Granular activated carbons from palm nut shells for gold di-cyanide adsorption

Granular activated carbons were produced from palm nut shells by physical activation with steam. The proximate analysis of palm nut shells was investigated by thermogravimetric analysis, and the adsorption capacity of the activated carbons, produced as a result of shell pyrolysis at 600℃ followed by steam activation at 900℃ in varying activation times, was evaluated using nitrogen adsorption at 77 K. Applicability of the activated carbons for gold dicyanide adsorption was also investigated. Increasing the activation hold time with the attendant increase in the degree of carbon burn-off results in a progressive increase in the surface area of the activated carbons, reaching a value of 903.1 m2/g after activation for 6 h. The volumes of total pores, mieropores, and mesopores in the activated carbons also increase progressively with the increasing degree of carbon burn-off, resulting from increasing the activation hold time. The gold di-cyanide adsorption of the activated carbons increases with the rise of pore volume of the activated carbons. The gold di-cyanide adsorption of palm nut shell activated carbon obtained after 6-h activation at 900℃ is superior to that of a commercial activated carbon used for gold di-cyanide adsorption.

Ensuring water security by utilizing roof-harvested rainwater and lake water treated with a low-cost integrated adsorption-filtration system

Drinking water is supplied through a centralized water supply system and may not be accessed by communities in rural areas of Malaysia.This study investigated the performance of a low-cost, self-prepared combined activated carbon and sand filtration(CACSF) system for roofharvested rainwater and lake water for potable use. Activated carbon was self-prepared using locally sourced coconut shell and was activated using commonly available salt rather than a high-tech procedure that requires a chemical reagent. The filtration chamber was comprised of local,readily available sand. The experiments were conducted with varying antecedent dry intervals(ADIs) of up to 15 d and lake water with varying initial chemical oxygen demand(COD) concentration. The CACSF system managed to produce effluents complying with the drinking water standards for the parameters p H, dissolved oxygen(DO), biochemical oxygen demand(BOD5), COD, total suspended solids(TSS), and ammonia nitrogen(NH_3-N). The CACSF system successfully decreased the population of Escherichia coli(E. coli) in the influents to less than 30 CFU/m L. Samples with a higher population of E. coli(that is, greater than 30 CFU/m L) did not show 100% removal. The system also showed high potential as an alternative for treated drinking water for roof-harvested rainwater and class II lake water.

Feasibility Study on the Treatment of Wastewater Containing High-concentration Hg by Coagulation Sedimentation-Adsorption

For the wastewater containing high-concentration Hg,the feasibility of high-concentration Hg in wastewater treated by coagulation sedimentation,adsorption and the combined process was studied. Research results showed that if using the single coagulation sedimentation process,when FeSO_4·7H_2O dosage was 1. 39 g / L,and NaOH dosage was 0. 40 g / L,it could meet discharge requirement,but the reagent cost was 13. 1yuan / t,which was high. Because that there was subsequent adsorption process,it was selected 0. 28 g / L of FeSO_4·7H_2O and 0. 36 g / L of NaOH,and the estimated reagent cost was 2. 62 yuan / t. In selection process of adsorption materials,powdered activated carbon,granular activated carbon and diatomite all could effectively adsorb Hg,and the technology was feasible. When using the combined process of coagulation sedimentation + adsorption to treat the wastewater containing high-concentration Hg( 800 μg / L),removal rate could reach 99%,and operation cost was 2. 71 yuan. It could meet the requirement of sewage discharged into sewer( 20 μg / L) at the technology,and was acceptable at the economy.Therefore,treatment of wastewater containing high-concentration Hg by the combined process was feasible at the aspects of technology and economy.

Processes for the Clarification of the Crude Oil of Baobab Seeds Extracted by Pressing on Activated Carbon Elaborated from the Capsules of the Fruit (Adansonia digitata L.)

