Effects of straw and biochar addition on soil nitrogen,carbon,and super rice yield in cold waterlogged paddy soils of North China

The additions of straw and biochar have been suggested to increase soil fertility, carbon sequestration, and crop produc- tivity of agricultural lands. To our knowledge, there is little information on the effects of straw and biochar addition on soil nitrogen form, carbon storage, and super rice yield in cold waterlogged paddy soils. We performed field trials with four treatments including conventional fertilization system （CK）, straw amendment 6 t ha^-1 （S）, biochar amendment 2 t ha^-1 （C1）, and biochar amendment 40 t ha^-1 （C2）. The super japonica rice variety, Shennong 265, was selected as the test Crop. The results showed that the straw and biochar amendments improved total nitrogen and organic carbon content of the soil, reduced N2O emissions, and had little influence on nitrogen retention, nitrogen density, and CO2 emissions. The S and C1 increased NH4^＋-N content, and C2 increased NO3^--N content. Both S and C1 had little influence on soil organic carbon density （SOCD） and C/N ratio. However, C2 greatly increased SOCD and C/N ratio. C1 and C2 significantly improved the soil carbon sequestration （SCS） by 62.9 and 214.0% （P〈0.05）, respectively, while S had no influence on SCS. C1 and C2 maintained the stability of super rice yield, and significantly reduced CH4 emissions, global warming potential （GWP）, and greenhouse gas intensity （GHGI）, whereas S had the opposite and negative effects. In summary, the biochar amendments in cold waterlogged paddy soils of North China increased soil nitrogen and carbon content, improved soil carbon sequestration, and reduced GHG emission without affecting the yield of super rice.

Effects of Rice Straw and Its Biochar Addition on Soil Labile Carbon and Soil Organic Carbon

Whether the biochar amendment could affect soil organic matter （SOM） turnover and hence soil carbon （C） stock remains poorly understood. Effects of the addition of ^13C-labelled rice straw or its pyrolysed biochar at 250 or 350℃ to a sugarcane soil （Ferrosol） on soil labile C （dissolved organic C, DOC; microbial biomass C, MBC; and mineralizable C, MC） and soil organic C （SOC） were investigated after 112 d of laboratory incubation at 25℃. Four treatments were examined as （1） the control soil without amendment （Soil）; （2） soil plus ^13C-labelled rice straw （Soil＋Straw）; （3） soil plus 250℃ biochar （Soil＋B250） and （4） soil plus 350℃biochar （Soil＋B350）. Compared to un-pyrolysed straw, biochars generally had an increased aryl C, carboxyl C, C and nitrogen concentrations, a decreased O-alkyl C and C：N ratio, but similar alkyl C and δ^13C （1 742- 1 877 %）. Among treatments, significant higher DOC, MBC and MC derived from the new C （straw or biochar） ranked as Soil＋Straw〉Soil＋B250〉Soil＋B350, whilst significant higher SOC from the new C as Soil＋B250〉Soil＋Straw≈Soil＋B350. Compared to Soil, DOC and MBC derived from the native soil were decreased under straw or biochar addition, whilst MC from the native soil was increased under straw addition but decreased under biochar addition. Meanwhile, native SOC was similar among the treatments, irrespective of the straw or biochar addition. Compared to Soil, significant higher total DOC and total MBC were under Soil＋Straw, but not under Soil＋B250 and Soil＋B350, whilst significant higher total MC and total SOC were under straw or biochar addition, except for MC under Soil＋B350. Our results demonstrated that the application of biochar to soil may be an appropriate management practice for increasing soil C storage.

