Adsorptive removal of mercury from water by adsorbents derived from date pits

The current work presented here focuses on the remediation of mercury from water using modified low-cost materials. Modified date pits, low cost, minimal pretreatment steps and locally abundant agricultural waste materials were effectively employed as an adsorbent for remediating Hg2+ from aqueous media. Physical and chemical modification were developed such as thermal roasting (RDP), sulfur (SMRDP) and silane (SIMRDP) based modifications. Results showed that maximum adsorption by RDP was at pH 6, AC and both modifications was at pH 4. Furthermore, RDP has exothermic adsorption mechanism while AC, SMRDP, and SIMRDP have endothermic. All adsorbents except SIMRDP have spontaneous adsorption process. SEM analysis showed that the surface morphology of RDP was not significantly affected by different treatments while surface of AC was affected. The investigation for good adsorbents for Hg2+ uptake from different anthropogenic sources has been carried out by many investigators worldwide towards having a safe environment. In the current study, the highest Hg2+ adsorption of SMRDP was relatively high compared to other known adsorbents. - 2019, The Author(s).This paper was made possible by UREP grant # (17-066-1-004) from the Qatar national research fund (a member of Qatar foundation). The statements made herein are solely the responsibility of the author(s). The authors would like to thank the Environmental Science Center – Qatar University in analyzing mercury ions in the samples, and the Central Laboratory Unit at Qatar University for performing the FTIR and SEM for the samples. The authors would also thank Dr Basem Shomar, Ms. Fatma Fahraei, Ms. Mariem Safi, Ms. Sana Khan, Ms. Maymoona Ayesh, and Ms. Haya Alduroobi for their participation in this UREP project. Special thanks to Mr. M. Y. Ashfaq for his efforts in reading the final version of the manuscript. The publication of this article was funded by the Qatar National Library.Scopu

Vertical distribution and radiological risk assessment of 137Cs and natural radionuclides in soil samples

The aims of this study were to investigate the vertical distributions of natural radionuclides 232Th, 226Ra and 40K as well as anthropogenic radionuclide 137Cs in soil samples and to analyze the correlation among the radioactivity of these radionuclides and the physiochemical characteristics of soil samples namely pH, grain size, carbonate content and organic matter. Risk assessment of the radiological hazard has also been estimated. Forty-four soil samples were collected from eleven locations in Qatar at four depth levels from 0 to 16 cm. The average concentrations of 232Th, 226Ra, 40K and 137Cs in the soil depth of 16 cm were 10, 17, 201 and 4 Bq/kg, respectively, which were within the reported world mean. The external absorbed gamma dose rate, the annual effective dose, the mean radium equivalent activity, the external hazard index and the lifetime cancer risk were 22 nGy/h, 0.027 mSv/y, 47 Bq/kg, 0.125 and 0.096 × 10−3, respectively. These values were far below the minimum recommended international values. The level of radioactivity concentrations in the soil was affected by the physiochemical characteristics of the soil. The positive correlation with highest R2 value was found among the radioactivity concentrations of 232Th and 40K and the soil clay content. Total organic carbon was also positively correlated for 226Ra and 137Cs activity concentrations, whereas, carbonate content was negatively correlated with the radioactivity concentrations of 232Th and 40K. As far as soil moisture content is concerned, the positive correlation with highest R2 value was obtained for 226Ra activity concentrations. © 2019, The Author(s).The authors wish to acknowledge the Environmental Science Center (ESC) and Central Laboratory Unit at Qatar University for providing support to physiochemical characteristics of the collected soil samples. We also thanks the ministry of municipality and environment-radiation and chemical protection for analyzing the radioactivity concentration. The publication of this article was funded by the Qatar National Library.Scopu

Brine management strategies, technologies, and recovery using adsorption processes