The baobab, Adansonia digitata L. plays an important role in the economy of local populations. The oil from the seeds of the baobab fruit is nowadays highly prized because of its numerous cosmetic and therapeutic applications and its composition of unsaturated fatty acids, sterols and tocopherols. However, unlike refined oils, locally extracted baobab oil has not undergone purification operations to ensure its quality. Only a filtration on special cloths is carried out after decantation. Indeed, the oil obtained after pressing is cloudy because of the presence of various impurities. It therefore requires treatment operations to make it more attractive and of higher quality. Therefore, in order to provide innovative solutions to local companies to improve the quality of vegetable oils, a study of clarification (treatment) of crude oil is necessary. An experimental device has been developed in the laboratory. It includes a glass column and a filter bed of dune sand and activated carbon. This study has shown the efficiency of the experimental device. Indeed, the activated carbon, thanks to its adsorbing power, has allowed a significant decrease in turbidity at the 5% threshold, from 14.61 NTU for the raw oil to 0.08 NTU for the oil filtered on 3% carbon and 0.033 NTU for the oil filtered on 5% carbon. That is to say an abatement higher than 95%. This decrease in turbidity could be correlated with the decrease in brown index from 187.39a for the initial crude oil to 128.53d for the oil treated with 3% activated carbon versus 187.59a for the oil filtered on cloths. The lowest brown index was observed with the filtration using 5% activated carbon (35.99b). Thus, for the yellowness index, only the filtration on 5% charcoal allowed to obtain a significant decrease in yellowness. The yellowing index of the oil with 5% was 44.67b against 79.04a for the oil filtered with 3% activated carbon, 86.33a for the crude oil and 86.46a for the oil filtered on cloths. Finally, the oil sample treated with 5% activated carbon had the clearest clarity than the other samples with a clarity (L) equal to 97.98c against 95.63d for the oil treated with 3% carbon and 94.99b for the oil filtered on filter cloths. According to the results obtained, the experimental device made it possible to obtain a clearer baobab oil with a low brown index, thus improving the sensory quality of the oil.

Multiscale Simulation Starting at the Molecular Level for Adsorption Process Development

This article presents a multiscale simulation approach starting at the molecular level for the adsorption process development. A grand canonical Monte Carlo method is used for the prediction of adsorption isotherms of methanol on an activated carbon at the molecular level. The adsorption isotherms obtained in the linear region （or adsorption constant） are exploited as a model parameter required for the adsorption process simulation. The adsorption process model described by a set of partial differential equations （PDEs） is solved by using the conservation element and solution element method, which produces a fast and an accurate numerical solution to PDEs. The simulation results obtained from the adsorption constant estimated at the molecular level are in good agreement with the experimental results of the pulse response. The systematical multiscale simulation approach addressed in this study may be useful to accelerate the adsorption process development by reducing the number of experiments.

Optimization Conditions of the Preparation of Activated Carbon Based Egusi (<i>Cucumeropsis mannii</i>Naudin) Seed Shells for Nitrate Ions Removal from Wastewater

Egusi seed shells (ESS) were used as precursor for the preparation of two activated carbons (ACs) following H3PO4 and ZnCl2 activation. The effect of factors controlling the preparation of ACs such as chemical activating agent concentration (2 - 10 M), activation temperature (400°C - 700°C) and residence time (30 - 120 min) were optimized using the Box-Behnken Design (BBD). The optimized activated carbons based H3PO4 (ACP) and ZnCl2 (ACZ) were characterized by N2 adsorption, elemental analysis, atomic force microscopy (AFM), Boehm titration and Fourier transformed infrared (FTIR) techniques. The specific surface area was found to be 1053.91 and 1009.89 m2·g-1 for ACP and ACZ respectively. The adsorbents had similar surface functionalities and were both microporous. The effect of various parameters such as initial pH, concentration, and contact time on the adsorption of nitrate ions on ACP and ACZ in aqueous solution was studied. ACZ demonstrated better adsorption capacity (8.26 mg·g-1) compared to ACP (5.65 mg·g-1) at the same equilibrium time of 20 min. The adsorption process was governed by a “physical interactions” phenomenon for both adsorbents.

Interference of iron as a coagulant on MIB removal by powdered activated carbon adsorption for low turbidity waters