Effect of Rice Straw Biochar on Soil Quality and the Early Growth and Biomass Yield of Two Rice Varieties

Sustainable rice production in Sierra Leone faces serious constraints due to soil acidity, low cation exchange capacity, low nutrient contents accelerated mineralization of soil organic matter and soil loss by erosion (particularly on the uplands). One possible approach to addressing the soil constraints to rice production both on uplands and lowlands of Sierra Leone is the recycling of rice residues through biochar production and application to soils. A pot experiment was conducted to investigate the effects of application of biochar from rice residues on (i) soil physicochemical properties and (ii) the early growth characteristics of two rice varieties, NERICA L19 and ROK3. The experiment was arranged in a completely randomized design (CRD) with two biochar levels (0 and 15 g/kg soil) and two rice varieties in three replications. For the biochar treated soils (+biochar), 75 g rice straw biochar was applied to 5 kg air-dry soil (15 kg biochar/kg soil), mixed thoroughly and placed into perforated black polythene bags. Seeds of two rice varieties, NERICA L19 and ROK3 were planted on the treated and untreated soils for eight weeks. Application of biochar improved available phosphorus, exchangeable cations and cation exchange capacity in biochar treated soils compared to the control soil without biochar. Plant height, tiller number, and dry biomass weight of both rice varieties grown in soils amended with rice straw biochar were significantly higher than those on untreated soils. The most remarkable increase in plant growth characteristics as a result of biochar addition to soil was reflected in the biomass yield and tiller numbers. Dry shoot biomass for ROK3 rice variety varied significantly from a mean of 3.5 g (control) to 26.2 g (+biochar) while tiller numbers significantly varied from 10 (control) to 29.6 (+biochar). Similarly, for NERICA L19 rice variety, dry shoot biomass increased significantly from 4.5 g (control) to 22.7 g (+biochar) while tiller numbers increased significantly from a mean of 12.3 (control) to 30 (+biochar). Thus converting rice residues to biochar and applying to soil holds promise for improving rice production in Sierra Leone.

Effects of Straw and Biochar Returned to the Soil on Soil Physical Properties and pH Value in Cold Rice Region

[Objectives]In order to explore the feasibility of using straw and biochar returned to the soil to improve soil physical properties and pH value in cold rice regions of China.[Methods]the effects of straw directly returned to the soil and charred straw(biochar)returned to the soil on soil bulk density,porosity,temperature and pH value of cold paddy soil were studied in this paper.[Results]The results showed that compared with conventional production,straw(6 t/ha),a small amount of biochar(2 t/ha)and a large amount of biochar(40 t/ha)returned to the soil reduced paddy soil bulk density at different growth stages by 6.02%-11.86%,2.69%-6.67%and 8.58%-11.32%,respectively,increased total porosity by 7.41%-14.93%,3.19%-8.38%and 9.81%-14.27%,respectively,and increased aeration porosity by 22.28%-192.11%,17.80%-92.11%and 52.44%-157.11%,respectively.Straw and a small amount of biochar returned to the soil had no significant effect on soil temperature and pH value of paddy field,but a large amount of biochar returned to the soil could significantly increase soil temperature by 5.13%-8.79%and pH value by 3.15%-5.96%in the later stage of rice growth.[Conclusions]The straw and biochar returned to the soil could reduce soil bulk density,increase total porosity and aeration porosity,and only a large amount of biochar returned to the soil could significantly increase soil temperature and pH value.

Sustainable Bio-Conversion of Rice Straw Waste into High Quality Organic Fertilizer

The aim of this study is to investigate the effect of different additives including biochar, effective micro-organisms (EM), animal manure and commercial microbial inoculants on the bioconversion of rice straw. Different compost piles were constructed, and each contained 50 kg of rice straw and mixture of natural rocks to enrich the compost nutritional value. The physical, chemical and biological parameters indicating the decomposition of organic material, maturation and quality of the organic fertilizer product were investigated during the composting process. A rapid increase in compost temperature was obtained in inoculated piles. All piles reached maturation after around 42 days. All analysis of the properties of the final compost products indicated that it was in the range of the matured level and can be used as organic fertilizer without limitation. The highest decomposition rate and highest organic fertilizer quality were obtained in the pile inoculated with EM and 10% biochar compared to other treatments.

