Priyabrata Pal

Low-cost field test kits for arsenic detection in water

Arsenic, a common contaminant of groundwater, affects human health adversely. According to the World Health Organization (WHO), the maximum recommended contamination level of arsenic in drinking water is 10 μg/L. The purpose of this research was to develop user-friendly kits for detection of arsenic to measure at least up to 10 μg/L in drinking water, so that a preventive measure could be taken. Two different kits for detection of total arsenic in water are reported here. First, the arsenic in drinking water was converted to arsine gas by a strong reducing agent. The arsine produced was then detected by paper strips via generation of color due to reaction with either mercuric bromide (KIT-1) or silver nitrate (KIT-2). These were previously immobilized on the detector strip. The first one gave a yellow color and the second one grey. Both of these kits could detect arsenic contamination within a range of 10 μg/L–250 μg/L. The detection time for both the kits was only 7 min. The kits exhibited excellent performance compared to other kits available in the market with respect to detection time, ease of operation, cost and could be easily handled by a layman. The field trials with these kits gave very satisfactory results. A study on interference revealed that these kits could be used in the presence of 24 common ions present in the arsenic contaminated water. Though the kits were meant for qualitative assay, the results with unknown concentrations of real samples, when compared with atomic absorption spectrophotometer (AAS) were in good agreement as revealed by the t-test.

Contaminants in Industrial Lean Amine Solvent and their Removal using Biopolymers: A New Aspect

Natural biopolymers are gaining increasing attention due to their extraordinary affinity towards adsorption of heavy metal ions. In this research, biopolymers such as chitosan and alginate were used to remove contaminants from lean alkanolamine (methyldiethnolamine; MDEA) solvent. The sweetening of natural gas is mostly done by absorption using single or mixed alkanolamine solutions. Alkanolamine solvent quality deteriorates abruptly while absorbing H2S/CO2 from natural gas and causes foaming in natural gas sweetening unit. Different types of organic as well as inorganic species are present as contaminant in lean MDEA solvent. Heat stable salts such as acetate and propionate are present in high amount in lean MDEA solutions and detected using Ion chromatograph and UV-VIS spectrophotometer. Substantial amount of elements (chromium, iron etc.) were detected using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) analysis. Chitosan coated sand (CCS) and calcium alginate (Ca-Alg) beads were prepared and used in batch adsorption studies to monitor the removal of these contaminants in MDEA solvents. FTIR studies and SEM analysis were done to observe the underlying principle of bio-adsorbent preparation. It was observed that both CCS and Ca-Alg removed heavy metal ions like chromium (40% and 61%) and iron (21% and 62%) significantly. Ca-Alg could also remove organic acid anions (36%) appreciably. The maximum uptake capacity for chitosan coated sand was found to be 59.88 μgm/gm for iron and 38.022 μgm/gm for chromium.

Isolation and characterization of phenol utilizing bacteria from industrial effluent-contaminated soil and kinetic evaluation of their biodegradation potential

Microbial degradation of phenol by pure bacterial species is a well-known approach towards alleviation of environmental pollution. In this study, five phenol-degrading bacterial species designated as CUPS-1 to CUPS-5 were isolated from the oil-effluent dumped sites of Haldia Industrial area of West Bengal, India. Detailed morphological, biochemical and molecular characterization identified CUPS-3 as a novel strain- Stenotrophomonas maltophilia (GU358076), while the others could be identified as Pseudomonas (CUPS-2, 5), Delftia (CUPS-1) and Micrococcus (CUPS-4) genera, respectively. Although all of these strains utilized phenol as their sole carbon source supporting growth, three among them, CUPS-2, CUPS-3 and CUPS-5 proved potential phenol degraders and hence used for further biodegradation studies. Degradation experiments were carried out for several initial phenol concentrations of 500 mg/L, 750 mg/L, 1000 mg/L, 1250 mg/L and 1500 mg/L. The novel strain, CUPS-3 could completely degrade 500 mg/L phenol within 48 h, with 0.0937/h substrate degradation rate and 16.34 mg/L/h substrate consumption rate. The strains degraded phenol via meta-cleavage pathway. Prediction of kinetic parameters of the biodegradation was accomplished Haldane model using the experimental data of degradation rate and phenol concentration as function of time.

Removal of iron from industrial lean methyldiethanolamine (MDEA) solvent by adsorption on sepiolite

ABSTRACT Sepiolite clay was used as an adsorbent for the removal of iron ions from industrial methyldiethanolamine (MDEA) solvent. The raw sepiolite clay was modified by different chemical and thermal treatments, and was characterized by FTIR, XRD, SEM-EDX, and BET-specific surface area analysis. Treating sepiolite with nitric acid significantly improved the adsorption capacity of iron ions from lean MDEA. The experimental equilibrium data were represented by Henry, Freundlich, and Langmuir isotherm models. The thermodynamic parameters indicated that the adsorption of iron ions on sepiolite was spontaneous and endothermic process. The kinetic studies showed that the adsorption followed pseudo-second order model.

