and electrolyte on the capacitive performance

Fir wood-derived carbons activated with steam, KOH, and KOH + CO₂ were found to exhibit the high-power, low ESR, and highly reversible characteristics between −0.1 and 0.9 V in aqueous electrolytes, which were demonstrated to be promising electrode materials for supercapacitors. The pore structure of these activated carbons was systematically characterized by the t-plot method based on N₂ adsorption isotherms. Activated carbons prepared through the above three activation methods under different conditions (i.e., the gasification time of CO₂, KOH/char ratio, and activation time of steam) generally showed excellent capacitive performance in aqueous media, mainly attributed to the development of both micropores and mesopores (with the meso-pore volume ratio, V_meso/V_pore, ranging from 0.18 to 0.52). Scanning electron microscopic (SEM) photographs showed that the surface morphologies of honeycombed holes were found to depend on the activation methods. The average specific capacitance of the activated carbon with a combination of KOH etching and CO₂ gasification (with gasification time of 15 min) reached 197 F g⁻¹ between −0.1 and 0.9 V in H₂SO₄. The capacitive characteristics of steam- and KOH-activated carbons in NaNO₃ and H₂SO₄ could be roughly estimated from the pore structure and BET surface area although the correlation may be only applicable for the fir wood-derived activated carbons.     

Carbon dioxide fixation by microalgae cultivated in open bioreactors

The biofixation of carbon dioxide (CO₂) by microalgae has been proven to be an efficient and economical method, mainly due to the photosynthetic ability of these microorganisms to use this gas as a source of nutrients for their development. The aim of this work was to study the growth of Spirulina LEB18 and Chlorella kessleri microalgae, exposed to controlled and non-controlled conditions, with the injection of different concentrations of CO₂. The cultures was carried out in 6 L open raceway ponds, under controlled conditions at 30 °C and 39 μE m^?2 s^?1 and under non-controlled conditions, protected by a tunnel of transparent film. The experiments were subjected to CO₂ injections at concentrations of 0.038, 6, 12 and 18% (v/v). The highest concentration of biomass (4.95 g L^?1) and maximum daily fixation (0.21 g g^?1 d^?1) were obtained for Spirulina LEB18 in culture that was prepared in non-controlled conditions with an injection of 6% (v/v) of CO₂. C. kessleri had maximum (p < 0.0008) specific growth rate (0.84 d^?1) when grown with 18% (v/v) of CO₂ in non-controlled conditions of cultivation.     

The effects of operating conditions on emissions from masonry heaters and sauna stoves

Emissions from masonry heaters and sauna stoves were studied. In the sauna stove the production of organic gaseous carbon (OGC) at 10 gC kg^?1 (per kilogram of fuel), carbon monoxide (CO) at 55 g kg^?1, fine particle mass (PM₁) at 5 g kg^?1 and number emissions (N) at 1.8 × 10¹⁵ kg^?1 was higher than in other measured appliances. In a modern technology masonry heater with a unique grate, the emissions were very low: 0.4 gC kg^?1 OGC, 14 g kg^?1 CO and 0.7 g kg^?1 PM₁. Conventional masonry heaters, using small logs, clearly produced higher emissions when compared to using large logs. Doubling the fuel load caused emission factors to increase by up to 4- times (OGC), except for the number emission, which decreased from 4.0 × 10¹⁴ to 2.0 × 10¹⁴ kg^?1. From the conventional masonry heater 90% of the PM was emitted during the firing phase. Its combustion process is different to that in stoves or conventional open fireplaces. The insufficient supply of air, due to too fast pyrolysis, and increased ash release, due to the high combustion temperature, are the main parameters which cause high particle and gas emissions in masonry heaters and sauna stoves.     

Assessment of nitrogen fertilization for the CO2 balance during the production of poplar and rye