Effects of Straw Utilization Methods on Dry Matter Production and Yield of Japonica Rice in Northern China

To study the effects of straw utilization methods on dry matter production and yield of japonica rice in northern China,taking the super japonica rice Shennong 265 as the test material,using the planting method of seedling transplanting,setting four treatments,namely,the conventional production,directly returning straws to field(6 t/ha),returning straws to field at low amount of biochar(2 t/ha)and returning straws to field at high amount of biochar(40 t/ha),this paper analyzed the changes in production and yield of super japonica rice Shennong265.According to the experimental results,compared with the conventional production,after the straws were directly returned to the field,the dry matter accumulation of japonica rice was insufficient,and the leaf output rate and contribution rate were significantly reduced by 41.19%and 34.69%,respectively;the number of filled grains per panicle,1000-grain weight,and panicles per plant showed negative effect,leading to a decline in the yield;under the condition of returning straws to field at high amount of biochar,the dry matter accumulation showed a decline trend,both the leaf and stem sheath significantly reduced by 21.41%and 17.43%,and the number of filled grains per panicle also declined;under the condition of returning straws to field at low amount of biochar,the dry matter accumulation increased,and the leaf contribution rate increased by 11.68%,the number of filled grains per panicle,1000-grain weight,and panicles per plant showed positive effect,showing the potential of yield increase.In conclusion,returning suitable straw biochar to field(2 t/ha)is favorable for promoting the japonica rice production in northern China.

化肥减量配施生物炭和秸秆对砂姜黑土区水稻产量、养分吸收和土壤碳的影响

为探讨砂姜黑土区养分资源高效管理和秸秆资源化利用方式,采用田间定位试验,连续2 a研究化肥减量配施生物炭和秸秆对该区域水稻产量、养分吸收和土壤碳的影响。试验设5个处理:①不施肥(CK);②常规施肥(100%NPK);③化肥减量20%(80%NPK);④化肥减量20%+秸秆(80%NPK+S);⑤化肥减量20%+生物炭(80%NPK+B),测定并分析水稻籽粒产量、地上部生物量、植株氮、磷、钾养分含量、土壤总有机碳(TOC)和微生物量碳(MBC)。结果显示,化肥减量20%配施生物炭或秸秆均有利于提高水稻产量和地上部生物量,且生物炭较秸秆的效果更为显著。化肥减量20%配施生物炭(80%NPK+B)处理的水稻产量和地上部生物量较100%NPK处理分别增加5.2%和4.7%,较80%NPK处理分别增加7.9%和7.2%;化肥减量20%配施秸秆(80%NPK+S)较100%NPK处理的水稻产量和地上部生物量分别增加3.4%和3.0%;80%NPK与100%NPK处理的籽粒和地上部生物量无显著差异;化肥减量20%配施生物炭显著提高了水稻地上部N、P_(2)O_(5)和K_(2)O养分累积量,较100%NPK处理分别提高了10.4%、7.2%和20.0%;化肥减量20%配施秸秆可显著提高氮、钾养分累积量,但却同时显著降低了磷素累积量;化肥减量20%配施生物炭或者秸秆,均有利于改善土壤总有机碳的累积,并且显著提高了土壤微生物量碳的含量,其中生物炭提高土壤总有机碳含量效果优于秸秆,而秸秆提高土壤微生物量碳含量效果优于生物炭。综合来看,在沿淮砂姜黑土区,化肥减量20%配施生物炭或者氮钾减量20%配施秸秆可增加或维持水稻产量,提高水稻对养分的吸收能力,利于固碳培肥。

