Syntheses and properties of associative acrylamide copolymers containing short hydrophobic chains used in a friction reducer for slick-water fracturing

Two allyldimethylalkyl quaternary ammonium salt(AQAS)monomers,N,N-dimethylallylphenylpropylammonium bromide(AQAS1)and N,N-dimethylallylnonylammonium bromide(AQAS2),were synthesized and used to prepare modified polyacrylamide materials.Two new drag reducers were synthesized from acrylamide(AM),sodium acrylate(Na AA)and a cationic modified monomer(AQAS1 or AQAS2)via aqueous solution polymerization,and the copolymers were named P(AM/Na AA/AQAS1)and P(AM/Na AA/AQAS2),respectively.The structures of the drag reduction agents were confirmed by IR and1H NMR spectroscopies.The molecular weight(Mw)of P(AM/Na AA/AQAS1)was 1.79×10^(6)g/mol.When the copolymer concentration was 1000 mg/L and the flow rate was 45 L/min,in fresh water the highest drag reduction rate was 75.8%,in 10,000 mg/L Na Cl solution the drag reduction rate decreased to 72.9%.The molecular weight of P(AM/Na AA/AQAS2)was 3.17×10^(6)g/mol.When the copolymer concentration was500 mg/L and the flow rate was 45 L/min,the drag reduction rate reached 75.2%,and in 10,000 mg/L Na Cl solution the drag reduction rate was 73.3%,decreased by approximately 1.9%.The drag reduction rate for partially hydrolyzed polyacrylamide(HPAM)was also investigated,and the results showed that the drag reduction rates for 500 and 1000 mg/L HPAM solutions were merely 43.2%and 49.0%in brine,respectively.Compared with HPAM,both of the above copolymers presented better drag reduction capacities.

A high salt tolerance and low adsorption drag reducer based on non-covalent enhancement

To formulate fluids with flowback water,produced water directly to improve the utilization rate of recycling and reduce the adsorption damage of slick water to reservoirs,a high salt tolerance and low adsorption drag reducer was designed and prepared by introducing polar cation fragments to enhance the non-covalent interactions between the chains.The drag reducer was characterized by IR and NMR.Friction resistance and viscosity tests were conducted to evaluate its salt resistance property.Static adsorption and dynamic adsorption retention tests were carried out to evaluate the damage of this reducer to shale reservoirs.The introduction of cation units into the molecular structure can weak the shielding effect of metal cations to some extent,so the drag reducer can keep a stable molecular structure and good resistant reducing performance under high salinity.The enhancement of non-covalent interaction between chains decreased the free polarity sites,further reduced the possibility of hydrogen bonding between drag reducer molecules and shale.In high salinity condition,both the adsorption capacity of the drag reducer on the shale surface and the average damage rate to the core permeability are low.Compared with the conventional salt-tolerant system,the overall liquid cost was reduced by 17%and the production per well increased by 44%.The application of this slick water system has achieved remarkable results.

THE SLUMP RETENTION OF N-2000 HIGH-RANGE WATER-REDUCING AND RETARDING ADMIXTURE

N-2000 is an admixture for concrete, with a low slump loss, high range water-reducing ratio and long-time retarding. The N-2000 is made up of naphthalene-sulfonic-maldehyde polycondensation (NSMP) and ATMP. Its characteristic results from the synergistic effects of NSMP and ATMP. The results show that when 0.7%-1.2% of N-2000 is added to concrete (by mass of cement), the water reducing ratio is up to 20%-30%, and the slump of fresh concrete can be retained for 2 hours without significant loss. N-2000 can not only improve the workability of fresh concrete but also increase the strength of the hardened concrete, especially early strength. It is also proved to have a good compatibility with various cements.