This study was designed to consider all nitrogen fertilizer-related effects on crop production and emission of greenhouse gases on loamy sandy soils in Germany over a period of nine years (1999–2007). In order to set up a CO₂ balance for the production of energy crops, different nitrogen pathways were investigated, such as direct N₂O emissions from the soil and indirect emissions related to NO₃ leaching and fertilizer production. Fluxes of N₂O were measured in an experimental field using closed chambers. Poplar (Populus maximowiczii × P. nigra) and rye (Secale cereale L.) as one perennial and one annual crop were fertilized at rates of 0 kg N ha^?1 yr^?1, 75 kg N ha^?1 yr^?1 and 150 kg N ha^?1 yr^?1. The mean N₂O emissions from the soil ranged between 0.5 kg N ha^?1 yr^?1 and 2.5 kg N ha^?1 yr^?1 depending on fertilization rate, crop variety and year. The CO₂ fixed in the biomass of energy crops is reduced by up to 16% if direct N₂O emissions from soil and indirect N₂O emissions from NO₃ leaching and fertilizer production are included. Taking into account the main greenhouse gas emissions, which derive from the production and the use of N fertilizer, the growth of poplar and rye may replace the global warming potential of fossil fuels by up to 17.7 t CO₂ ha^?1 yr^?1 and 12.1 t CO₂ ha^?1 yr^?1, respectively.     

Hybrid electrochemical capacitors based on polyaniline and activated carbon electrodes

The performance of a newly designed, polyaniline–activated carbon, hybrid electrochemical capacitor is evaluated. The capacitor is prepared by using polyaniline as a positive electrode and activated carbon as a negative electrode. From a constant charge–discharge test, a specific capacitance of 380 F g⁻¹ is obtained. The cycling behaviour of the hybrid electrochemical capacitor is examined in a two-electrode cell by means of cyclic voltammetry. The cycle-life is 4000 cycles. Values for the specific energy and specific power of 18 Wh kg⁻¹ and 1.25 kW kg⁻¹, respectively, are demonstrated for a cell voltage between 1 and 1.6 V.     

A high energy density lithium/sulfur–oxygen hybrid battery

In this paper we introduce a lithium/sulfur–oxygen (Li/S–O₂) hybrid cell that is able to operate either in an air or in an environment without air. In the cell, the cathode is a sulfur–carbon composite electrode containing appropriate amount of sulfur. In the air, the cathode first functions as an air electrode that catalyzes the reduction of oxygen into lithium peroxide (Li₂O₂). Upon the end of oxygen reduction, sulfur starts to discharge like a normal Li/S cell. In the absence of oxygen or air, sulfur alone serves as the active cathode material. That is, sulfur is first reduced to form a soluble polysulfide (Li₂S_x, x ≥ 4) that subsequently discharges into Li₂S through a series of disproportionations and reductions. In general, the Li/S–O₂ hybrid cell presents two distinct discharge voltage plateaus, i.e., one at ～2.7 V attributing to the reduction of oxygen and the other one at ～2.3 V attributing to the reduction of sulfur. Since the final discharge products of oxygen and sulfur are insoluble in the organic electrolyte, it is shown that the overall specific capacity of Li/S–O₂ hybrid cell is determined by the carbon composite electrode, and that the specific capacity varies with the discharge current rate and electrode composition. In this work, we show that a composite electrode composed by weight of 70% M-30 activated carbon, 22% sulfur and 8% polytetrafluoroethylene (PTFE) has a specific capacity of 857 mAh g^?1 vs. M-30 activated carbon at 0.2 mA cm^?2 in comparison with 650 mAh g^?1 of the control electrode consisting of 92% M-30 and 8% PTFE. In addition, the self-discharge of the Li/S–O₂ hybrid cell is expected to be substantially lower when compared with the Li/S cell since oxygen can easily oxidize the soluble polysulfide into insoluble sulfur.     

Genotypic and environmentally derived variation in the cell wall composition of Miscanthus in relation to its use as a biomass feedstock

Fifteen Miscanthus genotypes grown in five locations across Europe were analysed to investigate the influence of genetic and environmental factors on cell wall composition. Chemometric techniques combining near infrared reflectance spectroscopy (NIRS) and conventional chemical analyses were used to construct calibration models for determination of acid detergent lignin (ADL), acid detergent fibre (ADF), and neutral detergent fibre (NDF) from sample spectra. Results generated were subsequently converted to lignin, cellulose and hemicellulose content and used to assess the genetic and environmental variation in cell wall composition of Miscanthus and to identify genotypes which display quality traits suitable for exploitation in a range of energy conversion systems. The NIRS calibration models developed were found to predict concentrations with a good degree of accuracy based on the coefficient of determination (R²), standard error of calibration (SEC), and standard error of cross-validation (SECV) values. Across all sites mean lignin, cellulose and hemicellulose values in the winter harvest ranged from 76–115 g kg^?1, 412–529 g kg^?1, and 235–338 g kg^?1 respectively. Overall, of the 15 genotypes Miscanthus x giganteus and Miscanthus sacchariflorus contained higher lignin and cellulose concentrations in the winter harvest. The degree of observed genotypic variation in cell wall composition indicates good potential for plant breeding and matching feedstocks to be optimised to different energy conversion processes.     