稻秆生物炭添加对红壤性水稻土磷素生物有效性的影响

为明确稻秆生物炭添加对红壤性水稻土磷生物有效性组分的影响,基于水稻种植的盆栽试验,采用模拟生物活化的磷素分析方法(BBP法),分析了生物炭在不施加(CK)、施加一年(B1)和两年(B2)条件下,不同水稻生育期稻田土壤中可溶性磷(CaCl_(2)-P)、易被酶矿化的有机磷(Enzyme-P)、易被有机酸活化释放的磷(Citrate-P)和潜在无机磷(HCl-P)4个组分磷与全磷(TP)、有效磷(Bray-P)及磷素活化系数(PAC)的变化差异和影响因素。研究表明:与CK相比,B1处理的稻田土壤TP、Bray-P及BBP磷组分均无显著变化;B2处理稻田土壤TP、Bray-P、Citrate-P和HCl-P含量均显著增加,而CaCl_(2)-P、Enzyme-P含量无显著变化。随着水稻生育期的延长,各处理HCl-P/TP均显著上升;B2处理下CaCl_(2)-P/TP与Enzyme-P/TP均显著上升。相关分析表明:生物炭添加后稻田土壤Bray-P、TP与土壤pH显著正相关;CaCl_(2)-P与HCl-P、TP显著正相关,与土壤有效铁呈显著负相关;Citrate-P与TP、HCl-P极显著正相关,与Enzyme-P、pH显著正相关,与土壤有效铝极显著负相关。稻秆生物炭通过影响稻田土壤pH、有效铁和有效铝含量,间接地调控且显著增加了红壤性稻田土壤中TP、Bray-P、PAC及生物有效磷组分含量,稻秆生物炭的合理施用有利于农田生态环境保护和土壤磷素有效性的提升。

紫云英及氮肥减量下配施生物质炭对土壤理化性质和水稻产量的影响

【目的】为减少化学氮肥的使用,通过盆栽试验探究在紫云英还田条件下,氮肥减量配施生物质炭对稻田土壤养分提升、水稻增产的作用,旨在明确在紫云英替代部分氮肥的基础上,更有利于培肥和增产的最佳减氮量和生物质炭添加比例,以期为实际生产应用提供科学依据。【方法】采用双因素水稻盆栽试验,以冬闲+常规施肥(CK)为空白对照,设置了4个(0.25%、0.5%、1%、2%)生物质炭添加比例,在追肥时设置3个(减氮10%、减氮20%、减氮30%)减氮比例,共设置13个处理组合,每个处理重复4次,共计52盆,生长周期120 d,水稻成熟后比较各处理对土壤理化性质及水稻产量、性状的影响。【结果】在紫云英还田下,减氮30%配施2.0%生物质炭显著提高了土壤pH(P<0.01)与CK相比提高了12.02%;减氮20%配施2.0%生物质炭对土壤有机质(SOM)、有效磷(AP)、速效钾(AK)含量均具有极显著提升作用(P<0.01),显著提升了土壤全氮含量(P<0.05),比CK分别增加了38.8%、107.2%、25.4%、24.9%;减氮20%配施0.5%生物质炭时碱解氮含量显著提升了49.6%(P<0.01)。紫云英还田下减氮30%配施1.0%生物质炭时产量最高,与CK相比分别显著增产18.7%(P<0.01)。施加低量生物质炭(0.25%生物质炭)更有利于水稻地上部生物量积累,比CK显著增加了90.04%(P<0.01)。相关性分析表明,土壤有机质、有效磷、速效钾是提升水稻产量的主要土壤环境因子(P<0.05、r>0.5)。【结论】紫云英、氮肥减量及生物质炭联合施用的培肥增产效果显著,紫云英还田下减氮20%配施2.0%生物质炭更有利于提升稻田土壤养分含量,减少氮素流失,促进水稻生长增产,但施加过量生物质炭对水稻产量及生物量具有一定的抑制作用,在追肥时减氮30%配施1.0%生物质炭对水稻增产效果最佳。

