Activated Silica Gel Research Articles

Preparation of aragonite-rich whisker materials from magnesium slag and salt lake bischofite and its effects on cement properties

This study develops an innovative wet carbonation process utilizing Magnesium Slag(MS), Salt Lake Bischofite (SLB), and CO2 to prepare carbonized materials mainly composed of aragonite and active silica gel, all raw materials were solid wastes. Subsequently, it was employed as Supplementary Cementitious Materials (SCMs) additive in cement, with the goal of efficiently capturing carbon dioxide and transforming aragonite whiskers into high-value products. Investigated the parameters influencing the formation of aragonite, including temperature and the concentration of the SLB solution, while exploring the nucleation and growth mechanisms of aragonite. The findings reveal that under 80 °C, the suspension of MS with 0.83 % SLB solution swiftly produces needle-like aragonite whiskers with single crystal lengths ranging from 10-20 μm and diameters of 0.3–0.5 μm. With the increase in SLB concentration, the aspect ratio of aragonite whiskers decreases. Additionally, highly polymerized amorphous silica gel was also detected. Therefore, Carbonated Aragonite-type Magnesium Slag (CAMS) (34.0901 m2/g) exhibits a significantly larger specific surface area compared to MS (0.9877 m2/g), representing an enhancement factor of 34.5 times, which concurrently bolsters its capability to adsorb reactive ions. During the carbonation process, 1 g of MS can sequester and solidify 0.403 g of CO2. Furthermore, incorporating CAMS as SCMs into cement mixtures notably enhances both the compressive and flexural strengths of cement mortar. These findings offer a sustainable approach to the recycling of solid waste, CO2 sequestration, and the improvement of cement-based material properties.

Analysis of Dimethylsiloxanes in Hydrocarbon Matrices like Marine Fuels Applying a Novel Enrichment Procedure and a Two-Column Gas Chromatography – Mass Spectrometry Measurement

Marine fuels are consumed worldwide in quantities of more than 200 million tons per year. It is not a uniform product, but rather heterogeneous mixtures of hydrocarbons with a wide range of viscosities. Due to the production processes, marine diesel contains dimethylsiloxanes. These lead to damage to marine exhaust catalysts in connection with combustion reactions in the ships’ engines. A novel analytical method, presented here, was developed that allows to investigate these processes and to monitor the dimethylsiloxane contents in complex marine fuel matrices. The key steps of the analytical procedure are analyte enrichment by solid phase extraction (SPE) using thermally activated silica gel and chromatographic separation and measurement by heart-cutting gas chromatography - mass spectrometry. Authentic reference substances for quantification by standard addition are used for the dimethylsiloxane analytes. The clean-up enabled a 90% reduction of the matrix content in the analysis solutions compared to the initial sample. Recovery rates in the range of 87.8% to 111.4% were determined for all analytes (Si3 to Si9). The detection limits of analytes ranged from 0.06 μg/L to 5.68 μg/L. Values of 0.71 μg/L to 23.6 μg/L were determined for the limits of quantification. The newly designed analytical method was successfully applied to real marine fuel samples. The analytical procedure is to be made available to commercial and industrial laboratories as a practical method for controlling siloxane contents in marine fuels to contribute this way to efficiently functioning marine exhaust gas purification.

Contamination Levels and Accumulation Profiles of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediments from South Central Coast of Vietnam

Contamination Levels and Accumulation Profiles of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediments from South Central Coast of Vietnam

Analysis and Assessment of Contamination Degree and Emission Sources of Polycyclic Aromatic Hydrocarbons (PAHs and Me-PAHs) in Surface Sediments from Central Coast of Vietnam

