Adsorption of crystal violet dye from aqueous solutions applying olive leaves powder (OLP) as a biosorbent has been examined under various experimental circumstances. The influence of contact time, pH, initial concentration of studied dye and adsorbent dose on the adsorption process has been investigated applying batch experiments. The concentration of remaining dye has been determined using molecular absorption spectrometry at wave length of 580 nm. The maximum removal of studied dye has been realized at pH 7.5 with a percent removal of 99.2% after 20 min of agitation time. Langmuir, Freundlich, and Temkin isotherm models exemplify the best fit for the experimental data; while the elevated adsorption capacity was 181.1 mg.g1. Adsorption kinetics of crystal violet was expected sufficiently with the empirical pseudo-second-order model. Corresponding to the adsorption capacity, olive leaves powder thought as a low cost, effective, and environmentally friendly biosorbent for the removal of crystal violet dye from aqueous solutions.
Recently, process control in wastewater treatment plants (WWTPs) is, mostly accomplished through examining the quality of the water effluent and adjusting the processes through the operator’s experience. This practice is inefficient, costly and slow in control response. A better control of WTPs can be achieved by developing a robust mathematical tool for performance prediction. Due to their high accuracy and quite promising application in the field of engineering, Artificial Neural Networks (ANNs) are attracting attention in the domain of WWTP predictive performance modeling. This work focuses on applying ANN with a feed-forward, back propagation learning paradigm to predict the effluent water quality of the Habesha brewery WTP. Data of influent and effluent water quality covering approximately an 11-month period (May 2016 to March 2017) were used to develop, calibrate and validate the models. The study proves that ANN can predict the effluent water quality parameters with a correlation coefficient (R) between the observed and predicted output values reaching up to 0.969. Model architecture of 3-21-3 for pH and TN, and 1-76-1 for COD were selected as optimum topologies for predicting the Habesha Brewery WTP performance. The linear correlation between predicted and target outputs for the optimal model architectures described above were 0.9201 and 0.9692, respectively.
Optimum fish production is greatly dependent on the physical, chemical and biological qualities of water. Hence, successful fish pond management requires an in-depth understanding of water quality. A study to assess heavy metal (Cr, Cd, Mn, Pb and Zn) contamination and physicochemical parameters of water samples from eight selected fish ponds in Sunyani, Ghana, was conducted. The parameters included temperature, pH, salinity, total hardness, electrical conductivity (EC), chemical oxygen demand (COD) and biological oxygen demand (BOD). The results revealed detectable Mn and Zn levels in all the selected fish ponds; with Mn levels in three ponds being significantly higher than the World Health Organization (WHO) recommended limit (< 0.500 mg/L). Of the three samples, which showed detectable Cr and Cd levels, concentrations of two exceeded the permissible limits. Pb was below the detection limit in all the samples whilst Cu levels detected in two of the ponds were below the permissible limit. The investigated physicochemical parameters had the following ranges: temperature 26-29 C, pH 5.8-8.2, BOD 0.3-20 mg/L, Total Dissolved Solids (TDS) 37-249 mg/L, EC 73.67-498 μS/cm, total hardness 0.8-5.7 mg/L, salinity 0.03-0.22 psu and COD 2.9-9.7 mg/L. Most of these values were within WHO recommended levels. The findings suggest that regular monitoring of the heavy metal load is necessary to guard against long-term effects of its presence in the water, influencing fish and human uptake.
Yemeni clays (bentonite and kaolin) were used as catalysts and catalysts supported metals ions Ce, Pt, Pt-Ce, Pd, Pd-Ce, for the debutylation reaction of 2-tert-butylphenol. The two clays were characterized using atomic absorption spectroscopy, particle size analyzer and N2-BET adsorption method. The activity of debutylation reaction was found to depend on the type of the catalyst. Kaolin based catalysts were more active than those bentonite based. The Selectivity of the catalysts was found to depend on the type of treatment that each catalyst was subjected to. The catalysts that were treated by calcination were more selective towards phenol formation (debutylation reaction of 2-tertbutylphenol), while those treated by reduction were more selective toward the formation of 4-tert-butylphenol (isomerization reaction of 2-tertbutylphenol).
African toothbrush sticks have been used for centuries for the maintenance of oral hygiene. This is especially true in developing countries where economics, customs, religion and the availability of oral hygiene tools play a role in their continued use. Chewing sticks are used by the majority of the population in Ethiopia. The aim this study was to determine the levels of essential and non-essential metals in chewing sticks from three plants (Salix subserrata, Sida cuneifolia and Clausena anisata) in samples collected from three selected areas (Muger, Sendafa and Holleta) of Ethiopia. Samples were wet digested with mixture of HNO3 and HClO4 at optimized temperature and time. The levels of metals were determined by microwave plasma-atomic absorption spectrometry. The range of mean concentrations of the metals (mg/kg) in the S. subserrata, S. cunnefolia, and C. anisata samples were in the order of Ca (14150-25914) > Fe (514-1191) > Al (103-1263) > Zn (152-196) > Mg (46-102) > Ni (4-160) > Mn (25-78) > Cu (13-20) > Cr (7-8). The accuracy of the optimized procedure was evaluated by analyzing the digest of the spiked samples with standard solution and the percentage recoveries varied from 92% to 104%. The toxic metals Cd and Pb in the plant samples were not detected. Thus, people using “chewing stick” from studied plants are free from the risks of Cd and Pb toxicity.
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