稻秆炭还田对红壤双季稻田土壤碳氮磷钾生态化学计量学特征及其综合肥力的影响

为探究稻秆炭对红壤双季稻田土壤碳氮磷钾生态化学计量学特征及其综合肥力的影响,本研究采用大田定位试验,设置不施氮肥和生物炭(CK)、单施稻秆生物炭(B)、100%氮肥(N_(100))和100%氮肥+稻秆生物炭(N_(100)B)4个处理,分析不同处理稻田土壤碳、氮、磷、钾生态化学计量学特征及其综合肥力的变化情况。结果表明,与CK相比,B和N_(100)B处理土壤pH值分别提高0.05和0.13个单位。与N_(100)相比,N_(100)B处理不仅使土壤有机质、全氮、NO_(3)^(-)、NH_(4)^(+)、微生物生物量碳和氮含量增加5.13%、3.47%、11.7%、14.91%、60.89%、30.75%,还使土壤C/N、C/P、C/K、N/P、N/K化学计量比提升1.88%、2.10%、2.84%、3.62%、5.41%,并提升土壤综合肥力指数(IFI)2.97%。综上,稻秆炭还田有利于改善双季稻田土壤碳氮磷钾生态化学计量学特征及其综合肥力。本研究结果为合理高效利用南方红壤双季稻区稻秆资源提供了实践指导。

水稻秸秆生物炭对土壤理化性质及不同形态硫含量的影响

以不同炭化温度下制备的水稻秸秆生物炭(BC300和BC600)为对象,通过厌氧培育实验,考察了生物炭对土壤pH、电导率(EC)、土壤有机质(SOM)含量、酶活性、总硫(TS)含量和不同形态S含量的影响。实验结果表明:随生物炭添加量的增加,土壤pH和EC逐渐增大;添加生物炭后,初始阶段,SOM含量均增加,培养15周后,添加BC300的土壤中SOM含量增加,添加BC600的土壤中SOM含量有所降低;生物炭对土壤中脲酶和过氧化氢酶的活性具有一定的抑制作用;添加生物炭后,土壤中TS含量明显提高;初始阶段,随着生物炭添加量的增大,土壤中水溶性S含量明显增加、吸附性S和盐酸可溶性S的含量有所降低,培养15周后,土壤中水溶性S含量明显降低,吸附性S含量略有降低,盐酸可溶性S含量明显升高。

水铁矿-稻杆生物炭复合材料的制备及其对土霉素吸附、稳定性研究

以700℃稻杆裂解制得的生物炭为原料,通过碱液浸泡、加Fe^(3+)沉淀,制备了水铁矿-稻杆生物炭复合材料(Fh-BC),研究了Fh-BC对典型抗生素污染物土霉素的吸附性能,及其在Fe^(2+)共存时的稳定性。结果表明,pH=4.5、土霉素平衡质量浓度为27 mg/L时Fh-BC对土霉素的吸附容量高达6171 mg/g,远超已报道的系列活性炭吸附剂。根据表征分析,Fh-BC表面具有明显的Fe—O—Si红外吸收峰,生物炭的晶体衍射峰减弱,且比表面积比水铁矿及稻杆生物炭大幅增加,意味着Fh-BC在碱浸泡和Fe^(3+)沉淀处理中,生物炭的硅组分可能通过形成Fe—O—Si增强2线水铁矿的分散、降低生物炭结晶度增加比表面积,从而产生了土霉素的高吸附容量。与水铁矿不同,Fh-BC能够在Fe^(2+)共存时稳定存在,可在有Fe^(2+)的环境中持续发挥吸附作用以缓解土霉素污染。

不同龄期生物炭混凝土力学性能试验研究

将生物炭用于混凝土材料可改善其力学性能,实现固碳的同时丰富了生物质材料固废利用的途径。为研究不同龄期下椰壳、玉米秸秆、稻壳3种生物炭混凝土的工作性能与力学性能,将它以不同质量百分比替代水泥制备生物炭混凝土,对生物碳混凝土的塌落度、基本力学性能展开试验研究。采用SEM和XRD观察生物炭混凝土微观结构与水化产物。结果表明微观结构上生物炭促进了混凝土中水化硅酸钙的生成,水化产物间搭接密实,填充内部孔隙,增加密实程度,进而提升混凝土的宏观力学性能;生物炭可使混凝土7、14 d早期强度显著提升,早期抗压强度最高可提升19.7%,劈裂抗拉强度最高可提升21.7%,抗折强度最高可提升17.3%。

