Shihuai Deng

Biochar produced from oak sawdust by Lanthanum (La)-involved pyrolysis for adsorption of ammonium (NH4+), nitrate (NO3−), and phosphate (PO43−)

A series of biochars were prepared by pyrolyzing oak sawdust with/without LaCl3 involvement at temperature of 300-600 °C, and approximate and ultimate analyses were carried out to check their basic characteristics. Meanwhile, the releases of readily soluble NH4(+), NO3(-) and PO4(3-) from biochars and the adsorption of NH4(+), NO3(-) and PO4(3-) by biochars were investigated. Results indicated that the involvement of LaCl3 in pyrolysis could advance the temperature of maximum mass loss by 10 °C compared with oak sawdust (CK), and potentially promoted biochar yield. Overall, the releases of readily soluble NH4(+), NO3(-) and PO4(3-) from biochars were negatively related to pyrolysis temperature, and the releases were greatly weakened by La-biochars. Additionally, the adsorption to NH4(+) can be promoted by the biochars produced at low temperature. On the contrary, the NO3(-) adsorption can be improved by increasing pyrolysis temperature. The highest PO4(3-) adsorption was achieved by the biochars produced at 500 °C. According to the results of adsorption isotherms, the maximum adsorption capacity of NH4(+), NO3(-) and PO4(3-) can be significantly promoted by 1.9, 11.2, and 4.5 folds using La-biochars. Based on the observations of FT-IR, SEM-EDS, and surface functional groups, the improvement of NH4(+) adsorption was potentially associated with the existing acidic function groups (phenolic-OH and carboxyl C=O). The increased basic functional groups on La-biochars were beneficial to improve NO3(-) and PO4(3-) adsorption. Besides, PO4(3-) adsorption was also potentially related to the formed La2O3.

Photoelectrocatalytic degradation of recalcitrant organic pollutants using TiO2 film electrodes: an overview.

Photoelectrocatalytic (PEC) technology involved applying an electrical bias to a TiO(2) film electrode, has been widely applied to the degradation of refractory organic pollutants, owing to its high degradation efficiency. This paper reviews recent developments in the PEC degradation of recalcitrant organic contaminants using a TiO(2) film electrode. The preparation and application of various TiO(2) film electrodes have been investigated, as well as the parameters that influence PEC activity such as the crystal structure, the film thickness and substrate material, the applied electrical bias, the solution pH and conductivity. The improvement of PEC activity by doping the TiO(2) film electrode with metal and non-metal ions has been discussed. The mechanism and kinetics for the PEC degradation of organic pollutants have also been highlighted.

Preparation of activated carbon from edible fungi residue by microwave assisted K2CO3 activation—Application in reactive black 5 adsorption from aqueous solution

Preparation of activated carbon from the edible fungi residue (EFR) by microwave assisted K(2)CO(3) activation was studied. The optimum preparation conditions were as follows: radiation time of 16 min, K(2)CO(3)/EFR ratio of 0.8 and microwave power of 520 W. The iodine number, the amount of methylene blue adsorption and the yield of activated carbon prepared under optimum conditions were 732.74, 172.43 mg/g and 23.0%, respectively. The activated carbon was characterized by SEM, FT-IR, N(2) adsorption and pH(ZPC), and then they were used as adsorbent for removing reactive black 5 from aqueous solution. The highest removal efficiency of 100% could be achieved at the solution pH of 2.0, the adsorption efficiency descended with the increasing of pH and the optimum activated carbon dose was 8.75 g/L. The Langmuir isotherm well fit the adsorption process with the complete monolayer adsorption capacity of 19.6 mg/g and the equilibrium adsorption constant of 0.39 L/mg.

Preparation of TiO2-loaded activated carbon fiber hybrids and application in a pulsed discharge reactor for decomposition of methyl orange.

TiO(2)-loaded activated carbon fiber (TiO(2)/ACF) hybrids were prepared in a sol through a dip-coating method and added to a pulsed discharge reactor to enhance the decomposition of methyl orange. The crystalline phase transformation and the surface morphology of TiO(2)/ACF were investigated after calcination at various temperatures. X-ray diffraction results revealed the intensity of the diffraction peaks resulting from anatase increased in accordance with increasing calcination temperatures. An anatase-to-rutile phase transformation was observed for calcination at 1173 K. Morphology studies indicate that the TiO(2) film fractured into irregular flakes on the ACF surface. TiO(2)/ACF calcined at 1173 K demonstrated the highest photocatalytic activity compared with samples calcined at lower temperatures. The enhancement of chemical oxygen demand removal may be due to the adsorption of ACF and the photocatalytic ozonation of TiO(2) in the combined treatment. The surface morphology of TiO(2)/ACF showed no change after re-use. Although micropores slightly increased, mesopores significantly decreased, and some oxygen-containing surface groups increased on the ACF surface after re-use, the photocatalytic activity of TiO(2)/ACF was not affected.

Total petroleum hydrocarbons and heavy metals in the surface sediments of Bohai Bay, China: Long-term variations in pollution status and adverse biological risk

Surface sediments collected from 2001 to 2011 were analyzed for total petroleum hydrocarbons (TPH) and five heavy metals. The sediment concentration ranges of TPH, Zn, Cu, Pb, Cd and Hg were 6.3-535 μg/g, 58-332 μg/g, 7.2-63 μg/g, 4.3-138 μg/g, 0-0.98μg/g, and 0.10-0.68 μg/g, respectively. These results met the highest marine sediment quality standards in China, indicating that the sediment was fairly clean. However, based on the effects range-median (ERM) quotient method, the calculated values for all of the sampling sites were higher than 0.10, suggesting that there was a potential adverse biological risk in Bohai Bay. According to the calculated results, the biological risk decreased from 2001 to 2007 and increased afterwards. High-risk sites were mainly distributed along the coast. This study suggests that anthropogenic influences might be responsible for the potential risk of adverse biological effects from TPH and heavy metals in Bohai Bay.

