Hameed Ullah

Evaluation of coal as adsorbent for phosphate removal

This paper reports the adsorption of phosphate ions on coal, charcoal, and coal ash. The influences of factors such as contact time, and initial adsorbate concentration have been studied. Adsorption of phosphate ions on virgin coal was significant compared to charcoal, coal and coal ash evacuated at 200°C. The significant adsorption capability of coal is due to the porosity as well as due to organic carbon and inorganic elements present in coal. The evacuation of coal proved to be ineffective in enhancing its capability for phosphate ions retention. The adsorption behaviors of all the three adsorbent used was conformed using Freundlich’s adsorption model. The results suggest that coal could be used as an efficient adsorbent for removing phosphate ions from wastewater.

Enrichment, spatial distribution of potential ecological and human health risk assessment via toxic metals in soil and surface water ingestion in the vicinity of Sewakht mines, district Chitral, Northern Pakistan

This study focuses on enrichment, spatial distribution, potential ecological risk index (PERI) and human health risk of various toxic metals taken via soil and surface water in the vicinity of Sewakht mines, Pakistan. The samples of soils (nu202f=u202f54) of different fields and surface water (nu202f=u202f38) were analyzed for toxic metals including cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), nickel (Ni), zinc (Zn) and molybdenum (Mo). Soil pollution level was evaluated using pollution indices including geo-accumulation index (Igeo), contamination factor (CF), degree of contamination (CD), enrichment factor (EF) and PERI. CF showed moderate contamination of soil with Cd, Co, Fe and Mo, while Igeo values indicated moderate accumulation of Cu. For Cd, EF>u202f1.5 was found in agricultural soils of the study area. PERI findings presented a very high ecological risk (PERI >u202f380) at two sites (4%), considerable ecological risk at four sites (7.4%). Non-carcinogenic risk from exposure to Fe in soil was higher than limit (HI >u202f1) for both children and adults. Moreover, carcinogenic risk postured by soil contaminants i.e. Cd, Cr, Co and Ni in children was higher than their limits (except Pb), while in adults only Co posed higher risk of cancer than the limit (10-4) through soil exposure. Non-carcinogenic risks in children due to Cd, Co, Mo via surface water intake were higher than their safe limits (HQ >u202f1), while in adults the risk order was Cr >u202fCd >u202fCu >u202fPb >u202fCo >u202fMo. Moreover, carcinogenic risk exposure due to Co >u202fCd >u202fCr >u202fNi from surface water (except Pb) was higher than the tolerable limit (1u202f×u202f10-4) both for children and adults. However, Pb concentrations in both soil and surface water exposure were not likely to cause cancer risk in the local population.

Heavy metals effects on plant growth and dietary intake of trace metals in vegetables cultivated in contaminated soil

Arsenic, cadmium and lead are persistent environmental pollutants that severely affect the bioavailability of essential and other nonessential elements. The present study was conducted to evaluate the potential effects of these three notorious environmental pollutants on uptake and bioaccumulation of chromium, copper, nickel and zinc by lettuce, potato and tomato. Soil was contaminated with arsenic, cadmium and lead using three different levels of concentration for each metal. The concentrations of selected metals were determined using atomic absorption spectrophotometer. Substantial changes in growth parameters and trace element concentrations were observed in plants cultivated in contaminated soil, and the effects were more significant with increasing concentrations of heavy metal in the soil. Both synergistic and antagonistic effects were observed depending upon type of vegetables, concentration of pollutants in the soil and metal mixture used. Among the selected vegetables, the effects were more prominent on lettuce. The projected daily dietary intake of chromium, nickel and zinc was higher for vegetables grown in metals-contaminated soil than control. The contribution to recommended dietary allowance was significant for copper and nickel and less significant for zinc, although great variations were observed in recommended dietary allowance for different treatment levels. Food quality and elemental composition of vegetables cultivated in metals-contaminated soil were significantly affected, and their consumption may result in over and/or under nutrition affecting human health.

Morphological Evaluation of Variously Intercalated Pre-baked Clay

Abstract The use of porous materials is enjoying tremendous popularity and attention of the advance scientific communities due to their excellent adsorptive and catalytic activities. Clays are one of the most important candidates in the porous community which shows the above mentioned activities after modifing with a different intercalating agent. The paper is focused on the infiuence of some inorganic intercalating agents (NaOH) on the morphology of the variously intercalated clay samples. The alkali metal was used as the inorganic intercalating agent. The effect of intercalation temperature, intercalation agent concentration and intercalation time on the pre-baked clay morphology were also part of the study. Scanning electron microscopy (SEM) study was performed to evaluate the morphological changes of the resultant intercalates. Different morphological properties were improved significantly in the case of the inorganically modified clay samples. Thus, such intercalations are suggested to be effective if the clays under study are to be used for different industrial process at elevated conditions.

INFLUENCE OF SOME INTERCALATIONS ON ACTIVATION OF PRE-BAKED CLAY

ABSTRACT We report on the influence of temperature, mixing ratio and holding time of NaOH & KOH intercalations on the surface area, micropore volume and micropore width of pre-baked clay samples. Pore size & surface area analyzer was used to measure the surface area, micropore volume and average pore width using Dubinin–Radushkevich (DR) method. A meaning full effect was observed when the temperature was increased from ambient up to 150 o C in case of both intercalating agents. Increasing temperature beyond 150 o C caused a decline in surface area generation even up to 750 C. The results also show that mixing ratio has a positive effect on the porosity and the micropore surface area increases as the mixing ratio increases in case of both intercalating agents. The influence of holding time shows two different trends. In case of NaOH, the porosity increases as the time increases while in case of KOH, the porosity decreases as the time increases. SEM, EDX and XRD studies were also performed. The results show effective insertion of the sodium and potassium into the clay matrix thereby causing generation of porosity.