Suitability of pineapple,Aloe vera,molasses, glycerol,and office paper as substrates in the MixAlco process?

The MixAlco? process biologically converts biomass to carboxylate salts that may be chemically converted to a wide variety of chemicals and fuels. This study looked at the viability of the following substrates: office paper, pineapple residue, Aloe vera rinds, wood molasses, sugar molasses, and glycerol. All agricultural substrates were initially tested to determine their carbohydrate and lignin content because lignin reduces substrate digestibility. Only pineapple residue had a high enough lignin content (18.3%) to necessitate pretreatment. Pineapple residue was treated with excess lime (300 g kg^?1 Ca(OH)₂ on dry biomass, t = 1 h) and then neutralized with CO₂, which reduced the lignin content to 4.89%. All substrates were anaerobically fermented in batch culture with marine microorganisms for 24 days. The acid concentrations (g mixed acid L^?1) were Aloe vera (25.5), office paper (24.0), glycerol (22.6), pineapple residue (17.2), wood molasses (19.4) and sugar molasses (18.9). The conversions (g volatile solids digested g^?1 volatile solids fed) were Aloe vera (0.59), office paper (0.50), glycerol (0.62), pineapple residue (0.52), wood molasses (0.42) and sugar molasses (0.82). The selectivities (g acetic acid equivalents g^?1 VS digested) were Aloe vera (0.64), office paper (0.62), glycerol (0.51), pineapple residue (0.39), wood molasses (0.61) and sugar molasses (0.33).     

Development of high energy density small flat spiral cells and battery pack based on lithium/carbon monofluoride (Li/CFx)

Small spiral-wound lithium–carbon monofluoride (Li/CF_x) cells, which were discharged at the C/40 rate, had a nominal capacity of 300 mAh and a gravimetric energy density of about 464 Wh kg⁻¹. These cells delivered pulse current loads (>22 mA) with good capacity (>200 mAh) if they were subjected to a pre-discharge step. A 17 V, 2.2 kW battery based on Li/CF_x flat cell technology has also been fabricated and tested. The battery had gravimetric and volumetric energy densities of 360 Wh kg⁻¹ and 700 Wh dm⁻³, respectively. This compares with a value of 330 Wh kg⁻¹ and 522 Wh dm⁻³ for an equivalent battery based on Li/SOCl₂.     

Anaerobic digestion of by-products of sugar beet and starch potato processing

Anaerobic digestion (AD) is a promising option for the environmentally friendly recycling of agricultural by-products. However, overloading of the digester with sugar, starch or protein might cause inhibition of the anaerobic processes. The aim of the present project was to investigate the AD of sugar beet, starch potato by-products and effect of pre-treatment by steam on methane yield of potatoes pulp. The investigated by-products have been: sugar beet pulp silage (SBP), sugar beet tail silage (SBT), potato pulp (PP), potato peel pulp (PPP) and potato fruit water (PFW). All by-products were digested in 1 l eudiometer-batch digesters at 37.5 °C during 28–38 days. The specific methane yields of SBP and SBT were 430 and 481 l_N kg^?1 volatile solids (VS), respectively. The specific methane yields of PP, PPP and PFW were 332, 377 and 323 l_N (kg VS)^?1. A steam pre-treatment significantly increased the specific methane yield of PP up to 373 l_N (kg VS)^?1.     

Electrochemical behavior of polyamides with cyclic disulfide structure and their application to positive active material for lithium secondary battery