Powered activated carbon （PAC） is widely used in water treatment plants to minimize odors in drinking water. This study investigated the removal of 2-methylisoborneol （MIB） by PAC adsorption, combined with coagulation using iron as a coagulant. The adsorption and coagulation process were studied through different case scenarios of jar tests. The analysis evaluated the effect of PAC dosing in the liquid phase immediately before or after the coagulant addition. Ferric sulphate was used as the coagulant with dosages from 10 to 30 mg/L, and PAC dosages varied from 10 to 40 mg/L. The highest MIB removal efficiency （about 70%） was achieved without the coagulant addition and with the highest PAC dosage （40 mg/L）. Lower MIB removal efficiencies were observed in the presence of coagulant, showing a clear interference of the iron precipitate or coagulant in the adsorption process. The degree of interference of the coagulation process in the MIB removal was proportional to the ratio of ferric hydroxide mass to the PAC mass. For both cases of PAC dosing, upstream and downstream of the coagulant injection point, the MIB removal efficiency was similar. However, MIB removal efficiency was 15% lower when compared with experiments without the coagulant application. This interference in the MIB adsorption occurs potentially because the coagulant coats the surface of the carbon and interferes with the MIB coming in contact with the carbon＇s surface and pores. This constraint requires an increase of the PAC dosage to provide the same efficiency observed without coagulation.

陶瓷膜在饮用水处理中的应用现状

水是人类生存所必需的资源。近年来,我国的饮用水水质标准不断提高。为了满足更高的标准,自来水厂开始使用膜过滤技术取代传统过滤技术。作为一种先进的水处理技术,膜过滤技术已经在各个领域得到广泛应用。与有机膜相比,陶瓷膜具有化学性能稳定、耐酸碱、热稳定性好、机械强度高、回收率高、使用寿命长等优点,在饮用水领域有更广阔的应用前景。本文旨在阐述陶瓷膜的结构特点和过滤机理,并探讨陶瓷膜在饮用水处理中的研究进展。通过对陶瓷膜饮用水处理工艺进行分析,发现原水经过混凝、吸附、臭氧氧化预处理后,陶瓷膜的过滤性能有明显的提升。文章还分析了陶瓷膜的抗污染性能,并强调了其在维护成本方面的优势。最后,对优化陶瓷膜成本、多元陶瓷膜集成工艺和陶瓷膜大规模运行成本估算等未来研究方向进行了展望。

三种不同过滤方式对特香型白酒质量的影响研究

从白酒的气相色谱成分、离子色谱成分、感官评定等方面研究分析活性炭吸附过滤、冷冻过滤、聚能量膜过滤对特香型白酒的影响。结果表明:活性炭吸附过滤对酒体骨架成分及风味影响较大、净化能力较强,适用于过滤风味欠佳的酒体;冷冻过滤对酒体骨架成分及风味影响较小,适用于过滤风味一般的酒体;聚能量膜过滤对酒体骨架成分及风味基本无影响、滤后酒体的自然微黄颜色及风味可以最大程度地得以保留,适用于过滤风味较好的酒体。

天津某水库含嗅味物质原水应急处理方式研究

以天津某水库含嗅味物质原水为研究对象,利用小试研究了以传统混凝沉淀过滤为主体工艺的3座净水厂采用该水源进行应急供水的适宜处理方式。试验结果表明,粉末炭对原水中2-MIB和土臭素均具有较好吸附作用,其吸附效果主要受粉末炭投量和吸附时间影响,增加粉末炭投量和吸附时间可以提高二者去除率,根据去除率推算30 mg/L粉末炭吸附50 min最多可去除60 ng/L溶解态2-MIB和230 ng/L溶解态土臭素,吸附180 min最多可去除120 ng/L溶解态2-MIB和480 ng/L溶解态土臭素,2-MIB去除难度要高于土臭素;传统混凝沉淀过滤工艺可以去除大部分结合态嗅味物质,3座水厂采用厂内投加粉末炭后进行混凝沉淀过滤相对于直接混凝沉淀过滤而言,可以提高对2-MIB和土臭素的去除效果,但其效果提升主要受限于吸附时间,可应对的嗅味物质浓度较低;采用水库出口处投加粉末炭,可以增加吸附时间,明显提高2-MIB和土臭素的去除效果,该方式最终能处理的溶解态嗅味物质浓度基本与粉末炭吸附推算的浓度一致,满足安全供水需求。