Survey-Based Analysis of Water Consumption Law in High-Rise Public Buildings and Water-Saving Performance of Pressure-Reducing Measures

Facing the contradiction of water scarcity and water wastage in most cities of China, this study aims at probing into the factors influencing water-use efficiency and assessing water-saving potential by adopting pressure control measures based on field survey conducted in 23 high-rise buildings in Suqian, China and laboratory tests. Results showed that per capita water consumption (PCWC) exceeding water consumption norms is common in these buildings. The hourly water consumption variation law is quite different among different types of buildings. These differences should be considered in designing building water supply systems to lower water and energy consumption. On the basis of correlation analysis, the order of factors influencing the PCWC follows average tap water pressure, percapita building area, and building age, suggesting pressure management in high-rise buildings is a key water-saving measure. Field tests of outflow characteristics under different water pressures indicated that over-pressure outflow (OPO) is a common cause of water wastage in buildings, however, no branch pipe pressure control measures were found in all the surveyed buildings. Laboratory tests showed that branch pipe pressure-reducing measures can lower water consumption and improve the comfortability of use as well. Therefore, in addition to applying high efficiency water-saving devices, we strongly recommend that branch pipe pressure-reducing measures should be strictly implemented in designing new building water supply systems and reconstruction of existing old building water supply systems, thereby, promoting water, energy saving and development of green building.

水肥一体化模式下不同水肥套餐对蜜柚产量、品质及经济效益的影响

通过2020—2022年定位试验,研究水肥一体化条件下不同水肥套餐对蜜柚产量、品质及经济效益等的影响,为探索和实践蜜柚水肥一体化施肥模式提供依据。对平和蜜柚高低产园分别设置4种处理方式:(1)TF(常规施肥)、(2)30%WF(30%水肥套餐)、(3)50%WF(50%水肥套餐)、(4)70%WF(70%水肥套餐)。2020—2022年定位试验结果表明:水溶肥套餐不同程度减量施肥对蜜柚产量影响差异显著,高低产园年平均产量影响均为:70%W>50%WF>TF>30%WF;高产园50%WF、70%WF处理比TF处理年平均增产率分别为12.43%、24.67;低产园50%WF、70%WF处理比TF处理年平均增产率分别为15.05%、26.80%;高、低产园蜜柚年平均产量均以70%WF处理最高(高产园67845.5 kg/hm^(2)、低产园53495.5 kg/hm^(2)),低产园增产幅度大于高产园;高、低产园中年平均次果率均以70%WF效果最佳(高产园5.71%、低产园4.67%)。高、低产园不同水溶肥套餐施肥处理对蜜柚果肉粒化率无显著影响,但对单果重、果肉重影响较为显著;且不同水溶肥套餐施肥处理蜜柚裂果率年际变异大;70%水溶肥套餐施肥明显改善了蜜柚基本农艺性状,提高单果重,降低裂果率。2021、2021年高、低产园中4种处理可溶性固形物、可溶性糖、可滴定酸度增减幅度不大,各处理间差异不显著;70%水溶肥套餐蜜柚各品质指标均为最佳。高产园50%WF、70%WF处理年平均最终净收益较TF处理分别增收30.58%、47.79%。年平均产投比以70%WF处理最高(4.29∶1),较TF处理高1.31倍。低产园50%WF、70%WF处理年平均最终净收益较TF处理分别增收40.41%、59.67%。年平均产投比以70%WF处理最高(3.63∶1),比TF处理高1.17倍;高、低产园中均以70%水溶肥套餐处理经济效益最高,低产园经济效益增幅大于高产园。水肥一体化模式下不同水肥套餐减量施肥具有提高蜜柚产量、经济效益和改善品质等效果,且在高低产园中蜜柚施用70%WF处理对提高蜜柚产量、经济效益和改善品质等效果最好,为最佳施肥处理,推荐应用。

A Novel γ-Alumina Supported Fe-Mo Bimetallic Catalyst for Reverse Water Gas Shift Reaction