Pretreating lignocellulosic biomass by the concentrated phosphoric acid plus hydrogen peroxide (PHP) for enzymatic hydrolysis: Evaluating the pretreatment flexibility on feedstocks and particle sizes

In order to seek a high-efficient pretreatment path for converting lignocellulosic feedstocks to fermentable sugars by enzymatic hydrolysis, the concentrated H₃PO₄ plus H₂O₂ (PHP) was attempted to pretreat different lignocellulosic biomass for evaluating the pretreatment flexibility on feedstocks. Meanwhile, the responses of pretreatment to particle sizes were also evaluated. When the PHP-pretreatment was employed (final H₂O₂ and H₃PO₄ concentration of 1.77% and 80.0%), 71-96% lignin and more than 95% hemicellulose in various feedstocks (agricultural residues, hardwood, softwood, bamboo, and their mixture, and garden wastes mixture) can be removed. Consequently, more than 90% glucose conversion was uniformly achieved indicating PHP greatly improved the pretreatment flexibility to different feedstocks. Moreover, when wheat straw and oak chips were PHP-pretreated with different sizes, the average glucose conversion reached 94.9% and 100% with lower coefficient of variation (7.9% and 0.0%), which implied PHP-pretreatment can significantly weaken the negative effects of feedstock sizes on subsequent conversion.

Responses of biomass briquetting and pelleting to water-involved pretreatments and subsequent enzymatic hydrolysis.

Although lignocellulosic biomass has been extensively regarded as the most important resource for bioethanol, the wide application was seriously restricted by the high transportation cost of biomass. Currently, biomass densification is regarded as an acceptable solution to this issue. Herein, briquettes, pellets and their corresponding undensified biomass were pretreated by diluted-NaOH and hydrothermal method to investigate the responses of biomass densification to these typical water-involved pretreatments and subsequent enzymatic hydrolysis. The densified biomass auto-swelling was initially investigated before pretreatment. Results indicated pellets could be totally auto-swollen in an hour, while it took about 24 h for briquettes. When diluted-NaOH pretreatment was performed, biomass briquetting and pelleting improved sugar conversion rate by 20.1% and 5.5% comparing with their corresponding undensified biomass. Pelleting improved sugar conversion rate by 7.0% after hydrothermal pretreatment comparing with the undensified biomass. However, briquetting disturbed hydrothermal pretreatment resulting in the decrease of sugar conversion rate by 15.0%.

Enzymatic saccharification coupling with polyester recovery from cotton-based waste textiles by phosphoric acid pretreatment

In order to recycle the cotton-based waste textiles, a novel process was designed for pretreating waste textiles with phosphoric acid to recover polyester and fermentable sugar. The effects of pretreatment conditions including, phosphoric acid concentration, pretreatment temperature, time, and ratio of textiles and phosphoric acid were thoroughly investigated. Results indicated the mentioned four factors had significant influences on sugar and polyester recovery. Almost complete polyester recovery was achieved by enhancing phosphoric acid concentration, temperature and pretreatment time or reducing the ratio of textiles and phosphoric acid. However, these behaviors decreased the sugar recovery seriously. 100% polyester recovery with a maximum sugar recovery of 79.2% was achieved at the optimized conditions (85% phosphoric acid, 50°C, 7h, and the ratio of 1:15). According to the technical and cost-benefit analysis, it was technically feasible and potentially profitable to recover polyester and sugar from waste textiles by phosphoric acid pretreatment.

Magnetotactic bacteria: promising biosorbents for heavy metals.

Magnetotactic bacteria (MTB), which can orient and migrate along a magnetic line of force due to intracellular nanosized magnetosomes, have been a subject of research in the medical field, in dating environmental changes, and in environmental remediation. This paper reviews the recent development of MTB as biosorbents for heavy metals. Ultrastructures and taxis of MTB are investigated. Adsorptions in systems of unitary and binary ions are highlighted, as well as adsorption conditions (temperature, pH value, biomass concentration, and pretreatments). The separation and desorption of MTB in magnetic separators are also discussed. A green method to produce metal nanoparticles is provided, and an energy-efficient way to recover precious metals is put forward during biosorption.

Investigation of carbon dioxide emission in China by primary component analysis.

Principal component analysis (PCA) is employed to investigate the relationship between CO2 emissions (COEs) stemming from fossil fuel burning and cement manufacturing and their affecting factors. Eight affecting factors, namely, Population (P), Urban Population (UP); the Output Values of Primary Industry (PIOV), Secondary Industry (SIOV), and Tertiary Industry (TIOV); and the Proportions of Primary Industrys Output Value (PPIOV), Secondary Industrys Output Value (PSIOV), and Tertiary Industrys Output Value (PTIOV), are chosen. PCA is employed to eliminate the multicollinearity of the affecting factors. Two principal components, which can explain 92.86% of the variance of the eight affecting factors, are chosen as variables in the regression analysis. Ordinary least square regression is used to estimate multiple linear regression models, in which COEs and the principal components serve as dependent and independent variables, respectively. The results are given in the following. (1) Theoretically, the carbon intensities of PIOV, SIOV, and TIOV are 2573.4693, 552.7036, and 606.0791 kt per one billion