磷酸法低灰分活性炭的制备研究

磷酸活化法是目前工业上生产生物质基活性炭的主要方法,但较高的灰分含量限制其在医药、食品等高端领域应用。基于此,以湿法磷酸为活化剂、废木屑为碳源,研究活化条件(温度、时间等)和洗涤条件(介质、酸浓度、温度等)对活性炭灰分及性能的影响,运用TG、FT-IR、XRD、SEM和TEM等表征方法分析活性炭的表面性质和微观结构。结果表明,难溶性磷酸盐是活性炭灰分产生的主要因素,通过控制活性炭制备和洗涤工艺可调控难溶性磷酸盐含量,从而调控活性炭灰分、碘值和亚甲蓝值。获得最佳工艺条件:活化温度为500℃、活化剂H_(3)PO_(4)质量分数为70%、酸屑质量比为2∶1、活化时间为60min及N_(2)气氛保护;洗涤液用量为100mL、洗涤介质为H_(3)PO_(4)、H_(3)PO_(4)质量分数为20%、洗涤温度为80℃及洗涤时间为60 min。最佳工艺条件下制备的活性炭灰分为1.07%、碘值为1241.4 mg/g、亚甲蓝值为285 mg/g、比表面积为2290 m^(2)/g,表明该技术制备的活性炭具有应用于食品、医药等高端行业领域的潜质。

Removal of bromate ion using powdered activated carbon

Bromate ion （BrO3-） removal from drinking water by powdered activated carbons （PACs） in bath mode was evaluated under various operational conditions. Six kinds of PACs, including wood-based carbon, fruit-based carbon, coal-based carbon, and these three carbons thermally deoxidized in a nitrogen atmosphere, were selected to investigate their capacity on BrO3- removal. With the highest zeta potential value and being richly mesoporous, coal-based carbon had a high and an excellent BrO3- adsorption efficiency. The removal content of BrO3- by per gram of coal-based carbon was 0.45 mg within 5 hr in 100 μg/L bromate solution. The surface characteristics of PACs and bromide formation revealed that both physical and chemical PACs properties simultaneously affected the adsorptionreduction process. Under acidic conditions, PACs possessed high zeta value and adequate basic groups and exhibited neutral or positive charges, promoting BrO3- adsorption-reduction on the carbon surface. Interestingly, the PACs thermally deoxidized in N2 atmosphere optimized their properties, e.g. increasing their zeta values and decreasing the oxygen content which accelerated the BrO3- removal rate. The maximum adsorption capacity of fruit-based carbon was the highest among all tested carbons （99.6 mg/g）, possibly due to its highest pore volume. Remarkably, the thermal regeneration of PACs in N2 atmosphere could completely recover the adsorption capacity of PACs. The kinetic data obtained from carbons was analyzed using pseudo second-order and intraparticle diffusion models, with results showing that the intraparticle diffusion was the more applicable model to describe adsorption of BrO3- onto PACs.

活性炭吸附工艺治理VOCs的技术应用进展

挥发性有机物(VOCs)严重危害人体健康及大气环境,而吸附工艺具有VOCs去除效率高、成本低等种优势并在VOCs的治理中发挥着重要作用,其核心在于VOCs吸附功能材料研制,因而基于活性炭具有原料来源广泛、孔隙结构发达、可回收利用等优点则常作为吸附剂被应用于VOCs治理。综述活性炭吸附工艺在VOCs治理领域的研究及技术应用进展,阐述活性炭吸附VOCs的关键影响因素及改性方法,并总结当前活性炭吸附VOCs的工艺技术、再生方法及应用现状,旨在为活性炭的选择及工艺控制提供理论指导。在活性炭选择上,应根据VOCs性质及外部工况选择具有合适结构的活性炭,同时须开发具有疏水性质的活性炭。在实际应用中,开展多种吸附工艺耦合为未来VOCs吸附工艺发展的重要方向;但由于VOCs成分的复杂性,可根据实际合理选择1种或多种VOCs治理工艺与吸附工艺联用以保证治理效果。对于吸附VOCs至饱和的活性炭,应从经济性及再生效果等方面进行考量从而对活性炭进行合理再生、补充或更换。

生化—电催化氧化—炭吸附工艺处理水基泥浆压滤液

采用生化—电催化氧化—炭吸附组合工艺处理钻井水基泥浆压滤液。以COD为主要指标、其他污染物为辅助指标,考察去除效果,采用GC-MS和FTIR分析有机物的去除历程,XRF分析元素变化。表征结果显示,组合工艺可去除大部分有机物,顺-7-十四碳乙酸酯、3-氨基-6-甲基吡啶-2(1H)-酮和2-癸基噻吩是本工艺难去除的有机物。实验结果表明:水基泥浆压滤液经组合工艺处理后,出水COD小于50 mg/L,各项指标均可达到辽宁省《污水综合排放标准》(DB 21/1627—2008);经组合工艺处理后,压滤液中Ca、C、Cl、S、O元素含量降低。