Polyamides (DTA-I, DTA-II, and DTA-III) containing cyclic disulfide structure were prepared by condensation between 1,2-dithiane-3,6-dicarboxylic acid (DTA) and alkyl diamine, NH₂–(CH₂)_n–NH₂ (DTA-I; n=4, DTA-II; n=6, DTA-III; n=8) and their application to positive active material for lithium secondary batteries was investigated. Cyclic voltammetry (CV) measurements under slow sweep rate (0.5 mV s⁻¹) with a carbon paste electrode containing the polyamide (DTA-I, DTA-II, or DTA-III) were performed. The results indicated that the polyamides were electroactive in the organic electrolyte solution (propylene carbonate (PC)-1,2-dimethoxyethane (DME), 1:1 by volume containing lithium salt, such as LiClO₄). The responses based on the redox of the disulfide bonds in the polyamide were observed.Test cells, Li/PC-DME (1:1. by volume) with 1 mol dm⁻³ LiClO₄/the polyamide cathode, were constructed and their performance was tested under constant current charge/discharge condition. The average capacity of the test cells with the DTA-III cathode was 64.3 Ah kg⁻¹ of cathode (135 Wh kg⁻¹ of cathode, capacity (Ah kg⁻¹) of the cathode×average cell voltage (2.10 V)). Performance of the cell with linear polyamide containing disulfide bond (–CO–(CH₂)₂–S–S–(CH₂)₂–CONH–(CH₂)₈–NH–, GTA-III) was also investigated and the average capacity was 56.8 Ah kg⁻¹ of cathode (100 Wh kg⁻¹ of cathode, capacity (Ah kg⁻¹) of the cathode×average cell voltage (1.76 V)). Cycle efficiency of the test cell with the DTA-III cathode was higher than that with the GTA-III cathode.     

Conductivity percolation in carbon–carbon supercapacitor electrodes

Composite electrodes which comprise a non-conductive activated carbon of large surface area (1420 m² g⁻¹) and a conductive carbon black (CB) of small surface area (220 m² g⁻¹) have been prepared and studied for their capacitive properties in aqueous KOH and Na₂SO₄ electrolytes. For either electrolyte, maximum capacitance exists at the composition believed to correspond to the percolation threshold for CB, the conductive phase. At a CB content less than the threshold, the capacitance is limited mainly by the electronic resistance on the electrode side. The interfacial surface area becomes the limiting factor as the threshold is exceeded. A maximum capacitance of 108 F g⁻¹ at a voltage sweep rate of 20 mV s⁻¹ is obtained in 1 M KOH aqueous electrolyte with a CB content of 25 wt.% (or ∼14 vol.%).     

In situ polyol-assisted synthesis of nano-SnO2/carbon composite materials as anodes for lithium-ion batteries

Nano-SnO₂/carbon composite materials were synthesized in situ using the polyol method by oxidizing SnCl₂·2H₂O in the presence of a carbon matrix. All the as-synthesized composites consisted of SnO₂ nanoparticles (5–10 nm) uniformly embedded into the carbon matrix as evidenced by TEM. XRD confirmed the presence of nano-sized SnO₂ particles that are crystallized in a rutile structure and XPS revealed a tin oxidation state of +4. Cyclic voltammetry of the composites showed an irreversible peak at 1.4 V in the first cycle and a typical alloying/de-alloying process at 0.1–0.5 V. The best composite (“composite I”, 15 wt% SnO₂) showed an improved lithium storage capacity of 370 mAh g^?1 at 200 mA g^?1 (～C/2) which correspond to 32% improvement and lower capacity fade compared to commercial SnO₂ (50 nm). We have also investigated the effect of the heating method and we found that the use of a microwave was beneficial in not only shortening reaction time but also in producing smaller SnO₂ particles that are also better dispersed within the carbon matrix which also resulted in higher lithium storage capacity.     

Production of bioethanol and associated by-products from potato starch residue stream by Saccharomyces cerevisiae

Potato starch residue stream produced during chips manufacturing was used as an economical source for biomass and bioethanol production by Saccharomyces cerevisiae. Results demonstrated that 1% H₂SO₄ at 100 °C for 1 h was enough to hydrolyze all starch contained in the residue stream. Two strains of S. cerevisiae (y-1646 and commercial one) were able to utilize and ferment the acid-treated residue stream under both aerobic and semi-anaerobic conditions. The maximum yield of ethanol (5.52 g L^?1) was achieved at 35 °C by S. cerevisiae y-1646 after 36 h when ZnCl₂ (0.4 g L^?1) was added. Addition of NH₄NO₃ as a source of nitrogen did not significantly affect either growth or ethanol production by S. cerevisiae y-1646. Some secondary by-products including alcohol derivatives and medical active compound were found to be associated with the ethanol production process.     

