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Recycling of ceramic tiles waste and marble waste in sustainable production of concrete: a review Texto completo
2022
Mangi, Sajjad Ali | Raza, Muhammad Saleem | Khahro, Shabir Hussain | Qureshi, Abdul Sami | Kumar, Rabinder
Currently, recycling of waste materials in construction is being considered very important because waste generation is posing serious threats to our living environment. Hence, to induce sustainability in the ongoing urban development, researchers around the globe are using numerous wastes in concrete as partial substitutes of binders (cement, lime, etc.) and fillers (fine and coarse aggregates) with the aim of reducing the depletion of natural resources and cutting the carbon dioxide emissions emerging from increased demand and production of cement. This review paper has summarized the findings of literature relating to recycling of marble wastes and ceramic tiles wastes in production of concrete. The physical, fresh-state, and strength properties of concrete were reviewed from available extensive literature, and it was found that the concrete prepared from marble waste and ceramic waste as partial substitution of cement and aggregates is expected to perform at least comparable to conventional cement concrete and better if applicable. Both marble wastes and ceramic tiles wastes can be incorporated and recycled in concrete as cementitious materials and aggregate replacing materials. With such approach, the concrete can be made strong and durable, and the issues relating to depletion of natural resources and environmental degradation can also be solved without compromising sustainability in infrastructure development.
Mostrar más [+] Menos [-]From Hypersaline to Fresh-Brackish: Documenting the Impacts of Human Intervention on a Natural Water Body from Cores, Farmington Bay, UT, USA Texto completo
2022
Gunnell, Nathan | Nelson, Stephen | Rushforth, Samuel | Rey, Kevin | Hudson, Samuel M. | Carling, Gregory | Miller, Theron | Meyers, Leland | Engstrom, Daniel
Farmington Bay (FB), UT, has undergone major water quality changes due to human interventions. An arm of the Great Salt Lake (GSL), FB, is an endorheic body, actively accumulating nutrients. Human impacts to FB began in 1847 when European settlers arrived and major ecosystem changes have resulted through local development. Major impacts include anthropogenically impacted discharges (AID), causeway construction, and water-level declines. AID includes raw and treated sewage, septic leachate, irrigation returns, and feedlot or pasture runoff. Causeway construction produced freshening (hypersaline to fresh-brackish) via hydrodynamic isolation, whereas diversions and a drying climate prevent AID from mixing with the rest of the GSL. The timing of human interventions is known, allowing identification of ecosystem response in three sediment cores analyzed for ²¹⁰Pb chronology, mineralogy, C and N isotopes, pyrolysis, porewater chemistry, and diatom stratigraphy. From these proxies, three events have profoundly altered FB. A sewage canal (1911) brought raw effluent from Salt Lake City, causing a rise in the d¹⁵N of organic matter (OM). A corresponding increase in carbonate production occurred as enhanced productivity led to higher pH. Causeway construction (1969) spurred algal growth as FB freshened. Declining water levels (> 1990) resulted in a shrinking volume of bay water, resulting in increased eutrophication. P is elevated in porewater due to OM decay. ~ 0.9 gm⁻² year⁻¹ phosphate is released to the water column, compared to an estimated 3.0 gm⁻² year⁻¹ surface inflow loading. Although ecosystem improvements may result from AID reductions, improvements in water quality are most easily achieved by restoring surface inflows to FB.
Mostrar más [+] Menos [-]The relationship between staple food crops consumption and its impact on total factor productivity: does green economy matter? Texto completo
2022
Yaqoob, Nusrat | Jain, Vipin | Atiq, Zeeshan | Sharma, Paritosh | Ramos-Meza, Carlos Samuel | Shabbir, Malik Shahzad | Tabash, Mosab I.