Polycyclic aromatic hydrocarbons (PAHs) and their derivatives are a diverse group of organic pollutants, which are relatively persistent and toxic. Simultaneous determination of unsubstituted PAHs and methylated PAHs (Me-PAHs) is necessary to provide comprehensive insights into contamination levels and sources of these pollutants. In this study, we collected surface sediment samples in Vietnamese central coast to analyze 7 PAHs and 12 Me-PAHs. The sediment samples were extracted by using a focused ultrasonic processor with acetone/hexane (1:1) mixture and toluene. The extract was purified by column chromatography technique with activated silica gel and dichloromethane/hexane (1:3) as elution solvent. PAHs and Me-PAHs were determined by a gas chromatography/mass spectrometry (GC/MS) system operated in electron impact ionization (EI) and selected ion monitoring mode (SIM). Concentrations of total 7 PAHs and 12 Me-PAHs ranged from 30 to 246 (average 92) nanograms per gram sediment (ng/g). These levels were comparable to or lower than those measured in Vietnamese river sediments and marine sediments from some other countries in the world. The accumulation profiles of PAHs and Me-PAHs indicated that their emissions are likely associated with mixed pyrogenic and petrogenic sources. Our results have provided preliminary information about the pollution degree and accumulation characteristics of these substances in Vietnamese marine environments. Additional comprehensive studies should be performed to characterize contamination characterisrics, emission sources, and ecological risks of PAHs and their derivatives in this country.

A simple and efficient synthesis of 5-hydroxymethylfurfural from carbohydrates using acidic ionic liquid grafted on silica gel.

The catalytic application of 3-(4-sulfobutyl)-1H-imidazole-3-ium chloride immobilized on activated silica gel (SiO2-Imi-SO3H) for the production of 5-hydroxymethylfurfural is described here for the first time. This material was synthesized using a three-step method involving the grafting of chloropropyl groups onto activated silica gel, the substitution of zwitterions, and the acidification of zwitterions to form silica-supported ionic liquid. The successful immobilization of the IL on silica gel was confirmed through energy-dispersive X-ray (EDX) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and elemental mapping. SiO2-Imi-SO3H-2 demonstrated good catalytic activity and recycling ability in fructose dehydration to 5-HMF. Several conditions for reaction were investigated, and an excellent 5-HMF yield (94.1%) was obtained after 4 h at 160 °C in dimethyl sulfoxide (DMSO) from fructose. Furthermore, a mechanism was proposed, the catalyst's reusability was investigated, and the catalyst was applied for the conversion of glucose to 5-HMF with other metal salts.

Physiological quality of seeds of Mimosa bimucronata (DC) O. KTZE. subjected to different types of drying

Despite its potential, to date, work has not been carried out to identify the ideal drying conditions for Mimosa bimucronata (DC) O. Kuntze. Considering the scarcity of information on the drying process of this species, this work was with the objective of evaluating the sensitivity to desiccation by means of drying on activated silica gel (fast) and under laboratory conditions (slow). Rapid drying with silica was performed. For slow drying, the seeds were placed in plastic containers without lids, both at room temperature. Every hour, the seeds were weighed until reaching the pre-established points (30, 25, 20, 15 and 10%). The variables analyzed were: water content, first germination count, germination, germination speed index, dry mass and seedling length. The seeds of M. bimucronata (DC) show orthodox behavior, withstanding desiccation at levels below 15%. The desiccation of seeds at very low levels impairs the formation of seedlings, preventing their normal development.

Analysis and Pollution Assessment of Brominated Flame Retardants (PBDEs, DBDPE, and BTPBE) in Settled Dust from E-waste and Vehicle Processing Areas in Northern Vietnam

Polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) are typical brominated flame retardants (BFRs), which were widely added to polymeric and textile materials to meet fire safety requirements. PBDEs (including commercial penta-, octa-, and deca-BDE mixtures) have been classified as persistent organic pollutants (POPs) under the Stockholm Convention, while DBDPE and BTBPE are considered as PBDE replacements. In the present study, concentrations of PBDEs (major congeners of technical PBDE mixtures such as BDE-28, 47, 99, 100, 153, 154, 183, 197, 207, and 209), DBDPE, and BTBPE were simultaneously analyzed in settled dust samples collected from e-waste and end-of-life vehicle (ELV) processing areas in northern Vietnam. The dust samples were extracted by using an ultrasonic processor subsequently by acetone and acetone/hexane (1:1) mixture for 10 min each time. The dust extract was treated with concentrated sulfuric acid and activated silica gel to remove interferences. BFRs were analyzed by using gas chromatography/mass spectrometry (GC/MS) equipped with a DB-5ht column. The mass spectrometer was operated at electron capture negative ionization (ECNI) and selected ion monitoring (SIM) mode. Concentrations of total PBDEs, DBDPE, and BTBPE ranged from 77 to 240,000 (median 6000), from <20 to 240,000 (median 5500), and from <10 to 9200 (median 160) ng/g, respectively. Concentrations of BFRs in the e-waste dust were significantly higher than those measured in the ELV dust, suggesting e-waste processing activities as potential sources of BFRs in dust. Among BFRs analyzed, BDE-209 and DBDPE were the most predominant compounds, implying intensive application of deca-BDE mixtures and alternative formulations.