混凝沉淀+活性炭吸附工艺对生化尾水色度的研究

随着工业产能提高与人们生活节奏的加快,工业污水与生活污水排放量逐渐增多,对于环境的影响越来越大,色度是评价水污染的重要指标之一,因此成为了污水治理的重要研究方向。本文对色度的形成与危害进行了分析,并简要说明了目前色度处理的技术方法,介绍了混凝沉淀与活性炭吸附的原理,通过实验确定了混凝沉淀+活性炭吸附工艺所用PAM、PAC和活性炭的最佳用量,并确定了活性炭吸附的最佳时间,为后续该工艺的利用奠定了理论基础。

焦化废水生物出水物化协同技术及污染物去除机制研究

焦化废水溶液性质复杂,经生化处理后,仍残留多环芳烃、苯、胺等难降解有机物,不仅对生态环境造成污染,也会对水回用构成技术障碍。随着环保要求的日益提高,亟需强化焦化废水的深度处理工艺,实现焦化废水的“零排放”。本文根据焦化废水生物出水的性质特征,选择混凝沉淀、活性炭吸附和臭氧氧化这三种物化技术来分质去除生物出水中的有机物,考察物化技术协同机制及其工艺有效性,为焦化废水深度处理的工艺路径提供优选方案。

甲烷氯化物生产过程中环保措施的研究与应用

通过对甲烷氯化物生产过程中可能产生VOCs尾气的各环节进行讨论,详细分析了当前业内通用的治理措施,结合企业的实际情况,阐述了企业现有的VOCs治理措施,为其他相似工况提供了借鉴。

汽车行业VOCs废气治理工艺效果检测

本文对比了活性炭吸附、转轮蓄热式氧化炉(RTO)燃烧技术在汽车行业VOCs废气治理中的不同特点。对某汽车行业新扩建生产线车间的“活性炭吸附+转轮RTO燃烧”治理VOCs废气的工艺进行调试效果检测。结果显示,处理废气风量在14 000m^(3)/h以内、燃烧炉设置温度为820℃时,有机废气污染物处理效率较高,均能达到70%以上,总VOCs处理效率能达到91.8%,符合《表面涂装(汽车制造业)挥发性有机物排放标准》(DB 44/816—2010)表2中苯、甲苯、二甲苯、总VOCs在第二时段的排放限值要求。

臭氧-生物活性炭工艺的关键影响因素研究进展

作为现今净水厂深度处理的主流技术,臭氧-生物活性炭工艺通过将臭氧氧化、活性炭吸附降解联用,具有绿色、高效、处理效果好等优点。本文对O_(3)-BAC工艺的关键影响因素--臭氧氧化副产物及活性炭理化性质进行了探讨,综述了臭氧氧化有机污染物的过程,副产物对活性炭吸附以及生物降解的影响,深入分析了活性炭孔隙结构、官能团、π电子供受体及表面电荷等理化性质对其吸附以及生物降解过程的影响,对O_(3)-BAC工艺设计提出了合理建议。

Optimization Studies of Porous Carbon Preparation from Oil Shale Using Response Surface Methodology and Its Application for Phenol Adsorption

This paper discusses the elaboration of adsorbents from oil shale.The experimental designs a response surface methodology(RSM),which has been applied to optimize the significant preparation factors,such as tempera-ture,time,and the activating agent percentage.The results obtained from central composite design(CCD)revealed that the interaction between the factors was significant for the maximum quantity of adsorption(response).Planned results have shown that a maximum quantity of adsorption for methylene blue is 65 mg/g,which could be achieved with a temperature of 275℃over 2 h and a percentage of the activating agent of 45%.The predicted values agreed with the experimental finding,with a determination coefficient(R2)of 0.96.The model has been validated by experi-ments after conditions optimization.The new material(RHO)was characterized by cation exchange capacity,zero charge pH,surface functions,X-ray fluorescence,specific surface area,and electron microscopy analysis.Phenol adsorption was determined using Langmuir,Freundlich and Temkin,which were used to describe the adsorption iso-therms.The adsorption capacity of the material was about 263 mg/g,and the kinetic studies showed rapid adsorption.