In reverse water gas shift （RWGS） reaction COa is converted to CO which in turn can be used to pro- duce beneficial chemicals such as methanol. In the present study, Mo/AlaO3, Fe/AlaO3 and Fe-Mo/Al2O3 catalysts were synthesised using impregnation method. The structures of catalysts were studied using X-ray diffraction （XRD）, Brunauer-Emmett-Teller （BET） method, inductively coupled plasma atomic emission spectrometer （ICP-AES）, temperature programmed reduction （H2-TPR）, CO chemisorption, energy dispersive X-ray （EDX） and scanning electron microscopy （SEM） techniques. Kinetic properties of all catalysts were investigated in a batch re- actor for RWGS reaction. The results indicated that Mo existence in structure of Fe-Mo/AlzO3 catalyst enhances its activity as compared to Fe/AlaO3. This enhancement is probably due to better Fe dispersion and smaller particle size of Fe species. Stability test of Fe-Mo/AlzO3 catalyst was carried out in a fixed bed reactor and a high CO yield for 60 h of time on stream was demonstrated. Fez（MoO4）3 phase was found in the structures of fresh and used catalysts. TPR results also indicate that Fez（MoO4）3 phase has low reducibility, therefore the Fe2（MoO4）3 phase significantly inhibits the reduction of the remaining Fe oxides in the catalyst, resulted in high stability of Fe-Mo/Al2O3 catalyst. Overall, this study introduces Fe-Mo/Al2O3 as a novel catalyst with high CO yield, almost no by-products and fairly stable for RWGS reaction.

Electrochemical Fabrication of rGO-embedded Ag-TiO2 Nanoring/Nanotube Arrays for Plasmonic Solar Water Splitting

Effective utilization of hot electrons generated from the decay of surface plasmon resonance in metal nanoparticles is conductive to improve solar water splitting efficiency.Herein,Ag nanoparticles and reduced graphene oxide(rGO)co-decorated hierarchical TiO2 nanoring/nanotube arrays(TiO2 R/T)were facilely fabricated by using two-step electrochemical anodization,electrodeposition,and photoreduction methods.Comparative studies were conducted to elucidate the effects of rGO and Ag on the morphology,photoresponse,charge transfer,and photoelectric properties of TiO2.Firstly,scanning electron microscope images confirm that the Ag nanoparticles adhered on TiO2 R/T and TiO2 R/T-rGO have similar diameter of 20 nm except for TiO2 R-rGO/T.Then,the UV-Vis DRS and scatter spectra reveal that the optical property of the Ag-TiO2 R/T-rGO ternary composite is enhanced,ascribing to the visible light absorption of plasmonic Ag nanoparticles and the weakening effect of rGO on light scattering.Meanwhile,intensity-modulated photocurrent spectroscopy and photoluminescence spectra demonstrate that rGO can promote the hot electrons transfer from Ag nanoparticles to Ti substrate,reducing the photogenerated electron-hole recombination.Finally,Ag-TiO2 R/T-rGO photoanode exhibits high photocurrent density(0.98 mA cm?2)and photovoltage(0.90 V),and the stable H2 evolution rate of 413μL h?1 cm?2 within 1.5 h under AM 1.5 which exceeds by 1.30 times than that of pristine TiO2 R/T.In line with the above results,this work provides a reliable route synergizing rGO with plasmonic metal nanoparticles for photocatalysis,in which,rGO presents a broad absorption spectrum and effective photogenerated electrons transfer.

Reduced graphene oxide-based materials for electrochemical energy conversion reactions

There have been ever-growing demands to develop advanced electrocatalysts for renewable energy conversion over the past decade.As a promising platform for advanced electrocatalysts,reduced graphene oxide(rGO)has attracted substantial research interests in a variety of electrochemical energy conversion reactions.Its versatile utility is mainly attributed to unique physical and chemical properties,such as high specific surface area,tunable electronic structure,and the feasibility of structural modification and functionalization.Here,a comprehensive discussion is provided upon recent advances in the material preparation,characterization,and the catalytic activity of rGO-based electrocatalysts for various electrochemical energy conversion reactions(water splitting,CO2 reduction reaction,N2 reduction reaction,and O2 reduction reaction).Major advantages of rGO and the related challenges for enhancing their catalytic performance are addressed.