Synthesis and Characterization of Novel Thiosalicylate-based Solid-Supported Ionic Liquid for Removal of Pb(II) Ions from Aqueous Solution

The main objectives of this study are to synthesize a new solid-supported ionic liquid (SSIL) that has a covalent bond between the solid support, i.e., activated silica gel, with thiosalicylate-based ionic liquid and to evaluate the performance of this new SSIL as an extractant, labelled as Si-TS-SSIL, and to remove Pb(II) ions from an aqueous solution. In this study, 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium thiosalicylate ([MTMSPI][TS]) ionic liquid was synthesized and the formation of [MTMSPI][TS] was confirmed through structural analysis using NMR, FTIR, IC, TGA, and Karl Fischer Titration. The [MTMSPI][TS] ionic liquid was then chemically immobilized on activated silica gel to produce a new thiosalicylate-based solid-supported ionic liquid (Si-TS-SSIL). The formation of these covalent bonds on Si-TS-SSIL was confirmed by solid-state NMR analysis. Meanwhile, BET analysis was performed to study the surface area of the activated silica gel and the prepared Si-TS-SSIL (before and after washing with solvent) with the purpose to show that all physically immobilized [MTMSPI][TS] has been washed off from Si-TS-SSIL, leaving only chemically immobilized [MTMSPI][TS] on Si-TS-SSIL before proceeding with removal study. The removal study of Pb(II) ions from an aqueous solution was carried out using Si-TS-SSIL as an extractant, whereby the amount of Pb(II) ions removed was determined by AAS. In this removal study, the experiments were carried out at a fixed agitation speed (400 rpm) and fixed amount of Si-TS-SSIL (0.25 g), with different contact times ranging from 2 to 250 min at room temperature. The maximum removal capacity was found to be 8.37 mg/g. The kinetics study was well fitted with the pseudo-second order model. Meanwhile, for the isotherm study, the removal process of Pb(II) ions was well described by the Freundlich isotherm model, as this model exhibited a higher correlation coefficient (R2), i.e., 0.99, as compared to the Langmuir isotherm model.

Synthesis and characterization of novel solid-supported salicylate-based ionic liquid for adsorptive removal of Pb(ii) and Ni(ii) ions from aqueous solution.

Novel solid-supported ionic liquid (Si-Sal-SSIL) was synthesized by immobilization of 1-methyl-3-(3-trimethoxysilylpropylimidazolium) salicylate [MTMSPI][Sal] ionic liquid onto the activated silica gel. First, the [MTMSPI][Sal] ionic liquid was derived from the reaction of a metathesis product of 1-methyl-3-(3-trimethoxysilylpropylimidazolium) chloride [MTMSPI][Cl] with sodium salicylate through an ion-exchanged reaction. [MTMSPI][Sal] was purified and characterized through ion-chromatography, CHN and Karl-Fischer titration analyses. Further characterizations on [MTMSPI][Sal] were carried out by 1H NMR and FTIR analyses. Si-Sal-SSIL was successfully prepared and confirmed through BET and solid-state NMR analyses. Si-Sal-SSIL showed better removal capacities towards Pb(ii) and Ni(ii) ions in comparison to native activated silica gel. Si-Sal-SSIL was then applied as solid adsorbent for an efficient removal of Pb(ii) and Ni(ii) from the aqueous solution. A series of batch sorption study were performed to explore the influence of parameters i.e., loading ratio of activated silica gel to [MTMSPI][Sal], pH, mixing time, initial concentration of analyte towards the adsorption of Pb(ii) and Ni(ii) ions onto Si-Sal-SSIL as a function of removal efficiency. Under optimized conditions, the sorption kinetics for removal of both metals agreed with pseudo-second order linear plots. The mechanism of Pb(ii) and Ni(ii) sorption by Si-Sal-SSIL gave good fits for Langmuir model.