The world is experiencing serious shortages, unequal distributions, and contamination of the available freshwater resources. Many factors like geography, climate change, increasing populations, economic and technological development, industrialization, and inadequate water management are considered the main contributors to the issue. Many Gulf Cooperation Council (GCC), energy-rich arid and semi-arid countries, have set fossil fuel consumption and desalination of seawater as their main energy and freshwater resources resource. This poses significant economic and environmental risks due to the many challenges associated with non-renewable energy resources and desalination technologies. Some of the challenges of desalination technologies include complex processes, infrastructure, energy requirements, and harmful air emissions as well as environmental discharges. Geothermal energy extraction and CO2 sequestration are recognized as solutions to the global reliance on fossil fuels and global warming. However, these technologies are associated with various impacts. Brine streams are byproducts which contain various pollutants, chemicals, toxins, heavy metals as well as concentrated salts and metal ions. The impacts of brine on the environment through the direct disposal methods have led to the development of many types of brine treatment and recovery processes. These processes aim at removing pollutants and extracting valuable metals from brine, decrease its volume, and produce freshwater. Despite these benefits, the conventional brine treatment processes suffer from numerous implementation challenges, economic, environmental as well as energy constraints. Therefore, the adsorption process through the use of natural adsorbents is presented as a novel, efficient, cost-effective, and environmentally friendly approach to remediate and recover various brine streams. The GCC like Qatar relies heavily on desalination, which produces huge amounts of brine annually. Also, date production is high all year long, which results in the disposal of natural adsorbents such as date pits as wastes. Date pits are demonstrated as highly efficient adsorbents for the higher adsorption capacity of valuable metals, substances, and pollutants from aqueous solutions like brine. Therefore, the urgent need for constant development of the desalination industry as well as brine management strategies is needed. Adsorption could potentially fill the gap of the various mentioned challenges of the current brine management strategies.Scopu

Novel bioadsorbents based on date pits for organophosphorus pesticide remediation from water

The aim of the study was to examine the efficiency of date pits as an adsorbent to remove the organophosphate pesticide (profenofos) from water. A thermodynamic study was carried out to determine the homogeneity and spontaneous nature of the adsorbents. Three types of adsorbents, namely roasted date pits, activated date pits and nano-activated date pits were prepared from the date pits. Different physical and chemical characterizations were studied such as, scanning electron microscopy (SEM), Fourier transform infrared (FTIR), Brunauer-Emmett-Teller (BET) surface area, pore radius and pore volume. The surface area of the nano-activated date pit was the highest (485.4 m2/g). Moreover, the pore volume and pore radius were also the highest for the nano-activated date pits with values, 0.338 cm3/g and 17.8 �, respectively. Therefore, nano-activated date pits have resulted in high removal percentage and removal capacity of profenofos from aqueous solution. Based on Langmuir adsorption isotherm model, the values of R2 was the highest for the nano-activated date pits. The adsorption maximum capacity (Qm) increased with temperature and was maximum for the nano-activated date pit following Langmuir adsorption isotherm model. Thermodynamic parameters showed a negative ?Go for all three adsorbents and the values increased with temperature. The ?Ho value was positive for the three adsorbents and was the highest for roasted date pit (23.59 KJ/mol); resulting in an endothermic reaction. Whereas, the value of ?So was negative for the three adsorbents and was the highest for nano-activated date pits (-83.5 J/mol.K).Scopu

Mercury toxicity: The importance of microbial diversity for improved environmental remediation

Mercury is one of the naturally occurring elements found in the environment. This heavy metal occurs naturally in minute amounts and is the sixteenth rarest element on earth. It is ranked third among the most toxic biosphere occurring elements and when present in high concentration in a given soil, sediment and/or air compartments of the environment, it leaches and deposits in water bodies, eventually ending up in the food chain (Sinha and Khare, 2012), thereby causing a great health risks. Mercury pollution is a serious global environmental problem attracting the attention of many stakeholders around the world (Mason et al. 2012). Traditionally, chemical and physical methods were employed in the reduction or removal of mercury from contaminated aqueous and soil environments, however, owing to their labor intensiveness, high operational cost and low efficiency among other limitations, these remediation measures are adjudged unsatisfactory and hence the search for alternative means of clean-up of mercury contaminated environments becomes imperative (Wuana et al., 2011). Accordingly, natural remediation processes and technologies are being explored, among which bioremediation proved promising. Although a wide range of groups of organisms are used to degrade mercury, many challenges still persist, and much of the successes recorded are limited to laboratory scales (Xu et al., 2015). It will therefore be 249of interest to demonstrate the efficiency of these technologies at a much larger scale and optimize performance where necessary. This chapter overview the diversity of microorganisms, and prospects in the improvement of mercury contaminated environment remediation process. 2017 by Taylor & Francis Group, LLC

Occurrence and removal characteristics of phthalate esters from bottled drinking water using silver modified roasted date pits