The agriculture sector is a key driver of economic growth and provides employment opportunities across the globe generally. However, in today’s world, agricultural product demand is more influenced by taste, prices, and nutritional value due to climatic variation. The study has analyzed the current situation grain productivity by using the data of farm inputs and major grain crops of Pakistan from (1960–2020). The study consists of a two-stage analysis in the first stage, the total factor productivity (TFP) variable is obtained by using the parametric Tornqvisit-Theil index output-input-aggregation method separately for each crop; rice, maize, and wheat. After that, the unit root test is used to check the stationarity and trend of the variables in the long run. Subsequently, the autoregressive distributed lag (ARDL) model is applied to check the existence of cointegration in the long run and short run among the variables. The results of the study disclosed that the consumption of rice has a positive relationship with its total factor productivity, but, wheat and maize have a negative long-run cointegration relationship with the respective productivities. The study results have shown that the consumption pattern of staple crops has substantially changed, due to climatic variation, and the current food consumption trend is revealing new dimensions and trends owing to variation in climate change and anthropogenic pressure which demands to adapt climate resilient farm practices.
Mostrar más [+] Menos [-]Phytoremediation of cadmium-contaminated soils by Solanum nigrum L. enhanced with biodegradable chelating agents Texto completo
2022
Teng, Yue | Li, Zhishuai | Yu, An | Guan, Wenjie | Wang, Zhenjun | Yu, Hongyan | Zou, Luyi
The application of biodegradable chelating agents to enhance phytoremediation is a low-cost and promising method to improve the remediation efficiency of heavy metal–contaminated soil. The effects of N, N-bis glutamic acid (GLDA) on the growth and heavy metal absorption of Solanum nigrum were studied by pot experiment. The addition of chelate on the 20th day after sowing can improve the bioavailability of cadmium (Cd) in the soil. The results showed that the addition of chelating agents effectively improved the migration rate of the target heavy metal Cd in the soil, and significantly increased the accumulation of heavy metal in the roots, stems, and leaves of plants. The results showed that compared with the control group, the chelating agent could increase the extraction rate of total Cd by 28.65–68.74%. The application of GLDA significantly increased the accumulation of Cd (20 mg kg⁻¹ and 40 mg kg⁻¹), reaching 24.28–40.30 and 25.71–33.16 μg of pot⁻¹ DW, respectively. At the same time, GLDA increased Cd stress by decreasing plant biomass, inhibiting photosynthetic pigment synthesis and increasing MDA levels. These results indicated that GLDA could improve the absorption of Cd by S. nigrum, which provided a new idea for its practical application in the remediation of Cd-contaminated soil.
Mostrar más [+] Menos [-]Optimization of COVID-19 face mask waste fibers and silica fume as a balanced mechanical ameliorator of fat clay using response surface methodology Texto completo
2022
Zia-ur-Rehman, | Khalid, Usama
The balanced amelioration of mechanical characteristics of fat clay with an additive refers to the attainment of high strength without compromising ductility, which is unattainable by solitary usage of a cementing additive. For this purpose, an amalgamated binary admixture (ABA) is proposed by assimilating shredded face mask (FM) waste, which is posing serious environmental concerns these days, with a cementitious waste material, i.e., silica fume (SF). However, for such ABA, the optimization of mix design is desirable because an excessive amount of one component could disturb the required balance. To address this issue, response surface methodology (RSM) is used in the current study, which is a strong technique used during the process of production to develop, improve, and optimize product inputs. Several experiments are designed and conducted to evaluate mechanical responses, i.e., unconfined compressive strength (qᵤ), brittleness index (IB), deformability index (ID), and California bearing ratio (CBR) value, of treated fat clay by varying mix designs of ABA. Based on the test results, mathematical models are developed which are found to be statistically valid to predict the subjected responses using SF and FM as inputs. Afterward, an optimized mix design is determined by integrating developed models with a desirability function model and setting maximization of strength and ductility as the optimization goals. An ABA having 7.9% SF and 1.2% FM is observed to provide the highest strength and ductility for multiple applications, i.e., road and buildings, with desirability factor close to unity; responses of which are also validated by performing tests. Furthermore, analysis of cleaning aspect shows that the use of optimized ABA in place of cement for subgrade improvement of 1 km two-lane road could avoid CO₂ emission of around 79,032 kg of C, save 42,720 kWh and 1174.8 GJ of electrical and thermal energy, respectively, and clean 43 Mg of FM waste; however, astute protocols of COVID-19 FM waste handling and disinfection are needed to be established and followed.