Pemurnian Bioetanol Menggunakan Adsorben Silika Gel dari Limbah Botol Kaca di Industri Kecap

Waste glass bottles is an inorganic waste that amounts to 0.7 million tons per year with the main content of silica, so it can be used as the main ingredient to produce silica gel. In the soy sauce industry, waste glass bottles came from depalletizer activities, the activity of moving glass bottles to the cleaning area. This research aims to utilize waste glass bottles as a raw material for producing silica gel adsorbents using the hydrothermal method and the sol-gel approach. Silica gel becomes an adsorbent in the purification of bioethanol from wastewater washing dissolving tanks using the adsorption method. Variations in the bioethanol production are yeast weight as 0, 2, 5, and 8 g as well as fermentation time for 4, 7, and 10 days.The bioethanol purification process used variations in adsorption time for 40, 60, and 80 minutes. Characterization of silica gel using BET and SEM-EDX test. The BET test results show that activated silica gel has a surface area of ​​231,851 m2/g. Analysis by SEM-EDX showed that the Si and O elements in activated silica gel were 40,94% and 51,92%. Based on the results of the GC-MS test, 60 minutes is the best adsorption time to increase the bioethanol content from 39,8±9,9% to 72,0±1,1%.

Ingenious introduction of aminopropylimidazole to tune the hydrophobic selectivity of dodecyl-bonded stationary phase for environmental organic pollutants

Nowadays, the efficient detection of environmental organic pollutants has been a research focus in the field of chromatographic analysis. In this work, aminopropylimidazole was designedly introduced to adjust the hydrophobicity of the long-chain alkyl group, and a novel chromatographic stationary phase for the separation and analysis of environmental organic pollutants was specially prepared. Specifically, the waste aminopropyl silica gel (5 μm) was first recycled as the raw material, which was calcined at high temperature and then acidified with hydrochloric acid solution to obtain the activated silica gel. Afterwards, a new type of aminopropylimidazole/dodecyl dual-functionalized silica stationary phase (Sil-API-DD) was synthesized via one-pot reaction of the activated silica gel with 3-chloropropyltrimethoxysilane, dodecyltrimethoxysilane and 1-(3-aminopropyl)imidazole. The separation performance of Sil-API-DD was evaluated using environmental organic pollutants as the model analytes, and the results showed that an effective separation of seven alkylphenols, five bisphenols, six phthalates, seven steroid hormones and six benzophenones in reversed-phase chromatography was achieved. Moreover, the developed Sil-API-DD was found to exhibit more flexible selectivity and superior separation efficiency compared with the commercial C18 column under the tested conditions, suggesting a good application prospect.

Experimental Insights into Mesoporous Polyaniline-Based Nanocomposites for Anionic and Cationic Dye Removal.

This work presents the preparation of inorganic-organic hybrid nanocomposites, namely three-dimensional polyaniline (Pani)/activated silica gel (ASG) (3D Pani@ASG), their characterization, and in removing application as a potential adsorbent for cationic brilliant green (BG), crystal violet (CV), and anionic Congo red (CR), and methyl orange (MO) dyes. Pani@ASG nanocomposites have been prepared by the in situ polymerization method and characterized using various techniques such as Fourier transform infrared (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) with selected area electron diffraction, thermogravimetric analysis with derivative thermogravimetry, zeta potential analyses, and Brunauer-Emmett-Teller (BET). The scanning electron microscopy (SEM) study confirms the average particle size of the Pani@ASG nanocomposite is in the range of 5 nm. FESEM, TEM, FTIR, and XRD analysis proved the successful decoration of ASG over Pani. The BET result of Pani@ASG shows a mesoporous nature with a pore diameter of less than 3 nm and a surface area of 423.90 m2 g-1. Both SEM and TEM analyses show the proportional distribution of ASG over Pani's surface. The adsorption trend of BG and MO on the studied materials at pH 7 was found as follows: Pani@ASG > Pani > ASG. The highest sorption capacities of MO and BG on Pani@ASG were 161.29 and 136.98 mg/g (T = 298.15 K, and Pani@ASG dose: 0.04 g for MO and 0.06 g for BG), which were greater compared with bare Pani and bare ASG, respectively. The interaction mechanism behind the adsorption of BG and MO dyes onto the Pani@ASG nanocomposite includes electrostatic interaction, π-π interaction, and hydrogen bonding. The mechanistic pathway and the interactions between the targeted dyes and Pani@ASG were further studied using adsorption isotherm, adsorption kinetics, and thermodynamics.

POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) AND TRACE METALS IN SOME BRANDS OF SAUSAGE ROLL IN THE NIGERIAN MARKET

Background: Concentrations of PAHs and trace metals in five selected brands of sausage commonly available in the Nigerian market were determined in this study. The health risk assessment of both PAHs and trace metals were also evaluated. Methods: PAHs extraction of the sausage samples was carried out with Soxhlet extractor and clean-up of the extract was done using activated silica gel. The analysis of target analytes including the 16 priority PAHs was performed with Gas Chromatography equipped with Flame Ionization Detector (GC-FID) and the concentration of trace metals were determined using Atomic Absorption Spectrophotometry (AAS) after acid digestion of the sausage samples.Results: The amounts of Ʃ16 PAHs in sausage samples were in the range of 12.5-36.2 µg/g. All the samples investigated had concentration of Benzo (a) pyrene above 0.001 µg/g limit in processed cereal based food products stipulated by European Commission Regulation. In this study, the brands of sausages were majorly polluted with 4- and 5-ring PAHs. The concentrations (mg/Kg) of trace metals ranged as follows: Zn (1.01-71.0), Cu (ND-8.12) and Cr (ND-16.4). Cd was not detected in all the sample. Pb ranged from 2.34-13.0 mg/kg infringing the safe limit for cereals and cereal-based food products of 0.3 mg/kg and 0.05 mg/kg stipulated by FAO/WHO and European Commission, respectively. Conclusion: However, it is imperative to constantly monitor and control the concentrations of these pollutants in sausages since they are commonly consumed by Nigerian school children and youths.

EVOLUCIÓN TEMPORAL DE UNA DEPRESIÓN SOBRE LA SUPERFICIE DEL HIELO MONOCRISTALINO

The surface of a monocrystalline ice sample was observed at −5 ◦C (268 K). For which it was superficially polished and allowed to evolve in the presence of activated silica gel for three hours. The evolution of a depression was studied using three-dimensional micrographs obtained with an Olympus OLS4000 LEXT confocal microscope. A predominance of surface diffusion transport was found in the evolution of the depression. This is based both on the value obtained for the surface diffusion coefficient, as well as on the values found for the exponents corresponding to the evolution of the depth of the well and its width.

How 'Hydrophilic Sites' Work in Water Adsorption/Desorption by Natural Clinoptilolite

The kinetic mechanism of water adsorption/desorption on samples of natural clinoptilolite-K has been investigated by using an electrical method based on measurements of variation of AC current intensity during the time. In particular, a high-frequency sinusoidal voltage (5kHz) was applied to the sample (high frequency was required to avoid sample/electrode interface polarization phenomena) and the resulting AC micro-current intensity was monitored during the time. The sample was hydrated by exposition to a 75% humidity atmosphere, while dehydration was achieved by exposing the sample to activated silica gel in a close container or simply taking it in air. The hydration reaction followed a pseudo-zero-order kinetics, while the dehydration reaction followed a first-order kinetics both in air or dry atmosphere. The observed kinetic behaviors can be explained on the basis of a 'catalytic effect' of cations in both water adsorption and desorption from the 3D-framework walls.

How 'Hydrophilic Sites' Work in Water Adsorption/Desorption by Natural Clinoptilolite

The kinetic mechanism of water adsorption/desorption on samples of natural clinoptilolite-K has been investigated by using an electrical method based on measurements of variation of AC current intensity during the time. In particular, a high-frequency sinusoidal voltage (5kHz) was applied to the sample (high frequency was required to avoid sample/electrode interface polarization phenomena) and the resulting AC micro-current intensity was monitored during the time. The sample was hydrated by exposition to a 75% humidity atmosphere, while dehydration was achieved by exposing the sample to activated silica gel in a close container or simply taking it in air. The hydration reaction followed a pseudo-zero-order kinetics, while the dehydration reaction followed a first-order kinetics both in air or dry atmosphere. The observed kinetic behaviors can be explained on the basis of a 'catalytic effect' of cations in both water adsorption and desorption from the 3D-framework walls.