Rice straw management through biofuel,biochar,mushroom cultivation,and paper production to overcome environmental pollution in North India

Rice is the prominent food grain required by more than half of the world's population to fulfill their nutritional demand.With the continuous growth in the population at the global level,rice production has also been elevated.However,high rice production also creates a new problem in waste management worldwide.Rice straw,generated after rice harvest,possesses meager nutritional value,due to which it is less preferred as fodder and burned in the field.Paddy burning is one of the major causes of air pollution,leading to lung,heart,eye,and skin-related diseases and even premature death.This stubble burning also decreases soil fertility.In this review article,we have discussed the various economic uses of paddy straw which will help to reduce air pollution through the decline in paddy straw burning.Biochar is produced from paddy straw,which can be mixed into the soil to restore fertility and reduce toxic metals'bioavailability.The generation of biofuels such as biobutanol,bioethanol,and biogas from rice straw with their mechanism of synthesis is also discussed in this article.Rice straw can also be utilized in the preparation of solid fuel.Along with this,mushroom cultivation in paddy straw houses is also described.Paddy straw can be used for the pulp and paper industries,which will help to reduce the tree dependence of these industries.Apart from this,a bibliometric analysis of the Scopus database on rice straw uses for the last 20 years was done,including a bibliographic keyword analysis to show published documents'trends.This review will give an elaborated overview of the alternative uses of rice straw with a quantitative analysis of air pollution caused by paddy straw burning.This review will also help to improve the current uses of paddy straw for industrial and commercial benefits to make it more economical.

水稻秸秆炭施用对水稻土团聚体稳定性及其碳氮分布的影响

[目的]水稻长期种植过程中大量化肥施用导致土壤结构变差,研究不同用量水稻秸秆生物炭和化肥配施对水稻土结构和碳、氮分布的影响,探索稻田优化施肥管理方式。[方法]水稻田间试验在浙江衢州进行,试验设不施肥对照(CK)、常规施肥处理(NPK)以及常规施肥基础上添加22.5 t/hm^(2)(NPK+1%B)、45 t/hm(NPK+2%B)和90 t/hm^(2)(NPK+4%B)水稻秸秆炭处理,共5个处理。水稻收获后采集0-20 cm土层样品,测定土壤及不同粒级团聚体(>2、0.25~2、0.053~0.25和<0.053 mm)的有机碳和全氮含量,评价团聚体的稳定性。[结果]与NPK处理相比,施用水稻秸秆炭4年后,土壤>0.25 mm粒级团聚体含量提高了2.43%~7.99%,<0.25 mm粒级团聚体含量降低了2.93%~9.63%,土壤有机碳和全氮含量分别提高了16.40%~45.16%和14.67%~36.69%,各指标的变幅均以NPK+4%B处理最大。与NPK处理相比,秸秆炭处理土壤中>2 mm粒级团聚体中的有机碳和全氮含量分别提高了23.96%~70.87%和19.44%~47.56%,0.25~2 mm粒级团聚体中分别提高了21.87%~49.27%和17.18%~37.47%,增幅均以NPK+4%B处理最高,而0.053~0.25和<0.053 mm粒级团聚体中的有机碳和全氮含量无显著差异(P>0.05),说明施用水稻秸秆炭4年后,增加的土壤有机碳和全氮主要积累在>0.25 mm粒级团聚体中。与NPK处理相比,秸秆炭处理水稻土C/N值提高了2.40%~5.69%,但各处理间差异不显著,而4个粒级团聚体的土壤C/N值均显著提升,且均以NPK+4%B处理提高效果最好。此外,施用水稻秸秆炭提高了>2和0.25~2 mm粒级团聚体的碳、氮贡献率6.54%~17.43%、3.67%~7.28%和5.16%~11.55%、0.57%~1.83%,降低了0.053~0.25和<0.053 mm粒级团聚体的碳、氮贡献率7.25%~29.27%、15.93%~33.68%和10.26%~26.80%、12.61%~30.78%(P<0.05)。[结论]施用水稻秸秆炭能够迅速显著提高水稻土有机碳和全氮含量,增加>0.25 mm粒级团聚体质量占比,提高>2 mm粒级团聚体中有机碳的贡献率,降低<0.25 mm粒级团聚体中有机碳和全氮贡献率,且其影响幅度与水稻秸秆炭施用量呈正比。由此可见,施用水稻秸秆炭能在一定程度上改善水稻土结构,提高水稻土碳、氮固持潜力,对保证水稻土结构稳定性和维持水稻持续高产具有重要意义。