The impact of sulfate reduction on the distribution of methylmercury in reservoirs in the city of Guiyang

In this paper, the relationship between sulfate reduction potential and mercury methylation potential was studied in the Aha, Baihua and Hongfeng reservoirs from Guiyang City. The methylmercury (MeHg) concentrations of lake water in the Aha Reservoir were greatly elevated as compared to those of the Hongfeng and Baihua reservoirs, which was correlated with its distinctly high SRB abundance, SO42-, and S2- concentrations. Among the three reservoirs, however, the highest MeHg was observed in in the top several centimenters of pore water profile in the Hongfeng Reservoir where the lowest S2- in pore water occurred. The distributions of MeHg in lake water and pore water showed the highest methylation potential occurred at water-sediment surface for the Aha Reservoir and the in the top several centimenters of sediments for the Hongfeng Reservoir. It is guessed that the highest mercury methylation only occurs at the sites with certain sulfide concentrations.

Applied bias photon-to-current conversion efficiency of ZnO enhanced by hybridization with reduced graphene oxide

The role of reduced graphene oxide（rGO） in the enhancement of photo-conversion efficiency of ZnO films for photoelectrochemical（PEC） water-splitting applications was analyzed. ZnO and rGO-hybridized ZnO（rGO/ZnO） films were prepared via a two-step electrochemical deposition method followed by annealing at 300 °C under argon gas flow. The physical, optical and electrochemical properties of the films were characterized to identify the effect of rGO-hybridization on the applied bias photon-to-current efficiency（ABPE） of ZnO. Scanning electron microscopy and X-ray diffraction indicated the formation of verticallyaligned, wurtzite-phase ZnO nanorods. Diffuse-reflectance UV–visible spectroscopy indicated that rGO-hybridization was able to increase the light absorption range of the rGO/ZnO film. UPS analysis showed that hybridization with rGO increased the band gap of ZnO（3.56 eV） to 3.63 eV for rGO/ZnO sample,which may be attributed to the Burstein–Moss effect. Photoluminescence（PL） spectra disclosed that rGOhybridization suppressed electron-hole recombination due to crystal defects. Linear sweep voltammetry of the prepared thin films showed photocurrent density of 1.0 and 1.8 m A/cm;for ZnO and rGO/ZnO at+0.7 V, which corresponded to an ABPE of 0.55% and 0.95%, respectively. Thus, this report highlighted the multi-faceted role of rGO-hybridization in the enhancement of ZnO photo-conversion efficiency.

Five Years of Rice Cultivation in Paddy Fields for Treated Water from Humus Bioreactor-Type Rural Wastewater Treatment Plants

The treated sewage has a color as well as odor and is difficult to reuse.Physical methods to reduce color with odor are costly and more difficult to reuse.Since the color and odor were reduced by pellet-type bioreactor sewage treatment using humus,rice was cultivated for 3 years.Industrially,3 years is sufficient to investigate the stability of treatment facilities,but when biological treatment is applied,5 to 10 years of investigation is required.In addition,in rice cultivation,a similar 5 to 10 years survey is required to investigate the accumulation of low-concentration pollutants.This report is a five-year report and is the result of paddy rice cultivation in a stable wastewater treatment facility.The cultivated rice fully satisfied the edible standards and was able to obtain safe rice,and the effect of reducing fertilizer applied was obtained by using nitrogen and phosphorus from the treated water.In addition,the yield was able to be within the range of the standard yield of 500 kg to 550 kg/1,000 m^(2).

Sprinkler Irrigation and Soil Tillage Practices in Sugarcane Plantations as Influenced by Soil Texture and Water Storage in Northern Ivory Coast

Soil survey investigations were carried out in Ferk6 1 as well as Ferk6 2 sugar mills of northern Ivory Coast to determine soil texture and water storage capacity for sprinkler irrigation and tillage management. A 5-year term observation experiment on reduced tillage compared with conventional tillage was also conducted in Ferk6 1 over an irrigated cane crop of 28 ha for yield optimization purpose. Soil sampling was achieved after harvest or prior to re-plantation at five different spots along two transects over 30 cm depth in every farmland which covers about 30-40 ha with 432 m long cane rows as to get an average soil sample of 1.5-2 kg. Soil physical properties like texture and water retention curves were determined locally in the sugar company＇s soil laboratory. It came out that the majority of soils investigated was coarse-textured for about 64% in Ferk6 1 and 85% in Ferk6 2, with a lower to medium water storage capacity （70-89 mm） over 60 cm depth which corresponds to a readily available moisture less than 60 mm. Except for the sugarcane plant crop, no significant difference in cane yields resulting from tillage practices was observed over four consecutive cropping seasons. The yield decline from plant cane to first ratoon was very high under conventional tillage （-16 t/ha） compared with the reduced tillage （＋3 t/ha）. Even higher cane yield was obtained on the second ratoon （89 t/ha） compared with the conventional tillage （83 t/ha）.