Background: This paper aims to investigate the occurrence and removal characteristics of phthalate esters from bottled drinking water using silver modified roasted date pits. Three adsorbents, namely roasted date pits (RODP), silver-modified roasted date pits (S-RODP), and activated carbon (AC) were used to investigate their adsorption characterizations in removing dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), di-2-ethylhexyl phthalate (DEHP), and di-n-octyl phthalate (DNOP) from the collected bottle water samples. Methods: The occurrences of the phthalate esters in the collected bottled water samples were carried out at different temperatures (30, 50, and 60��C), and analyzed using gas chromatography-mass spectrometry analysis - selected ion monitoring. Batch adsorption isotherms were used to study and establish the efficiency of such adsorbents in removing phthalate esters, in which they describe the adsorbent-adsorbate interaction systems. Adsorption efficiency of the various adsorbents was investigated by using different adsorbent masses (0.05�g, 0.10�g, and 0.15�g) and temperature (30��C, 50��C, and 60��C). Different physical and chemical characterizations were studied using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), Brunauer-Emmett-Teller (BET) surface area, pore radius, and pore volume. Results: The results indicated that the most abundant phthalate esters were DMP followed by DEP under 30��C; however, DNOP was not detected in any of the tested water samples, except for one sample under 30��C with a concentration of 0.031�?g/mL. The obtained results showed that phthalate esters leaching to the bottled drinking water were affected by storage temperature. The phthalate esters levels were increased with increasing the temperature to 60��C. It was concluded that the ability of S-RODP for the adsorption of phthalate esters was better than the removal percentage obtained by AC and RODP. The removal percentage was increased from 90 to 99% by increasing the temperature from 30 to 50��C and then decreased to 92.3% at 60��C. Conclusion: RODP was successfully used as an effective adsorbent for phthalate esters removal from drinking water. However, S-RODP has the highest removal abilities than other adsorbents due to the newly formed functional groups on its surface.Scopu

Determination of aflatoxins in coffee by means of ultra-high performance liquid chromatography-fluorescence detector and fungi isolation

In this study, fourteen coffee samples were collected from local markets in Doha, Qatar according to different variables i.e. packed or unpacked, beans or powder, roasted or raw bean samples. The coffee samples were subjected to both microbiological and chromatographical analyses. The microbiological isolation was achieved using direct plating of the coffee on malt agar extract and potato dextrose agar plates. The chromatographical analytical method was conducted using ultra-high-performance liquid chromatography-fluorescence detector (UHPLC-FLD) to quantify the contamination of four classes of aflatoxins (B1, B2, G1, and G2). In the UHPLC-FLD validation process, no interfering peaks were present and the aflatoxins G1, B1, G2, and B2 were well separated. The R2 or coefficient of determination of the calibration plots for all compounds was � 0.995. The limit of quantitation for all compounds was 2 ?g/kg. The precision or the relative standard deviation calculated for six replicates of samples spiked at 2 ?g/kg were less than 20%, and the limit of detection was 0.17�?g/kg, 0.14�?g/kg, 0.12�?g/kg and 0.09�?g/kg for Aflatoxins G1, Aflatoxins B1, Aflatoxins G2, and Aflatoxins B2, respectively. The average recovery calculated for six replicates of samples spiked at 2 ?g/kg was from 74.5?80%. The results for the chromatographical part showed that there was no contamination of aflatoxin in most of the coffee samples collected. Only two samples exhibited low concentrations of aflatoxin G, which are sample A (4.27�?�10?1 ?g/kg) and sample O (1.99�?�10?2 ?g/kg). Direct plating showed growth of microorganisms, such as Aspergillus niger, Mucor sp., Bacillus sp., Fusarium sp., and two yeast species. Although some of the isolated species have the potential to produce mycotoxins in coffee, they might be in the spore phase in the coffee samples and did not germinate.Scopu

Potential application of microalgae in produced water treatment

The current study examines pollutant removal efficiency from the produced water of a local petroleum industry by five different local microalgae species. The five microalgae strains Monoraphidium, Chlorella, Neochloris, Scenedesmus, Dictyosphaerium, Chlorella and Dictyosphaerium species showed a significant amount of biomass generation within all different concentrations of produced water. Although the biomass yield of Neochloris strain was low, it was able to remove a higher amount of organic carbon than the other microalgae strains. Although biomass yield varied significantly among the microalgae strains, nitrogen removal efficiency was similar for all strains. Similar results were also obtained for most of the BTEX components. On an average, Dictyosphaerium sp. produced 0.5 g/L biomass density on different strength of produced water. Total nitrogen removal efficiency reached up to 63.76% when Scenedesmus sp. was grown in produced water. Only in case of phosphorus and various metals, removal efficiencies were better by Dictyosphaerium specie; reached up to 88.83%. Despite low biomass generation, Neochloris sp. removed 41.61% of total organic carbon from the different concentrations of produced water. Although benzene and ethylbenzene removal efficiency was 100% for all the different produced water, small amount of toluene and xylene remained in the produced water. Thus, the results indicate that microalgae strains can be used to remediate produced water effluents-derived from petroleum industries.Scopu