Prediction of foaming and surface tension of lean MDEA solutions with corrosion inhibitor (bis(2-hydroxyethyl)cocoalkylamine) in continuous foam fractionation column

ABSTRACT Amine foaming is a common problem in gas sweetening unit. Prediction of foaming behavior will help in unraveling the operational challenges faced by the gas industry. This study was performed with the aim of predicting the foam volume and surface tension of lean methyldiethanolamine solutions in presence of bis(2-hydroxyethyl)cocoalkylamine (BHCL) corrosion inhibitor using continuous foam fractionation technique. The effect of BHCL as a model foam creators on foaming tendency was explored. The obtained experimental results were used to determine the empirical parameters k and n of the power law relation previously derived for high viscous fluid (i.e., ), both and are dimensionless parameters. The prediction model gave a good agreement with the experimentally observed results (<6% deviation). The foam height model helped in envisaging the surface tension profile and in turn the separation performance and efficiency of foam creators. The foam height increased with increasing superficial gas velocity and BHCL concentration. For low BHCL concentrations, the minimum surface tension was noticed at superficial gas velocity of 0.02 m/s.

Copper Deposition and Formation of Nano-Particles

The cementation of copper ions from copper sulfate solution was studied using iron wire and iron powder. The influence of initial copper concentration has considerable effect on cumulative copper deposition. The copper deposition rate data could be interpreted by using shrinking core model. The effects of temperature and pH were substantial and have been studied and interpreted. The activation energy of the system within the temperature range of 23–54°C was found to be 14.23 (iron wire) and 30.20 kJ per mol (iron powder), respectively. The morphology of copper deposits studied showed that the reactions have the potential to produce particle sizes within nano range.

Effect of different solvents and clay loading on Polyacrylamide hydrogel to remove Iron from Lean Methyldiethanol solvent

The polyacrylamide (PAAM) hydrogel consisting of acrylamide and 2(methacryloyloxy) ethyl aceto acetate as monomer, N, N/-methylenebisacrylamide as crosslinker and ammonium peroxodisulfate as initiator was prepared using different solvents. Methanol, ethanol, dimethylsulfoxide and deionized water was used as solvent to prepare the hydrogel. Its usefulness as adsorbent for the removal of iron as contaminants from industrial lean methyl diethanol amine solvents (MDEA, 50 weight % used by GASCO Company, Abu Dhabi for natural gas sweetening) was tested. Finally, PAAM hydrogel in water with nitric acid treated sepiolite having different loading were prepared to increase the mechanical strength of the composite hydrogel. SEM and FTIR analysis of the PAAM clay composite hydrogel explained the morphology and adsorption process. PAAM composite hydrogel with 12.5 % clay loading was found to be best using batch adsorption studies for the removal of iron (45.15% having uptake capacity 6.397 μg/g using 1.0 g hydrogel) from industrial lean MDEA solvent.

Indirect Solar Cooking Using a Novel Fresnel Lens and Determination of its Energy and Exergy Efficiencies

This paper proposes a new kind of system for effective indirect solar cooking by utilizing a novel Fresnel lens. A semi-cylindrical vessel (solar boiler) for producing steam and a jacketed cooker was designed, fabricated and tested experimentally for cooking applications. The solar boiler produced high temperature steam of 146°C and pressure of 3.15 barg which was used for cooking purposes. The international standard for evaluating cooker performance was implemented on this system and heating power was determined to be 51.2 Watt at a temperature difference of 50°C. The maximum energy and exergy efficiencies for boiler were found to be 30.18 % and 2.86%, respectively. This represents a 92% increment in energy efficiency and 128.8% increment in exergy efficiency as compared to solar parabolic cookers. The maximum energy efficiency of 5.02% and maximum exergy efficiency of 0.378% were achieved in this cooking system.Copyright

Copper cementation on iron using copper sulphate solution with different organic solvents

Cementation reaction has been used to remove copper from aqueous solution using iron. The objective of the research has to study and characterise the particles obtained during reaction and also to determine purity of the particles by using different solvents. The reactions have been carried out with a specific concentration of copper sulphate with fixed volume of different solvents and iron of standard dimensions. The size of the particles was measured using scanning electron microscopy (SEM) and copper purity using energy dispersive x-ray spectroscopy (EDX). In this study, 1-butanol, acetone, tricholoroethylene and n-heptane were used with water as solvents. It was found that 1-butanol is the most suitable with respect to the smallest size of the particles having 93.78% (by weight) of copper. It was found that solvents have considerable effect on the particle size and purity of the produced copper particles.