镁改性水稻秸秆生物炭对酸性矿山废水中Cd(Ⅱ)和Pb(Ⅱ)的吸附研究

为提高水稻秸秆生物炭对酸性矿山废水中重金属的去除能力,采用浸渍-热解法制备镁改性水稻秸秆生物炭(MBC)。通过批量吸附试验探究浸渍比、溶液pH、吸附时间及重金属离子初始浓度对MBC去除酸性矿山废水中Cd(Ⅱ)和Pb(Ⅱ)的影响,并采用表征技术对吸附前后MBC的特征进行表征分析和探究潜在的吸附机理。结果表明,浸渍-热解法制备的MBC拥有更发达的孔隙结构。吸附试验表明,在浸渍比和溶液pH分别为2∶1和5.0时,MBC对10 mg/L的Pb(Ⅱ)和Cd(Ⅱ)的去除达到最佳值,分别为93.58%和97.95%。此外,MBC去除Cd(Ⅱ)和Pb(Ⅱ)的过程符合拟二级动力学模型和Langmuir吸附等温模型。根据Langmuir模型,MBC对Cd(Ⅱ)和Pb(Ⅱ)最大的吸附量分别为90.45 mg/g和138.50 mg/g。FTIR和XRD分析结果表明,MBC对Cd(Ⅱ)和Pb(Ⅱ)的去除机理包含络合、共沉淀、离子交换及静电作用。五次再生后,MBC对Cd(Ⅱ)和Pb(Ⅱ)的去除率分别为75.62%和80.16%,以上结果说明,MBC在处理含Cd(Ⅱ)和Pb(Ⅱ)酸性矿山废水方面具有很大的潜力。

水稻秸秆生物炭对水体中磷酸盐的吸附特性研究

水稻秸秆是一种常见的农业废弃物,将其制备为生物炭,在水污染控制领域具有良好的应用前景。本研究通过一系列室内实验,考察了投加量、温度、pH等因素对水稻秸秆生物炭吸附磷酸盐效果的影响。在此基础上,进一步通过等温吸附模型及吸附动力学模型,探讨了水稻秸秆生物炭对磷酸盐的吸附机理。结果表明,投加量为1g·L^(-1)时,水稻秸秆生物炭对20 mg·L^(-1)磷酸盐(以磷计)的吸附去除率可达67.25%;温度及pH对磷酸盐的吸附效果存在显著影响,温度越高(0~30℃)吸附效果越好。此外,酸性条件下的吸附效果要好于碱性条件。通过等温吸附及吸附动力学模型拟合发现,磷酸盐在水稻秸秆生物炭上的吸附主要以单分子层吸附为主,理论最大吸附容量可以达到41.92mg·g^(-1);1h内的吸附容量可达平衡吸附容量的96%,吸附速率快,吸附过程受化学吸附控制。本研究可为水稻秸秆生物炭应用于吸附除磷提供理论与技术支持。