水溶肥替代及减量对朝天椒产量、品质和土壤养分残留的影响

为探究适于朝天椒生产的水溶肥最佳施用方式,通过田间试验研究水溶肥替代常规化肥及减量对朝天椒产量、品质及土壤养分残留的影响,共设置7个处理:CK(常规化肥)、T1(100%替代)、T2(T1减量20%,100%替代)、T3(T1减量40%,100%替代)、T4(50%替代)、T5(T4减量20%,50%替代)、T6(T4减量40%,50%替代)。结果表明,与CK相比,T1和T4处理产量分别提高21.09%和26.92%,品质提高;减量20%条件下,T2和T5处理产量分别提高14.28%和15.23%,品质提高;减量40%条件下,T3和T6处理产量分别提高7.41%和4.29%,品质提高,土壤养分残留量降低。综合考虑朝天椒的产量、品质及环境效益,水溶肥50%替代优于100%替代,替代后减量20%~40%在生产上是可行的。T5处理是生产上适宜推广的最佳施用方式。

水分优化管理对稻虾共作模式水稻产量及土壤还原性物质的影响

通过探索水分优化管理对稻虾共作模式水稻产量及土壤还原性物质的影响,为该模式下水稻水分管理和土壤改良提供科学依据。在水稻直播和机插两种种植方式下,分别设置以水稻分蘖后期和成熟期两次重晒田等措施为主的水分优化管理处理、以水稻分蘖后期和成熟期两次轻晒田等措施为主的水分常规管理处理,于湖北省潜江市采用田间定位试验开展研究。结果表明,在水稻直播和机插条件下,水分优化管理相对于常规管理平均增产率分别为8.5%和9.4%,增产效果均达到显著水平。相对于常规管理,水分优化管理对水稻有效穗数和每穗粒数的正效应大于结实率和千粒质量。水稻分蘖后期,水分优化管理相对于常规管理0~10 cm土层亚铁含量下降40.8%~41.8%,0~20 cm土层还原性物质总量下降45.1%~46.4%;与分蘖后期相比,水稻收获后0~20 cm土层亚铁和还原性物质总量总体呈下降趋势。由此表明,稻虾共作模式下分蘖后期和成熟期两次重晒田等水分优化管理措施能够显著增加水稻产量,缓解土壤潜育化程度。

纤维素基共聚型聚羧酸减水剂的合成及其性能

以天然纤维为原料,采用接枝醚化-烯丙基氯双键改性-水溶液自由聚合路线制备纤维素基共聚型聚羧酸减水剂(HEPCEs),通过傅里叶变换红外光谱、凝胶渗透色谱对产品HEPCEs进行分子结构分析,通过净浆流动度、经时变化流动度测试对HEPCEs减水性能进行评价,并同时进行了分子粒径、zeta电位以及吸附层厚度的测试,探究HEPCEs对水泥净浆的作用机理。结果表明,纤维素基共聚型聚羧酸减水剂中改性纤维素聚醚(DBHECs)适宜替代量为5%~10%,过多替代会出现支链缠绕并阻碍羧酸基团锚固,适量替代的纤维素结构引入可以在保持较好吸附性能的同时进一步提升减水剂的性能,超过商用高效减水剂标准,并表现出一定的缓释作用。