Isolation and characterization of two soil derived yeasts for bioethanol production on Cassava starch

Two ethanol-producing yeast strains, CHY1011 and CHFY0901 were isolated from soil in South Korea using an enrichment technique in a yeast peptone dextrose medium supplemented with 5% (w v^?1) ethanol at 30 °C. The phenotypic and physiological characteristics, as well as molecular phylogenetic analysis based on the D1/D2 domains of the large subunit (26S) rRNA gene and the internally transcribed spacer (ITS) 1 + 2 regions suggested that they were novel strains of Saccharomyces cerevisiae. During shaking flask cultivation, the highest ethanol productivity and theoretical yield of S. cerevisiae CHY1011 in YPD media containing 9.5% total sugars was 1.06 ± 0.02 g l^?1 h^?1 and 95.5 ± 1.2%, respectively, while those for S. cerevisiae CHFY0901 were 0.97 ± 0.03 g l^?1 h^?1 and 91.81 ± 2.2%, respectively. Simultaneous saccharification and fermentation for ethanol production was carried out using liquefied cassava (Manihot esculenta) starch in a 5 l lab-scale jar fermenter at 32 °C for 66 h with an agitation speed of 2 Hz. Under these conditions, S. cerevisiae CHY1011 and CHFY0901 yielded a final ethanol concentration of 89.1 ± 0.87 g l^?1 and 83.8 ± 1.11 g l^?1, a maximum ethanol productivity of 2.10 ± 0.02 g l^?1 h^?1 and 1.88 ± 0.01 g l^?1 h^?1, and a theoretical yield of 93.5 ± 1.4% and 91.3 ± 1.1%, respectively. These results suggest that S. cerevisiae CHY1011 and CHFY0901 have potential use in industrial bioethanol fermentation processes.     

Effects of ball-milling on lithium insertion into multi-walled carbon nanotubes synthesized by thermal chemical vapour deposition

The effects of ball-milling on Li insertion into multi-walled carbon nanotubes (MWNTs) are presented. The MWNTs are synthesized on supported catalysts by thermal chemical vapour deposition, purified, and mechanically ball-milled by the high energy ball-milling. The purified MWNTs and the ball-milled MWNTs were electrochemically inserted with Li. Structural and chemical modifications in the ball-milled MWNTs change the insertion–extraction properties of Li ions into/from the ball-milled MWNTs. The reversible capacity (C_rev) increases with increasing ball-milling time, namely, from 351 mAh g⁻¹ (Li_0.9C₆) for the purified MWNTs to 641 mAh g⁻¹ (Li_1.7C₆) for the ball-milled MWNTs. The undesirable irreversible capacity (C_irr) decreases continuously with increase in the ball-milling time, namely, from 1012 mAh g⁻¹ (Li_2.7C₆) for the purified MWNTs to 518 mAh g⁻¹ (Li_1.4C₆) for the ball-milled MWNTs. The decrease in C_irr of the ball-milled samples results in an increase in the coulombic efficiency from 25% for the purified samples to 50% for the ball-milled samples. In addition, the ball-milled samples maintain a more stable capacity than the purified samples during charge–discharge cycling.     

Growth,biomass and petroleum convertible hydrocarbons' yield of Grindelia camporum planted on an alluvial soil (Entisol) of North India and its response to sulphur fertilization

Four-week-old seedlings of Grindelia camporum Greene were planted in a mild calcareous alluvial soil collected from Mahibullapur, in Lucknow district (26° 30′ N latitude–80° 30′ E longitude) in pot culture. The soil, rated sulphur deficient on the basis of available soil sulphur, was fertilized with calcium sulphate to provide sulphur at the rate of 10, 25, 50, and 100 mg kg^?1 soil. Observations on growth (height, branching, leaf area) were recorded periodically. Plants were harvested 26 weeks after transplantation (wat) and measured for biomass and biocrude yields. After harvest, the pot soil was measured for available sulphur using three extractants: 0.15% CaCl₂, 0.5 M NaHCO₃, pH 8.5, and Morgan's extract.The native soil (control) is rated deficient in available sulphur; and availability of sulphur increased with increasing levels of sulphur fertilization. The vegetative growth of plants reached the maximum in response to sulphur amendment at the rate of 50 mg kg^?1 soil 14 weeks after transplantation to pots. At the time of harvest, 26 weeks after transplantation, plants showed best growth and maximum number of capitula and weight, in response to sulphur amendment at the rate of 100 mg kg^?1 soil. Thus, G. camporum showed a higher requirement of sulphur during the reproductive phase than for its vegetative growth and biomass yield. Maximum biocrude yield, both the total and ethyl acetate and methanol extractable fractions, was also obtained when sulphur was applied at the rate of 100 mg kg^?1 soil.