低温裂解水稻秸秆生物炭对水体中Pb/Cd吸附的应用研究

为寻找一种来源丰富、价格低廉、经济有效的生物炭治理水体中Pb/Cd污染,在限氧条件下将粉碎的水稻秸秆(RY)400℃热裂解30 min制备了水稻秸秆生物炭(RS).本研究对RS进行了表征,研究了RY及RS对溶液中Pb^(2+)/Cd^(2+)的吸附特性.结果表明:RS具有丰富的官能团,表面具有明显的孔隙结构.RS吸附Pb^(2+)的最佳条件为:在室温条件下,pH在6.0~8.0之间,固液比为1.0 g·L-1;生物炭吸附Cd^(2+)的最佳条件为:在25℃条件下,pH在7.0附近,固液比为10.0 g·L-1.吸附动力学实验分析发现,RS对Pb^(2+)、Cd^(2+)的吸附率远远高于RY对Pb^(2+)、Cd^(2+)的吸附率,在35 min时RS对Pb^(2+)的吸附已经基本达到平衡,在40 min时RS对Cd^(2+)的吸附已经达到平衡.等温吸附实验分析发现,RS对溶液中Pb^(2+)的等温吸附更符合Freundlich等温吸附模型,主要为多层吸附;生物炭对溶液中Cd^(2+)的等温吸附过程更符合Langmuir等温吸附模型,主要为单层吸附.研究表明,利用廉价丰富的水稻秸秆材料在低温少时条件下制备生物炭来治理水体中Pb/Cd污染是可行的,本研究以期为重金属环境污染治理提供经济有效的方法.

Ice-phobic properties of MoS_(2)-loaded rice straw biogas residue biochar-based photothermal and anti-corrosion coating with low oxygen to carbon ratio

Icing of wind turbine blades will seriously hinder the development of the wind power industry,and the use of biomass resources to solve the icing problem is conducive to promoting the synergistic development of biomass and wind energy.In this study,ice-phobic coatings with photothermal and anti-corrosion properties were prepared by surface modification pyrolysis and hydrothermal reaction with rice straw biogas residue as raw material.The erosion of KOH and the surface modification of MoS_(2) produced a rough structure of the material,and the high-temperature pyrolysis and hydrothermal reaction promoted the dehydrogenation and decarboxylation reactions,which reduced the number of oxygen-containing functional groups and decreased the surface energy of the material.The ice-phobic coating has superhydrophobic properties with a contact angle of 158.32°.Due to the small surface area in contact with water,the coating was able to significantly reduce the icing adhesion strength to 53.23 kPa.The icing wind tunnel test results showed that the icing area and mass were reduced by 10.54%and 30.08%,respectively,when the wind speed was 10 m s^(−1) and the temperature was−10°C.Photothermal performance tests showed that the MoS_(2)-loaded material had light absorption properties,and the coating could rapidly warm up to 58.3℃under xenon lamp irradiation with photothermal cycle stability.The loading of MoS_(2) acts as a physical barrier,reducing the contact of corrosive media with the substrate,thus improving the anti-corrosion of the coating.This study has practical application value and significance for the development of the anti-icing field under complex environmental conditions.

Transformation mechanism of nutrient elements in the process of biochar preparation for returning biochar to soil

Returning biochar to soil is a heavily researched topic because biochar functions well for soil improvement. There is a significant loss of nutrients, which occurs during biochar preparation before biochar is returned to soil,thereby seriously undermining biochar＇s efficacy. Therefore, the transformation mechanisms of biochar p H,mass, nutrients and metals during pyrolysis under different atmospheres and temperatures were studied such that the best method for biochar preparation could be developed. Several conclusions can be reached：（1） a CO2 atmosphere is better than a N2 atmosphere for biochar preparation, although preparation in a CO2 atmosphere is not a common practice for biochar producers;（2） 350 ℃is the best temperature for biochar preparation because the amount of nutrient loss is notably low based on the premise of straw transferred into biochar; and（3） transforming mechanisms of pH, N, P and K are also involved in the biochar preparation process.