利用制浆黑液研制混凝土减水剂及其在建筑工程上的应用研究

在制浆造纸过程中产生的大量制浆黑液对环境有很大危害,处理制浆黑液时要把环境和水源的保护考虑在内。目前制浆黑液混凝土减水剂的研发及应用于建筑工程,是安全绿色处理制浆黑液的有效途径,不仅使废料重新利用,还节约了减水剂制造成本,达到双赢效果。制浆黑液研制的减水剂对混凝土制品抗压性能和抗渗性能的提升及其在建筑工程上的应用是建筑行业及制浆造纸行业的巨大突破。废料的二次利用不仅节约了制造成本,还降低了混凝土的生产成本,更好地保护了环境,从而实现了可持续发展,为以后的制浆黑液废液处理提供了新的思考方向和借鉴价值。

一种具有超长侧链的疏水缔合型聚合物的合成及减阻性能评价

采用曲拉通和丙烯酰氯醇解合成一种水溶性可聚合单体,仅使用水作为溶剂合成一种具有超长侧链的疏水缔合型聚丙烯酰胺(HAPAM)作为减阻剂,通过分子动力学模拟方法对比了聚丙烯酰胺、部分水解聚丙烯酰胺和合成的具有超长侧链的HAPAM与水的相互作用,并分别以去离子水和盐水配液改变HAPAM含量,测量不同HAPAM含量的滑溜水在不同流速下的摩阻,并计算相应的减阻率。实验结果表明,具有超长侧链的HAPAM与水的相互作用最强;减阻率随流速的增加而增大,HAPAM含量越高,减阻率达到70%所需的流速越高,减阻率最高可达80%以上;盐对滑溜水的减阻率和黏度有显著负面影响,需提高HAPAM含量才能获得理想的减阻率;SEM表征结果显示,HAPAM在清水和盐水中的分布形态均为网状结构。

取代真空联合堆载预压膜上砂保护垫层的流态固化土研究

真空联合堆载预压地基处理工程中需要砂保护垫层,许多地区砂源紧张,因此开展研究利用淤泥质渣土配制流态固化土用于替代预压膜上砂保护垫层.通过进行大量的无侧限抗压强度和流动度等实验,探究淤泥质渣土含水率、固化剂掺量和外加剂等因素对制配流态固化土流动度和无侧限抗压强度的影响.结果表明:提高土体含水率或添加外加剂均可有效改善流动度,其中外加剂改善效果更显著;固化剂掺量是影响无侧限抗压强度的最主要因素,添加外加剂会降低无侧限抗压强度;对于含水率120%~140%的土体,不需要外加剂,固化剂掺量为土体质量的5%~7%时配制的流态固化土可以替代砂保护垫层;对于含水率80%~100%的土体,在5%~7%固化剂掺量下需添加一定的外加剂.

预制构件用水泥基修补砂浆的制备及应用研究

为修补预制构件施工过程中缺角、裂缝等缺陷,以硅酸盐水泥、硫铝酸盐水泥和半水石膏作为胶凝体系,掺加适量减水剂、乳胶粉和其他助剂,制备一种凝结时间短、早期强度高的水泥基修补砂浆,并对其性能进行研究。结果表明,掺加减水剂可以提高修补砂浆的抗压强度和流动度,掺加乳胶粉会延长砂浆的凝结时间,降低抗压强度,同时砂浆流动度则随乳胶粉掺量的增加先增大后减小。减水剂掺量以0.20%为宜,乳胶粉掺量以5.0%为宜,此时修补砂浆的初、终凝时间分别为15.8、22.4 min,7、28 d抗压强度分别为32.2、55.1 MPa,流动度为212 mm。

水下流态固化土强度与流动性能试验研究

为了完善流态固化土水下施工性能与无侧限抗压强度研究,通过向不同初始含水率的土体中添加减水剂、水泥和絮凝剂,研究含水率、减水剂掺量、水泥掺量和絮凝剂掺量对流态固化土浆体的流动性、抗分散性和流态固化土的力学性能的演化规律。结果表明,只使用水泥不能明显调节流态固化土浆体的流动性和抗分散性;絮凝剂和水泥掺量的增加可以提高流态固化土浆体的抗分散性和固化土的力学性能,对流态固化土浆体的流动性有抑制作用;减水剂和含水率升高对流态固化土浆体的流动性具有促进作用,对流态固化土浆体的抗分散性和力学性能有抑制作用。