Impact of fast and slow desiccation on Garcinia imberti seed and seedling vigour

Garcinia imberti Bourd. endemic to the southern Western Ghats is classified as endangered by the IUCN (2018). The seeds as the sole means of propagation with initial moisture content (MC) of 62.8% are sensitive to desiccation. Studies on the responses of the seed to drying require ascertaining of the critical moisture content (CMC) as a basic requisite for germplasm conservation. Responses of G. imberti seeds to fast drying with activated silica gel (25 ± 2 °C, 6 ± 1% RH) and to slow drying under laboratory conditions (28 ± 2°C, 60 ± 2% RH) were evaluated for seed and seedling vigour. When the MC was reduced to 56% by 48 hours of slow drying or 6 hours of fast drying, 75 to 90% normal seedlings were produced respectively. In the case of fast dried seed (6 hours), seed associated parameters except mean germination time showed peak values with maximum germination and enhanced root length. Below the CMCs of 16.4 and 26.3% (fast and slow drying respectively), half of the tested seeds become non viable. Thus for germplasm conservation the present study proposes 6 hour’s of fast drying to retain viability and normal seedling development of G. imberti.

SIMPLE DESIGN OF MINIATURIZED CABINET FOR COMPOUNDING VITAMIN C EFFERVESCENT TABLET IN LABORATORY SCALE

Objective: The aim of this study was to design miniaturized cabinet that needs the tight requirements in formulating the ingredients of the effervescent tablets to minimize the relative humidity value in order to prevent the initial effervescent reaction.Methods: The compounding workspace was created by designing cabinet arranged with special equipment so that the humidity and temperature of the mixing chamber could be monitored. The conditioning of the workspace was carried out using a variety of methods ie lights, active silica gel and a combination of both during certain observation times. In this study, all of the components in the effervescent tablet formula were mixed using two steps of the wet granulation method. The evaluation of effervescent tablets included: the appearance of the tablet, diameter, tablet thickness, weight uniformity, hardness, friability, tablet disintegration time, pH of the solution, and hedonic test.Results: The results of moisture control optimization indicated that the most rapid method of lowering moisture was using a combination of active light and silica gel. After 100 min, this method could decreased the relative humidity (RH) by 0.415% per min. Based on the evaluation results, all formulas achieved the requirements of good effervescent tablets.Conclusion: In this research, the design of compounding cabinets with dimensions of 60x40x59.5 cm was proven to produce effervescent tablets that fulfill the requirements.

Drying and reduction in sensitivity to desiccation of seeds of Alibertia edulis: the influence of fruit ripening stage.

The intense environmental degradation in tropical regions suitable for agriculture has decreased native forest populations of plants with important fruits and medicinal properties. Alibertia edulis is a native tree from the Brazilian Cerrado. Knowledge about the effects of drying and storage on the physiological behavior of its seeds may aid in its sustainable exploitation and conservation. The goal of the present study was to determine which fruit ripening stage results in A. edulis seeds with higher tolerance to desiccation, and to investigate the effectiveness of polyethylene glycol (PEG) induced osmotic stress in combination with abscisic acid (ABA) in increasing seed desiccation tolerance during storage. Seeds were dried in activated silica gel (fast) or under ambient conditions (slow). Seeds originating from mid-ripe or fully ripe fruits exhibited better physiological performance than those obtained from green fruits. Slow drying resulted in seeds with high physiological potential. Seeds may be stored for up to 180 days without losing viability when treated with -0.73 MPa PEG without ABA.

Multi-Residue Levels of Persistent Organochlorine Pesticides in Edible Vegetables: A Human Health Risk Assessment

Background: This study evaluates the quantitative assessment of persistent organochorine pesticide (OCPs) residues in vegetables (Senecio biafrae) from four selected cocoa plantations in Ekiti State, Nigeria. Methods: The pesticides were extracted from the vegetable samples by using USEPA 3500C method and later clean-up on activated silica gel. The pesticides residues in the samples were determined using Gas Chromatography coupled with Electron Capture Detector (GC-ECD). Results: The results showed that the analyzed samples were contaminated with ten OCPs. The mean OCPs concentration ranged from ND—0.399 mg/kg to ND—0.379 mg/kg during the wet and dry seasons respectively. α-BHC, β-BHC, p, p’-DDE, dieldrin, endrin, endosulfan sulphate and methoxychlor were not detected in the samples. Pesticides such as aldrin, endosulfan II, endrin aldehyde and heptachlor slightly exceeded their maximum residue limit. Conclusion: The hazard indices (HI) of heptachlor, endosulfan I, endosulfan II, aldrin, heptachlor-epoxide and p, p’-DDT exceeded 1 and thus pose likely potential non-carcinogenic health risk.