Mostrar más [+] Menos [-]How surfactants affect the depuration of polycyclic aromatic hydrocarbons adsorbed on the mangrove leaf surfaces: insight from an in situ method Texto completo
2022
Guo, Shuai | Wei, Chaoxian | Zhu, Yaxian | Zhang, Yong
The effects of sodium dodecyl benzene sulfonate (SDBS), polyoxyethylene (20) sorbitan monolaurate (Tween 20), and their mixtures on the depuration of anthracene (Ant) and fluoranthene (Fla) individually adsorbed on the Kandelia obovata (Ko) leaf surfaces were in situ investigated. The Ko original leaf-wax microstructures have been destroyed by SDBS, Tween 20, and their mixtures at or above their critical micelle concentration (CMC). The volatilization rate constants (kV) of the adsorbed PAHs decreased with surfactants at or above their CMC resulting from the plasticizing effect and a decrease in the polarity of the Ko leaf-waxes induced by surfactants. Moreover, the photolysis rate constants (kP) of the adsorbed PAHs decreased with SDBS while increased with Tween 20 and their mixtures at or above their CMC, which can be attributed to effects of surfactants on the light adsorption behavior of Ko leaf-waxes. Overall, the effects of surfactants on the depuration of the adsorbed PAHs were dependent not only on the physical–chemical properties of surfactants but also on the micro-environment of the substrates adsorbed the PAHs. These results are of great significance for further understanding the accumulation of PAHs and could expand our knowledge about the migration mechanism of PAHs from the atmosphere by mangrove leaf surface micro-zones.
Mostrar más [+] Menos [-]Water Quality and Anthropogenic Impact Assessment Using Macroinvertebrates as Bioindicators in a Stream Ecosystem Texto completo
2022
Sabha, Inam | Hamid, Aadil | Bhat, Sami Ullah | Islam, Sheikh Tajamul
Dachigam-Dara catchment feeding the world-famous Dal Lake was assessed and evaluated for water quality and anthropogenic impacts using physico-chemical and biological data from 2016 to 2018. Seven sites belonging to Dachigam (DACZ) and Dara zone (DARZ) catchment, three sites from the confluence zone (WANZ), and two sites at the downstream end (TELZ) were selected characterized by varying degrees of anthropogenic pressures. Biological Monitoring Working Program, and Average Score Per Taxon at the upstream zones (DACZ, DARZ, and WANZ) recorded significantly higher scores with water quality indices falling within the good category than the downstream zone (TELZ). Taxa richness, and diversity indices of benthic macroinvertebrates recorded higher values at the upstream zones (DACZ, and DARZ), and confluence zone (WANZ), compared to the downstream zone (TELZ). Results revealed that phylum Arthropoda was most dominant contributing 37 invertebrate families (constituting 90% of the total macroinvertebrate community, including Crustacea and Arachnida) while phylum Mollusca and Annelida constitute 5% each. Macroinvertebrate families Baetidae, Erpobdellidae, Gammaridae, Chironomidae, and Heptagenidae contributed significantly to the similarity and dissimilarity between the sampling zones. The best subset of environmental variables (BIOENV) test revealed that the distribution of benthic macroinvertebrate assemblage in the Dachigam-Dara catchment is driven by pH, electrical conductivity, dissolved oxygen, and phosphate phosphorous. The upstream zones (DACZ, and DARZ) and confluence zone (WANZ), compared to the downstream zone (TELZ) suggest progressive shift of pollution sensitive macroinvertebrate taxa to pollution tolerant taxa in response to anthropogenic activities in the stream ecosystem over time.
Mostrar más [+] Menos [-]Role of ACC deaminase producing bacteria for abiotic stress management and sustainable agriculture production Texto completo
2022
Chandwani, Sapna | Amaresan, N.
Plants are immobile and are exposed to various biotic and abiotic stresses, including heat, cold, drought, flooding, nutrient deficiency, heavy metal exposure, phytopathogens, and pest attacks. The stressors significantly affect agricultural productivity when exceed a certain threshold. It has been reported that most of the stressed plants are reported to have increased ethylene synthesis from its precursor 1-aminocyclopropane-1-carboxylic acid (ACC). Ethylene is a plant hormone that plays a vital role in the regulation of various physiological processes, such as respiration, nitrogen fixation, and photosynthesis. The increment in the plant hormone ethylene would reduce plant growth and development, and if the ethylene level increased beyond the limit, it could also result in plant death. Therefore, plant growth–promoting bacteria (PGPB) possessing ACC deaminase activity play an essential role in the management of biotic and abiotic stresses by hydrolysing 1-aminocyclopropane-1-carboxylic acid using ACC deaminase. In this review, the importance of ACC deaminase–producing bacteria in promoting plant growth under various abiotic stressors is discussed.
Mostrar más [+] Menos [-]Preparation and performance of photocatalytic NO degradation superhydrophobic coatings for tunnel Texto completo
2022
Liu, Guanyu | Xia, Huiyun | Niu, Yanhui | Yan, Minjie | Li, Hao | Song, Lifang
Due to the semi-closed structure of the tunnel, serious air pollution in tunnels from vehicle exhaust becomes an issue which needed to be addressed. Among the exhaust, nitric oxide (NO) is typically considered as one of the main pollutants. In this paper, a superhydrophobic photocatalytic coating was fabricated by a spraying method by airbrush with a WO₃/TiO₂ photocatalysis for NO degradation. The water advanced contact angle (WACA) of the coating reached 166.32°, and the WACA was still above 145° after the 30 times abrasion test. The coating exhibited an excellent ability to remove inorganic and organic pollutants. Also, the NO degradation efficiency of this superhydrophobic coating under ultraviolet and visible light sources and humid environments was tested. When the relative humidity reached 98%, the NO degradation efficiency of the coating remained unchanged under visible light irradiation compared with the relative humidity of 45%. In addition, the coating exhibited prominent stability of NO degradation during the cyclic test. Furthermore, the WT coating showed stability and synergy of self-cleaning and photocatalysis toward NO degradation, which ensured the long-term use of the coating. Finally, a synergistic mechanism for self-cleaning and photocatalysis was proposed. This may provide a new idea and support for the application of photocatalytic technology in the degradation of NO in the tunnel.
Mostrar más [+] Menos [-]Sunlight-mediated photocatalytic removal of phenanthrene from wastewater using carbon-doped zinc oxide (C-ZnO) nanoparticles Texto completo
2022
Shaban, Yasser | Alharbi, Nojoud A.
In an effort for efficient solar energy harvesting, carbon-doped zinc oxide (C-ZnO) nanoparticles with intriguing properties were synthesized by sonicated sol–gel technique with the aid of activated charcoal. Compared to pure ZnO, the incorporation of carbon has drastically promoted the photocatalytic activity of C-ZnO towards the degradation of phenanthrene under illumination of both UV and sunlight. The characterization of the as-synthesized nanoparticles by scanning electron microscope (SEM), UV–vis spectra, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS) confirmed the carbon doping of C-ZnO. The highest degradation rate of phenanthrene was obtained at pH 7 and C-ZnO loading of 0.5 g L⁻¹. Finally, the kinetic studies of the photocatalytic degradation of phenanthrene by using C-ZnO were well-fitted with the Langmuir–Hinshelwood model and followed the pseudo-first-order rate expression.
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